2010: Stability of Biodegradable Peptide anospheres with PEG Brush Layer for Hydrolysis and Sterilization

Statement of Purpose: Polymeric nanoparticles have been widely studied in biomedical fields such as the drug delivery system (DDS), medical diagnosis, and bioimaging. For the long-term drug delivery system, stability for hydrolysis, stealth property for inhibition of unspecific protein adsorption, and surface functionality for immobilization of specific molecules to target tissues are required. Furthermore, stability for sterilization is also important property for drug delivery carriers. However, there is no report about nanoparticles which satisfy the above requirements. Recently, we reported a novel method for the preparation of the peptide nanospheres with a high density poly(ethylene glycol) (PEG) brush layer. 1-3) The peptide nanospheres were synthesized by the one-step polymerization of L-phenylalanine -carboxyanhydride (Phe-NCA) with the dual initiators of hydrophobic nbutylamine and hydrophilic NH2-monoterminated PEG (NH2-PEG). The peptide nanospheres can avoid nonspecific protein adsorption owing to the surface PEG corona layer, while they can immobilize covalently the target molecules on their surface functional groups (Figure 1). This PEG brush peptide nanosphere is expected to have high stability for hydrolysis due to stable hydrophobic phenylalanine (Phe) core and high density PEG brush. In the present study, we investigated stability of the peptide nanospheres for hydrolysis and autoclaving sterilization.