Use of radiation technology in preparing materials for bioengineering and medical science

There is a wide variety of materials which are foreign to the body and which are used in contact with body fluids. These materials are called biomaterials. They include polymers (fibres, rubbers, moulded plastics, emulsions, coatings, fluids, etc.), metals, ceramics, carbons, reconstituted or specially treated natural tissues, and composites of various combinations of such material classes. By far the most diverse use of biomaterials exists within the polymer class: in these organic materials, ionizing radiation has a unique ability to initiate free radical and ionic reactions without the need to add catalysts or to heat. Thus, new polymers or new forms of polymers may be synthesized or existing polymers may be chemically modified by a relatively simple, additive-free processing step at room temperature - sometimes with potential for simultaneous sterilization. Other advantages may be obtained by cooling to the glassy state before irradiation. There are three basic radiation processes which are utilized for preparing new or modified biomaterials. These are: (1) graft co-polymerization of monomers and polymers; (2) radiation polymerization, as pure monomer(s), in solution, as an emulsion, or in the solid state (e.g., below Tsub(G)); and (3) radiation crosslinking, in a solution or swollen state, or in the solid state. Simultaneous or subsequent chemical or biochemical processing steps can yield novel biomaterials having specific biological activity. Immobilization of enzymes, antibodies, drugs, cells etc., on or within the radiation-processed material, can yield novel biomaterials with great potential in the clinic or clinical laboratory. All these processes and products are reviewed. (author)