biological · growth, and promote osteoblast adhesion and proliferation. nanoporous structures have...

MATERIALS SCIENCE amp BIOMEDICAL ENGINEERING

BIOLOGICAL and BIOMEDICAL COATINGS HANDBOOK Processing and Characterization

Written in a versatile contemporary style that will benefit both novice

and expert alike Biological and Biomedical Coatings Handbook

Two-Volume Set covers the sta te of the art in the development and

implementation of advanced thin films and coatings in the biologica l field

Consisting of two volumes-Processing and Characterization and

Applications-this handbook details the latest understanding of

advances in the design and performance of biological and biomedical

coatings covering a vasl array of material types including biD-ceramics

polymers glass chitosan and nanomaterials Contributors delve Into

a wide range of novel techniques used In the manufacture and testing

of clinical applications for coatings in the medical field particularly In the emerging area of regenerative medicine

An exploration of the fundamental elements of biological and biomedical

coatings the first volume Processing and Characterization addresses

bull Synthesis fabrication and characteriza tion of nanocoanngs

bull The sol-gel method and electrophoretic deposition

bull Thermal and plasma spraying

bull Hydroxyapatite and organically modified coatings

bull Bioceramics and bioactive glass-based coatings

bull Hydrothermal crystallization and self-healing effects

bull Physical and chemical vapor deposition

bull Layered assembled pOlyelectrolyte films

With chapters authored by world experts at the forefront of research

in their respective areas this timely set provides searing insights and

practical information to explore a subject that is fundamental to the

success of biotechnological pursuits

K122 69

6000 Broken Sound Pa rkwa y NW ISBN 976-1-4396-4995-6 Suite 300 Boca Raton FL 33467 270 Madison Avenue ~~Y~~F~C~~~P New York NY 10016 eJ an informa business 2 Park Square Millon Park Ilil~lrl~~ IIwwwcrcpresscom Abingdon Oxon OX14 4RN UK 9

Contents

Serjes Preface _ _ vii Preface i x Editor xi Contributors xii i

1 Bone-Like Mineral and Organically Modified Bone-Like Mineral Coatings 1 fanani Ramaswamy Harsha Ramamjll and Dwid H Kahn

2 Synthesis and Characterization of Hydroxyapatite Nanocoatings by Sol-Gel Method for Clinical Applications 37 B Bcn-Nissan Ali Clwi DW Green BA Latella f Chou alld A Bendavid

3 Hydroxyapatite and Other Biomedical Coatings by Electrophoretic Deposition 81 Charles C Sorrell Hariali Tilib Timothy C Pallller rei Peng Zelglllin Xia mId Mei Wi

4 Thermal Sprayed Bioceramic Coatings Nanostructured Hydroxyapatite (HA) and HA-Based Composites 137 Hua Li

5 Nanostructured Titania Coatings for Biological Applications Fabrication and Characterization 203 Yunclmng Xin alld Paulllt Chit

6 Hydrothermal Crystallization with Microstructural Self-Healing Effect on Mechanical and Failure Behaviors of Plasma-Sprayed Hydroxyapatite Coatings 237 Clumg- Wei Yang and Truan-Sheng Lui

7 Bioceramic Coating on Titanium by Physical and Chemical Vapor Deposition 299 fakashi Goto Takayuki Narushillw and Kyoslike tIeda

8 Coating of Material Surfaces with Layer-by-Layer Assembled Polyelectrolyte Films 333 Thomas Crortzier Thomas Boudotl K~feng RtI1J nnd Callicrine Picarl

9 Bioactive Glass-Based Coatings and Modified Surfaces Strategies for the Manufacture Testing and Clinical Applications for Regenerative Medidne 377 Joson vfarooth~adell

Index 431

v

Contributors

B Ben-Nissan Faculty of Science University of Technology Sydney NSW Australia

A Bendavid Commonwealth Scientific and Industrial

Research Organisation Materials Science and Engineering

Lindiield NSW Australia

Thomas Boudou Grenoble-INP LMGP-MINATEC CNRS UMR 5628 Grenoble France

AH Choi Faculty of Science University of Technology Sydney NSW Australia

J Chou Faculty of Science University of Technology Sydney NSW Australia

Paul K Chu Department of Physics and Materials

Science City University of Hong Kong Hong Kong China

Thomas Crouzier CNRS UMR 5235 Universite de Montpellier 2 Montpellier France

Takashi Goto Institute for Materials Research Tohoku University Send ai Japan

D W Green Queensland Eye Institute South Brisbane QLD Australia and Australian Institute of Bioengineering

and Nanotechnology and School of Life Sciences

The University of Queensland Brisbane QLD Australia

David H Kohn Department of Biomedical Engineering

and Department of Biologic and Materials Sciences

University of Michigan Ann Arbor Michigan

B A Latella Commonwealth Scientific and Industrial

Research Organisation Process Science and Engineering

Waterford WA Australia

Bua Li Biology Department Brookhaven National Laboratory Upton New York

Truan-Sheng Lui Department of Materials Science and

Engineering National Cheng Kung University Tainan Taiwan

Jason Maroolhynaden Leilak Biosystems European Space Agency BIC Noordwijk The Netherlands

Takayuki Narushima Department of Materials Processing Tohoku University Senda i Japan

xiii

xiv

Timothy C Palmer School of Materials Science and

Engineering University of New South Wales Sydney NSW Australia

Fei Peng Materials Science and Engineering

Program Department of Chemical Materials and

Biomolecular Engineering University of Connecticut Storrs Connecticut

Calherine Picarl Grenoble-INP LMGP-tvlfNATEC CNRS UMR 5628 Grenoble France

Harsha Ramaraju Department of Biomedical Engineering University of Michigan Ann Arbor Michigan

Janani Ramaswamy Department of Biomedical Engineering University of Michigan Ann Arbor Michigan

KefengRen Grenoble-INP LMGP-MINATEC CNRS UMR 5628 Grenoble France

Charles C Sorrell School of Materials Science and


Contributors

Hariali Taib School of Materials Science and


Kyosuke Veda Department of Materials Processing Tohoku University Sendai Japan

Mei Wei Materials Science and Engineering



Zengmin Xia M1terials Science and Engineering



Yunchang Xin Department of Physics and Materials

Science City University of Hong Kong Hong Kong China and School of Materials Science and

Engineering Chongqing University Chongqing China

Chung-Wei Yang Department of Materials Science and

Engineering National Formosa University Yunlin Taiwan

5 Nanostructured Titania Coatings

for Biological Applications I Fabrication and Characterization

Yunchang Xin and Paul K Chu

CONTENTS

Introduction 203

BioactivityBone Conductivity 215

Fabrication of Nanoporous Titania Coatings 220

Nanonetworked Titania Coatings 222 Fabrication of Compact Nanocrystalline Titania Coatings 224

Titania 204 Fabrication and Characterization of Kanostructured Titania Coatings 205

Fabrication of Titania Kanotube Arrays 205 Equipment for Anodization 205 Background of Titania Nanotubes 205 Mechanism of Nanotube Array Formation 207 Geometry Control of Titania Nanotube Arrays 210 Structure Characterization of Titania Nanotube Arrays 210

Biological Performance and Applications 214 Cell Response to Titania Kanotubes 214

Drug Delivery 216

Fabrication of Interconnected Porous Coating 220

Plasma Spraying 224 Sol-Gel Processing 226 Physical Vapor Deposi tion 228 Chemical Vapor Deposition 229

Conclusion 231 References 232

Introduction

Since the interactions between artificial biomaterial and biological tissues occur mainly at their interface the surface properties of biomaterials such as topography roughness chemshyistry and physical characteristics exert a large influence on their biologic11 response On the other hand nanomaterial can mimic the surface properties (including topography energy

203

204 Biological and Biomedical Coatings Handbook Processing and Characterization

etc) of natural tissues and may provide the preferred environment for tissue growth (Zhang and Webster 2007) There is increasing evidence that nanoscaled topography can enhance the activity of alkaline phosphate (ALP) accelerate hydroxyapatite (HA) nucleation and growth and promote osteoblast adhesion and proliferation Nanoporous structures have been observed to not only accelerate HA growth and improve adhesion and proliferation of osteoblasts but also enhance biological fixation of the implants to the natural tissues (Sun et at 2007 Popat et at 2007a Yao et at 2006 2008 Karlsson et al 2003 Khang et at 20080 Khang et a 2008b Ruckh et aL 2009) These results suggest that if the surface architecture can be further refined optimization of the various cellmatrixsubstrate interactions and gene expression on the nanoscale can be accomplished (Nanci et a 2006)

Biocompatible titania possesses excellent tribological performance and good corrosion resistance The abundant Ti-OH groups on the surface can immobilize various functional substances Owing to the nanosize effect a nanostructured titania coating is a desirable candidate on biological devices In this chapter the strategies pertaining to the fabrication of various TiO nanostructured coatings including nanotube arrays nanoporous strucshytures and nanocrystalline films are reviewed Structure characterization of the derived nanopatterns is described and the biological performance and applications of these nanoshysized titania coatings are succinctly discussed FinallYf the future trend of titania coating is discussed

Titania

Titania is an n-type semiconductor and the conductivity decreases with O2 partial presshysure at temperature above 6000e The ilctivalion energy for electronic conductivity is found to be 175 eV and the band gap energy is reported to be 305 eV Rutile anatase and brookite constitute the three main phases of TiO There are three main crystal faces in the rutile structure in which two of them (110) and (100) possess quite low energy The most thermally stable one is (110) in which an degatom is connected to two Ti atoms The Ti atoms are 6-coordinated (DOl) is less thermallv stable and restructures above 475degC There are 5-coordinate Ti atoms parallel to the rws of bridging deg (Ramamoorthy et a 1994) The two low-energy faces in the anatase structure are (101) and (001) The (101) face is the multt prevalent one in anatase nanoscrystals and is corrugated with 5-coordinate Ti atoms (BurnSide et a1 1998) In the brookite phase the order of stability of the crystal faces is (010) lt (110) lt (100) (Beltran et a1 2006 fujishima et a1 2008) The stability of the various nanoscaled titania phases is believed to be size-dependent Rutile is the most stable phase when the particle size is above 35 nm Below 11 nm anatase is more stable Brookite is found to be the most stable for partidesize ranging from 11 to 35 nm (Zhang and Banfield 2000 Shklover et a 1997 fUjishima et aL 2008)

Good biocompatibility of titania has been demonstrated in many in vivo and in vitro experiments (Erli et a 2006 U et al 2004 Khang et aL 2008b) Titania coatings also posshysess ultrahigh hardness excellent tribology behavior as well as good corrosion resistance (Uu and Ding 2002 Zhao et at 2007) TiO is well known for its photocatalytical propershyties The photogenerated charge carriers from reactive oxygen species include 0 and OH radicals Matasunaga et aL demonstrate that UV-irradiated platinized TiO powders can kill bacteria in an aqueous environment (Matsunaga et at 1985) Titania is now becoming a desirable candidate as functional coatings and materials on biomedical devices

205 Nanostructured Titania Coatings for Biological Applications

Fabrication and Characterization of Nanostructured Titania Coatings

Fabrication of Titania Nanotube Arrays

A highly ordered and vertically oriented titania nanotubes array has been fabricated by simple anodization of pure titanium and its alloys in various solutions This nanoscaled topography constitutes a materials architecture that offers a large surface area without concomitant reduction in the geometric and structural order (Doohun et al 2008 Grimes and Mor 2009) The anodization process is economical easy to operate and capable of proshycessing targets with complex shapes The geometry of the titania nanotube such as tube length tube diameter tube spacing wall thickness and bonding strength can be precisely designed and controlled by modifying the processing parameters This nanoscaled archishytecture has aroused increasing attention in applications such as filtration drug delivery and so forth

Equipment for Anodization

Anodization is an electrolytic process that generates a protective or decorative oxide film on a metallic surface Electrochemical anodization of titanium is usually carried out in an aqueous electrolyte using a cell with the titanium sheet as the anode and a Pt or graphite sheet as the cathode Figure 51 illustrates a typical electrochemical anodization apparashytus The applied voltage forces the electron to the pOSitive anode and surface metal atoms are exposed to oxygen ions within the electrolyte These metal atoms and oxygen react and become an intrinsic part of the oxide layer Initially the increased voltage generates no additional current flow until a threshold is reached where the electric field intensity in the barrier is sufficient to force oxygen ions to diffuse across it and generate an ionic current The oxygen ions react with the metal and thicken the oxide layer This process goes on until the maximum applied voltage is reached above which no desired reactions become obvious Two processing modes namely constant current mode and constant voltshyage mode are commonly used (Grimes and Mor 2009)

Background of Titania Nanotubes

From an historical perspective fabrication of titania nanotubes has gone through four generations In 2001 Gong et a1 fabricated the first generation of titania nanotube arrays up to 500 nm in length by electrochemical oxidation of pure titanium in an aqueous HF

Powr supply

Ii sheet (anode)

Pt sheet cathode

flGURES1 Scheme of typical electrochemical anodization (ell fl)r fltlbricntion of titaniil nanotube arrays

