Near-Infrared Electrochemiluminescence of Dual-Stabilizer-Capped Au Nanoclusters for Immunoassays

Surface engineering of electrochemiluminescence (ECL) emitters with capping agents is highly important, yet it remains a challenge. Herein, using N- acetyl-L-cysteine and cysteamine as model capping agents, a dual-stabilizer-capped strategy was proposed to achieve red-shifted ECL in the near-infrared region (NIR) via surface engineering water soluble and biocompatible Au nanoclusters (NCs). The dual-stabilizer-capped Au NCs were environment-friendly and exhibited efficient ECL emission at around 860 nm when utilizing triethanolamine as a coreactant, thus providing an NIR ECL tag for bioanalysis in aqueous medium. Benefiting from the low background of NIR emission and the good biocompatibility of the dual-stabilizer-capped Au NCs, a signal on-genre NIR ECL immunosensing method was obtained. Then, the immunosensor was established by using the carcinoembryonic antigen as a model analyte and the aforementioned Au NCs as a tag to label the signal antibody, which exhibited a broad linear range from 1 fg/mL to 0.5 ng/mL with a limit of detection of 0.33 fg /mL (S/N = 3). The work offers a method toward deepened understanding of the surface engineering of Au NCs with capping agents for tuning the ECL waveband and developing ECL systems in even longer wavebands.

Automated summary

The study introduces a dual-stabilizer-capped strategy for achieving red-shifted ECL in the near-infrared region using N-acetyl-L-cysteine and cysteamine as model capping agents. This method enables bioanalysis in aqueous medium and has successfully developed a signal on-genre NIR ECL immunosensing method.