Electrochemiluminescent DNA sensing using carbon nitride nanosheets as emitter for loading of hemin labeled single-stranded DNA

Carbon nitride nanosheets (CNNS) have been reported as a cathodic electrochemiluminescence (ECL) emitter in the presence of dissolved oxygen to produce an endogenous coreactant H2O2 on electrode surface. This work uses this emitter to construct an ECL sensing platform for sensitive DNA detection through its adsorption ability toward single-stranded DNA (ssDNA). The adsorption of hemin-labeled ssDNA on CNNS leads to in situ consumption of dissolved oxygen via hemin-mediated electrocatalytic reduction, thus decreases the formation of coreactant and quenches the ECL emission of CNNS. The ECL sensing platform is designed using hemin-labeled ssDNA to recognize the target DNA, which results in the departure of hemin-labeled hybridization product from the CNNS modified electrode, thus inhibits the annihilation of coreactant and recovers the ECL emission. Under optimized conditions, the proposed sensing strategy shows a wide detection range over 6 orders of magnitude and wondrously high sensitivity with a detection limit down to 2.0 fM. Moreover, the ECL sensor exhibits good performance with excellent selectivity, high reliability, and acceptable fabrication reproducibility. The sensitive sensing strategy provides a new paradigm for the design of ultrasensitive detection method.