In this study, thermo-responsive poly(N-isopropyl acrylamide)-g-gold nanorods (PNIPAAm-g-GNRs) were prepared by grafting telechelic PNIPAAm-SH to the GNRs. They were stable in aqueous medium where the GNRs were protected by PNIPAAm chains as revealed by transmission electron microscope. The longitudinal surface plasmon absorbance had a red shift to 810 nm, and the lower critical solution temperature (LCST) of the PNIPAAm was increased to 34.9 degrees C. After being irradiated by near-IR for 5 min, the PNIPAAm-g-GNRs solution indicated a temperature increment above its LCST. The opto-thermal effect thus could induce the morphology change of the PNIPAAm, which was found to be reversible. Furthermore, the PNIPAAm-g-GNRs had a much lower cytotoxicity than the surfactant-stabilized GNRs. The cell viability of fibroblast after two days of culture could still reach 89.0% relative to the control. Therefore, the PNIPAAm-g-GNRs could be used as drug carriers in which the drug-release could be controlled by remote near-IR. (C) 2015 Elsevier Ltd. All rights reserved.