206 Biological and Biomedical Coatings Handbook Processing and Characterizatio

J

t ~

-Ii

~ ~ A r bull tr I bull r I ri bull ~ tt

bull b - ~ C v ( 1~ ~1

~ Jlaquoj~f~--ajt JIl ( -11

r ~ 1 J

FIGURE 52 SEM micrograph of first-generation l1lnotuJeuros on surface and crosssectton (From Conget at r Maier Res lb 3331-3142001 With permission)

electrolyte The typical surface and crosssectional morphologies are depicted in Figure 52 (Gong et aL 2001) Recently Allam and Grimes (2008a) reported successful fabrication of titania nanotubes 25 Im long by using an Fe cathode The secondgeneration fabrication feature increased nanotube lengths to several micrometers and growth rates of around 025 f1mh This is accomplished by adjusting the pH of both the aqueous KF and NaF elecshytrolytes to reduce the chemical dissolution rate of oxide (Michailowski et aL 2001) The repshyresentative morphology of these second-generation titania nanotube arrays is displayed in Figure 53 The thirdgeneration synthesiS employs organic electrolytes such as ethylene

FIGURE 53 Ld(eral and cross-sectional views of second~gtnerution htania flitnotubes hom Ci et al Maler Re 10z

230--2362005 With permission)


FIGURE 54 (ross--sectional views of a 720~llm-thick membrlne ~ynthti7ed using a fixed 60 V pohmtbl for jouble-sidtd anooiLatiofl ofTi plate (From PrakaS1nl et al f Phys ChIII C 111 7235--7241 2007 With permission)

glycol (EG) di-ethylene glycol formamide (fA) N-methyformamide (NMf) and diethyl sulfoxide (DMSO) in combination with HF Kf NaF NHF or BnMeNF to provide fluoshyride ions to produce nanotube arrays with lengths up to 1000 ~m (Micha ilowski et al 2001 lung et al 2002 Kobayashi et al 2002 Cai et aL 2(05) A typical morphology of this type of titania nanotube arrays is presented in Figure 54 The fourth-generation fabrication technique utilizpounds nonfluoride-based anodization electrolytes (Grimes and Mor 2009) and a representative example is shown in Figure 55 Some important electrolytes used in the fabrication of the four generations of nanotube arrays are summarized in Table 51

Mechanism of Nanotube Aay Formation

The key processes in the growth of nanotube arrays are

1 Growth of oxide at the metal surface due to reactions between the metal and 0 or OH ions

2 Migration of the metal ions through the metal to the metaloxide interface

3 Field-assisted dissolution of oxide at the OXideelectrolyte interface

4 Chemical dissolution of the metaloxide in the acidic electrolyte

RGURE 55 Representation lf SEM morpholugy of fourth generaHomi of nanotube arrays fabricated in Hel electrolytes (From Allam etlL t Mata 01(111 IS 2341-2148 2008b With permission)

208 Biological and Biomedical Coalings Handbook Processing and CharaeierizatiOl

TABLE 51

Typical Electrolytes Four-Generation Synthesis of Titania Nanotubes

Electrolyte Systems

The firampt generation HF HN01

aqueou-lt clectrolyttgt HF + H25ltJI

HF + HCrO

NH~F + CHl COOHH1SO j

HF + HPO~

The second generation Citrk add + NaF + JltlSO (buffered electrolyte Citric acid+ KF NaSO The third generation Formamide + dimthy (polar organic elt1twlyte) Dimethly sulfoxide

Ethytent glycol

Glycerol + NH4F

Methanol +gt HO +HF The fourth generation flCl (nonf1uoridemiddotbused electrolyte) HoG

HCl+ H~O--~ -- -___ _ ~- -- -__ ----shySource GrimesCA MorCK TiONmwtltill Arrays Synthesis Proptrficsfll1d ApplicatioNs

Springer Science New Yvrk N( 2009 AHilm et at f Maler CfI1III 182341-2143 200Bb PrakaSlt)fnet a1 Pfrys 011111 C HI 7235-7241 2007ChristophelSen et al Phy Stattls Solid A 19734-382003 Uu et ai J Pltys Cflem C 112 253259 200amp Paulose et ll f Pitys Cf1l11I 6 110 16179 16184 2006 Shankar et alI PhYl ClIiIIL C 111 21-middot26 2007 Yoriya ef 11- PhYfi_ C11i1II C 111 13770-13776 2Q07 Yoriyaet L f Mater Chem 18 3332-333t 2008 Rlchter et aL J Mater Res 22 1624-1i13L 2007a Richter d l Adv Mater 19946-948 2007b Chen et aL Thin Solid Ftrws 51 8511-8514 2007 Allam KK Grimes cA I PI5I~ Chtllt C 111 l3028-13lTI2 2007 With permiampltgtion

As anodization commences Ti ions react with oxygen ions in the electrolyte and the oxide layer uniformly spreads across the surface The reaction is shown below (Jaroenworaluck et al 2007)

Ti + HO - TiO + 2H (51)

Fluoride ions can attack the oxide and hydrated layer or the ions are moved across the anodic layer LInder the applied electric held and interact with Tih as shown below (LohrengeI1993)

TiO + 6F- + H - TiF- + 2Ho (52)

Ti(OI-l) + 6 F- - TiF + 4OH- (53)

Ti + 6Fmiddot - TiFmiddot (54)

Field-aSSIsted dissolution dominates chemical dissolution due to the relatively large elecshytric field across the thin oxide layer (Hwang and I-Iwang 1993) Small pits form from localshyized dissolution of the oxide and serve as the pore formation centers The pores grow due to the inward movement of the barrier layer (Pakes et al 2003) Ti- ions move from the

209 Nanoslructured Titania Coatings for Biological Applications

metal to the oxideelectrolyte interface and dissolve in the electrolyte The growth rate of oxide at the metal and nxide interface and the dissolution rate of oxide at the pore-bottom electrolyte interface are ultimately equal Therefore the thickness of the barrier remains unchanged although it migrates further into the metal leading to increasing tube length The SEM results demonstrate that formation of small pits at the interpore region eventushyany leads to pore separation and tube formation The thickness of the nanotubes ceases to increase when chemical dissolution of the oxide at the mouth of the tube equals to the rate of inward movement of the metaloxide interface This process is schematically illustrated in Figure 56 (Grimes and Mor 2(09)

Chemical dissolution plays a key role in the formation of self-organized nanotube arrays I reduces the thickness of the oxide layer (barrier layer) and keeps the electrochemical etching active No nanotubes can be fabricated when chemical dissolution is too high or too low The electrochemical dissolution rates depend on the applied potential as well as electrolyte concentrations When electrochemical etching proceeds faster than chemical dissolution the thickness of the barrier layer increases leading to reduced electrochemical etching to the rate determined by the chemical dissolution In the F containing system the chemical dissolution rate is controlled by the F concentration and pH of the electrolyte Chemical dissolution increases with increased F and H+ concentration The anodization potential at which nanotubes form is related to the F concentration with higher potentials required for an electrolyte with higher F concentration (Grimes and Mar 2(09)

(a) OxiQt

Barriet layer -leta

(el

Metal Tube

(e) Pores Void

I Barrier layer

Batrk-r layer

RGURE 56 Schematic j 1ustration of nanotube formation process (a) OxjJe lltlyer formMlon (b pit formation on tixidf 13ytgtf () growth of pit lot) lK1110p shaped pores (d) metl11ic regIon between pores undergoes oxidation and field assisted dissolution and (e) fully developed nmotubes with it corresponding top view (From Grimes CA Mor CK TiO Nouvlube Arravs SYI1t115is Protertiegt (lid AFpiinrtimro Springer Science New York NY 2009 With permission)


In an organic electrolyte system water usually serves as the source of O The exac mechanism is not yet well understood (Vlelody et al 1998) There is evidence of OH- injee tion from the electrolyte into the oxide layer during anodization If more water is presenl hydroxyl groups are injected into the oxide layer and influence the structure sufficientlJ to impede ion transport through the barrier layer When less water is used it is difficult te extract oxygen or hydroxyl ions from the solution and the growth rate of the overall oxid film is reduced The barrier layer possesses increased ionic conductivity caused by nonmiddot stoichiometry due to the insufficient supply of OR (Grimes and Mor 2(09)

Geometry Control of Titania Nanotube Arrays

The geometrical features of the nanolube arrays can be controlled by parameters including applied potential electrolyte composition conductivity and viscosity as well as treatment duration and temperature Furthermore chemical dissolution and elelttrochemical etchshying are critical factors in the growth of nanotube arrays and the electrolyte temperature influences the rate of both etching processes In an HF-base electrolyte a low temperature tends to increase the wall thickness and reduce the tube length (Mor et a 2005) It has been shown that the cathode materials playa significant role in the appearance of surface precipitates An overpotential is referred to the excess potential required for discharge of an ion at the electrode above the equilibrium potential of the electrode The overpotential at the cathode is a critical factor affecting the dissolution kinetics of the Ti anode and in turn the activity of the electrolyte and morphology of the architecture Up to now foils of Pt Pd Ni Fe Co Cu Ta W So and Al as well as graphite sheets have been used and the details have been described (Grimes aod Mar 2009) In buffered electrolyte systems the pH of the electrolyte also influences electrochemical etching and chemical dissolution due to hydrolysis of titanium ions An enhanced pH leads to increased hydrolysis subseshyquently reducing the rate of chemical dissolution The best pH values to produce longer tubes are between 3 and 5 Shorter but clean nanotubes are generated at lower pH values and higher pH values produce longer tubes with unwanted precipitates Alkaline solushytions do not favor the formation of self-organizltd nanotubes In highly acidic electrolytes for example pH lt 1 a longer treatment time does not increase the tube length At a specific applied voltage the pore size is independent of the pH whereas at a specific pH the pore size increases with the applied potential In polar organic electrolytes the key to successshyful growth of long nanotubes is to keep the water content below 5 Compared to water the reduced availability of oxygen reduces the formation of oxide in the organic electroshylyte At the same time the reduced water content retards chemical dissolution of the oxide in a Iluoride-containing solution thereby benefiting formation of long tubes The applied voltage range in organic electrolyte typically 10 to 60 V is broader compared to that in tgtaF or KF which is typically 10 to 30 V (Grimes and Mor 2009)

Virtually identical tubes can be acquired in dissimilar electrolytes by controlling the difshyferent anodization processes Pore sizes of 12 to 350 nm outer diameters of 48 to 256 nm wall thickness of5 nm with discernable wall to 34 nm and tube-to-tube spacing from adjashycent to micrometers can be controlled by careful selection of the processing parameters (Grimes and Mor 2009)

Structure Characterization of Titania Nanotube Arrays

The typical morphology of titania nanotube a rrays is shown in Figure 57 Vertically orishyented nanotube arrays attach to the substrate with an open top and the bottom is closed

211 Nanostrllctured Titania Coatings for Biological Applications

FIGURE 57 Morphologits l)f TiO nanotube arrays acquired by iln()tlizatiuH or Ti Upper image are archit(Cture from modmiddot iZiiHon in ethylene glycol dectrnlyte lower image Igt architecture from Ti mndiz tion in m tlqueolls KF bilth (From Grimes CA Mor CK TiO NnrwlIbc Armys SylllJft~is Properties alld ApplicatioJ Springer ampiencl Nt Ynrk NY 2Ll09 With permissjon)

by a barrier layer of metal oxide Both wen-separated stand-alone nanotubes and densely packed arrays Can be acquired by using different electrolytes

Generally the as-prepared titana nanotubes are amorphous as suggested by both x-ray diffraction (XRD) and selection area diffraction (SAD) patterns As shown in Figure 58 only peaks from crystalline titanium are present in the spectrum acquired after anodizashytion in the NaF +NaSO electrolyte Nguyen has systematically studied the detailed strucshytureof titania nanotubes using TEM and high-resolution TEM (HR-TEM) The nanotube is fabricated in an ethylene glycol solution containing 05 wt NHF at a constant potential of 20 V ror 1 h (Nguyen et al 20(9) As shown in cross-sectional TEM pictures in Figure 59 the tubes are always oriented perpendicular to the metal surface Adjacent tubes are connected by ridges that run perpendicular to the tube length In addition a barrier layer

eTi

20 30 4(] 5V 6n 7() 8)

28 (deg)

FIGURE 58 XRD pattern of titania nanotube arrays iHXtlired by anodinitiQn in electrolyt( Cnntalning tU miL NaP and 1 ML Na2S01 at 20 V fOf 2 h

212 Biological and Biomedical Coatings Handbook Processing and Characteriatw

FIGURE 59 TEM views at various siteuro5 of the nallotube (a) and (b) an cross-ection views (c) HRTEM image of Ti 5ub~

frate barrier layer and nanotube oxide (From fguyen et aL Elrcfrochil11 Ada 54 4340-4344 2009 With perm i5sion)

approximately 5 to 10 nm thick can be observed between the tube and metal (Figure 59b) This barrier layer is sculpted not only along the lube barrier interface but also along the barriermetal substrate interface The high-resolution TEM images disclose the amorshyphous structure of the nanotube wall and that the barrier layer is actually semicrystalline in nature Most of the oxides are indeed amorphous but there are small crystalline regions embedded in the amorphous matrix

