In this study, O-phospho-l-serine dithiocarbamic OF-1 functionalized gold nanoparticles (PSDTC-AuNPs) were synthesized for detecting Cr3+. Gold nanoparticles were prepared through the citrate-mediated reduction of HAuCl4. O-phospho-l-serine dithiocarbamic acid (PSDTC) was attached to the surface of AuNPs through the thiol group, and the resulting PSDTC-AuNPs can be used for metal ion detection (Scheme 1). Metal ions, such as Ag+, Al3+, Ca2+, Cd2+, Co2+, Cu2+, Cr3+, Fe2+, Fe3+, Hg2+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+ were tested for metal ion selectivity but Cr3+ was the only metal ion that caused the aggregation of PSDTC-AuNPs. This caused the SPR absorption band of PSDTC-AuNPs to shift to a longer wavelength, and consequently a color change from red to blue that can be used to detect the presence of Cr3+ ions. The SPR absorption at 651 nm directly indicated the degree of PSDTC-AuNPs aggregation caused by the addition of Cr3+ ions (Scheme 2).
Scheme 1. Schematic illustration of the analytical process for detecting Cr3+ based on the aggregation of PSDTC-AuNPs.Figure optionsDownload full-size imageDownload as PowerPoint slide