Cooling: A facile, rapid, reagent-free and DNA-saving method for functionalization of gold nanorods with thiolated DNA

Abstract Conventional methods of functionalization of gold nanorods (AuNRs) with thiolated DNA include salt aging, pH-assisted method, ligand exchange, etc., most of which have limitations such as poor stability, operational difficulty, time consuming, strong cytotoxicity, and low predictability. Here, we demonstrate a facile, rapid, reagent-free and DNA saving method from freezing to cooling (−196 to 4 °C). No reagent is required for Au-S bond and more than 180 thiolated DNAs could be attached while feeding DNA/AuNR molar ratio is as low as 1000, within only several minutes. Cooling (4 ℃) is a preferred modification temperature. Nanoscale ice might occur on the ternary interface of gold, water and DNA, while hydrogen bond is not strong enough to restrict DNA thermal motion.