The elemental distribution and chemical states along the nanotube length of titania nanoshytube are studied by x-ray photoelectron spectroscopy (XlS) and the results are presented in Figure 510 This nanotube is prepared by anodization in an electrolyte containing 1 molL NaSOO1 molL IaF 02 molL dtrk acid at a voltage 20 V for 20 b The surface contains a high content of 0 The Ti and 0 Signals are stable during the initial ltgt min of sputtering Progressively increasLlti Ti concentrations and quick drop in the 0 content are observed after about 58 min corresponding to the thickness of the barrier layer formed by anodshyization The Ti 2p signal in the surface region only consists of one chemical state Ti TiO After sputtering for about ltgt min peaks corresponding to Tj2 TiO and Ti TiGJ also appear When the sputtering time reaches about 70 min a high Ti content is observed

213 Nanoslruclured Titania Coatings for Biological Applications

1OIJ

SO

60

40

20

0

T101-NT -b-Ti2p

-O-Os

0 20 4() 60 ampl H]O

Sputter time (min)

1 6mtn

t =2 min

Omi

470

fiGURE 510 XPSdepth profile 01 Ti and 0 and fine scanning spectra of Ti 2p in titloi nanotubt acquired by anodiZiltion in electrolyte contdining OJ mIL laF 02 maUL citrit add ltlI1d 1 MIL Na2SO~ at 20 V for 2 h (sputtering rate is about 20 ommin referenpoundd to that SiO~)

together with a small amount of Ti TiO as shown in the spectrum The XPS results sugshygest that insufficient oxidization takes place during anodization of pure titanium and the anodized nanotubes consist of not only litania but also other forms of titanium oxides such as TiP and TiO

Crystalline titania nanotubes can be obtained by annealing in oxygen or air As shown in Figure 511 peaks from the anatase phase begin to appear at about 280degC At temperatures

Binding energy (eV)


Ridmiddot ~ ~ 8 n 5 ~ 8flOC g 2a ii 6- ~ R amp L 11 R

R 6SO-C c

R R R R R R RR R

620CR R tl12

~A 1(1( ~T T~~f ~ dl Rl2 580~C 2 A-e RiRlR R Ii R RR RT L i

~ TI _T T 480C

~ c j

=

AliA T A ~ R

T T

J AI ~~ Air T

TI

A

lT

T 1 T

430C I I TT i

i T

TI JT

A T_1 T

280C

T T ~ I

T T 230C

T 1 T T

j ~T 20 30 4() 50 6) 70 80

20 (deg)

FIGURE 511 XRD piltt~rns of the mmotubc Joooaled at tcmplrature ranging from 230~C to 880( in oxyge-n ambient for 3 h A Iflatagtc R rutiie T titanium (From Varghese t ctL f Mater rltllt 18 156-165 2003 With permission)

near 430degC peaks from the rutile phase emerge from the XRD spectrum Above this temshyperature the rutile (110) peak becomes more intense while the anatase (101) peak is weaker Complete transformation to rutile takes place in the temperature range from 620C to 680c C (Varghese et a1 2003) Annealing at a high temperature damages the nanotubes Yang and coworkers had conducted crystallization of 42middot~m long nanotubes with a pore size of about 80 nm at 300C to 8000C The length and average diameter of the nanotube are not changed substantially after calcinations at up to 500 C However the nanotube length decreases to 3 ~m after treatment at 5S0degC After calcination at higher temperature of 600degC and 700GC the length diminishes to 28 and 15 ~m respectively At 700C small protrusions occur through the nanotubes leading to cracking The nanotube structure completely collapses when calcinated at 800nC (Yang et a1 2008a)

Biological Performance and Applications

Cell Response to Titania Nanotubes

The geometry of titania nanotubes that can be tailored influences the cell response Popat and coworkers have carried out systematical investigation on the cell response for engishyneered titana nanotube arrays A nanotube array about 80 nm in diameter and 500 nm in length is used Progressively enhanced cell proliferation and ALP activity are observed compared to pure titanium No adverse immune response occurs under in vivo conditions


(popat et al 2007a) However the difference between this nanoscaled topography and dense titania films is not given Park et al have systematically investigated the influence of the pore size of the nanotube on the cell response Titania nanotube arrays with diameters ranging from 15 to 100 nm are prepared by controlling the applied potential The morpholshyogy of the as-prepared titania nanotube arrays is exhibited in Figure 512 Cell adhesion and spreading are highest on the IS-nm tubes and decline significantly for larger pore size Cell growth experiments conducted on the 30-nm and smaller diameter nanotubes show extensive formation of paxillin-positive focal contact to which actin stress fibers are anchored and the cells have a highly migratory morphology with long protrusions (Park et at 2009 Park et 01 2007) An enhanced cell migration behavior has been reported on titania nanotubearrays by Brammer et aL (2008) Cell differentiation of mesenchymal stem cells into osteogenic lineages has been observed and osteocaldn immunofluorescence is the highest on the IS-om tubes but severely impaired on the loo-nm nanotubes The most remarkable discovery is the strong induction of apoptosis on the 10ll-nm tubes (Park et a1 2007) As the predicted surface occupancy size by the head of an iotegrin heterodimer consisting of a ~-propellerof the R-chain and the domain of ~-chain is about 10 nm (Takagi etal 2002) it is believed that 15 to 20 nm spacing allows or force clustering of integrins into the nearly closest spacing possible resulting in optimal integrin activation

BioactivilyBone Conductivity

Bioactivity or named bone conductivity is referred to as the capability that the materials can induce growth of bone like HA from body fluids This performance can be evaluated both in vivo and in vitro Tsuchiya has reported HA growth behavior on anodic titania nanotubes Their study demonstrates that apatite formation on titania nanotubes depends on the nanotube length and crystallographic phase of titania The SOO-nm-Iong nanotube hardly induces precipitation of apatite while a thick HA layer forms on the 25-~m-long nanotube after soaking in SBF for 2 weeks It has been reported that a crystalline structure greatly affects the bioactivity of titania nanotubes Anatase or anatase and rutile strucshytures can induce more effective apatite growth on the nanotubes It is interesting that the

FIGURE 5l2 SEM views of a highly ordered titanitub with V1rious pore sizes betwten 15 and 100 nm flbricated by tailoring applied potentials ranging from 1 to 20 V (From Park et aL NrllO LIlI 7 1686-lffll 2007 With permission)

216 Biological and Biomelical Coatings Handbook Processing and Characterizatio

SOO-nm-Iong crystalline nanotubes can also induce growth of HA rapidly Both the Ti-OH and crystallography influence the bioactivity of titania nanotubes (Tsuchiya et aL 2006)

Kunze et at have uncovered more details about the precipitation process of HA on titashynia nanotube arrays During the early stages of apatite nucleation more Ca and Pare found on the nanotubes than on flat TiO Initial nucleation proceeds better on unannealed substrates than that on the annealed one on account of a higher degree of hydration The crystallography does not appear to playa major role in the initial stage of apatite formashytion and it is believed that there are similar nucleation mechanisms for crystalline and on amorphous nanotubes At the later stage of precipitation the crystallography of the substrate plays an important role in homogeneous apatite formation as stable growth can only proceed on a crystalline substrate surface It has also been found that titania nan()shytubes promote formation of very thick apatite films whereas thin but incompletely dosed precipitated layers form on the compact Ti02 surface (Julia et aL 2008)

It has been found that titania nanotubes enhance apatite deposition from simulated body fluids (SBFs) compared to compact Ti02 layer A possible reason is the higher nucleshyation rates on titania nanotubes than on a flat surface This mainly results from the higher specific surface area that provides a larger amount of OH on the surface The surface area in a titania nanotub 166 ~m long 100 nm in diameter and 20 nm thick (wall thickness) is about 45 times larger than that of a flat surface The TiOsolution interface has positively polarized titanium and negatively polarized oxygen sites In body fluids OH~ can adsorb onto the TiO surface and Ti-OH forms at the solid-liqu id interface The Ti-OH groups are acidic or basic depending on the pH of the surrounding solution The isoelectric point at which the surface shows zero charge corresponds to a pH of about 54 for titanium oxide In a physiological pH of about 74 the surface is slightly negatively charged due to the presshyence of deprotonated acidic hydroxides This negatively charged surface attract cations such as Ca2bull followed by the arrival of HPOzmiddot or HPO - resulting in nucleation of HA The HA will grow by consuming Ca and P from the SBFs In addition faster and better nucleation on the nanotubes may stem from the fact that the ions from the SBFs have betshyter access to the nanotubular surface because they can diffuse into the channels and form nuclei uniformly over the walls

Drug Delivery

Generally orally supplemented or injection of drugs cannot effectively reach the implantshytissue interface particularly necrotic or vascular tissues left after surgery This limitation cannot be overcome by increasing the doses because of organ toxicity associated with high quantities of certain drugs On the other hand oral administration leads to increased drug concentration in the blood plasma immediately after intake but it subsequently decreases resembling a sinusoidal behavior as a function of time (Popat et at 2007b) A desirable method is to effectively load the drug on the surface of implants to achieve sustained and controlled release of the drug so that the released drug can be effectively absorbed by the tissues in the vicinity directly

The high specific area and hollow tubular structure of nanotubes are desirable attributes in the drug loading and delivery platform In particular the TiO surface has abundant hydroxyl groups that can enable immobilization of many functional substances Stable fixation depends largely on the interfacial integrity between the bone tissue and implant A promising strategy to elicit specific cellular response is to provide cell-specific signals to control and improve the osseointegration of implants RGD peptides growth factor including transforming growth factor-jl (TGF-jl) bone morphogenetic proteins (BMPs)

217 Nanostruclured Titania Coatings for Biological Applications

insulin-like growth factors (IGFs) fibroblast growth factors (FGFs) bone morphogenetic protein-2 (BMP-2) bovine serum albumin (BSA) and lysozyme (LYS) have been investishygated as model proteins for the loading and release efficiency from nanotube platforms BSA is a large molecule with a net negative charge at neutral pH as opposed to LYS which is smaller in size with a net positive charge at neutral pH Nanotube can be filled with BSA and LYS by the simplified lyophilization method The release characteristics of BSA and LYS are studied in PBS (pH = 7) and acetate buffer (pH 45) When loaded with 200 to 800 pg of BSA and LYS approximately 60 to 80 of the protein is retained in the nanoshytubes after washing regardless of the initial loading As expected slower and sustained release from nanotub-s takes place The release curves also suggest that leaching rate of the positively charged LYS is much slower than that of negatively charged BSA This is believed to stem from the difference between the negatively and positively charged proshyteins interacting with the surface charges of the nanotube interface There are stronger electrostatic interactions between the positive charged LYS and negatively charged nanoshytube surface (Popat et al 2007b)

The release of functional substances using the above method can only be sustained lOr h In order to be clinically useful drug release from implants should last for days or weeks The release rate of drugs can be tailored by changing the length and diameter of the nanotubes Using titania nanotube with variable diameters from 100 to 300 nm and lengths from 1 ~m and 5 ~m paclitaxel (with hydrodynamic radius about 05 nm) eJution in PBS at 31C from nanotube arrays suggests that the maximum drug release is reached at approximately 2 weeks The release of drug as a function of time is presented in Figure 513 With the same nanotube pore size the nanotube length profoundly affects the total drug eJution The 1-pm-Iong nanotube hoJds less than half the amount of drug compared to a 5-~m-long nanotube The drug delivery dependence on the nanotube dimensions shows that the nanotopography of the tubes is directly responSible for the drug elution behavior Elution is largely insensitive to the tube diameter but rather to the total length of nanotube Elution measurements of large molecule BSA have been performed and the results indicate elution durations on the order of months Larger diameter nanotubes elute less drug than loo-nm nanotubes with the same length (Peng et al 2009)

Song et al (2009) have recently developed an actively controllable drug delivery sysshytem based on titania nanotubes The amphiphilic Ti02 nanotube serves as the controllable drug release system based on a hydrophobic cap on a hydrophilic titania nanotube This

6

d lOOnmh ~m

~ d 300 lm h -- 5 pm

d lOOnmh= IJJm

- FlatTi

o 5 JO 15 20 25

Time (days)

fiGURE 513 Paditaxc dutiolls lor n noiubfi army of variuus dimension (from l~ng d al Nallo Left 9 1J32-1936 20(1 With permbsion )

218 Biological and Biomedical Coatings Handbook Processing and Characierizaliol

hydrophobic cap prevents uncontrolled leaching of the hydrophilic drugs into the aque ous environment By exploiting the photocatalytic properties of TiO for UV induced chair scission of the attached organic monolayer the cap can be removed and highly controllee release of drugs is achieved Figure 514 schematically describes the procedures to fabricalf amphiphilic TiO nanotubes and the drug loading methods The procedures begin with an anodization step followed by hydrophobic surface modification Afterward a second tube (hydrophilic) layer is grown underneath the first one by a second anodization proshycess The first layer is grown in an electrolyte containing giycerolwaterNHF to a thickshyness of about 750 nm and a diameter of 90 nm Subsequently a hydrophobic monolayer of octadecylphosphonic acid (OPDA) is attached to the tube wall The nanotube is then anodized again in an ethylene glycolNHF electrolyte The second layer consists of I-f11l1shy

