Synthesis and characterization of amphiphilic photocleavable polymers based on dextran and substituted-ε-caprolactone

In this study, we synthesized photocleavable amphiphilic block copolymers containing photodegradable linkers, 5-hydroxy-2-nitrobenzyl alcohol, as junction points between hydrophilic dextran (or maltodextrin) and hydrophobic poly(4-substituted-ε-caprolactone) chains, by using a combination of ring-opening polymerization and nucleophilic substitution reactions. When the polymer solutions were exposed to ultraviolet (UV) irradiation, major structural and morphological changes were observed in the particles. The copolymers were biodegradable and biocompatible, and they can self-assemble into spherical photoresponsive micelles. Fluorescence emission measurements indicated the release of Nile red, a hydrophobic dye, encapsulated by the Dex-ONB-PXCL micelles, in response to irradiation caused by the disruption of the micelles. Light-triggered bursts were observed for indomethacin (IMC)-loaded Dex-ONB-PXCL micelles during the first 5 h. The nanoparticles were associated with nonsignificant toxicityat concentrations of less than 100 μg mL¹. The confocal microscopy and flow cytometry results showedthat the uptake of DOX-loaded micelles by HeLa cells was slightly less than that of free DOX, and it waspredominantly retained in the cytoplasm.