Antimony speciation on a dithiothreitol-functionalized two-dimensional Au@Ag array by surface-enhanced Raman spectroscopy

Abstract

Surface-enhanced Raman spectroscopy (SERS), a fast and non-destructive detection technique, can be potentially used for the on-site analysis of antimony species. However, SERS quantification of antimony species has been rarely performed. This study fabricated a two-dimensional (2D) Au@Ag–dithiothreitol (DTT) array for antimony speciation analysis. This array was able to detect antimony at concentrations as low as Sb(III) = 1.05 µg·L−1 and Sb(V) = 3.81 µg·L−1. Moreover, it exhibited good uniformity with a relative standard deviation of 16.2% and recoveries of 88–93%. The results of three-dimensional finite-difference time-domain simulations revealed that the 2D Au@Ag array with 25 nm-Au cores, 6 nm-Ag shells, and 2 nm-interparticle gaps created a strong localized surface plasmon resonance. The DTT functionalization of the 2D Au@Ag array facilitated selective adsorption and SERS detection of antimony ions. By combining the electromagnetic and chemical mechanisms, antimony speciation analysis was successfully performed using the 2D Au@Ag–DTT array, suggesting a new on-site method for monitoring small molecules.