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Abstract: Reversibly light-responsive and biocompatible micelles with an appropriate size were constructed from an amphiphilic spiropyran-containing hyperbranched polyphosphate (denoted as HPHEEP-SP). The polymer was conveniently synthesized based on the modification of a biodegradable hyperbranched polyphosphate with carboxyl-containing spiropyran molecules. HPHEEP-SP can self-assemble to biocompatible micelles with an average diameter of 186.3 nm and a critical micelle concentration of 0.052 mg mL−1. After 5 min of UV irradiation, the diameter of the micelles decreased gradually to about 100 nm, which is ascribed to the transformation of hydrophobic spiropyran to hydrophilic merocyanine. Subsequent exposure the micelles to visible light, the diameter of the micelles was restored. Model drug coumarin 102 was then encapsulated into the micelles successfully. Light-controlled release and re-encapsulation behaviours were lastly demonstrated by fluorescence spectroscopy. This study provides a convenient way to construct smart nanocarriers for controlled release and re-encapsulation of hydrophobic drugs. [Copyright &y& Elsevier]

Photo-responsive micelles with reversible self-assembly and disassembly behaviours were constructed via the supramolecular host–guest interaction of β-cyclodextrin (β-CD) and an amphiphilic azobenzene-containing hyperbranched polymer (denoted HPHEEP-Azo). The polymer was prepared through the carboxylation of hydroxyl groups in hyperbranched polyphosphate (HPHEEP-OH) with succinic anhydride and the subsequent esterification reaction with 4-hydroxyazobenzene. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements reveal that HPHEEP-Azo can self-assemble into spherical micelles with an average diameter of 169.9 nm in aqueous solution. The critical micelle concentration (CMC) of the micelles is 0.013 mg mL−1. After addition of β-CD into the micellar solution, the micelles dissociated gradually upon increasing the addition amount of β-CD. Irradiation experiments show that reversible self-assembly and disassembly behaviours can be controlled by irradiating with UV and visible light. These photo-responsive micelles self-assembled from hyperbranched polymers might have great potential in various practical applications such as controlled drug release. [ABSTRACT FROM AUTHOR]