Hydroxyapatite-coated liposomes for the controlled release of quantum dots and bupivacaine

This work reports the development of hydroxyapatite-coated liposomes to encapsulate drug bupivacaine and quantum dots (CdSe) to be used as a theranostic tool. Systems like this allow monitoring drug distribution in vivo (because of the quantum dots) and they can modulate the rate of drug delivery by increasing drug concentration in situ (due to the hydroxyapatite coating). Liposomes were prepared by the injection technique, and their hydroxyapatite coating was obtained by co-precipitation of calcium and phosphate precursors. The increase in diameter and decrease in zeta potential of the hydroxyapatite-coated liposomes (LHAP) when compared to conventional liposomes evidenced that a core-shell was formed around the vesicles. X-ray diffraction and infrared spectroscopy measurements confirmed the presence of hydroxyapatite in the coating. The liposomes were then functionalized with CdSe to be used as theranostic and detected by photoluminescence. The bupivacaine was incorporated in liposomes/hydroxyapatite and its in vitro release kinetics was modulated, showing slower rates than those measured with the conventional liposomes. Graphic abstract