Nanotube fabricationmiddot

r 1iO)TI Anorlization

1 0

Hydrophobic ~ ~ II 11111 III I~nndlion lJlmMMr

HydrophlHc AmphiphilicTiO Alkvl modifii-d no nanotube layer nanotube layer

Drug delivery methods - HRP -OPDA

- AITES tftij HRP attalthed by APTES bull bull I

~O~) 0lt

0 ~~ am~s-

__l~f~) 11 ~hC3 bull

ltl(ntfCO gt- Jn~llW~ lim

TiO) nanotubei vijJ IIItv ~Itit~ hiJl(cP fd

t1~IV fiGURE 514 Scheme of procedure for fabricMing Jmphiphilic fiO l naflvtubc layers and fnur methods for drug loading using horseradish permdde (HRP) ~Y1 hydrophilic model drug (1) immerion without any Ti02 surface modishyfiCAtion (for reference) (ll) immersion after OPDA modificltllion in upper flltlnolube layer (hydrophobic cap) (W) wvalently attached HRP over entire nanotube layer lt1nd ([V) OPDA cap in upper nanotube layer and covalently attached HRP in lower nanolube layer (From Son) et aL f Am Citem Soc 1314230--42322009 With pcrmissiorq

219 Nanostruetured Titania Coatings for Biological Applications

long tubes with a diameter of about 90 nm The grafted OPDA monolayer after the first step of anodization generates a hydrophobic top on the tube After the second anodization step a new hydrophilic surface is created Four loading methods have been developed Unmodified nanotubes are loaded by simple immersion in the drug system to allow free and physisorbed drug molecules inside the tube In the second approach capped tubes are exposed to the drug solution with DMSO which acts as a surfactant This approach leads to free HRP molecules in the lower part of the tubes After evaporation of DMSO the drugs are trapped by the hydrophobic cap The drugs are grafted onto the hydrophilic tube walls by an APTESvitamin C monolayer linker The fourth approach combines approaches 2 and 3 resulting in loading of the drugs to the lower part of the nanotubes Different release curves in the phosphate buffering solution (PBS) are obtained Quick and uncontrolled release is observed in nanotubes loading by approach 1 Almost 90 of the drug is released during the first 1 min With regard to the OPDA-capped nanotube and surface-linked drug nanotube the release rate can be adjusted by UV irradiation Strong UV irradiation yields a faster release rate The amphiphilic nanotube layer with OPDA and covalently linked drugs allows controllable release

Mg Zn and Sf are important biological elements By a simple hydrothermal treatment titania nanotubes can be transformed into crystalline SrTiOMgTiOZnTiO nanotube arrnys More detailed information about the SrTiO nanotubes can be found in (Xin et al 2009) This SrTiO or (MgTiO and Zn TiO) can leak Sr (Mg Zn) slowly for a prolonged period by slow dissoluUon and ion exchange After the hydrothermal treatment the nanoshytube architecture is retained A representative morphology of the SrTiO nanotubes arrays prepared by the hydrothermal treatment in 002 molL Sr(OHh is shown in Figure 515 As Mg(OHl and Zn(OH) are nearly insoluble transformation from titania nanotube to MgTiO nanotubes can be realized in two steps-hydrothermal treatment in a diluted NaOH solution forming the Na TiO nanotube a trays and subsequent ion exchange reacshytion of the derived NaTiO in the MgCl or ZnCl solution It should be kept in mind that the NaOH solution should not be too concentrated as a high content of OH- destroys the tubular structure Generally the NaOH concentration does not exceed 005 molL The nanotube arrays are capable of leaching biological elements but also leave room for loading

ICURE 515 EM micrograph of SrTi01 nanotube arrays fabricated by hydrothermal treatment titmia nanotubl arrily~ in 02 moJL Sr(OH) solution


other fundiona I substances In addition the well-retained nanotube arrays also retain the scale effects on the biological response

The success of implants depends not only on the bone-implant integration process but also a sterile environment around the implant preventing bacterial infection In fact bacteshyrial infection is one of the most common problems after orthopedic surgery and can result in serious and life-threatening conditions such as osteomyelitis_ Acute infection or chroshymic osteomyelitis develops in as many as 5 to 33 of implant surgeries (Popat et aL 2007c Sujata 2005 Wong and Bronzino 2007) Hence antibiotic treatment is usually prescribed to patients to prevent any complications that may arise after implant surgery_ In situ loadshying of antibiotic substances (gentamicin Ag and Cu elements) on titanium nanotube is a desirable solution In the work of Popat et a1 (2007c) gentamicin is filled by a simplified lyophilization method The gentamicin solution is prepared in a phosphate bufferingsolushytion and introduced onto the nanotube surface to ensure even coverage Afterward the surface is dried under vacuum at room temperature for 2 h The above process is repeated several times Finally PBS is used to remove the excess drugs It has been found that the gentamicin-loaded nanotubes are effective in minimizing initial bacterial adhesion Cell cultures up to 7 days a Iso suggest higher cell adhesion and proliferation compared to titashynium surfaces Gibbins et aL have loaded silver on titania nanotubes byelectrodeposition and the antibiobacterial properties and biocompalibility are examined 99 of bacteria are killed However the TiO nanotube surfaces with and without silver show good cell-to-cell attachment high cell proliferation and enhanced bone cell-material interactions in comshyparison to the Ti control (Das et al 2008)

Surface modification with the nanotube layers may be particularly desirable as it not only enhances the mechanical properties biocompatibility and bioactivity of the medical implants by controlling the geometry but also offers the opportunity to additionally regushylate the cell response by loading biologically active signaling molecules In conclusion by tailoring the geometry and functionalization TiO nanotubes can be designed to support functions of osteoblasts including differentiation and are useful in coatings on osteointeshygratin implants

Fabrication of Nanoporous Titania Coatings

fabrication of Interconnected Porous Coating

An interconnected porous structure on the micrometer scale can contain living bone cells leading to tissue growth and enhanced bonding strength between the implants and adjashycent bone tissues A nanoscaled porous structure cannot provide room for living cells However it can allow filopodia of the growing cells to go into the nanoscaled pores producing a locked-in cell structure that in the long term can increase the stability of implants (Oh and Jin 20(6) There has been more evidence that when the surface roughness approaches the nanoscale many surprising biological benefits can be achieved (Popat et a 2007a Brammer et al 2008 Nanci et al 1998 de Oliveira et al 2004)

A porous nanotextured surface can be fabricated by controlled chemical oxidiation of Ti in an electrolyte containing a mixture of H2SO and lI0 (5050 of 37 N sulfuric acid and 30 aqueous hydrogen peroxide) The SEM pictures of the surface morphology of the untreated and oxidized specimens are shown in Figure 516 The ontreated samples show a very smooth surface at high magnification and a distjnctive nanotexture character~ ized by nanopits formed after chemical oxidization The inset in Figure 516b reveals 3-D spongelike porosity with a 22 plusmn 05 nm average diameter of the nanopits The surface of the

Nanostructured Titania Coatings jor Biological Applications 22]

FIGURE 516 SEM mkrogfltlphs of the control (il and the chernicdl oxidied pllre Ii (b) (From Nlnlti et aL Surf Sd 600 4613-462L 2006 With ptrmisslon)

oxide layer is nearly TiO as suggested by the XPS results XRD results further show that the formed layer is mainly amorphous In fact oxide layers formed by chemical oxidizashytion or electrochemical oxidization are usually amorphous (Nanci et at 2(06)

Variola et aL have produced a nonporous structure in Ti-6AI-4V alloy as shown in Figure 5Ji (Variola et aL 2008) As this alloy consists of two phases different etching behavshyior is observed The Jl phase tends to form the nanotexture morphology more quickly However after about 2 h of etching the nanoscaled morphologies in the Jl and phase grains become similar That is a uniform nanopit surface is formed As etching proceeds the diameter of pits increases slightly It has also been demonstrated that the nanoporous

FIGURE 517 MQrphology of nanoporous structure on Ti-6Al-4V alloy fabriclted by etching in HNO j tor electrolyte containshying H~SO~ dnd Hol for 30 min From Variola et at BiollflllCrlilf 24 1285-129f1 2008 With pltgtrmission)


surface selectively promotes the growth of osteoblasts while inhibiting that of fibroblasts effectively realizing regulation of the activities of cells in a biological environment

Besides chemical oxidization anodization of pure titanium can also generate a nanoshyporous titanium oxide layer Shih et al have fabricated multinanoporous titania by anodmiddot ization in an NaOH solution The surface morphology of the multinanoporous titania is shown in Figure SJB A pretreatment named cathodization is performed before anodizamiddot tion By cathodization in H 2SO titanium hydride is formed and it is claimed to benefit the formation of the porous structure (Shih et a 2(07) XPS depth profiles 01 Ti and 0 reveal that the thickness of the oxide layer with cathodization (300 nm) is much thicker than that without cathodization (200 nm) Here it is noted that the mechanically polished sample gU Hers from acid pickling (2 ammonium fluoride a solution of 2 hydrofluoric add and 10 nitric acid at room temperature for 60 s) and chemical etching (HF (2 vol) and HN01

(4 vol) at room temperature for several seconds) Generally the oxide layer fabricated by chemical oxidization and anodization does not

consist of only titania Both TiO or TiO are usually present in the layer and the formed titanium oxide is also amorphous

Nanonetworked Titania Coatings

There is an interesting type of nanoscaled porous structure of titania namely the nnoshynetwork This structure can be fabricated by galvanic-static anodization in a highly conmiddot centrated NaOH solution (Chiang et al 2009 Yang et al 2009) The typical morphology of the nanoscaled network is shown in Figure 519 A multilayered network structure with lateral pore size of about 65 plusmn 33 nm is observed The thickness 01 the grid ranges from 5 to 30 nm It is also found that a higher anodization current results in a greater lateral pore size XRD results indicate that the network is composed of mainly anatase TiO Subsequent in vitro experiments disclose good bioactivity This morphology also stimushylates huma n bone marrow mesenchymal stem cells growth as demonstrated by in vitro and in vivo experiments

This kind of network structure can also be acquired by anodization in the potentiamiddot static mode (Huang et aL 2(04) The pore size depends on the applied voltage but the wall thickness is not very sensitive to the potential At larger potentials the thickness of oxide layer is increased A similar morphology can be obtained by direct exposure of pure

c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID

FIGURE 516 Surfa(e morphology of Tl tvith 15 Acm2 lttnodizatirm and 5 Aern1 (othodk pretreatments (Prom Shih ct a1 Appl Sll~r Sci 253 3678-3682 2007 With permission)

223 Nallostructured Titania Coatings for Biological Applicatiolls

FIGURE 519 A typical SEM view of nanonetwork titan I coating on titanium fabrk~teJ by iHlodiLatiOf) in high COOCtgtntratfun

of NaOH solution (From Yang et aL I Alloy COIl1u1 479 642-647 2009 With p~rmissk)O)

Ti to a concentrated NaOH solution Pigure 520 shows the cross-sectional view of this type of porous structure The pore size increases with the NaOH concentration but it is not affected much by the treatment time (15-15 MIL) The pore size is also progressively enhanced compared to the anodization method TEM view discloses that the net has a rumotubular structure 200 to 300 nm long and about 10 nm in diameter SAD patterns

fIGURE 520 TEM views of ont type of network structure on pure Ti after exposure in concentrated KOH (or 10 h (a) Crossshysection views (b) views of single net and (c) SAD pattern of single n(1 in (b) (From Lee et a1 Cllrr At1pl PIIYS 9 e266-e269 2009 With permission)


suggest that the net is nanocrystallined K TiO (Lee et al 20(9) Usua lIy the network strucshyture obtained by chemical treatment needs a processing time of more than 10 h whereas the electrochemical treatment can be completed in no more than half an hour In addition the pore size achieved by anodization is much smaller

fabrication of Compacl Nanocryslalline Titania Coalings

Plasma Spraying

Titania coating with nanosized particles can be fabricated by plasma spraying Both cold spraying and plasma spraying can produce nanocrysta line coatings (Zhu and Ding 2000) Usually nanosized titania powders are utilized during the spraying process The partides size in the as-deposited coating depends mainly on the size of the powders

Plasma spraying includes atmospheric plasma spraying (APS) and vacuum plasma spraying (VIS) Figure 521 iHustrates this process An electrkal arc is used to melt and spray materials onto a surface The high energy and density available in the plasma jet make it one of the popular thermal spraying techniques The density temperature and velOcity of the plasma plume are crucial to the formation of coatings The temperature of the plasma depends mainly on the degree of ionization which in turn is determined by the type of plasma gas and parameters of the plasma At present gases such as Ar He N and H are commonly used in a plasma torch To ensure environmental inertness a mixture of argon and hydrogen is commonly used Formation of the plasma sprayed coatshying consists of three stages (1) melting and accelerating of the particle from the supplier (2) transportation of the powder to the plasma torch and (3) interaction between the molshyten materials and plasma beam and surrounding atmosphere Currently DC plasma arc devices dominate the com mercial market whereas radio frequency (RF) and inductively coupled plasma (lCP) have a few commercial applications (Uu et al 2004)

Uu et a have fabricated nano-TiO coatings on Ti~6Al~4V substrate using atmospheric plasma spraying The deposited coating is about 100 pm in thickness Figure 522 shows the SEM and TEM pictures of the surface morphology and cross section (Uu et al 2005) High rnagni fication views of the SEM picture show that the nanosized TiO coating is comshyposed of particles less than 50 nm in size TEM observation of the as-prepared coatings also reveals that the surface mainly consists of grains less than 50 nm in size The coating

