Aqueous ROPISA of α-amino acid N-carboxyanhydrides: polypeptide block secondary structure controls nanoparticle shape anisotropy

Abstract

Polymerization-induced self-assembly (PISA) is an efficient one-step process to obtain nanomaterials. In this work, aqueous ring-opening polymerization induced self-assembly (ROPISA) of α-amino acid N-carboxyanhydride (NCA) affords controllable well-defined nanoassemblies. ROPISA with the PEG_{5 kDa}-NH₂ macroinitiator and either the benzyl-L-glutamate NCA (BLGNCA) or L-leucine NCA (LeuNCA) monomer yields amphiphilic block copolymers, with different polypeptide molar masses, which spontaneously form nanostructures. In contrast to the previous PISA process where the hydrophobic to hydrophilic ratio was the main parameter defining nanomaterial morphology, the secondary structure of the polypeptides is the main driving force to stabilize the anisotropic rod-like nanostructures with this ROPISA process.