Biodegradation of random co-polypeptide hydrogels consisting of N-hydroxypropyl l-glutamine as one component

Two component random co-polypeptide hydrogels consisting of N-hydroxypropyl l-glutamine and l-alanine (Ala) or l-phenylalanine (Phe) were prepared by performing aminolysis reactions with 3-amino-1-propanol together with crosslinking reaction with 1,8-octamethylenediamine on hydrogels of the starting co-polymers consisted of γ-benzyl l-glutamate and Ala or Phe. The relationship between their bulk structure and properties was evaluated with regard to the swelling ratio in water (q), the rate of water vapor permeability (Vf), tensile properties, and enzymatic degradation behaviors of hydrogels in a pseudo-extracellular fluid (PECF). The tensile property of the hydrogels was highly dependent on q in PECF, and on the hydrophobicity of the side chains. A relationship was obtained between the Vf and q of hydrogels in PECF regardless of the differences in the nature of the side chains. Biodegradation of the hydrogels in vitro by bromelain indicated that degradation took place in bulk rather than on the surface, and that the rate of degradation was also highly dependent on q in the samples as well as on the hydrophobicity of the side chains of the samples.