Molecular designing of biodegradable copolypeptide membranes

Abstract

Two‐component random copolypeptide membranes consisting of N‐(hydroxyalkyl)‐ L‐glutamine and L‐leucine or L‐alanine were prepared by carrying out aminolysis reactions with 3‐amino‐l‐propanol (P) together with crosslinking reaction with octamethylenediamine (OMDA) on membranes of the starting copolymers consisting of γ‐methyl L‐glutamate (M) and L‐leucine (L) or L‐alanine (A). The relation between their bulk structure and properties was investigated with regard to the swelling ratio in water (q), the rate of water vapor permeability (Vf), tensile properties, and enzymatic degradation behavior in a pseudo‐extracellular fluid (PECF). The tensile property of the membranes was highly dependent on q in PECF, and on the hydrophobicity of the side chains. It was shown that a common relation was obtained between Vf and q of membranes in PECF regardless of the difference of the nature of side chains. Biodegradation of the membranes in vitro by bromelain indicated that degradation took place in bulk rather than on a surface, and that the rate of degradation was also highly dependent on q of samples as well as on the hydrophobicity of side chains of samples.