Photon to thermal response of a single patterned gold nanorod cluster under near-infrared laser irradiation.

The potential applications of the photon to thermal conversion technique by gold nanorods has attracted attention for biomedical applications since they show an intense absorption spectrum in the near-infrared region, and therefore, penetrate more deeply into biological tissues. The goal in this study is to assess a local heating phenomenon with a single patterned cluster of gold nanorods that are prepared as a wet chemically synthesized gold nanorod solution and mixed with aqueous 1% alginate and 0.1 M calcium chloride. In particular, we utilized the initiated chemical vapor deposition method to coat the cluster with poly(2-hydroxyethyl methacrylate) to enhance its high temperature resistance in the solution. The influence of the thermal energy on the surroundings is studied by measuring the surface temperature of the single patterned gold nanorod cluster as a function of laser irradiation time. The experimental results were compared with numerical simulation results. The results showed that the irradiated gold nanorods could rapidly heat to maximum surface temperatures of over 60 °C within 120 s. Furthermore, the temperature remained almost constant (i.e. reached a steady state) under continuous laser irradiation and rapidly cooled to the initial temperature within 90 s when the laser was turned off.