Thermal properties of gold nanoshells in lipid vesicles studied by single particle tracking measurements

Photothermal therapy employing nanomaterials is a promising approach to selectively treat targeted tissues with abnormal characteristics such as tumors. While vital research has focused on the use of these materials in biomedical applications, net effects of these materials in biological environments are still not well understood. For reliable biomedical applications, it is crucial to quantitatively evaluate thermal properties of these materials in biological and physiological environments. To this end, we have developed a highly integrated measurement platform and examined local thermal properties of single gold shell nanocrystals in biomimetic environments. These nanoshells consist of a silica core with an outer gold coating. For quantitative measurement of the local thermal profile of gold nanoshells, we monitor lipid phase transitions triggered by gold nanoshell thermal excitation. Dried lipid layers with adsorbed gold nanoshells were placed in an aqueous environment. Photothermal excitation of the gold nanoshells induced localized liposome budding as the lipids were raised above their transition temperature. Single particle tracking of gold nanoshells in solution and within liposomes revealed larger diffusion rates for the confined nanoparticles, likely due to a raised local temperature.