polymers for medical applications

8/10/2019 Polymers for Medical Applications

1/23

Polymer for Medical

Applications


2/23

Biodegradable Polymers as Drug

Carrier Systems

Polyesters

Lactide/Glycolide Copolymers Have been used for the delivery of steriods,

anticancer agent, antibiotics, etc. PLLA is found as an excellent biomaterials and

safe for in vivo (Lactic acid contains an asymmetric-carbon atom with three different isomers as D-,L- and DL-lactic acid)

PLGA is most widely investigated biodegradablepolymers for drug delivery.

Lactide/glycolide copolymers have been subjectedto extensive animal and human trials without any

significant harmful side effects


3/23

Poly(amides)

Natural Polymers

Remain attractive because they are natural

products of living organism, readily available,relatively inexpensive, etc.

Mostly focused on the use of proteins such as

gelatin, collagen, and albumin


Carrier Systems


4/23

Polymer Processing

Drug-incorporated matrices can be formulated

either compression or injection molding

Polymer & drug can be ground in a Micro Mill,

sieve into particle size of 90-120 m, then

press into circular disc

Alternatively drug can be mixed into moltenpolymer to form small chips, then it is fed into

injection molder to mold into desired shape


Carrier Systems


5/23

Why nanoparticles are desired for drug

delivery system?


Carrier Systems


6/23

Nanoparticles can be used to increase drug

solubility, have lower toxicity & target drug

delivery

In order to use nanoparticle as drug delivery,

they must satisfy number of criteria;

Biocompatible

Good drug payload

Manufacturing cost must be reasonable


Carrier Systems


7/23

Polymer for Dental Application

Four main groups of materials used in

dentistry;

Metal and alloys

Ceramics

Synthetic organic polymers & biopolymers

(derived from natural tissues)

Composites (an organic matrix polymers filledwith inorganic fine particles)


8/23

In 19thcentury, gutth-percha was used forfilling

In 1909, PMMA was used as artificial teeth

filling In 1930s, polyamide, polyester,

polyethylene were prepared in different

forms (rigid, soft, fibers, adhesives, etc) forseveral applications (filling, implant,sutures, etc)



9/23

Schematic of different area of

chemistry


10/23

Bases, liners and varnishes for cavities

There is a large diversity or organic and

inorganic materials for this purposes

Zinc polycarboxylate (or polyacrylate) cement

is prepared by mixing zinc oxide and the

polymer solution, and water solution ofpolyacrylic acid



11/23

Filling & Restorative Materials

Made up of organic matrix and inorganicparticulate or fibrous filling. Held together by

coupling agent PMMA resins have been used as filling

materials, but they have severaldisadvantages

Nonadhesion to dental structures Low colour stability

Low molecular weight of monomer

High polymerization shrinkage



12/23

2000 BC, natural fibers like linen, silk, horsehairwere used as suture materials

After world war II revolution of medical textile,

used of steel wire and synthetic fibers (PP,nylon, polyester)

In early 1970s, two synthetic absorbable woundclosure biomaterials, i.e. Dexon & Vicyrl were

introduced The four most widely used textile structure;

woven, knitted, nonwoven and braided

Textile based Biomaterials for

Surgical Application


13/23

Commercial Suture materials

Braided PolyesterMultifilament nylon

Polythetrafluoroethylene


14/23

Wound closure biomaterials are divided

into;

Suture materials

Tissue adhesives

staplers




15/23

Suture- is a strand of textile materials (natural orsynthetic), used to ligate blood vessel and drawtissue together

Ideal suture should Physical and mechanical properties (adequate tensile

strength, etc)

Handling properties (easy to handle)

Biological properties (unfavourable for bacterialgrowth)

Biodegradation properties (absorbable; its tensilestrength loss must match the healing rate of the tissueto be closed)




16/23

Table of Relative Tissue Reactivity

to Sutures


17/23

Suture materials can be classified into 2

broad categories;

Absorbable;loss their entire tensile strength

within two to three months

Nonabsorbable; retain their strength longer

than two to three months




18/23

Biocompatibility of Elastomer

Elastomer-definition

Flexible- i.e.have low rigidity

Highly deformable, i.e. able to withstand

strong deforming forces without rupturing and

have elongation at rupture over 200%

Elastic or resilient, i.e. able to return to their

original shape and size after deforming forcesis removed


19/23

Various famililes of Elastomers

General-use elastomer- natural rubber (NR),styrene butadiene rubber (SBR), etc

Special elastomer- ethylene propylene anddiene copolymer (EPM, EPDM), nitrilebutadiene copolymer (NBR)

Very special elastomers- high thermal and/or

chemical resistance elastomer-fluoroelastomer, silicone elastomer, etc

Thermoplastic elastomer



20/23

Silicone elastomer

Widely used because it is strong, very mobile

bone of their Si-O-Si (siloxane) caternary

backbone; which provide chemical inertnessand flexibility, stable over time at a body

temp., show little tissue reactivity, and highly

resistant to chemical attack and heat.



21/23


22/23


23/23

Medical device

in human body

polymers for medical applications

Documents