Spray deposit

Cathode

E1e(tricil t~) connection Substrate dlld water (Jut

Eledricltal (+) connection dod water in

FIGURE 521 Schematic Illustration of plasma-spraying technique (From Liu et I Mntn Sci Eng R 47 49~121 2004 With permis~ion)

225 Nanostruciured Titania Coatings for Biological Applications

AGURE 522 SEM micrographs o( nanosiLtd titania (oiltin~ on pure titlnium prepared by plasma spraying (a) Low magni~ fkaHan b high magnification (From Lm et aJ Biollliltcriafs 26 6l43-6150 2U05 With permission)

is composed of two layers The outer layer is about 500 nm thick with grains size of less than SO nm whereas the interior layer contains columnar grains with sie ranging from 100 to 200 nm as shown in Figure S23b The SAD patrern discloses a crystalline structure of the TiO XRD results further confirm that the coating mainly consists of rutile titania with a small amount of anatase and TiO_ suboxide

Fan et aL have also successfully prepared nanosized titania coatings using vacuum cold spraying This system is composed of a vacuum chamber and vacuum pump an aerosol room an accelerating gas feltding unit a particle-accelerating nozzle a two-dimensional work table and the control unit Ti02 particles are accelerated by high-pressure He gas and

fIGURE 523 TEM views of cross section of nanosized titania coating fabricated by plasma spraying mrl SAD pattCfn ilt

selected region (From Liu (I ilL fiwmt1tcrillls 26 6143-6150 2005 With permission)

226 Biological and Biomedical Olatings Handbook Processing and Characterization

a coating with 25-nm particle size and 40 jlm thick is deposited It is found that the smaller the particle size in the powder the denser is the coatings (Fan et aJ 2006) As the coatings are deposited at a low temperature poor bonding strength is suspected

The plasma-sprayed coatings deposited on stainless and titanium alloys are intended to enhance the bioactivity and tribological performance In the study conducted by Liu et al (2005) an HA layer about 20 jlm thick are grown on the nanosized coatings fabricated by plasma spraying after exposure in simulated body fluids for 4 weeks Liu et aJ (2008b) have tried to further modify the as-prepared coating by ultraviolet light irradiation and hydrogen plasma immersion ion implantation These two treatments increase the amount of Ti-OH groups that are considered to play an important role in the growth of HA It is widely accepted that the atomic coordination on the TiO surface differs from that in the bulk due to truncation of atomic arrangements on the surface The perfect surface is conshystructed from 5-coordinated Ti atoms and 3-coordinated 0 atoms which are more enershygetically reactive than the 6-coordinated Ti and 3-coordinated 0 atoms in the bulk By UV illumination oxygen vacancies are most likely created at the 2-coordinated bridging sites resulting in the conversion of the corresponding Ti sites to Ti sites Ti sites bode well for dissociation of water that is absorbed from the atmosphere (Hugenschmidt et aJ 1994) This leads to an abundance of Ti-OH groups at the bridging oxygen sites on the surface of titania coating The reactions can be explained as follows

2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing

The sol-gel process can be employed to fabricate metal oxide and ceramic materials with high purity and high homogeneity This technique allows good control of the composition and structure at the molecular level In genera I sol-gel processing involves the generation of a colloidal suspension (sol) which is subsequently converted to various gels and solid materials_ Thin sol-gel coatings can also be obtained by a surface process in which the sol-gel reaction proceeds only on the surface of substrate to form a monolayer of thin TiO on each circle (Ichinose et al 1996 Chen 2007 Biju and Jain 2008) The process proceeds in a sequential manner involving chemisorption to an OH- functionalized surface in a titanium alkoxide solution followed by rinsing hydrolysis and drying of the film A calcishynation treatment may be needed if a denser more crystalline coating is desired This heat treatment can also remove organic groups from the coating This process is reuroadily applishycable to any hydroxylated surface using metal alkoxide to react with hydroxyl groups The sol-gel process can be conducted separately That is each different cycle allows the indishyvidual layer to be nanostructured (Acharya and Kunitake 2003 He et aJ 2002 Advincula et al 2006) As coatings produced by the sol-gel process are usually prone to cracking during densilication and crystallization chemicals such as PEG polyvinyl alcohol (PVA) (Larbot et aJ 1988) and hydroxypropyl-celJulose (HPC) (Lucie and Turkovi 2002) have been introduced into the colloidal solution to improve the drying properties of the gel adjust the viscosity of sol and increase the strength of the materials to prevent crack forshymation (Larbot et aJ 1988 Maria et aJ 2006) The coatings produced by the sol--gel method have abundant hydroxyl groups and possess the desirable capability of inducing growth

227 Nallostrudured Titania Coatings for Biological Applications

of HA or formation of mineralized matrix by osteoblasts (Wu et al 2002) The most freshyquently used sols are obtained by hydrolyzing acetic acid and acetHacetone complexed titanium alkoxides Shimizu et at have successfully fabricated anatase titania thin films Cf1 glass and various organic substrates at 40degC to One using aqueous solutions of titashynium tetrat1uoride (TiF4l (Shimizu et aL 1999) Wu et at have also fabricated anatanse titashynia coatings on titanium In vitro experiments disclose that the coatings have good bone bonding ability (Wu et aL 2002)

Controlling the grains size of the titania particles can be accomplished by two techshyniques The most frequently used method to suppress the agglomeration and growth of nanoparticles is the substitution of the surface hydroxyl groups by other functional groups such as organic complex molecules that do not condense like OH- and that can eventually provide the redispersibility of the powdered xerogel (Kaminski et lt11 2005) Nevertheless subsequent heat treatments that should be carried out in order to remove the organic groups may strongly affect the regular nanostructure of the prepared film

Shen et aL (2005) have reported the fabrication of hydrophobic nanoporous titania by the sol-gel and dip method However it is generally accepted that a hydrophilic surface benshyefits cell attachment but the biological performance of a hydrophobic surface is unknown It is noted that this hydrophobic surface can greatly improve the corrosion resistance of the coated metal as demonstrated by Shen et a1 (2005) As the titania coatings produced by the sol-gel method are usually prone to cracking during densification and crystallization immersion in boiling water for 5 to 10 min can alleviate the problem and the morpholoshygiesof the coating before and after exposure in water are exhibited in Figure 524 Kuyyadi has fabricated nanocrystalline titania coatings using titanium isopropoxide Ti(OCH7)1 and ethanoL Water is added for hydrolysis and polycondensation and nitric acid is used to control precipitation (Biju and Jain 2008) The coating is then annealed and Figure 525 shows the typical morphology of the sol-gel coating after heating at 550deg( The anatase titania coating with a grain size of about 25 nm is observed from the picture and the grain size increases with sintering temperature

FtGURE 524 SEM imagls of nanoTi02 cOltlted 316L stainles steel by sol-gel processing ()) before hydrothermal posttnatshyment and (b) after hydrothermal treatment From Shen et aL ElertfocJiJ ArM 50 5083-5089 2005 With permiampiunl

228 Biological and Biomedical Coatings Handbook Processing and Cilaracterization

FIGURE 525 SEM micrograph of nanocrystalline titani) coatlng fabricated sol-geurol~deriveurod coating alter annealing at 550( (From Biju KP Jain MK Tliill Solid Films 516 2175-2180 2008 With permission)

Physical Vapor Deposition

Physical vapor deposition (PVD) is a powerful technique to fabricate hydrophilic nanoshyTiO coatings Magnetron sputtering offers uniform deposition and precise control of the deposition rate High quality of nanocrystalline TiO coatings can be produced by careful control of the processing parameters As reported by Ye et a1 (2007) a TiOl target is used and annealing can transform the amorphous titania into a crystalline coating However a low heating rate can prevent iilm cracking As shown in Figures 526 and 527 the wallr contact angle is progressively influenced by the treatment temperature The mean diamshyeter of the grain is about 30 nm The annealing temperature influences the tinal grain size Generally a higher temperature induces a larger grain size and the contact angle drops but from about 600cC the contact angle is nearly independent of the processing temperature

A pure Ti target can also be used as the target and a mixture of Ar and 0 serves as the working gas (Yang et a 21108b) The deposition rate is about 70 nmh and the mean grain size around 40 nm Subsequent annealing enlarges the grain size Cell adhesion measuremiddot ment shows that the longer heating time enhances cell adhesion and a heat treatment for 3 h increases the ALP activity of the cells The nanoscaled coating significantly improves

FIGURE 526 Surfdce morphology (1fT[O~ thin film prepared by RF magnetron sputtering with annealing treatment at200C (From Yt et aL i(lClfUJII 81 627-631 2007 With permission)

229 Nanoslntctllred Titania Coatings for Biological Applications

70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800

Annealing teOlperatun ee)

fiGURE 527 Relationship between water contad angles and annealing temperature Df TiO~ film fabricated by RF magnetron sputtering (Prom Ye et 11 FfiCUJlfI 81627-631 2007 With ptrmissimLj

cell adhesion in the first hour However the cell proliferation and differentiation behavior is similar on the nanoscale surface and microscale Ti control

Chemical Vapor Deposition

Chemical vapor deposition is a chemical process to fabricate pure and high-performance solid materials This process is common in the fabrication of functional films Figure 528 depicts the schematic of a CVD apparatus In a typical CVD process the substrate is exposed to one or more volatile precursors that react andor decompose on the subshystrate surface to conduct deposition The volatile by-products are removed by the gas flow through the reaction chamber Various monocrystalline polycrystalline amorphous and epitaxial layers can be produced The CVD process can be performed at atmospheric presshysure and ultrahigh vacuum below lO~M Pa There are many types of CVD processes such as (Seifried et aL 2000)

bull Atmospheric-pressure chemical vapor deposition (AlCVD)

bull Low-pressure chemical vapor deposition (LPCVD)

bull Plasma-assisted (enhanced) chemical vapor deposition (PACVD PECVD)

bull Photochemical vapor deposition (PCVD)

bull Laser chemical vapor deposition (LCVD)

Heater

Carrier gas

bull bull Source

gas

RGURE 528 Schernatk layout of CVDequiprnlnt


bull Metal-organic chemical vapor deposition (MOCVD)

bull Chemical beam epitaxy (CBE)

Compared to PVD a CVD reactor is relatively simple and can be scaled up easily to accommodate multiple substrates Ultrahigh vacuum is not essential for CVD and changes and addition of precursors are typically straightforward tasks As the process is gas phase in nature and gives a uniform temperature and concentration of deposition species within the chamber deposition is usually quite uniform If the appropriate coating powders or gases are used surfaces with diiferent topography can be coated evenly The high temshyperature in CVD results in considerable diffusion action and consequently if the thermal expansion coefficients are compatible between the coating and substrate film adhesion will be excellent Other advantages of CVD include growth of high-purity films (Seifried et a1 2000) The source materials are usually transported by the carrier gas to the chamber When heated to certain temperature the substances decompose and reactions take place on the substrate At the same time the by-products are flushed out of the chamber by the carrier gas The mechanism for eVD growth is generally complex In some cases small molecular clusters as weI as sma I molecules have been identified as the growth species (Seifried et al 2000 Md et al 2009 Wavhal et al 2009)

Evans and Sheel have fabricated thin titania films on stainless steel using APCVD with different precursors (TTlI and TiCl) Fairly spherical grains are observed in Figure 529 which also shows the SEM pictures of titania coatings produced using different source materials The two coatings are found to possess antibacterial properties (Evans and Sheel 2007) On a time scaJe between 120 and 180 min 100 of the bacteria can be killed

Titanium tetrachloride and ethyl acetate are usually used as precursors in the fabricashytion of titania films TTlI (Ti(OCH7)) is usually used in MOeVD (Backman et al 2005) Oxygen is used as the carrier gas to transport the reagent gas to the reaction chamber The processing conditions dramatically influence the structure of the coating The TTlI is thershymally decomposed as shown below when heated to 400degC (Fictorie et al 1994)

TTIP - TiO + 4CHh + 2HO

TiCl4 + 0 - TiO + 2Cl

FIGURE 519 SEM images of no deposihd directly on stinls steel using TTIP ill Ht 500~C and (b) TiCl t at 650degC (from Evans P Sheet DW Surf eva TcdlllOl 201 9319-324 2007 With permisSion)

231 Nanosrueured Titania Coatings for Biological Applications

ACURE 530 SEM mkrogrltlph of calcined nanocrystalliTll TiO thin film fnset shows high magnificatIon image at setffted area mMked by lt1 white rectangle (From Liu et I J Nmr-CrV$t S(llids 352 2284-2287 2006 With permission)

The slower growth rate may favor evolution of larger crystal grains At a high deposition temperature the coatings are generally crystalline The exact structure (rutile or anatase) depends on the reaction temperature A titania coating with uniform morphology and narshyrow crystallite size distribution is obtained by using TiCl as the inorganic source and triblock copolymer EOP070EO (pluronic PI23 EO ethylene oxide) as the uniform-structureshydirecting agent Their method is based on the evaporation-induced assembly (EA) approach for the titania thin films synthesis The EIA method combines the advantages of sol-gel dip coating and organic-inorganic cooperative assembly technique (Uu et aJ 20(6) Figure 530 shows the representative SEM pictures of the coatings Uniform nanocrystalline titania coatshyings are shown The grains size is about 12 nm in diameter XRD patterns acquired from the coating after annealing at 400degC revea an anatase crystalline structure For more details about the method and preparation procedure please refer to Liu et al (2006)

