Detection of Cobalt Ion Based on Surface Plasmon Resonance of L-Cysteine Functionalized Silver Nanotriangles

Abstract

A facile and sensitive spectroscopic detection method for the detection of cobalt ion was introduced by the use of the surface plasmon resonance of silver nanotriangles (AgTrngs). After successful capping and functionalizing of AgTrngs, with an average edge length of ~ 54 nm, by trisodium citrate (TSC) and L-Cysteine, they were employed for the detection of cobalt ion based on the change in their in-plane dipole resonance. According to the obtained results, the developed sensor showed a response time as short as 10 s with a detection limit of 3.5 nM in the concentration range of 10–100 nM; in addition, this sensor needs a small volume of samples for cobalt ion determination that makes it ideal for the analysis of the body fluids as well as other aqueous effluents. Finally, based on the transmission electron microscopy, the oxidation of AgTrngs by cobalt ion was proposed as the detection mechanisms that result in the decrease in the in-plane dipole plasmon resonance of AgTrngs.