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.

Most electrochemiluminescence (ECL) studies focus on the single emission of luminophores, which severely limits the development of the multi-color ECL fundamental theory and applications. Herein, we prepared a multi-color ECL supramolecular nanomaterial self-assembled by 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and aniline (An) through hydrogen bonding. This PTCDA–An supramolecular nanomaterial simultaneously produced multi-color emissions peaking at 486, 692 and 760 nm with K₂S₂O₈ as a coreactant. These multi-color emissions were assigned to the excited PTCDA monomer (486 nm), H-dimer (692 nm) and J-dimer (760 nm). The simultaneously increased dual-color ECL intensity significantly enhanced the total ECL intensity of PTCDA–An. Furthermore, this highly efficient ECL nanomaterial was used as an ECL platform to construct a label-free immunosensor for tumor marker carcinoembryonic antigen (CEA) detection. The total ECL intensity of the immunosensor sensitively decreased due to the simultaneously decreased ECL of multiple emissions. Also, this immunosensor exhibited a wide linear range from 1 pg mL⁻¹ to 10 μg mL⁻¹ with a low detection limit of 0.23 pg mL⁻¹. The multi-color ECL from the same luminophore PTCDA in this work also provides a new perspective for multi-color ECL biomaterial design.