PEG−Polypeptide Block Copolymers as pH-Responsive Endosome- Solubilizing Drug Nanocarriers

Abstract
Herein we report the potential of click chemistry-modified polypeptide-based block copolymers for the facile fabrication of pH-sensitive nanoscale drug delivery systems. PEG−polypeptide copolymers with pendant amine chains were synthesized by combining N-carboxyanhydridebased ring-opening polymerization with post-functionalization using azide−alkyne cycloaddition. The synthesized block copolymers contain a polypeptide block with amine-functional side groups and were found to self-assemble into stable polymersomes and disassemble in a pH-responsive manner under a range of biologically relevant conditions. The selfassembly of these block copolymers yields nanometer-scale vesicular structures that are able to encapsulate hydrophilic cytotoxic agents like doxorubicin at physiological pH but that fall apart spontaneously at endosomal pH levels after cellular uptake. When drug-encapsulated copolymer assemblies were delivered systemically, significant levels of tumor accumulation were achieved, with efficacy against the triple-negative breast cancer cell line, MDA-MB-468, and suppression of tumor growth in an in vivo mouse model.
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PEG–Polypeptide Block Copolymers as pH-Responsive Endosome-Solubilizing Drug Nanocarriers. - Mol Pharmaceutics. (- 7):- 2420.