Dual responsive micelles based on poly[(R)-3-hydroxybutyrate] and poly(2-(di-methylamino)ethyl methacrylate) for effective doxorubicin delivery

We present novel pH and thermo-sensitive amphiphilic triblock copolymers with two hydrophilic poly(2-(di-methylamino)ethyl methacrylate) (DMAEMA) blocks flanking a central hydrophobic poly[(R)-3-hydroxybutyrate] block. The release of doxorubicin from the micelles can be controlled by pH and temperature triggers. Using this system, extremely long duration sustained drug release was achieved, better than most micelle systems currently described in the literature. Sustained release of the drug was achieved at pH 7 and 37 °C. Cytotoxicity tests of the copolymers showed that they have significantly lower toxicity towards fibroblast cells compared with the PDMAEMA homopolymer. The doxorubicin-loaded micelles were effective in controlling the growth of HeLa cells. The results demonstrated that the copolymers could be potentially used in chemotherapeutic applications.