Bio-recognizable and photo-cleavable block copolymers based on sugar and poly(4-substituted-ε-caprolactone) bearing a photo-cleavable junction

In this study, we synthesized bio-recognizable and photo-cleavable amphiphilic block copolymers containing photodegradable linkers, 5-hydroxy-2-nitrobenzyl alcohol, as junction points between bio-recognizable hydrophilic glucose (or maltose) 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, substantial structural and morphological changes were observed in the particles. The copolymers were biodegradable and biocompatible, and they could self-assemble into spherical photo-responsive micelles. Fluorescence emission measurements indicated the release of Nile red, a hydrophobic dye, encapsulated by the Glyco-ONB-PXCL micelles, in response to irradiation caused by the disruption of the micelles. Selective lectin binding experiments confirmed that the glycosylated Glyco-ONB-PXCL could be used to bio-recognition applications. The nanoparticles were associated with negligible levels of toxicity at concentrations of less than 30 μg mL⁻¹. The confocal microscopy and flow cytometry results showed that the uptake of doxorubicin (DOX)-loaded micelles by HeLa cells was faster than that of free DOX.