Ratiometric electrochemiluminescence sensing platform for sensitive glucose detection based on in situ generation and conversion of coreactants

Abstract

A novel ratiometric electrochemiluminescence (ECL) biosensor was developed for sensitive detection of glucose in combination of graphitic-phase carbon nitride-supported Au nanocomposites (Au-g-C3N4) and luminol as cathodic and anodic ECL emitters, respectively, only with dissolved oxygen in aqueous solution. Glucose oxidase-immobilized Au-g-C3N4 nanocomposites (GOx/Au-g-C3N4) were modified on a glassy carbon electrode to construct a sensing platform in the presence of luminol. Before glucose was added, the g-C3N4 nanosheets could give a strong cathodic ECL emission with dissolved oxygen as a coreactant in aqueous solution. In the presence of glucose, hydrogen peroxide was in situ generated from dissolved oxygen, catalyzed by GOx and further by Au nanoparticles, and was then converted to reactive oxygen species, which led to an anodic ECL emission from luminol, concomitant with a decrease in the cathodic ECL emission from the g-C3N4 nanosheets. The ratiometric ECL responses were closely related to the competitive consumption of dissolved oxygen by the g-C3N4 nanosheets and luminol (by means of the GOx-immobilized Au nanoparticles). The constructed ratiometric ECL biosensor showed high sensitivity and selectivity for the detection of glucose, with a wide concentration range of 0.1–8000μM and a low detection limit of 0.05μM (S/N=3). Furthermore, this constructed ratiometric ECL sensing platform was successfully applied to detect glucose in real samples independent of interference from other biomolecules. This proposed strategy opens an alternative avenue for ECL signal transduction and shows a promising application in clinical diagnostics.