The dextrin coated AuNRs synthesized using the alkaline procedure were functionalized with a thiolated probe following a common methodology applicable for citrate coated AuNRs ligand exchange [13]. Briefly, the thiolated DNA probe was reduced with Dithiothreitol (DTT) and purified using a Sephadex column (Nap-5,GE Healthcare). The dextrin molecules coating the surface of the nanoparticles were exchanged for the thiolated DNA probe over a series of salting steps. After the ligand exchange, the particles were stored under refrigeration until use.[8, 9]