Hydrogels assembled from star-shaped polypeptides with dendrimer as core

A second or fourth generation dendrimer with primary amine as peripheral terminal groups was firstly synthesized via Michael addition and thiol-yne addition. A series of star-shaped polypeptide was synthesized by ring opening polymerization (ROP) of γ-(2-(2-methoxyethoxy)ethyl) L-glutamate (LEG2Glu) N-carboxyanhydride (NCA) using amine group terminated dendrimer as initiator. Taking advantage of well-defined dendrimer and ROP, the arm number and arm length can be easily controlled. 10 These star-shaped poly(L-EG2Glu) can spontaneously form hydrogels instead of micelles in water at low concentration. The critical gelation concentration (CGC) and hydrogel strength displayed stronger dependence on arm numbers than the arm length given similar conditions. These properties can be easily modulated by varying poly(L-EG2Glu) arm length and arm number. The hydrogels showed shear thinning and rapid recovery properties. TEM and AFM characterizations revealed the hydrogel networks were 15 constituted by entangled and branched fibrils.