1 POLYMERIC BIOMATERIALS VASCULAR GRAFTS

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 n StateGasLiquidmed. visc. liquid hi visc. liq. solidtough plastic

Cardiovascular Disease Proportion of global NCD deaths under the age of 70, by Cause of death,

Normal Coronary Anatomy 6

Coronary Artery Disease 7 (Plaque, Atherosclerosis)

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.

Samples of coronary arteries 9

10 Treatment Angioplasty & Stent

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 ).

Coronary Artery Properties Tensile Strength (MPa) Young Modulus ( GPa ) Elongation 1.40– ± 345–99% 13 Mechanical Properties

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

Coronary Artery from present work 16

Thanks 17