Trypsin-inspired poly(urea-urethane)s containing phenylalanine-lysine ethyl ester-phenylalanine units

A novel tri-peptide derivative phenylalanine-lysine ethyl ester-phenylalanine (PLP) was synthesized by carbodiimide hydrochloride (EDC·HCl) mediated coupling reaction from phenylalanine and lysine ethyl ester in the presence of NHS. Then PLP was used as a chain extender to synthesize a kind of trypsin-inspired poly(urea-urethane)s (PLP-PU) with polyethylene glycol (PEG) as soft segment and hexamethylene diisocyanate (HDI) as hard segment. Enzymatic degradation tests showed that PLP unit was very sensitive to trypsin in its solution. Experimental results indicated that the degradability was obviously improved by introducing PLP into the main chain of poly(urea-urethane) because the PLP was effectively broken by the action of trypsin in the process of degradation.