title: Facile preparation of well-defined AB2 Y-shaped miktoarm star polypeptide copolymer via the combination of ring-opening polymerization and click chemistry.
abstract: Well-defined AB2 Y-shaped miktoarm star polypeptide copolymer, PZLL-b-(PBLG)2, was synthesized via a combination of ring-opening polymerization (ROP) of alpha-amino acid N-carboxyanhydride (NCA) and click chemistry, where PZLL is poly(epsilon-benzyloxycarbonyl-L-lysine) and PBLG is poly(gamma-benzyl-L-glutamate). First, two types of primary-amine-containing initiators, N-aminoethyl 3,5-bis(propargyloxyl)-benzamide and 3-azidopropylamine, were synthesized and employed for the ROP of NCA, leading to the formation of dialkynyl-terminated PZLL and azide-terminated PBLG, dialkynyl-PZLL and PBLG-N3, respectively. The subsequent copper(I)-catalyzed cycloaddition reaction between dialkynyl-PZLL and slightly excess PBLG-N3 led to facile preparation of PZLL-b-(PBLG)2 Y-shaped miktoarm star polypeptide copolymer. The excess PBLG-N3 was scavenged off by reacting with alkynyl-functionalized Wang resin. The obtained Y-shaped miktoarm star polypeptide copolymer was characterized by gel permeation chromatograph (GPC), Fourier transform-infrared spectroscopy (FT-IR), and (1)H NMR. Moreover, after the hydrolysis of protecting benzyl and benzyloxycarbonyl groups of PZLL-b-(PBLG)2, water-soluble pH-responsive Y-shaped miktoarm star polypeptide copolymer, PLL-b-(PLGA)2, was obtained, where PLL is poly(L-lysine) and PLGA is poly(L-glutamic acid). It can self-assemble into PLGA-core micelles at acidic pH and PLL-core micelles at alkaline pH, accompanied with the coil-to-helix transition of PLGA and PLL sequences, respectively. The spontaneous pH-responsive supramolecular assembly of PLL-b-(PLGA)2 miktoarm star polypeptide copolymer has been investigated via a combination of (1)H NMR, laser light scattering (LLS), transmission electron microscopy (TEM), and circular dichroism (CD) spectroscopy.
authors.affiliation: Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Jingyi
authors.initials: J
authors.lastname: Rao
authors.forename: Yanfeng
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jingyan
authors.initials: J
authors.lastname: Zhang
authors.forename: Shiyong
authors.initials: S
authors.lastname: Liu
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D000812:Anhydrides / Q000737:chemistry; D001672:Biocompatible Materials / Q000737:chemistry*; D002845:Chromatography / Q000379:methods; D003300:Copper / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D046529:Microscopy, Electron, Transmission; D008968:Molecular Conformation; D010455:Peptides / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry
chemical_list: D000596:Amino Acids; D000812:Anhydrides; D001672:Biocompatible Materials; D008823:Micelles; D010455:Peptides; D011108:Polymers; D014867:Water; D003300:Copper