Au-Pt alloy nanoislands for highly sensitive localized surface plasmon resonance sensing of antimony(III) ions

Alloy nanomaterials exhibit superior plasmonic properties that can exceed traditional single-metal nanomaterials. Hence, they hold great potential for developing highly sensitive sensors capable of detecting small analytes in nanoscale. The self-assembly Au-Pt alloy nanoislands structure is used, for the first time, for localized surface plasmon resonance sensing. Its nanostructure has been studied and characterized by using various microscopy and spectroscopy techniques. It was found that Au0.94-Pt0.06 was the optimum composition with the best sensitivity toward the change of refractive index over various concentrations of NaCl solution and double the sensitivity than that of pure Au nanoislands. The Au-Pt chip with its surface functionalized with nitrotyrosine was successfully developed for highly sensitive detection of antimony (III) ion, the electronic properties of the interaction between nitrotyrosine and Sb during the biosensing was explored using density functional theory simulation to explain their strong adsorption to make nitrotyrosine a successful receptor. The sensor achieved a limit of detection of 0.0504 ppb, which is the best ever value among all those reported for Sb(III) ions sensing. With its high selectivity tested among 14 other common elements, the present Sb(III) ion LSPR sensor also possesses attributes of label-free, easy to fabricate and simple to operate.