Highly sensitive and selective determination of copper(II) based on a dual catalytic effect and by using silicon nanoparticles as a fluorescent probe.

The authors describe a silicon nanoparticle-based fluorometric method for sensitive and selective detection of Cu. It is based on the catalytic action of Cu on the oxidation of cysteine (Cys) by oxygen to form cystine and the by-product HO. The generated HO is catalytically decomposed by Cu to generate hydroxyl radicals which oxidize and destroy the surface of SiNPs. As a result, the blue fluorescence of the SiNPs is quenched. The method has excellent selectivity due to the dual catalytic effects of Cu, which is much better than most previously reported nanomaterial-based assays for Cu. Under the optimal conditions, the method has low detection limit (29 nM) and a linear response in a concentration range from 0.05 μM to 15 μM. The method has been successfully applied to the determination of Cu in spiked real water samples, and the results agreed well with those obtained by the Chinese National Standard method (GB/T 7475-1987; AAS). Graphical abstract Schematic presentation of a fluorometric method for the determination of Cu based on the dual catalytic effects of Cu, and the oxidative effect of hydroxy radicals on the surface of silicon nanoparticles (SiNPs). The method has a 29 nM detection limit and good selectivity.