Rapid, reversible release from thermosensitive liposomes triggered by near-infra-red light

A novel drug carrier is presented consisting of plasmonic hollow gold nanoshells (HGN) chemically tethered to liposomes made temperature sensitive with lysolipids (TSL). Continuous-wave irradiation by physiologically friendly near-infra-red light at 800 nm for 2.5 min at laser intensities an order of magnitude below that known to damage skin generates heating localized to the liposome membrane. The heating increases the liposome permeability in an irradiation dose dependent, but reversible manner, resulting in rapid release of small molecules such as the self-quenching dye carboxyfl uoresce in or the chemotherapeutic doxorubicin, without raising the bulk temperature. The local rise in nanoshell temperature under laser irradiation is inferred by comparing dye release rates from the TSL via bulk heating to that induced by irradiation. Laser-irradiation of TSL enables precise control of contents release with low temperature gradients confi ned to areas irradiated by the laser focus. The combined effects of rapid local release and localized hyperthermia provide a synergistic effect as shown by a near doubling of androgen resistant PPC-1 prostate cancer cell toxicity compared to the same concentration of free doxorubicin.