Functional Controlled Release Systems Triggered by Photothermal Effect of Gold Nanorods

Gold nanorods, rod-shaped gold nanoparticles, have transverse and longitudinal surface plasmon (SP) bands at visible and near-infrared (IR) regions, respectively. Since the absorbed light energy is converted into heat, photothermal effect of gold nanorods can be triggered without damaging the tissues in the path of near-IR laser light. In this study, we tried to construct controlled release system of functional molecules from surface of gold nanorods mediated by the photothermal effect. First, we evaluated controlled release of poly(ethyleneglycol) (PEG) chains from PEG-modified gold nanorods (PEG-NR). Next, we employed double stranded oligonucleotide as a thermo-responsive dissociating group (DNA-NR). Finally, we evaluated photothermal release of PEG chains mediated retro-Diels-Alder reaction (PEG-DA-NR). For construction of controlled release system of functional molecules, these studies will provide important information about the photothermal reactions of surface molecules on the gold nanorods triggered by near-IR light irradiation.