PEG Brush Peptide Nanospheres with Stealth Properties and Chemical Functionality

Abstract

Peptide nanospheres with PEG brushes were prepared by the one-step polymerization of l -phenylalanine (Phe) N -carboxyanhydride with the dual initiators of hydrophobic n -butylamine and hydrophilic NH 2 -monoterminated PEG (NH 2 -PEG). We successfully prepared peptide nanospheres with CH 3 O or COOH groups using CH 3 O- or COOH-terminated PEG as one of the initiators. The high-density PEG brush conformation of the peptide nanospheres was confirmed by 1 H NMR measurements. FT-IR measurements suggested closely packed Phe polymer chains in the core in a β-strand conformation. The results of protein adsorption experiments onto both nanosphere surfaces indicated that PEG-brush corona layers inhibited nonspecific protein adsorption, even in Eagle's medium (10% FBS). Furthermore, target proteins were covalently immobilized onto the surface of the COOH-PEG peptide nanospheres by amide bond formation. Peptide nanospheres with PEG brushes may be useful as novel nanospheres possessing both stealth properties and chemical functionality for drug delivery systems and biological diagnosis.