Photo-responsive, biocompatible polymeric micelles self-assembled from hyperbranched polyphosphate-based polymers

Photo-responsive biocompatible micelles were constructed from amphiphilic hyperbranched polyphosphate based polymer (denoted as HPHEEP-DNQ) and applied in the controlled release of coumarin 102. HPHEEP-DNQ was designed and synthesized by modification of hydrophilic hyperbranched polyphosphate (HPHEEP) with hydrophobic, light-responsive 2-diazo-1,2-naphthoquinone (DNQ) molecules. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements revealed that the polymer can self-assemble into spherical micelles with an average diameter of about 186 nm in aqueous solution. The critical micelle concentration (CMC) of the micelles was 0.025 mg mL−1 determined by fluorescence spectroscopy using Nile Red as a fluorescence probe. By illuminating the micelles with 365 nm UV light, light triggered destabilization procedure was investigated by TEM and DLS. In addition, model drug coumarin 102 was successfully encapsulated into the micelles and the controlled release behavior under 365 nm UV light was investigated by fluorescence spectroscopy. Cell viability tests against two types of cells indicated that the micelles have excellent biocompatibility. These photo-responsive and biocompatible polymeric micelles self-assembled from hyperbranched polyphosphate based polymer might have great potential as smart carriers in the field of drug delivery.