A modified CVD method called chemistry vapor synthesis (CVS) has been developed CVS is performed at a higher processing temperature and precursor partial pressure as well as for a longer time than common CVD It can produce particle- and void-free films Thick nanocrystalline CVS films exhibiting a noncolumnar morphology have also been fabricated under conditions intermediate to that of CVD and CVS Here both nanoparshytieles and molecular species are used for the film formation (Seifried et al 2000)

Conclusion

Nanoscaled titania coatings possess excellent mechanica properties and good biocompatshyibility thereby making them desirable in biological coatings and materia Is The nanoscaled topography may also provide additional biological benefits to natural tissues Among the various types of nanoscaled titania coatings well-ordered titania nanotube arrays fabrishycated by anodization are attracting increasing attention Various applications pertaining to drug delivery biosensing and so forth are proposed and being developed In the future precise design of various nanoscaled titania patterns on biological devices is called for and so more systematic and fundamental investigations on the effecls and corresponding mechanism of nanosized titania coatings on biological tissues are necessary


References

Acharya G and Kunitake T 2003 A general method for fabrication of biocompatible surfaces by modification with titania layer umgmuit 192260-2266

Advincula MC Rahemtulla FG Advincula RC Ada ET Lemons jE and Bellis SL 2006 Osteoblast adhesion and matrix mineralization on sol-gel-derived titanium oxide Biomatcrials 272201-2212

Allam NK and Grimes CA 2007 Formation of vertically orientt---d Ti02 nanotube arrays using a fluoride free HCI aqueous electrolyte J Plrys Chem C 11113028--13032

Allam NK and Grimes CA 2008a Effect of cathode material on the morphology and photoeJecshytrochemical properties of vertically oriented TiO nanotube arrays Sol Energy Mater Sol CrUs 9214~1475

Allam NKI Shankar K and GrimLS CA 20OSb Photoelectrochemical and water photoelectrolysis properties of ordered TIOznanotubcs fabricated by Ti anodization in fluoride-free HCl electro~ lyres Mater Ole 182341~2348

Backman U Auvinen A and ]okiniemi JK 2005 Deposition of nanostructured titania fiJms hy particle-assisted MOCVD SlIrf Coal Techllol 19281-87

Beltran A L Gracia J and Andres J 2006 Density functional theory study of the brookite surfaces and phase transitions between natural titania polymorphs rPhIS Chel1L B 11023417-23423

Biju KP and jain MK 2008 Effect of crystallization on humidity sensing properes of sol-gel derived nanocrystalline Ti02 thin fllms Tlthl Solid Ftlt1ls 5162175-21811

Brammer K$ Oh SH Gallagher )0 and jin SH 2008 Enhanced cellular mobility guided by Ti01 nanotube surfaces Nmw uti 8786--793

Burnside SD Shklover V and Barbe C et ill 1998 Self-organization of TiOz nanoparticles in thin films Cirelli Mala 102419-2425

Cai Q Paulose M Varghese OK and Grimes CA 2005 The effect of electrolyte composition on the fabrication of self-organized titanium oxide nanotube arrays by anodic oxidation J A1ate-r Re 2023(-236

Chen X Schriver M Suen T and Mao Ss 2007 Fabrication of 10 nm diameter n02 nanotube arrays by titanium anodization Thin Solid Film 5158511-8514

Chiang CY Chiou SH and Yang WE ct aL 2009 formatlon of TiOz nano-network on htanium surface increases the humm cell growth DtrJL Maltf 251022-1029

Chri~tophcrsen M Carstensen JJ Voigt K and FoU H 2003 Organic and aqueous electrolytes used for etching macro- and mesoporous silicon PIIl(s Status Solid A 19734--3R

DtlS K BoseS Bandyopadhyay A Karandikar 3 and Gibbins BL 2008 Surface coatings for improvement of bone (ell materiaL and antimicrobial activities of Ti implants J Biomed Mater Res 87455-460

de Oliveira PT and Nanci A 2004 Nanotexturing ot titanium-based surfaces upregulates expresshysion of bone sialoprotein and osteopontin by cultured osteogenic cells Biomaterias 25403-41J

Doohun K Fujimoto S Schmuki P and Tsuchiya H 200R Nitrogen doped anodic TiO nanotubes grown from nitrogen-containing Ti alloys Eicrtmchem Co1tJmwl 10910-913

Erli HJ Ruger M and Ragoss e et al 2006 The effecl of surface modification of a porous TiO perlite composite on the ingrowth of bone tissue in vivo Riortatrials 271270-1276

Evans P and Sheel DW 2007 Photoactive and antibacterial TiO thin films on stainless sleel 511rf Coal Teelllol 2019319-9324

Fan SQ Yang CJ Li cj Liu Gj li ex and Zhang LZ 2006 Characterization of microshystructure of nano~Ti02 coating deposited by vacuum cold spraying J Therm Spray Techno 15513-517

Fictorie cp Evani lE ltlnd Ciandfelter WL 1994 Kinetic and mechanistic study of thechemical-vaporshydeposition of titanium-oxide thinfilms using tetrakis-(isopropoxo)-titanium Vae Sci Tcchnol A 121I08--11J3


Fujishima A Zhan~ XT and Tryk DA 2008 TiD photocatalysis and related surface phenomena SIIf SCI Rep 63515-582

Gong D Grimes CA and Varghese OK et a1 2()()1 Titanium oxide nanotubc arrays prepared by anodic oxidation f Aiater Res 163331-3334

Grimes CA and MOT CK 2009 TiO Nmwtllbc Arrays StJWitcsi Properftc5 and Applicatioftf New York Springer Science

He IH chinose I Fujikawa S Kunitake T and Nakao A 2002 A general eHkient method of incorporation of metal ions into ultrathin TiO fHms Chell Milter 143493-3500

Huang HH Pan Sl Lai Yl Lee TH Chen cc and Lu FH 2004 Osteoblast-like cell initial adhesion onto a nehvork~structured titmlurn oxide layer Sa Mata 51 1017~102L

Hugenschmidt MB Gameble 1 and Campbell CT 1994 The interaction of HO with a TiO (110) surface Surf Sd 30232Q-340

Hwang BJ md Hwang JR 1993 Kjnetk~model of anodicDxidation of titanium in sulfuric add J Appl ElcctroclwnI 231056--1062

Tcrunose L Senzu H and Kunitake r 1996 Stepwise adsorption of metal alkoxides on hydrolyzed surfaces A surface sol~gel process Chem Lett 25831~832

Jaroemmiddotoraluck A Regonini D Bowen CR Stevens R and Macro DA 2007 ~iicro and naner structure of Ti02 anodised films prepared in n fluorine-containing electrolyte Mllter Sci 426729-6734

Julia K Lenk M Jan MM Peter G Patrik S and Frank AM 2008 Time-dependent growth of biomimetk apatite on nnodje n02 nanotubes Elcctrochim Acta 536995-7003

Jung J-H KobayashI- H van Bommel KJC Shinkai 5 and Shimizu T 2002 Creation of novel helical ribbon and double-layered nanotube TiOzstructures using an organogel template Cltem Milkr 141445-1447

Kaminski RC PuldneHi SH Craievich AF and Santilli CV 2005 Nanocrystalline anatase thin films prepaaltl from redispersibfe sol-gel powders f Eur Ceram SOL 25217~2180

Karlsson M Palsgard E Wilshaw PR and D1 Silvio L 2003 Initial in vitro interaction of osteoshyblasts with nanD-porous alumina Biomaterial- 243039-3046

Khang D Lu L Yao f C Haberstroh KM dnd Webster TJ 2008(1 The role of nanometer and subshymicron surface features on vascular and bone cell adhesion on titilOium BivmakriaJs 29970-983

Khang D Park GE and Webster TJ 2008b Enhanced chondrocyte densities on cZlrbon nantJtube composites The combined role of nanosurfaee roughness and electrical stimulation J BiNned Maler Hcs A 86A253~260

KobayashiS Hamasaki ~ Suzuki M Kimura M Shirai H and Hanabusa K 2002 Preparation of helical transition-metal ollide tubes using organogelators as structure-directing agents r Am Chem Soc 1246550-6551

Larbot A Fabre JP Guizard C and Cot L 1988 Inorganic membranes obtained by sol-gel techshyniqueamp hfell1br Sci 39203-212

LeeS Taka M Kim H and Ishihara K 2009 Preparation of nano-structured titanium oxide film for biosensor substrate by wet corrosion process Curr Appl PIIl5 9e266middotmiddote269

Li LH Kong YM and Kim HvV et aL 2004 [mproved biological performance ofTi implants due to surface modification by micro-arc oxidation BiollI1ltcriais 252867middotmiddot-2875

Liu KS Zhang ML Shl K Y Zhou W and Fu HG 2006 Unifonn TiO thin films with arultase nanoshycrystalliteS syntheSized through evaporation~induced assembly J Non-Crysl Solieigt 3522284-2287

Liu XY Chu PK and Ding CX 2004 Surface modification of titanium titanium alloys and related materials for biomedicltJ applications A1ater Sci Eng R 4749-121

Liu XY and Ding CX 2002 Plasma sprayed wollastoniteTiO composite coatings on titanium alloys Bio1latlriais 234065-4077

Liu XY Zhao XB Fu RKY Ho lrY Ding ex and Chu PK 2005 Plasma-treated nanostrucshylured Ti02 surface supporting biomimetic growth of lpatite Bionaiaiais 266143-6150

Uu Z Zhang X and Nishimoto S et at 2008L Highly ordered TiO nanotube arrays with controlshylable length for photoelectrocatalytic degradation of phenol J PI ClleJl C 112253-259


Liu XY Zhao XB ilnd Li R et aL 2oo8b UV-irrddiation-induced bioactivity on TiO coatings with nanostructural surface Acta Biomafel 4544-552

Lohrcngcl MM 1993 Thin anodic oxide layers on aluminum and other valve metals-high-field regime Mater Sci EUR R 1124~294

Luck M and Turkovt LA 2002 Small-angle X-ray scattering and wide-angle X-ray diffraction on thermally annealed nanostructured TiD] films Thin Solid Films 419105-113

Marja CA Firaz GR Rjgoberto CA Earl TA Jack EL and Susan LB 2006 Osteoblast adheshysion and matrix mineralization on sol-gel-derived titanium oxide Biomaterias 272201-2212

Matsunaga Tor Tomada R Nakajima T and Wake H 1985 Photodectrochemical sterlHzation of microbial-cells by semicondudor powders FEMS Microbial Left 29211-214

~d IA Bhattacharya S$ and Hahn H 2009 Structure thermal stability and optical properties of boron modified nanocrystalline anatase prepared by chemical vapor synthesis j ArJpl Phys 105113526

Melody B Kinard T and Lessner P 1998 The non-thickness-limited growth of anodic oxide films on valve metals Electrodl(tn Solid State Lett 1126-129

Michailowskj A A1Mawlwm D Cheng GS and Moskovits ~ 200t Highly regular anatase nanotubule arrays fabricated in porous anodic templates OUtt1 Phys Lett 3491-5

Mor GK Shankar K Paulosc M Varghese OK and Grimes CA 2005 Enhanced photodeavage of water using titania nanotube arrays Nano LcU 5191-195

iiand A i~Hyun Y and Bernard C d al 2006 Characterization of a bioactive nanotextured SUIshy

face created by controlled chemical oxidation of titanium Sur] Sci 6004613--4621 Nand A Wuest JD and Peru L et al 1998 Chemica modification of titanium surfaces for cova~

lent attachment of biological molecules j Biomcd Mnter Res 40324middotmiddotmiddot335 ~guyen QAs Yash YB Radmilovic YR and Devine TM Structural study of elLdrochemishy

cally synthesized TiO~ nanotubes via cross-sectional and high-resolution TEM Elcctrochim Acta 544340-4344

Oh S and lin S 2006 Titanium oxide nanolubes with controlled morphology for enhanced bone growth MilkY Sci Ellg C 261301-1306

Pakes A Thompson GE- Skeldon E and Morgan PC 20t13 Development of porous anodic films on 2014-T4 aluminium aHoy in tetraborate electrolyte Carro Sci 451275-1287

Park L Bauer S Schlegel KA Neukam Fw von der Mark K and Schmuki P 2009 TiO nanoshytube surfaces l5 nm-An optima11cngth scale of surface topography tor celt adhesion and differentiation SwaIl5666-671

Park L Bauer S von der Mark K and Schmuki P 2007 Nanosize ilnd vitality Ti02 nanotube diameter diRXts cell fate Nal1( Lett 71686-1691

Paulose M Shankar K and Yoriya S ct a1 2006 Anodic growth of highly ordered TiOgt nanotube arrays to 134 ~m jn length IlIy Cllen B 11016179-16184

