| Research Abstract |
The development of tissue adhesion prevention material has been long awaited in surgery. Tissue adhesion after surgery occasionally causes serious complications. Various studies have been undertaken to develop materials that prevent tissue adhesion. These function as a barrier to enable traumatized tissue to be separated from adjacent tissues during the healing process. These materials should be free from cellular adhesion, should be flexible and tough enough to provide for a tight cover over the traumatized soft tissues, and should be biodegradable and resorbable after the injured tissue is completely regenerated. To fully realize these requirements, natural polymers such as fiberous proteins or polysaccharides, which exist as highly water-adsorbable biomaterials filling interstices of tissues, have been considered to be best suited as basic materials. Synthetic polypeptides and their copolymers which carry hydrophilic components offer potential for enzymatic degradable medical applic
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We have prepared many types of hydrophilic polypeptide membranes which are composed of hydrophilic and hydrophobic amino acid components as models of natural fibrous proteins. These includes ; A-B-A type block copolymers consisting of a hydrophilic polypeptide as the A component and polyisoprene as the B component, copoly (N-hydroxyalkyl-D,L-glutamaine)s, two-component random copolypeptides consisting of N-hydroxyalkyl-L-glutamine and L-alanine, L-leucine, or L-valine, and three-component random copolypeptides consisting of N-hydroxyalkyl-L-glutamine, L-glutamic acid, and L-lysine. Hydrophilic membranes or hydrogels were prepared by using a crosslinking reaction with diamine on the starting membranes. It was commonly shown that the effective crosslink density was proportional to the molar % of diamine in the reaction mixture. The relation between their bulk structure and properties was investigated with regard to the swelling ratio in water, tensile properties, and enzymatic degradation behavior in a pseudo-extracellular fluid (PECF). The tensile properties of the hydrophilic membranes were highly dependent on the swelling ratio in PECF,and on the hydrophobic portions in molecular chains, whose behavior was typical of an elastomer. Biodegradations of these membranes in viro by a protease indicated that the degradation took place in bulk rather than on a surface, and that the rate of degradation was also highly dependent on the swelling ratio of membranes, the hydrophobicity, effective charge density, as well as D,L-comonomer composition, of the side chains of samples. Less
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