Electrochemistry and electrochemiluminescence of resorufin dye: Synergetic reductive-oxidation boosted by hydrogen peroxide

To develop robust field diagnostic systems capable of responding to medical needs, miniaturization of devices and high target sensitivity remain significant challenges. Electrochemiluminescence (ECL) is an ideal analysis tool to meet these challenges, and developing novel ECL materials is essential. Here we report the reversible electrochemical properties of resorufin, a commercial fluorescent dye, and its highly stable cathodic ECL. We find the cathodic ECL emission from the resorufin quantitatively changes upon the H2O2 content and propose the selective ECL molecular sensor against it. Resorufin undergoes reversible two-electron-transfer electrochemical reduction, and it generates cathodic ECL via a reductive-oxidation pathway with the S2O82− co-reactant. Interestingly, highly enhanced, synergetic ECL is produced in the dual K2S2O8–H2O2 co-reactant system, and especially, it can be used for selective molecular recognition of H2O2. Via the chronoamperometric application, the resorufin ECL signal reveals the linear correlation with the H2O2 concentration range of 0–150 µM with a detection limit of 6.8 µM. Resorufin exhibits strong potential as a new ECL luminophore. Also, selective enhancement of ECL suggests potential applicability to various immunoassays using H2O2.