Treatment Efficacy of Laser Photothermal Therapy Using Gold Nanorods: Tumor Shrinkage Study

Gold nanorods can be tuned to a specific laser wavelength and serve as strong laser energy absorbers. Due to the powerful optical absorption, the laser energy is concentrated in an area congregating by nanorods, and then the energy absorbed can be transferred to the surrounding tumor tissue by heat conduction.^1–4 Previous studies have shown a wide range of heating parameters with or without temperature measurements. Our previous experiment⁴ has demonstrated that using only 0.1 cc gold nanorod solution can lead to tumor temperature higher than 50°C when the laser irradiance is only 2 W/cm². Based on the measured temperature elevation and heating duration, thermal damage to the tumor is highly likely. However, some researchers raised the question whether temperature sensors used in those experimental studies are truly reflecting the temperatures in the tumors. The objective of this study is to measure quantitatively tumor shrinkage after laser irradiation to evaluate efficacy of laser photothermal therapy.