Despite considerable research advances in trace metal analysis, rapid and accurate detection of environmentally and/or clinically important trivalent metal ions pose significant challenges to the scientific community. In this presentation, we report a unique surface-enhanced Raman scattering (SERS)-based sensing strategy, in which gold nanoparticles (Au NPs) were coupled with individual chelating ligands or mixed ligand systems for micromolar detection of trivalent metal ions such as aluminium, gallium, and iron. A seed-mediated growth approach to the synthesis of Au NPs of different colors was developed, and Au NPs with a longitudinal surface plasmon resonance that overlapped with the laser excitation wavelength (i.e., 785 nm) were shown to be the optimal SERS substrates. A strong linear correlation was found between metal ion concentrations ranging from 5-100 μM and the intensities at the characteristic Raman peaks corresponding to each specific metal-ligand interaction. The methodology offers great opportunities for the design of novel chemical and biological sensors.
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