Polymer for Medical Applications

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 α-carbon atom with three different isomers as D-, L- and DL-lactic acid) PLGA is most widely investigated biodegradable polymers for drug delivery. Lactide/glycolide copolymers have been subjected to extensive animal and human trials without any significant harmful side effects

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 Biodegradable Polymers as Drug Carrier Systems

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 µm, then press into circular disc –Alternatively drug can be mixed into molten polymer to form small chips, then it is fed into injection molder to mold into desired shape Biodegradable Polymers as Drug Carrier Systems

Why nanoparticles are desired for drug delivery system? Biodegradable Polymers as Drug Carrier Systems

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 Biodegradable Polymers as Drug Carrier Systems

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 filled with inorganic fine particles)

In 19 th century, gutth-percha was used for filling In 1909, PMMA was used as artificial teeth filling In 1930s, polyamide, polyester, polyethylene were prepared in different forms (rigid, soft, fibers, adhesives, etc) for several applications (filling, implant, sutures, etc) Polymer for Dental Application

Schematic of different area of chemistry

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 of polyacrylic acid Polymer for Dental Application

Filling & Restorative Materials –Made up of organic matrix and inorganic particulate or fibrous filling. Held together by coupling agent –PMMA resins have been used as filling materials, but they have several disadvantages Nonadhesion to dental structures Low colour stability Low molecular weight of monomer High polymerization shrinkage Polymer for Dental Application

2000 BC, natural fibers like linen, silk, horsehair were 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 wound closure 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

Commercial Suture materials Braided Polyester Multifilament nylon Polythetrafluoroethylene

Wound closure biomaterials are divided into; –Suture materials –Tissue adhesives –staplers Textile based Biomaterials for Surgical Application

Suture- is a strand of textile materials (natural or synthetic), used to ligate blood vessel and draw tissue together Ideal suture should –Physical and mechanical properties (adequate tensile strength, etc) –Handling properties (easy to handle) –Biological properties (unfavourable for bacterial growth) –Biodegradation properties (absorbable; its tensile strength loss must match the healing rate of the tissue to be closed) Textile based Biomaterials for Surgical Application

Table of Relative Tissue Reactivity to Sutures

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 Textile based Biomaterials for Surgical Application

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 forces is removed

Various famililes of Elastomers –General-use elastomer- natural rubber (NR), styrene butadiene rubber (SBR), etc –Special elastomer- ethylene propylene and diene copolymer (EPM, EPDM), nitrile butadiene copolymer (NBR) –Very special elastomers- high thermal and/or chemical resistance elastomer- fluoroelastomer, silicone elastomer, etc –Thermoplastic elastomer Biocompatibility of Elastomer

Silicone elastomer –Widely used because it is strong, very mobile bone of their Si-O-Si (siloxane) caternary backbone; which provide chemical inertness and flexibility, stable over time at a body temp., show little tissue reactivity, and highly resistant to chemical attack and heat. Biocompatibility of Elastomer

Medical device in human body