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This Defense Intelligence Agency reference document, dated 7 January 2010 and prepared under the Acquisition Threat Support series, surveys biomaterials used in medicine. It covers biocompatibility, biosensor membranes, silicones, Teflon, biodegradable polymers, hydrogels, titanium, bioceramics, tissue constructs, cardiovascular stents, contact lenses, drug delivery and dialysis. It concludes that biomaterial performance underlies many medical devices, that the industry is slow to adopt new materials because of testing costs, and that innovation mainly involves new applications of established materials.
UNCLASSIFIEDJ'71POR OPPICIIIIL t.HH! 8HL-■' An appropriate selection of the polymer matrix is necessary in order to develop a successful drug delivery system. The most commonly used polymers for this application, polylactide (PLA) and poly(lactide-co-glycollde) (PLGA), have been used in biomedical applications for more than 20 years and are known to be biodegradable, biocompatible, and nontoxic. A vast amount of literature is available on the characterization of these polymers and their biodegradation and drug-release properties. • MEDICAL TITANIUM AS A BIOMATERIAL Titanium metal has qualities of strength, inertness, and a biological c:ompatibility that make it desirable as a biomateriaf. Essentially all pacemakers, neurostimulators, and various other implanted medical devices use titanium as a packaging case material. Titanium metal exposed briefly to the atmosphere oxidizes to form a microscopically thin layer of titania (titanium oxide). Titania is a hard, adherent, and inert ceramic-like compound and ls thought to be largely responsible for titanium's acceptability in biomedical applications where metal corrosion in warm, salty body fluids ordinarily would be a problem. Titanium is used for its high strength in replacement hip and knee joints. In these cases, it is important how the metal integrates with living tissue and bone because load must be transferred from the metal to the bone. Titanium generally does exceedingly well and is used as the metal of choice in nearly all biomedical applications where high strength and impact resistance is important. Titanium has a particular ability among the various metals that might otherwise be chosen in that it can integrate itself well with living bone. The recognition of this dates back to 1952, when Swedish Professor Per-Ingvar Branemark conducted an experiment in which he studied blood flow in living rabbit bone. The bone was fixed in a roughly machined titanium holder. At the conclusion of the experiment, after many days, he found that the bone had integrated so completely with the titanium that removing it was impossible. He called this osseointegration and saw the possibilities for human use. Figure 29 shows a photomicrograph of a titanium-bone interface. The close approximation of the titanium (black) to the tissue is an indicator of a close-metal- tissue integration. Osseointegration was first implemented in dentistry to fixate teeth. It is now also is used for head and jaw reconstruction. 22 UNCLASSIFIED 1 <&OR O&&ICI0I 11€6 At!' Y ' ;
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 32 pages are in the text index: search them above, or from the library's search.