High efficiency electrochemiluminescence of 3D porous g-C3N4 with dissolved O2 as co-reactant and its sensing application for ultrasensitive detection of microRNA in tumor cells

Abstract

In this work, the electrochemiluminescence (ECL) phenomenon of three-dimensional graphitic carbon nitride (3D g-C3N4) was reported. Firstly, the proposed 3D g-C3N4 possessed 3D porous interconnected open-framework which enabled faster charge transport and efficient penetration of co-reactants due to “pore confinement effect”. Then, we found that the dissolved O2 could serve as an excellent co-reactant for cathodic ECL of 3D g-C3N4. And the high specific surface area was beneficial to better adsorbing and gathering of dissolved O2 and reactive oxygen species (ROSs), which made them full contact on the surface or inside of 3D g-C3N4, giving a more sufficient ECL reaction and higher ECL signal. Based on the proposed 3D g-C3N4-O2 ECL system, a sensitive biosensor was constructed for microRNA-21 (miRNA-21) detection with assistance of 3D spherical tracks assisted 3D DNA walking machine, which exhibited superior performance for miRNA-21 with detection limit of 0.22 fM. The proposed 3D g-C3N4-O2 ECL system with high ECL efficiency and the effective target conversion and amplification strategies were beneficial to construct ultra-sensitive ECL sensing platform, which would be better applied to clinical bioanalysis.