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Dr. Alagiriswamy A A, (M.Sc, PhD, PDF)Asst. Professor (Sr. Grade),

Dept. of Physics, SRM-University,Kattankulathur campus,

Chennai

UNIT IIILecture 2

ABCs of Biomaterials

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A simple “THANK YOU” makes a difference

Display supportive behavior to ensure team success

To keep up efficiency limit your work : - FATIGUE

Key to people related problems is always with you

Betrayal, however small, causes displeasure among staffs

Interesting cuesInteresting cues

Courtesy : - The Hindu, opportunities, Mar. 18/2014

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CLASSIFICATION OF BIOMATERIALS

COMPARISON OF PROPERTIES OF

BIOMATERIALS

EFFECT OF PHYSIOLOGICAL FLUIDS

BIOLOGICAL RESPONSES

Outline of the Outline of the presentationpresentation

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TYPICAL BIOMATERIAL APPLICATIONs

a biomaterial should not GIVE OFF its mass unless it is specifically designed to do so

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BIOMATERIALS- CLASSIFICATION

Bioinert Biomaterials : -minimal interaction with the tissue stainless steel, titanium, alumina, partially

stabilized zirconia, and ultra high molecular weight polyethylene

Bioactive Biomaterials : - maximum functionality synthetic hydroxyapatite [Ca 10 (PO4)6(OH)2],

glass ceramic and bioglass Bioresorbable Biomaterials : - maximum absorption and

dissolves leads to the maximum advantage of bones tricalcium phosphate [Ca3(PO4)2] and polylactic-

polyglycolic acid copolymers

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SURFACE PROPERTIES

Surface Energy What is a true surface ?

At the surfaces, there are asymmetric forces involved

Quantification of disruption of bonds/surfaces

Metals/ceramics:- high surface energies ranging from 102 to 104 ergs/cm2.

Polymers/plastics have much smaller surface energies, usually <100 ergs/cm2.

Adsorption of gases and/or organic species makes the quantification tougher even for simpler systems.

Why don’t you think off some acute remedies????????????????????????

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Surfaces and Interfaces

“A region of space in which the system undergoes transition from one phase to

another”

Liquid/GasLiquid/LiquidSolid/Solid Solid/Gas Solid/Solid

Surface: Region between condensed phase (S or L) and a gas phase

Interface: Region between two condensed phases

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Contact Anglequantitative measure of the WETTING of a solid by a liquid angle at which a liquid/vapor interface MEETS the solid

surfaceThree interfaces determines the interactions and so angle used to discriminate hydrophobics and hydrophilicsContact angle analysis characterizes the wettability of a

surface by measuring the surface tension of a solvent droplet at its interface with a homogenous surface

Some more surface properties

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Goniometry

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Young-Dupree equation depicts at equilibrium conditionss/g, s/l and l/g are the interfacial free energy

between the solid and gas; solid and liquid, liquid and gas respectively and the contact angles/g = s/l + l/g

cos

Contact angle analysis

The wetting characteristic can be generalized as

= 0, complete wetting ; 0 900, partial wetting ; > 900 , no wetting.

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Critical Surface Tension: - Surface tension is a measurement of the cohesive

energy present at an interface bulk of a liquid are balanced by an equal attractive

force in all directions Molecules on the surface of a liquid experience an

imbalance of forces

Polar liquids, such as water, have strong intermolecular interactions and thus high surface tensions. If temperature increase, surface energy decreases, system collapses

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Critical surface tension by Zisman plot A concept developed in the 1960`s by Walter Zisman The surface tension of a liquid that would completely wet the solid

of interest. Surface energy of surface can be expressed by critical surface

tension. Low critical surface tension means that the surface has a low

energy. Measure on one surface for a series of liquids varying in surface

tension Plot cos Vs lv. Extrapolate to cos = 1.0 ( = 0˚ ) Define c at cos = 1.0 ( = 0˚ )

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Determination of Surface Energy Using Contact Angle (Zisman Plot)

Contact angle measurement of a solid with various liquidsof known surface tension

(Adamson, 1997)

Cos = 1 – b(l - c)

– Contact angleb – 0.03 –0.04l – Surface tension of liquidc – Critical surface tension1

Cos

Extrapolate curve to Cos = 1, obtain c , characteristic of Surface Energy

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Why critical surface tension is so important

Thrombus formation

Blood clotting studies

Other tissue related studies

how to figure it out the biocompatibility, bioinert issues???

Critical Surface Tension

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Examples of interfacial phenomenon

Paints Opacity Color Strength Gloss Viscosity

Food Texture Structure

- Creaming- Settling

Paper Quality

Uniformity Strength

Microelectronics Chemical Mechanical

Polishing (CMP) Stabilization / dispersion of particulate systems impact

the performance of industrial processes.

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