Biocompatability

Much of tire science of biocompatibility can be reduced to tire principles of how to detennine tire interfacial energies between biopolymer and surface. The biopolymer is considered to be large enough to behave as bulk material witli a surface since (for example) a water cluster containing only 15 molecules and witli a diameter of 0.5 nm already behaves as a bulk liquid [132] it appears tliat most biological macromolecules can be considered to... 

Refreshingly original approach to a topic of central importance in biology and biocompatibility. 

Applications. Polymers with small alkyl substituents, particularly (13), are ideal candidates for elastomer formulation because of quite low temperature flexibiUty, hydrolytic and chemical stabiUty, and high temperature stabiUty. The abiUty to readily incorporate other substituents (ia addition to methyl), particularly vinyl groups, should provide for conventional cure sites. In light of the biocompatibiUty of polysdoxanes and P—O- and P—N-substituted polyphosphazenes, poly(alkyl/arylphosphazenes) are also likely to be biocompatible polymers. Therefore, biomedical appHcations can also be envisaged for (3). A third potential appHcation is ia the area of soHd-state batteries. The first steps toward ionic conductivity have been observed with polymers (13) and (15) using lithium and silver salts (78). 

To be biocompatible is to interact with all tissues and organs of the body in a nontoxic manner, not destroying the cellular constituents of the body fluids with which the material interfaces. In some appHcations, interaction of an implant with the body is both desirable and necessary, as, for example, when a fibrous capsule forms and prevents implant movement (2). 

Vitahium FHS ahoy is a cobalt—chromium—molybdenum ahoy having a high modulus of elasticity. This ahoy is also a preferred material. When combiaed with a properly designed stem, the properties of this ahoy provide protection for the cement mantle by decreasing proximal cement stress. This ahoy also exhibits high yields and tensile strength, is corrosion resistant, and biocompatible. Composites used ia orthopedics include carbon—carbon, carbon—epoxy, hydroxyapatite, ceramics, etc. 

M. Szycher, Biocompatible Polymers, Metals and Composites, Technomic Publishing Co., Inc., Lancaster, Pa., 1983. 

Requirements. Requirements for dental implant materials are the same as those for orthopedic uses. The first requirement is that the material used ia the implant must be biocompatible and not cause any adverse reaction ia the body. The material must be able to withstand the environment of the body, and not degrade and be unable to perform the iatended function. 

Hydroxyapaite, the mineral constituent of bone, is appHed to the surfaces of many dental implants for the purpose of increasing initial bone growth. Some iavestigators beHeve that an added benefit is that the hydroxyapatite shields the bone from the metal. However, titanium and its aHoy, Ti-6A1-4V, are biocompatible and have anchored successfuHy as dental implants without the hydroxyapatite coating. 

The realization of sensitive bioanalytical methods for measuring dmg and metaboUte concentrations in plasma and other biological fluids (see Automatic INSTRUMENTATION BlosENSORs) and the development of biocompatible polymers that can be tailor made with a wide range of predictable physical properties (see Prosthetic and biomedical devices) have revolutionized the development of pharmaceuticals (qv). Such bioanalytical techniques permit the characterization of pharmacokinetics, ie, the fate of a dmg in the plasma and body as a function of time. The pharmacokinetics of a dmg encompass absorption from the physiological site, distribution to the various compartments of the body, metaboHsm (if any), and excretion from the body (ADME). Clearance is the rate of removal of a dmg from the body and is the sum of all rates of clearance including metaboHsm, elimination, and excretion. 

J. Hermansson, A. Grahn and I. Hermansson, Direct injection of large volumes of plasma/semm of a new biocompatible exti action column for the determination of atenolol, propanolol and ibuprofen . Mechanisms for the improvement of clrromato-grapliic performance , J. Chromatogr. A 797 251-263 (1998). 

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