Theoretical and in vivo experimental investigation of laser hyperthermia for vascular dermatology mediated by liposome@Au core-shell nanoparticles.

The 1064 nm Nd:YAG laser shows a good prospect for the treatment of port-wine stain (PWS), but it is necessary to enhance the blood absorption to laser energy by exogenous chromophore. Owing to the conjunction effect of local surface plasmon resonance (LSPR) by gold nanoparticle and drug delivery as well as lumen blockage abilities by liposome, liposome@Au core-shell nanoparticles are used as exogenous chromophore, and the efficiency of photothermal therapy is studied systematically. In this work, theoretical simulations were conducted to investigate the electric field and solid heat conduction of liposome@Au core-shell nanoparticles with various size and particles distance, aiming to achieve maximum photothermal conversion efficiency during the laser irradiation. Thereafter, liposome@Au core-shell nanoparticles with optimal size and structure were prepared, and in vivo experiments were conducted to evaluate the thermal damage of blood vessels enhanced by liposome@Au core-shell nanoparticles. Theoretical results imply that maximum temperature rise (167 K) is obtained when radius is 45 nm and shell thickness is 5 nm with distance of 4 nm. Liposome@Au core-shell nanoparticles were prepared with diameter of 101 nm and shell thickness of 5 nm according to the finite element simulation of electric field and solid heat conduction. When the molar ratio of chloroauric acid to phospholipid is 2.25, the LSPR absorption peak is about 981 nm, which is close to the wavelength of Nd:YAG laser. In vivo experiments show that injecting liposome@Au core-shell nanoparticles into the blood vessels can effectively reduce the number of laser pulses and the corresponding energy density required for obvious vasoconstriction.