Spectrum-Based Electrochemiluminescence Immunoassay for Selectively Determining CA125in Greenish Waveband

Spectrum-based and color-selective electrochemiluminescence (ECL) is crucial for the multicolored ECL assay strategy. Herein, a spectrum-based ECL immunoassay of high color purity was performed on a home-made ECL-acquiring system by spectrally imaging the ECL emission of highly passivated CdSe nanocrystals (NCs), that is, the ECL tags, which were labelled onto sandwich-type immuno-complexes with CA125 as the target molecule. The ECL tags could give off efficient ECL around 555nm with a full width at half-maximum of 39nm, so that the spectrum-based ECL strategy could color-selectively determine CA125 with a linear response range from 10-4 to 1U/mL and a limit of detection of 5×10-5U/mL. The intrinsically improved signal-to-noise ratio of ECL to fluorescence might eventually enable the spectrum-based ECL immunoassay to be a promising alternative to the NCs-based multicolored fluorescent assay strategy.