One-step preparation of disposable multi-functionalized g-C3N4 based electrochemiluminescence immunosensor for the detection of CA125

Abstract

A novel, disposable and label-free electrochemiluminescence (ECL) immunosensor, based on multi-functionalized graphitic carbon nitride (g-C3N4) coated on the one-off screen-printed carbon electrodes (SPCEs), for the detection of tumor marker carbohydrate antigen 125 (CA125) was developed. The multi-functionalized g-C3N4 was prepared with amino-coated Fe3O4 nanoparticles and CA125 antibody (anti-CA125) chemically bound to the surface of carboxylated g-C3N4 simultaneously. The Fe3O4 nanoparticles ensured the presence of multi-functionalized g-C3N4 in the outer Helmholtz plane (OHP) of the ECL immunosensor and even becoming part of the electrode surface. This assembly promoted the electron transfer between g-C3N4 and the electrode resulting in greatly enhanced ECL intensity. The CA125 was selectively captured by anti-CA125 leading to effective inhibition of the ECL signal. Under optimal conditions, this disposable ECL immunosensor exhibited a wide dynamic linear detection range for CA125 (0.001–5U/mL) with a lower detection limit of 0.4mU/mL, providing high sensitivity. In addition, the immunosensor also exhibited high specificity, good reproducibility and long-term stability. All these properties offer great promise for rapid, simple, selective and effective detection of CA125 in clinical applications.