A new type of toothbrush like polypeptide with poly-L-lysine (PLL) as backbone was synthesized via a combination of ring opening polymerization (ROP) and atom transfer radical polymerization (ATRP).A N-bromoisobutyryl functionalized N-CBZ-L-lysine was prepared and subsequently converted into -amino acid N-carboxyanhydride (Br-Lys-NCA).Then

a series of well-defined PZLL-PBrLL diblock copolypeptides were prepared via Ni(COD)depe mediated living ROP and sequential monomer addition strategy.These diblock copolypeptides containing a block of bromo-functionalized poly-L-lysine were then used as macroinitiator for subsequent ATRP of EGMA monomers to make toothbrush copolypeptides.The structure and composition of block and toothbrush copolypeptides were characterized using GPC/LLS

1H-NMR and FTIR.The successful reaction and chain extensions were firstly supported from FTIR characterization for NCA characteristic absorbance.The GPC results demonstrated the apparent increase of samples' molecular weight as the linear copolypeptide was converted into copolypeptide brushes.1H-NMR spectra verified the formation of homopolypeptide and copolypeptides.The secondary structures of both block and toothbrush copolypeptides were investigated using circular dichroism (CD).It was found that the -helical content of PZLL-b-PBrLL diblock copolypeptide decreased with the reduction of mass fraction and chain length of PZLL.For toothbrush copolypeptides

the helicity was substantially lower than corresponding diblock precursors

and decreased with growing side chain length of PEGMA.Herein

we demonstrated a facile method to synthesize the biodegradable copolypeptide toothbrush with tunable spatial configurations and secondary structures by combining NCA ring opening polymerization and controlled ATRP technology.Moreover

such strategy can be easily expanded to make temperature and pH responsive copolypeptide toothbrushes.