Polyampholyte Nanoparticles Prepared by Self-Complexation of Cationized Poly(γ-glutamic acid) for Protein Carriers

A novel amphoteric poly(amino acid) is synthesized by grafting a cationic amino acid (L-Arg) to ?-PGA to prepare charged NPs. ?-PGA-Arg NPs can be prepared by the self-complexation of a single polymer by intra-/inter-molecular electrostatic interactions when the polymer is dispersed in water. The size and surface charge of the NPs can be regulated by the grafting degree of Arg (41, 56, and 83%). The smallest NPs are obtained at 56% grafting degree of the ?-PGA-Arg copolymer. The 56 and 83% grafting degree NPs are stable for at least 1 week. Depending on their surface charge, these NPs can selectively adsorb anionically or cationically charged proteins.