Synthesis of controlled, high-molecular weight poly(L-glutamic acid) brush polymers

We report the synthesis and characterization of high-molecular weight poly(L-glutamic acid) based brush polymers. Utilizing a combination of ring-opening metathesis polymerization of norbornene based monomers and ring-opening polymerization of gamma-benzyl-L-glutamate N-carboxyanhydride, high-molecular weight.-benzyl protected poly(L-glutamic acid) brush polymers are synthesized. Controlled and complete deprotection of the benzyl groups using trimethylsilyl iodide resulted in poly(L-glutamic acid) based brush polymers with molecular weights up to 3.6 MDa, which may potentially be used to prepare size-controlled unimolecular polymeric nanomedicine for drug delivery applications. Camptothecin brush poly(L-glutamic acid) conjugates were prepared and their stability, drug release kinetics, and in vitro toxicity were studied.