In vitro Enzymatic Degradation of Nanoparticles Prepared from Hydrophobically-Modified Poly(γ-glutamic acid)

Amphiphilic poly(γ‐glutamic acid) (γ‐PGA) was prepared by the introduction of L‐phenylalanine ethylester (L‐PAE) as a side chain. This γ‐PGA‐graft‐L‐PAE formed monodispersed nanoparticles in water. The particle size of the γ‐PGA nanoparticles could be controlled by the degree of L‐PAE grafting. The hydrolytic degradation and enzymatic degradation by γ‐glutamyl transpeptidase (γ‐GTP) of these γ‐PGA nanoparticles was studied by gel permeation chromatography (GPC) and scanning electron microscopy (SEM). The hydrolysis ratio of γ‐PGA was found to decrease upon increasing the hydrophilicity of the γ‐PGA. The degradation of the γ‐PGA backbone by γ‐GTP resulted in a dramatic change in nanoparticle morphology. With increasing time, the γ‐PGA nanoparticles reduced in size and finally disappeared completely. Time‐course of the changes in the morphology of the γ‐PGA nanoparticles following incubation with γ‐glutamyl transpeptidase.