Poly prosthetic materials

Poly(2-hydroxyethyImethacrylate) gels (PHEMA) and its composites have been widely proposed for several uses as prosthetic materials for the good biocompatibility and/or hemocompatibility which seems to be connected to the water structure inside the gel. ... 

The suitability of poly(ethylene terephthalate) as an arterial prosthetic material has been reviewed and collected clinical experiences of its role in the correction of transposition of the great arteries have been reported together with cases of its failure in arterial prostheses. The suitability of polytetrafluoroethylene e.g. Goretex) has been similarly considered. Vascular access for chronic haemodialysis presents particular problems associated with the need for repeated usage. 

For much of the last century, scientists attempted to make useful plastics from hydroxy adds such as glycolic and lactic acids. Poly(glycolic acid) was first prepared in 1954, but was not commercially developed because of its poor thermal stability and ease of hydrolysis. It did not seem like a useful polymer. Approximately 20 years later it found use in medicine as the first synthetic suture material, useful because of its tendency to undergo hydrolysis. After the suture has served its function, the polymer biodegrades and the products are assimilated (Li and Vert 1995). Since then, suture materials, prosthetics, artificial skin, dental implants, and other surgical devices made from polymers and copolymers of hydroxy carboxylic acids have been commercialized (Edlund and Albertsson 2002). 

The electrochemistry of the PQQ (pyrrolo-quinoline quinone) prosthetic group has been investigated at poly(pyrrole)-coated electrodes, and PQQ has been entrapped within poly(pyrrole) films " good electrochemistry was observed in both cases. Poly(pyrrole) has also been used to entrap adenosine triphosphate (ATP) anions, again by growing the film in the presence of the anion, " and as an electrode material for oxidizing ascorbate. " In the latter case the oxidation... 

The way in which Cherian et al. fabricated the nanobiocomposites was by stacking the cellulose nanofiber mats between polyurethane films and pressing by compression molding. With the addition of 5 wt% cellulose nanofbers into polyurethane the strength and stiffness increased by nearly 300% and 2600%, respectively. The developed composites were utilized to fabricate various versatile medical implants. Cellulose poly-urethanes-based materials are sufficiently durable and blood compatible for potential use in a prosthetic heart valves and effectively showed less mineralization than glutar-aldehyde-fixed bovine pericardial tissue [231]. 

A major use of plastics in surgery is to replace soft tissue such as a prosthetic breast, testicles, etc. The major polymer used here is poly(dimethylsiloxane) and these uses have been summarized in some recent articles (46,47). The major requirements for soft tissue replacements are (a) a consistency similar to the natural tissue being replaced, (b) no change in this consistency on aging in the body, (c) no fibrous ingrowth and (d) no adverse reactions with the body tissues. Porous and/or woven materials are usually unsuitable for this use since fibrous ingrowth normally leads to a pronounced loss in flexibility and a hard feel to the implant. Soft tissue implants usually do not come into direct contact with the blood and this problem is not particularly critical in this use. In... 

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