Biocompatible/biocompatibility

The response reaction of the host to a foreign material remaining in the body for an extended period of time is a concern. Thus, any polymeric material to be integrated into such a delicate system as the human body must be biocompatible. Biocompatibility is defined as the ability of a material to perform with an appropriate host response in a specific application [79]. The concept include all aspects of the interfacial reaction between a material and body tissues initial events at the interface, material changes over time, and the fate of its degradation products. To be considered bio compatible, a biodegradable polymer must meet a number of requirements, given in Table 2. 

Titanium alloys have also become popular in body implants, such as artificial hips and knees. These alloys are light, strong, long-lasting, and biocompatible. Biocompatible means that the alloy does not cause a reaction when placed into the body. 

The demonstration of metabolism in compressed biphasic systems allowed us to explore the effect of solvent choice and pressure on biocompatibility. Biocompatibility of liquid solvents is frequently correlated with the -octanol water partition coefficient (log F) of the solvent (46). The log P of a substance is defined as the ratio of the molarity of the substance at infinite... 

Evidently chromatography [4] is by far the most imporant technique and it is the fastest growing area. Chromatrographic methods are used extensively in industrial laboratories which purchase about 708 o of the devices made for separation, purification, and analysis. One of the most frequent demands in all forms of chromatography is biocompatibility. Biocompatible instruments are designed to have chemically inert, corrosion-resistant surfaces in contact with biological samples. 

One of the requirements very often placed on polymers designed for the use in an organism (and, at the same time, a very vaguely defined requirement) is their biocompatibility . Biocompatibility should not be understood as an inherent property of a certain polymer but rather as a result of a dynamic process including the rate of polymer accumulation and duration of its persistence in a given compartment, its modification, and the rate of its clearance from the cells and ultimately from the body. All these variables are controlled not only by the molecular parameters of a particular polymer but also by the dose, route and frequency of its administration, which, on the other hand, are conditions dictated by the purpose of its application. 

The problem arises when we start employing biocompatibility for describing material properties in contexts other than the regulatory. Statements like the material is known to be biocompatible, biocompatibility was assessed by ceU culture, or biocompatibility was tested by subcutaneous implantation might sound familiar, but what value do they have to predict clinical outcome ... 

Last but not least, it is worth to mention the studies of cell adhesion to multiple surfaces. This is a broad topic and we cannot even refer to thousands of papers in the field. Here, we will only mention two reviews from the biochemical and physical points of view as well as a more recent review on the relation between wetting properties of implantable materials and its biocompatibility.Biocompatibility of implantable material is probably the hottest topics in material science with application in medicine. 

Facial prostheses may fail due to the limitations in the properties of existing materials, especially the biocompatibility. Biocompatibility of PDMS elastomers (LIM 6050, MDX 4-4210, Silastic 732) was tested in subcutaneous tissue of rats [85]. A histomorphometric evaluation was conducted to analyze the biocompatibihty of the implants. Mesenchymal cells, eosinophils, and foreign-body giant cells were counted. Initially, all implanted materials exhibited an acceptable tissue inflammatory response, with tissue reactions varying from light to moderate. Afterward, a fibrous capsule around the sihcone was observed. In conclusion, the tested silicones were found biocompatible and suitable to use for implantation in both medical and dental areas. Their prosthetic indication is conditioned to their physical properties. Solid sihcone is easier to adapt and does not suffer apparent modifications inside the tissues [85]. 

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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