(512a) Photothermal Phase-Transition Nanodroplets and Their Drug Delivery Applications

My lab has recently developed gold nanorod-coated nanodroplets as theranostic agents and investigated photothermal temperature increase in the nanodroplets . Drug payload inside the nanodroplets released upon near-infrared light irradiation via photothermal phase-transition of the liquid nanodroplets to gas bubbles. The brightness of gas bubbles monitored by real-time ultrasound imaging was analyzed to quantify drug dosage released. Cell viability test results suggested that drug was delivered in a controlled manner from the nanodroplets with no cytotoxicity.

The phase-transition temperature of a gold nanorod-coated perfluorocarbon nanodroplet, i.e. the temperature of a nanodroplet when phase-transition occurs to a gas bubble by laser irradiation, was determined by Arrhenius equation and time it takes for phase-transition. Assuming the phase-transition process follows a first-order kinetic model, the activation energy and Arrhenius constant of the phase-transition process were obtained via light transmittance through the nanodroplet suspension at different temperatures. Time it takes for phase-transition by a femtosecond laser was measured using an optical microscope for C₅F₁₂ nanodroplets. The temperature calculated matches theoretical values well, suggesting one can choose laser parameters without trial and error.