A ratiometric luminescence probe for selective detection of Ag+ based on thiolactic acid-capped gold nanoclusters with near-infrared emission and employing bovine serum albumin as a signal amplifier.

Abstract

When thiolactic acid-capped gold nanoclusters (AuNCs@TLA) with strong near-infrared (NIR, 800nm) emission were applied to detect metal ions, only Ag+ induced the generation of two new emission peaks at 610 and 670nm in sequence and quenching the original NIR emission. The new peak at 670nm generated after the 800-nm emission disappeared utterly. The ratiometric and turn-on responses showed different linear concentration ranges (0.10-4.0μmol·L-1 and 10-50μmol·L-1) toward Ag+, and the limit of detection (LOD) was 40nmol·L-1. Especially, the probe exhibited extremely high selectivity and strong anti-interference from other metal ions. Mechanism studies showed that the novel responses were attributed to the anti-galvanic reaction of AuNCs to Ag+ and formation ofbimetallic nanoclusters. Thetwo new emission peaks were due to the composition change and size growth of the metal core. Besides, bovine serum albumin (BSA) has been employed as a signal amplifier based on the assembly-induced emission enhancement properties of AuNCs, which improved the LOD to 10nmol·L-1. Moreover, the ratiometric method is feasible for Ag+ detection in diluted serum with high recovery rates, showing large application potential in the biological system. The present study supplies a novel ratiometric probe forAg+ with a two-stage response and provides a novel signal amplifier of BSA, which will facilitate and promote the application of NIR-emitted metal nanoclusters in biological system.