A coreactant-free electrochemiluminescence (ECL) biosensor based on in situ generating quencher for the ultrasensitive detection of microRNA

In a common electrochemiluminescence (ECL) detection, both introducing exogenous species and applying dissolved oxygen (O-2) as coreactant may lead to a poor stability and reproducibility of the ECL system, and labeling the quencher for achieving signal changes is not only expensive but also inefficient. Since it was found that the carboxyl-functionalized poly[(9,9-dioctylfluorene-2,7-diyl)-co-(1,4-benzo-{2,1'-3}-thiadiazole)] (C-PFBT) dots exhibited a strong ECL emission without exogenous coreactant and dissolved oxygen, and H2O2 could quench the ECL emission of C-PFBT dots highly effectively, a coreactant-free ECL biosensor with in situ generation of quencher was proposed for ultrasensitively determining microRNA (miRNA). With the combination of a target cycle and hybridization chain reaction (HCR), large amounts of glucose oxidase (GOD) were introduced to generate the quencher H2O2 in situ, thereby achieving an ECL detection of miRNA with a low detection limit of 33 aM. The biosensor exhibited a potential practicability for detecting miRNA in specific cell lysates. The combination of C-PFBT dots and quencher H2O2 would arouse a significant interest in an ECL analysis, especially in coreactant-free ECL enzyme based-sensing field.