Amphiphilic photocleavable block copolymers based on monomethyl poly(ethylene glycol) and poly(4-substituted-ε-caprolactone): synthesis, characterization, and cellular uptake

This paper presents the synthesis of a novel amphiphilic block copolymer containing photodegradable linkers as junction points between hydrophilic and hydrophobic chains. MPEG-ONB-PXCL block copolymers were synthesized by a combination of ROP and clicks from a difunctional photoresponsive initiator (ONB). The copolymers are biodegradable and biocompatible, and can self-assemble into photoresponsive micelles. When polymer solutions were exposed to UV, we observed significant changes in the structure and morphology of particles. Fluorescence emission measurements showed that Nile red (NR), a hydrophobic dye, encapsulated by the MPEG-ONB-PXCL micelles, is released upon irradiation because of disruption of the micelles. Light-triggered bursts were observed for Indomethacin (IMC)-loaded MPEG-ONB-PXCL micelles upon at 30 min of light irradiation. No significant toxicity of these nanoparticles was found, at concentrations up to 1000 mu g mL(-1), before or after light irradiation. The doxorubicin (DOX)-loaded micelles facilitated improved uptake of DOX by HeLa cells within 60 min, and were retained primarily in the cytoplasm.