Selective detection of Cysteine via plasmonic silver nanotriangles in the presence of KI with an emphasis on mechanism

Abstract

Silver nanotriangles (Ag NTs), as the plasmonic sensor, were synthesized for the selective and sensitive detection of Cysteine in the aqueous media in the presence of KI. The identification of Cysteine, among other biogenic amino acids, was achieved within the range of 5–80 μM using UV–Vis spectroscopy; i.e., a red-shift was observed in the wavelength of the dipole plasmon resonance (λDPR) in the presence of Cysteine. The detection limit of the sensor was estimated 120 nM. The mechanism behind this selective detection was attributed to the inhibition effect of the Cysteine in the oxidation of the sharp corners of Ag NTs that would happen in the presence of KI. The concentration of Cysteine was correlated with the λDPR red-shift that stems from the Cysteine stabilization of Ag NTs against KI.