Abstract:
A novel colorimetric assay based on silver nanoplates (AgNPls) for detecting nickel ions (Ni2+) has been developed. Glutathione (GSH) and l-cysteine (Cys) were used to modify the AgNPls surface, exhibiting extremely high selectivity towards Ni2+ over other metal ions under specific conditions. Upon addition of Ni2+ to the modified AgNPls solution, a distinctive color change can be clearly observed by naked eyes as a result of the aggregation of AgNPls induced by the binding between Ni 2+ and the modified ligands. To verify a complete self-assembly of the GSH and Cys onto AgNPls surface, the modified AgNPls were characterized using Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis) and transmission electron microscopy (TEM), respectively. Moreover, various parameters affecting the Ni2+ quantification including the modifier ratio, pH, reaction time, and interferences were investigated. With UV-vis spectrophotometric measurement under optimal conditions, a quantitative linearity was established in the range of 10-150 ppb (R2=0.9971) with the detection limit of 7.02 ppb or 120 nM (S/N=3). In addition, the developed sensor was applied to the determination of Ni 2+ in waste samples from a jewelry factory and a car manufacturer with satisfactory results. Overall, this alternative approach presents a simple, rapid, sensitive and selective detection of Ni2+. © 2014 Elsevier B.V.