Enhanced Electrochemiluminescence of Zn 2+ Aggregation-Induced Dual Stabilizers Capped Au Nanoclusters and Its Immunosensing Applications

Screening a novel electrochemiluminescence (ECL) system with enhanced ECL efficiency is crucial to ECL evolution. Aggregation-induced short-chain Au nanoclusters (AuNCs) are an intriguing strategy to tune their ECL properties. However, achieving superior ECL efficiency involving an aggregation-induced strategy of long-chain stabilizer-capped AuNCs in aqueous phase remains a formidable challenge. Herein, the high ECL efficiency of AuNCs was synthesized from Zn2+-mediated aggregation-induced AuNCs involved in short/long chain ligands including d-penicillamine/11-mercaptoundecanoic acid (d-DPA/MUA) as dual stabilizers and tert-butylamine borane as reductant (Zn2+-d-DPA/MUA@AuNCs). Specifically, the formation of aggregation-induced superstructures resulted in nearly complete quenching of vibrations and dipole moments of the −CH2– moieties in MUA, which was attributed to the conformational contraction of the overall structure and constrained intramolecular motion. Moreover, with the addition of Zn2+ into the d-DPA/MUA@AuNCs, the morphology of spheroidal assembled structure grew up, the carrier concentration of the AuNCs increased, the electron–hole recombination at the interface was promoted, and thus the carrier separation efficiency decreased. This was beneficial to the enhanced NIR (beyond 800 nm) ECL around 9-fold compared with Zn-free AuNCs. Zn2+-d-DPA/MUA@AuNCs were utilized as a probe for the detection of prostate-specific antigen (PSA) in the linear concentration range 5–800 ng/mL with a limit of detection of 1 ng/mL (S/N = 3) with ECL image and wavelength-based intensity dual mode.