Presentation on theme: "1 POLYMERIC BIOMATERIALS VASCULAR GRAFTS. 2 Biomaterials The normal description of a biomaterial is “any substance (other than a drug) or combination."— Presentation transcript:
2 Biomaterials The normal description of a biomaterial is “any substance (other than a drug) or combination of substances, synthetic or natural in origin, which can be used for any period of time, as a whole or as a part of a system which treats, augments, or replaces any tissue, organ, or function of the body’’
3 Biomaterials Selection Criteria The physicochemical properties Biocompatibility Mechanical requirements The nature of the physiological environment at the organ/tissue level The desired function of the prosthesis Cost
Polymeric Biomaterials 4 Polymers - long chain molecules of high molecular weight [-(CH 2 ) n - ] Covalent, H-bonding, Entanglements Replacement and augmentation of various soft tissues(vascular grafts, heart valves, artificial hearts, breast implants and contact lenses). Polytetrafluoroethylene, and Silicone rubber n1-45-119-1616-25 25- 50 1000- 3000 StateGasLiquidmed. visc. liquid hi visc. liq. solidtough plastic
Cardiovascular Disease Proportion of global NCD deaths under the age of 70, by Cause of death, 2008. 5
What is Heart Attack? 8 Coronary artery becomes blocked - usually by a clot. Blood flow is closed off and a heart attack begins. If blockage continues, parts of the heart muscle start to die. Heart may stop beating.
11 Treatment Coronary Artery Bypass Graft (CABG) Surgery
12 History of Polymer Biomaterial in Artery Prosthesis late of 1800s Autologous grafting (veins and arteries).. Early of 1900s Synthetic implants become available (PVA,PA,PTFE,PE) 1958 PU become available 2005 A multiwalled carbon nanotubes-polyurethane composite (MWNT-PU) 2007 Enhancement of the polyurethane properties, were prepared in various compositions and in medical purity without using any solvent, catalyst or additives. 2009 Fabricated Small diameter vascular grafts from pure Polyurethane (PU), as well as PU reinforced with a weft-knitted tubular fabric(Polyester filament ).
Polyurethane Elastomer Polyurethanes possess more complex chemical structures that typically comprise three monomers: a diisocyanate, a macroglycol (which is an oligomeric macromonomer) and a chain extender Due to this unique composition, the structure of polyurethanes is quite different from that of other polymers. In fact, PU elastomers usually show a two-phase structure in which hard segment-enriched domains are dispersed in a matrix of soft segments. The hard segment-enriched domains are composed mainly of the diisocyanate and the chain extender, while the soft segment matrix is composed of a sequence of macroglycol moieties. 14
Polymer Blend Mixing of two or more different polymers together makes it possible to achieve various property combinations of the final material—usually in a more cost-effective way than in the case of synthesis of new polymers. Silicone rubber (SR): is a rubber-like material composed of silicone itself a polymer containing silicon together with carbon, hydrogen, and oxygen. biocompatibility superior chemical resistance. Good mechanical properties. low bacterial action and thrombogenicity. 15