Perylene diimide as a cathodic electrochemiluminescence luminophore for immunoassays at low potentials.

In the cathodic electrochemiluminescence (ECL) field, most reported luminophores produced ECL emission at high potentials (more than -1.3 V vs. Ag/AgCl), which was adverse for both fundamental studies and practical application. It was important to screen novel ECL luminophores and coreactants for the development of ECL. In this work, N,N'-dimethyl-3,4,9,10-perylenedicarboximide (PDI-CH3) is reported to produce ECL at -0.47 V using K2S2O8 as a coreactant in an aqueous system. In addition, the ECL wavelength was 689 nm, which was interpreted with the emission of excited PDI-CH3 dimers. Finally, this low-triggering-potential ECL system was used to construct sandwiched immunosensors to detect carcinoembryonic antigen (CEA) with the potential range from 0 to -0.8 V. In this immunosensor, PDI-CH3 and gold nanoparticles (AuNPs) reduced by citrate were grafted onto graphite oxide (GO) to label secondary antibodies (Ab2). This immunosensor could sensitively detect CEA with the linear response range between 1 fg mL-1 and 1 μg mL-1 and detection limit 0.29 fg mL-1. In addition, this immunosensor showed good feasibility in various cancer serum samples.