An ultrasensitive electrochemiluminescent immunosensor based on graphene oxide coupled graphite-like carbon nitride and multiwalled carbon nanotubes-gold for the detection of diclofenac.

In this study, a novel competition-type electrochemiluminescent (ECL) immunosensor for detecting diclofenac (DCF) was fabricated with graphene oxide coupled graphite-like carbon nitride (GO-g-C3N4) as signal probe for the first time. The ECL intensity of carboxylated g-C3N4 was significantly enhanced after being combined with graphene oxide (GO) which exhibited excellent charge-transport property. The sensing platform was constructed by multiwalled carbon nanotubes and gold nanoparticles (MWCNTs-AuNPs), which not only provided an effective matrix for immobilizing a large amount of coating antigen but also facilitated the electronic transmission rate to enhance the ECL intensity. Based on the synergistic effect of GO-g-C3N4 and MWCNTs-AuNPs composite, the proposed sensor showed high sensitivity, good stability, and wide linearity for the detection of DCF in the range of 0.005-1000ngmL-1 with a detection limit of 1.7pgmL-1. Furthermore, the developed immunoassay has been applied to real samples with satisfactory results. Therefore, this work provided a promising method for the detection of DCF and other small molecular compounds in the future.