To conjugate NTs with bDNA on AuNPs, 1-ethyl-3-[3- dimethylaminopropyl] carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) were used to link the carboxylic group on NTs and amine group on bDNA. EDC (5 mg) was added to 25 L NTs, then 50 L of 9% NHS in dimethyl sulfoxide were added.