Peng Lt Mendelsohn AD LaTemptl T Yoriya 5 Grimes CA and Desai TA 2009 Longshyterm small molecule and protein elution from TiOl nanotubes Nano Left 91932~ 1936

Popae Ke Leoni L Grimes CA and Desai l TA 20073 Influence of engineered titania nanotubushylar surfaces on bone re1h Biomaterilis 283188-3197

Popat KC Eltgroth M LaTempa T) Grimes CA and Desai TA 2oo7b Titania nanotublts A novel platform for drug-eluting cOiltings for medical implants Small 31878---1881

Popat KC E1tgroth M LaTempa fJ Grimes CAand Desai TA 200k Decreased Staphylococcus epidermis adhesion and increased osteoblast functionality on antibiotic-loaded titania nanoshytubes Bionwcrials 284880-4888

Prakasam HE Shankar K Pauiose M and Grimes CA 2007 A new benchmark for Ti02 nanomiddot tube array growth by anodizationJ- Phy Chem C 1117235-7241

Ramamoorthy M Vanderbilt D and Kjng-Smith RD 1994 First-principles calculations of the energeticS of stoichiometric TiO surfaces Pity Rev B 4916721

Richter C Panaitescu E WIHey R and Menon L 2007a Titania nanotubes prepltred by anodlzashytion in fluorine-free acids J Malrr Hes 221624-1631

235 NallOslructured Titania Coatings for Biological Applications

Richter C Wu Z Panaitescll E vV1lIey K and Menon L 2007b Ultrl-high aspect ratio tit(loia nanotubes Ad( Mater 19946-948

Ruckh T Porter jR Allam NK Feng Xj Grimes CA and Papat KC 2009 Nanostructured tantalil as a template for enhanced osseointegration NmlOledmoiogy 2045102

SeifriedS Winterer M and Hahn H 2000 Nanocrystalline titania films and particles by chemical vapor synthesis Adp Mater 6239-244

Shankar K Mor GK lt Fitzgerald A and Grimes CA 2007 Cation eff(ct on the electrochemkaJ formation of very high aspect ratio no nanotube arrays in formamide-water mixtures f PIy Chm C 11121-26

Shen GX Chen YC Lin L Lin cJ and Scantlcbury D 2005 Study on a hydrophobic nano-TiOt

coating and its properties for corrosion protection of metals Elecirociliw Acta 5050amp1-5089 Shih YH Lin CT Uu CM Chen CC Chen CS and Ou KL 2007 Ellect of nano-titnium

hydride on formation of multi-nitfiOporous TiO) film on TL Appl Sli~f Sci 2333678~3682

Shimizu K ImaL H Hirashima IL and Tsukuma K 1999 Low-temperature synthesis of m1tase thin films on glass and organic substrate~ by direct deposition from aqueous solutions Thill So[h films 3512W-224

Shklover~ V Nazeeruddln MK and Zakccruddin SM et aL 1997 Structure of nanocrystaHine 1102 powders and precursor to their highly efficient photosensitizer CUIII Mater 9430---439

Song YY Schmidt-Stein E Bauer S and Schmuki P 209 AmphiphiJic TiO nanotube arrays An actively controHJble drug delJvery system Am CIIem Soc 1314230-4232

Sujata VB 2005 BionJaterials Harrow Alpha Science InternationaL Sun 11 Puzas JE Sheu TJ Liu X and Fauchd PM 2007 Nano-to microscale porous silicon as a

ceH interface for bone-tiltsuc engineering Adulvfatcr 19921~924 Takagi L Petre BM Witlz T and Springer TA 2002 Global conformational rearrangements in

integrin extracellular domains in outside-in and inside-out signaling Cell 110S99-61L Tsuchiya H Matdk JM and Muller L et at 2006 Hydroxyapatite growth on anodic TiO nannshy

tubes f BioNled Mater IltC) A 77 A534-541 Varghese OKGong D Pauiose M Ong KG Grimes CA and Dickey EC 20m Crystallization and

high-temperature structural stability of titanium oxide nanotube arrays lvIafct Res 18156-165 Variolat E YL JH Richert Lf Wuest J 01 Rosei E and Nanci A 2008 Tailoring the surface propershy

ties of Ti6AI4V by controlled chemical oxidation Biolllot(ritlis 291285-1298 Wavhal 05 Goyal S and Timmons RB 2009 Synthesis of electrically conducting tin films by

low-temperature plasma-cnhdnced CVO GILIIl vial 214442-4447 Wong Y and BronzinoJD 2007 Biomnfcrinls Boca Raton CRC Press WU JM Hayakawa S Tsuru K and Osaka A 2002 In vitro bioactivity of anatase film

obtained by direct deposition from aqueous titanium tetrafluoride solution~ Tllill Solid Films 414275-280

Xin YCf Jiang J Huo KE Hu T and Chu EK 2009 BioactiveSrTi03 nanotube arrays Strontium delivery platform on Ti-based osteoporotic bone jmplants ACS Nau(l33228-3234

Yang wE Hsu ML Lin MC Chen ZH Chen LK and Huang HH 2009 Nanosubmicronshyscale TiO network on titanium surface for dental implant application Alloys COlupd 479642-647

Yang Y Vang X and U L 200amp1 CrystolHzation and phase transition of titan um oxide nanotube arrays f Am Cram StI 91632-635

Yang YZ Park SW Liu IX I d a1 2008b Oevdopment of sputtlfmiddotd nanoscale titanium oxide coatshying on osseointegrated implant devices and their biological evatuotion VnclIlIIlI 83569-574

Yao C Siamovich EB and Veb3ter TJ 2008 Enhunced osteoblast functions on anodized titanium with nanotube-like structures f Biamed fifacr R bull s A 85A157~166

Yan C and Webster TJ 2006 Anodization A promising nano-modification technique of titanium Implants for orthopedic pplications f NtJllosi NmlOtccmoi 62682-2692

Ye Q Uu PY Tang ZE and 711a L 2007 Hydrophilic properties of nano-nO thin films deposshyited by RF magnetron sputtering IncIlIU1181627-631

236 Biological and Biomedical Coatings Handbook Processing and Characierizalicm

Yoriya S MOT GK Sharma S and Grimes CA 2008 Synthesis ot ordered arrays of discrete partially crystalline titania nanotubes by Ti anodization using diethylene glycol electrolytes Maler Chelll 183332~3336

Yoriya S Paulose M Varghese OK Mor GK and Grimes CA 2007 Fabrication of verlimiddot caBy orientt-xi no nanotube arrays using dimethyl sulfoxide electrolytes f Ph~Js Chern C 1111377~13776

Zhang H and BanfieldT E 2000 Understttnding polymorphic phase transformation behavior durshying growth of nanocrystalline aggregares Insights from riO f Phys Chcl11 B 1 043481 ~3487

Zhang LJ and Webster 1J 2007 Nanotechnology and nanomaterials Promises for improved tissue regeneration Nano Today 466--80

Zhao XB Liu Xy Ding ex and Chu PK 2007 Effects of plasma treatment on bioactivity of no coatings Slirf COllf Teemot 2016878--6881

Zhu YC and Ding ex 2000 Characterization of plasma sprayed nano-titania coatings by impedshyance spectroscopy r Elir Ceran Soc 20127-132

Contents

Serjes Preface _ _ vii Preface i x Editor xi Contributors xii i

1 Bone-Like Mineral and Organically Modified Bone-Like Mineral Coatings 1 fanani Ramaswamy Harsha Ramamjll and Dwid H Kahn

2 Synthesis and Characterization of Hydroxyapatite Nanocoatings by Sol-Gel Method for Clinical Applications 37 B Bcn-Nissan Ali Clwi DW Green BA Latella f Chou alld A Bendavid

3 Hydroxyapatite and Other Biomedical Coatings by Electrophoretic Deposition 81 Charles C Sorrell Hariali Tilib Timothy C Pallller rei Peng Zelglllin Xia mId Mei Wi

4 Thermal Sprayed Bioceramic Coatings Nanostructured Hydroxyapatite (HA) and HA-Based Composites 137 Hua Li

5 Nanostructured Titania Coatings for Biological Applications Fabrication and Characterization 203 Yunclmng Xin alld Paulllt Chit

6 Hydrothermal Crystallization with Microstructural Self-Healing Effect on Mechanical and Failure Behaviors of Plasma-Sprayed Hydroxyapatite Coatings 237 Clumg- Wei Yang and Truan-Sheng Lui

7 Bioceramic Coating on Titanium by Physical and Chemical Vapor Deposition 299 fakashi Goto Takayuki Narushillw and Kyoslike tIeda

8 Coating of Material Surfaces with Layer-by-Layer Assembled Polyelectrolyte Films 333 Thomas Crortzier Thomas Boudotl K~feng RtI1J nnd Callicrine Picarl

9 Bioactive Glass-Based Coatings and Modified Surfaces Strategies for the Manufacture Testing and Clinical Applications for Regenerative Medidne 377 Joson vfarooth~adell

Index 431

v

Contributors


























xiii

xiv












Contributors


















CONTENTS

Introduction 203







Drug Delivery 216




Introduction


203




Titania











Powr supply

Ii sheet (anode)

Pt sheet cathode



J

t ~

-Ii


bull b - ~ C v ( 1~ ~1


r ~ 1 J
















TABLE 51


Electrolyte Systems



HF + HCrO


HF + HPO~


Ethytent glycol

Glycerol + NH4F





Ti + HO - TiO + 2H (51)


TiO + 6F- + H - TiF- + 2Ho (52)

Ti(OI-l) + 6 F- - TiF + 4OH- (53)






(a) OxiQt

Barriet layer -leta

(el

Metal Tube

(e) Pores Void

I Barrier layer

Batrk-r layer













eTi

20 30 4(] 5V 6n 7() 8)

28 (deg)








1OIJ

SO

60

40

20

0

T101-NT -b-Ti2p

-O-Os

0 20 4() 60 ampl H]O

Sputter time (min)

1 6mtn

t =2 min

Omi

470




Binding energy (eV)



R 6SO-C c

R R R R R R RR R

620CR R tl12


~ TI _T T 480C

~ c j

=

AliA T A ~ R

T T

J AI ~~ Air T

TI

A

lT

T 1 T

430C I I TT i

i T

TI JT

A T_1 T

280C

T T ~ I

T T 230C

T 1 T T

j ~T 20 30 4() 50 6) 70 80

20 (deg)















Drug Delivery







6

d lOOnmh ~m

~ d 300 lm h -- 5 pm

d lOOnmh= IJJm

- FlatTi

o 5 JO 15 20 25

Time (days)






1 0





~O~) 0lt

0 ~~ am~s-






























c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References










































































































Contributors


























xiii

xiv












Contributors


















CONTENTS

Introduction 203







Drug Delivery 216




Introduction


203




Titania











Powr supply

Ii sheet (anode)

Pt sheet cathode



J

t ~

-Ii


bull b - ~ C v ( 1~ ~1


r ~ 1 J
















TABLE 51


Electrolyte Systems



HF + HCrO


HF + HPO~


Ethytent glycol

Glycerol + NH4F





Ti + HO - TiO + 2H (51)


TiO + 6F- + H - TiF- + 2Ho (52)

Ti(OI-l) + 6 F- - TiF + 4OH- (53)






(a) OxiQt

Barriet layer -leta

(el

Metal Tube

(e) Pores Void

I Barrier layer

Batrk-r layer













eTi

20 30 4(] 5V 6n 7() 8)

28 (deg)








1OIJ

SO

60

40

20

0

T101-NT -b-Ti2p

-O-Os

0 20 4() 60 ampl H]O

Sputter time (min)

1 6mtn

t =2 min

Omi

470




Binding energy (eV)



R 6SO-C c

R R R R R R RR R

620CR R tl12


~ TI _T T 480C

~ c j

=

AliA T A ~ R

T T

J AI ~~ Air T

TI

A

lT

T 1 T

430C I I TT i

i T

TI JT

A T_1 T

280C

T T ~ I

T T 230C

T 1 T T

j ~T 20 30 4() 50 6) 70 80

20 (deg)















Drug Delivery







6

d lOOnmh ~m

~ d 300 lm h -- 5 pm

d lOOnmh= IJJm

- FlatTi

o 5 JO 15 20 25

Time (days)






1 0





~O~) 0lt

0 ~~ am~s-






























c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References










































































































xiv












Contributors


















CONTENTS

Introduction 203







Drug Delivery 216




Introduction


203




Titania











Powr supply

Ii sheet (anode)

Pt sheet cathode



J

t ~

-Ii


bull b - ~ C v ( 1~ ~1


r ~ 1 J
















TABLE 51


Electrolyte Systems



HF + HCrO


HF + HPO~


Ethytent glycol

Glycerol + NH4F





Ti + HO - TiO + 2H (51)


TiO + 6F- + H - TiF- + 2Ho (52)

Ti(OI-l) + 6 F- - TiF + 4OH- (53)






(a) OxiQt

Barriet layer -leta

(el

Metal Tube

(e) Pores Void

I Barrier layer

Batrk-r layer













eTi

20 30 4(] 5V 6n 7() 8)

28 (deg)








1OIJ

SO

60

40

20

0

T101-NT -b-Ti2p

-O-Os

0 20 4() 60 ampl H]O

Sputter time (min)

