Folate-Conjugated Poly(N-(2-hydroxypropyl) methacrylamide)-block-Poly(benzyl methacrylate): Synthesis, Self-Assembly, and Drug Release

Well-defined amphiphilic diblock copolymers of poly(N-(2-hydroxypropyl)methacrylamide)-block-poly(benzyl methacrylate) (PHPMA-b-PBnMA) are synthesized using reversible additionfragmentation chain transfer polymerization. The terminal dithiobenzoate groups are converted into carboxylic acids. The copolymers self-assemble into micelles with a PBnMA core and PHPMA shell. Their mean size is <30 nm, and can be regulated by the length of the hydrophilic chain. The compatibility between the hydrophobic segment and the drug doxorubicin (DOX) affords more interaction of the cores with DOX. Fluorescence spectra are used to determine the critical micelle concentration of the folate-conjugated amphiphilic block copolymer. Dynamic light scattering measurements reveal the stability of the micelles with or without DOX. Drug release experiments show that the DOX-loaded micelles are stable under simulated circulation conditions and the DOX can be quickly released under acidic endosome pH.