Highly efficient resonance energy transfer in g-C3N4-Ag nanostructure: Proof-of-concept toward sensitive split-type electrochemiluminescence immunoassay

Nowadays, electrochemiluminescent resonance energy transfer (ECL-RET) as a promising signaling mechanism has been proved its promising perspective for bioassay, whereas the limitation of energy transfer efficiency remains a big challenge. Herein, we highlight a high-efficient ECL-RET mode between luminescent materials and noble metal nanoparticles, in which luminescent materials (g-C 3 N 4 nanosheets as the energy donor) and noble metal nanoparticles (Ag nanoparticles as the energy acceptor) were innovatively combined into one nanostructure, greatly reducing the energy loss and effectively promoting the RET efficiency. To prove the concept of the RET mode in ECL bioanalysis, a split-type ECL immunosensor was developed using interleukin-6 (IL-6) as a model. In the presence of IL-6, a sandwich immunoreaction occurred in anti-IL-6 antibody-coated 96-well plate by using glucose oxidase and anti-IL-6 antibody-conjugating silicon dioxide nanoparticles (anti-IL-6-SiO 2 -GOx) as signal label. The carried GOx oxidized glucose to generate H 2 O 2 , which etched Ag nanoparticles in g-C 3 N 4 -Ag nanostructure, thereby destroying the ECL-RET between g-C 3 N 4 and Ag and thus recovering the ECL intensity. The high-efficient ECL-RET in one nanostructure and GOx-induced H 2 O 2 etching modulation in this proposed system endowed the high sensitivity of the immunoassay toward IL-6 with the detection limit of 3.2 × 10 −14  g/mL and the dynamic working range of 1.0 × 10 −13 –1.0 × 10 −8  g/mL. It’s believed that this ingenious combination of g-C 3 N 4 and Ag into one nanostructure provides a new perspective to expand the application of ECL-RET of luminescent materials and noble metal nanoparticles.