Synthesis of Dual Red-Emitting Fluorescent Silver Nanoclusters in Aqueous Lipoic Acid-Based Polymer Solutions and Application for Cu²⁺ Detection and Cell Imaging

Dual red-emitting fluorescent and water-soluble silver nanoclusters (AgNCs) were synthesized in aqueous solutions through the reduce reaction method using lipoic acid-modified-poly(vinyl alcohol) as a novel protective ligand and sodium borohydride as a reducing agent. The obtained AgNCs exhibited a large Stokes shift and high stability. The fluorescence lifetime of the obtained AgNCs was 1.4×10⁴ ns and the corresponding quantum yield reached 7.1 %. The obtained AgNCs showed highly sensitive and selective detection of Cu²⁺, in which the evaluation of Cu²⁺ was allowed in the range of 0–28 μM with a limit of detection (LOD) as low as 0.71 μM. Moreover, the obtained AgNCs are explored to application for bioimaging through incubation with ID8 cells.