1 6mtn

t =2 min

Omi

470




Binding energy (eV)



R 6SO-C c

R R R R R R RR R

620CR R tl12


~ TI _T T 480C

~ c j

=

AliA T A ~ R

T T

J AI ~~ Air T

TI

A

lT

T 1 T

430C I I TT i

i T

TI JT

A T_1 T

280C

T T ~ I

T T 230C

T 1 T T

j ~T 20 30 4() 50 6) 70 80

20 (deg)















Drug Delivery







6

d lOOnmh ~m

~ d 300 lm h -- 5 pm

d lOOnmh= IJJm

- FlatTi

o 5 JO 15 20 25

Time (days)






1 0





~O~) 0lt

0 ~~ am~s-






























c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References













































































































CONTENTS

Introduction 203







Drug Delivery 216




Introduction


203




Titania











Powr supply

Ii sheet (anode)

Pt sheet cathode



J

t ~

-Ii


bull b - ~ C v ( 1~ ~1


r ~ 1 J
















TABLE 51


Electrolyte Systems



HF + HCrO


HF + HPO~


Ethytent glycol

Glycerol + NH4F





Ti + HO - TiO + 2H (51)


TiO + 6F- + H - TiF- + 2Ho (52)

Ti(OI-l) + 6 F- - TiF + 4OH- (53)






(a) OxiQt

Barriet layer -leta

(el

Metal Tube

(e) Pores Void

I Barrier layer

Batrk-r layer













eTi

20 30 4(] 5V 6n 7() 8)

28 (deg)








1OIJ

SO

60

40

20

0

T101-NT -b-Ti2p

-O-Os

0 20 4() 60 ampl H]O

Sputter time (min)

1 6mtn

t =2 min

Omi

470




Binding energy (eV)



R 6SO-C c

R R R R R R RR R

620CR R tl12


~ TI _T T 480C

~ c j

=

AliA T A ~ R

T T

J AI ~~ Air T

TI

A

lT

T 1 T

430C I I TT i

i T

TI JT

A T_1 T

280C

T T ~ I

T T 230C

T 1 T T

j ~T 20 30 4() 50 6) 70 80

20 (deg)















Drug Delivery







6

d lOOnmh ~m

~ d 300 lm h -- 5 pm

d lOOnmh= IJJm

- FlatTi

o 5 JO 15 20 25

Time (days)






1 0





~O~) 0lt

0 ~~ am~s-






























c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References













































































































Titania











Powr supply

Ii sheet (anode)

Pt sheet cathode



J

t ~

-Ii


bull b - ~ C v ( 1~ ~1


r ~ 1 J
















TABLE 51


Electrolyte Systems



HF + HCrO


HF + HPO~


Ethytent glycol

Glycerol + NH4F





Ti + HO - TiO + 2H (51)


TiO + 6F- + H - TiF- + 2Ho (52)

Ti(OI-l) + 6 F- - TiF + 4OH- (53)






(a) OxiQt

Barriet layer -leta

(el

Metal Tube

(e) Pores Void

I Barrier layer

Batrk-r layer













eTi

20 30 4(] 5V 6n 7() 8)

28 (deg)








1OIJ

SO

60

40

20

0

T101-NT -b-Ti2p

-O-Os

0 20 4() 60 ampl H]O

Sputter time (min)

1 6mtn

t =2 min

Omi

470




Binding energy (eV)



R 6SO-C c

R R R R R R RR R

620CR R tl12


~ TI _T T 480C

~ c j

=

AliA T A ~ R

T T

J AI ~~ Air T

TI

A

lT

T 1 T

430C I I TT i

i T

TI JT

A T_1 T

280C

T T ~ I

T T 230C

T 1 T T

j ~T 20 30 4() 50 6) 70 80

20 (deg)















Drug Delivery







6

d lOOnmh ~m

~ d 300 lm h -- 5 pm

d lOOnmh= IJJm

- FlatTi

o 5 JO 15 20 25

Time (days)






1 0





~O~) 0lt

0 ~~ am~s-






























c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References


















































































































Powr supply

Ii sheet (anode)

Pt sheet cathode



J

t ~

-Ii


bull b - ~ C v ( 1~ ~1


r ~ 1 J
















TABLE 51


Electrolyte Systems



HF + HCrO


HF + HPO~


Ethytent glycol

Glycerol + NH4F





Ti + HO - TiO + 2H (51)


TiO + 6F- + H - TiF- + 2Ho (52)

Ti(OI-l) + 6 F- - TiF + 4OH- (53)






(a) OxiQt

Barriet layer -leta

(el

Metal Tube

(e) Pores Void

I Barrier layer

Batrk-r layer













eTi

20 30 4(] 5V 6n 7() 8)

28 (deg)








1OIJ

SO

60

40

20

0

T101-NT -b-Ti2p

-O-Os

0 20 4() 60 ampl H]O

Sputter time (min)

1 6mtn

t =2 min

Omi

470




Binding energy (eV)



R 6SO-C c

R R R R R R RR R

620CR R tl12


~ TI _T T 480C

~ c j

=

AliA T A ~ R

T T

J AI ~~ Air T

TI

A

lT

T 1 T

430C I I TT i

i T

TI JT

A T_1 T

280C

T T ~ I

T T 230C

T 1 T T

j ~T 20 30 4() 50 6) 70 80

20 (deg)















Drug Delivery







6

d lOOnmh ~m

~ d 300 lm h -- 5 pm

d lOOnmh= IJJm

- FlatTi

o 5 JO 15 20 25

Time (days)






1 0





~O~) 0lt

0 ~~ am~s-






























c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References











































































































J

t ~

-Ii


bull b - ~ C v ( 1~ ~1


r ~ 1 J
















TABLE 51


Electrolyte Systems



HF + HCrO


HF + HPO~


Ethytent glycol

Glycerol + NH4F





Ti + HO - TiO + 2H (51)


TiO + 6F- + H - TiF- + 2Ho (52)

Ti(OI-l) + 6 F- - TiF + 4OH- (53)






(a) OxiQt

Barriet layer -leta

(el

Metal Tube

(e) Pores Void

I Barrier layer

Batrk-r layer













eTi

20 30 4(] 5V 6n 7() 8)

28 (deg)








1OIJ

SO

60

40

20

0

T101-NT -b-Ti2p

-O-Os

0 20 4() 60 ampl H]O

Sputter time (min)

1 6mtn

t =2 min

Omi

470




Binding energy (eV)



R 6SO-C c

R R R R R R RR R

620CR R tl12


~ TI _T T 480C

~ c j

=

AliA T A ~ R

T T

J AI ~~ Air T

TI

A

lT

T 1 T

430C I I TT i

i T

TI JT

A T_1 T

280C

T T ~ I

T T 230C

T 1 T T

j ~T 20 30 4() 50 6) 70 80

20 (deg)















Drug Delivery







6

d lOOnmh ~m

~ d 300 lm h -- 5 pm

d lOOnmh= IJJm

- FlatTi

o 5 JO 15 20 25

Time (days)






1 0





~O~) 0lt

0 ~~ am~s-






























c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References





















































































































TABLE 51


Electrolyte Systems



HF + HCrO


HF + HPO~


Ethytent glycol

Glycerol + NH4F





Ti + HO - TiO + 2H (51)


TiO + 6F- + H - TiF- + 2Ho (52)

Ti(OI-l) + 6 F- - TiF + 4OH- (53)






(a) OxiQt

Barriet layer -leta

(el

Metal Tube

(e) Pores Void

I Barrier layer

Batrk-r layer













eTi

20 30 4(] 5V 6n 7() 8)

28 (deg)








1OIJ

SO

60

40

20

0

T101-NT -b-Ti2p

-O-Os

0 20 4() 60 ampl H]O

Sputter time (min)

1 6mtn

t =2 min

Omi

470




Binding energy (eV)



R 6SO-C c

R R R R R R RR R

620CR R tl12


~ TI _T T 480C

~ c j

=

AliA T A ~ R

T T

J AI ~~ Air T

TI

A

lT

T 1 T

430C I I TT i

i T

TI JT

A T_1 T

280C

T T ~ I

T T 230C

T 1 T T

j ~T 20 30 4() 50 6) 70 80

20 (deg)















Drug Delivery







6

d lOOnmh ~m

~ d 300 lm h -- 5 pm

d lOOnmh= IJJm

- FlatTi

o 5 JO 15 20 25

Time (days)






1 0





~O~) 0lt

0 ~~ am~s-






























c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References













































































































(a) OxiQt

Barriet layer -leta

(el

Metal Tube

(e) Pores Void

I Barrier layer

Batrk-r layer













eTi

20 30 4(] 5V 6n 7() 8)

28 (deg)








1OIJ

SO

60

40

20

0

T101-NT -b-Ti2p

-O-Os

0 20 4() 60 ampl H]O

Sputter time (min)

1 6mtn

t =2 min

Omi

470




Binding energy (eV)



R 6SO-C c

R R R R R R RR R

620CR R tl12


~ TI _T T 480C

~ c j

=

AliA T A ~ R

T T

J AI ~~ Air T

TI

A

lT

T 1 T

430C I I TT i

i T

TI JT

A T_1 T

280C

T T ~ I

T T 230C

T 1 T T

j ~T 20 30 4() 50 6) 70 80

20 (deg)















Drug Delivery







6

d lOOnmh ~m

~ d 300 lm h -- 5 pm

d lOOnmh= IJJm

- FlatTi

o 5 JO 15 20 25

Time (days)






1 0





~O~) 0lt

0 ~~ am~s-






























c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References





















































































































eTi

20 30 4(] 5V 6n 7() 8)

28 (deg)








1OIJ

SO

60

40

20

0

T101-NT -b-Ti2p

-O-Os

0 20 4() 60 ampl H]O

Sputter time (min)

1 6mtn

t =2 min

Omi

470




Binding energy (eV)



R 6SO-C c

R R R R R R RR R

620CR R tl12


~ TI _T T 480C

~ c j

=

AliA T A ~ R

T T

J AI ~~ Air T

TI

A

lT

T 1 T

430C I I TT i

i T

TI JT

A T_1 T

280C

T T ~ I

T T 230C

T 1 T T

j ~T 20 30 4() 50 6) 70 80

20 (deg)















Drug Delivery







6

d lOOnmh ~m

~ d 300 lm h -- 5 pm

d lOOnmh= IJJm

- FlatTi

o 5 JO 15 20 25

Time (days)






1 0





~O~) 0lt

0 ~~ am~s-






























c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References
















































































































1OIJ

SO

60

40

20

0

T101-NT -b-Ti2p

-O-Os

0 20 4() 60 ampl H]O

Sputter time (min)

1 6mtn

t =2 min

Omi

470




Binding energy (eV)



R 6SO-C c

R R R R R R RR R

620CR R tl12


~ TI _T T 480C

~ c j

=

AliA T A ~ R

T T

J AI ~~ Air T

TI

A

lT

T 1 T

430C I I TT i

i T

TI JT

A T_1 T

280C

T T ~ I

T T 230C

T 1 T T

j ~T 20 30 4() 50 6) 70 80

20 (deg)















Drug Delivery







6

d lOOnmh ~m

~ d 300 lm h -- 5 pm

d lOOnmh= IJJm

- FlatTi

o 5 JO 15 20 25

Time (days)






1 0





~O~) 0lt

0 ~~ am~s-






























c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References












































































































R 6SO-C c

R R R R R R RR R

620CR R tl12


~ TI _T T 480C

~ c j

=

AliA T A ~ R

T T

J AI ~~ Air T

TI

A

lT

T 1 T

430C I I TT i

i T

TI JT

A T_1 T

280C

T T ~ I

T T 230C

T 1 T T

j ~T 20 30 4() 50 6) 70 80

20 (deg)















Drug Delivery







6

d lOOnmh ~m

~ d 300 lm h -- 5 pm

d lOOnmh= IJJm

- FlatTi

o 5 JO 15 20 25

Time (days)






1 0





~O~) 0lt

0 ~~ am~s-






























c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References



















































































































Drug Delivery







6

d lOOnmh ~m

~ d 300 lm h -- 5 pm

d lOOnmh= IJJm

- FlatTi

o 5 JO 15 20 25

Time (days)






1 0





~O~) 0lt

0 ~~ am~s-






























c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References














































































































6

d lOOnmh ~m

~ d 300 lm h -- 5 pm

d lOOnmh= IJJm

- FlatTi

o 5 JO 15 20 25

Time (days)






1 0





~O~) 0lt

0 ~~ am~s-






























c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References














































































































1 0





~O~) 0lt

0 ~~ am~s-






























c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References



































































































































c -

- ~ bull

- ~~ ~ bull gt

4 II ~ bull 51

~ bull 11

bull

lID










Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References


















































































































Plasma Spraying




Spray deposit

Cathode













2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References



















































































































2Ti +0 + hI _ 2TP- + Va + 120

Ti- + HO _ Ti- OH + 112H

Sol-Gel Processing














70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References






















































































































70

60

Oil 50

s 40 I 30~

20 C8 10

0 0 200 400 60n 800











Heater

Carrier gas

bull bull Source

gas















Conclusion



References























































































































Conclusion



References











































































































References










































































































biological · growth, and promote osteoblast adhesion and proliferation. nanoporous structures have...

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