Bovine serum albumin-stabilized silver nanoclusters with anodic electrochemiluminescence peak at 904 nm in aqueous medium and applications in spectrum-resolved multiplexing immunoassay.

Abstract Near-infrared electrochemiluminescence (NIR ECL) luminophores are strongly anticipated in ECL bioimaging and spectrum-resolved multiplexing assays. Herein, bovine serum albumin-stabilized Ag nanoclusters (BSA-Ag NCs) are demonstrated promising NIR ECL performance, exhibiting strong anodic ECL spectrum peak at 904 nm in aqueous medium. The ECL intensity of BSA-Ag NCs-triethanolamine system was enhanced 3.2 times by adding TiO2 nanoparticles as co-reactant accelerator. In a spectrum-resolved triplex-color ECL multiplexing immunoassay, CdSe NCs, CdTe NCs and BSA-Ag NCs were used as the ECL tags, carbohydrate antigen 125 (CA125), carbohydrate antigen 19-9 (CA19-9) and cardiac troponin I (cTnI) were chosen as model analytes. The ECL peaks of three antigen-NCs pairs were simultaneously measured via one ECL potential scan. The composite of carbon nanotubes-TiO2 nanoparticles-chitosan was served as the conductivity and co-reactant accelerators, enhancing the ECL intensity by 16 folds. With the integral intensity over the ECL peaks as the analytical signal to improve further the signal-to-noise ratio, the limits of detection were 0.035 mU mL-1 for CA125, 0.087 mU mL-1 for CA19-9, and 0.016 pg mL-1 for cTnI, respectively.