Rapid and selective detection of trace Cu2+ by accumulation- reaction-based Raman spectroscopy

Developing detection method for trace copper ions (Cu2+) has attracted great attention since Cu2+ ions would threaten to human health, including cellular toxicity, liver damage, and neuro degenerative diseases. In this work, adding L-cysteine (L-Cys) into inositol hexaphosphate (IP6) modified Ag nanoparticles (designated as L-Cys/IP6@Ag) induces the certain aggregation of nanoparticles, resulting in increasng the surface enhanced Raman scattering (SERS) signal of rhodamine 6 G (R6 G). The presence of Cu2+ ions could be adsorbed by IP6 and the concentrated Cu2+ ions could further selectively oxide Cys molecules under certain pH value, which disperses the IP6@Ag again and decreases the SERS signal of R6 G. The linear range of determination of Cu2+ ions is from 10−5 to 10-1° M as well as a low detection concentration is of 10 pM. Furthermore, the L-Cys/IP6@Ag-R6 G-based SERS sensor has been successfully applied to detect trace Cu2+ in river water.