Synthesis and self-assembly of thermoresponsive amphiphilic biodegradable polypeptide/poly(ethyl ethylene phosphate) block copolymers.

We report the design and synthesis of new fully biodegradable thermoresponsive amphiphilic poly(γ-benzyl L-glutamate)/poly(ethyl ethylene phosphate) (PBLG-b-PEEP) block copolymers by ring-opening polymerization of N-carboxy-γ-benzyl L-glutamate anhydride (BLGNCA) with amine-terminated poly(ethyl ethylene phosphate) (H2NPEEP) as a macroinitiator. The fluorescence technique demonstrated that the block copolymers could form micelles composed of a hydrophobic core and a hydrophilic shell in aqueous solution. The morphology of the micelles as determined by transmission electron microscopy (TEM) was spherical. The size and critical micelle concentration (CMC) values of the micelles showed a decreasing trend as the PBLG segment increased. However, UV/Vis measurements showed that these block copolymers exhibited a reproducible temperature-responsive behavior with a lower critical solution temperature (LCST) that could be tuned by the block composition and the concentration.