Photo-responsive amphiphilic poly(α-hydroxy acids) with pendent o-nitrobenzyl ester constructed via copper-catalyzed azide-alkyne cycloaddition reaction

Photo-responsive block copolymer mPEG-b-poly(Tyr)-g-NB was prepared by introduction of o -nitrobenzyl ester group into the side chain of amphiphilic poly(ethylene glycol)-b-poly( α -hydroxy acids) (mPEG-b-poly(Tyr)) containing pendent alkynyl group via copper-catalyzed azide-alkyne cycloaddition reaction. The amphiphilic mPEG-b-poly(Tyr) was synthesized via the ring-opening polymerization of O -carboxyanhydrides, with monomethoxy poly(ethylene glycol) (mPEG) as macroinitiator. The molecular structure, self-assembly, and photo-controlled release of the obtained mPEG-b-poly(Tyr)-g-NB were thoroughly investigated. mPEG-b-poly(Tyr)-g-NB could self-assemble into spherical micelles in water and showed disassembly under UV light irradiation, which was demonstrated by means of UV-vis spectroscopy, scan electron microscopes, and dynamic light scattering measurement. Fluorescence emission measurements demonstrated that Nile red, encapsulated by micelles, can be released upon UV irradiation. This study provides a convenient way to construct smart poly( α -hydroxy acids)-based nanocarriers for controlled release of hydrophobic drugs. Copyright © 2015 John Wiley & Sons, Ltd.