A novel potential-regulated ratiometric electrochemiluminescence sensing strategy based on poly(9,9-di-n-octylfluorenyl-2,7-diyl) polymer nanoparticles for microRNA detection

The ratiometric electrochemiluminescence (ECL) sensing strategies commonly involved two ECL illuminants and achieved the signal conversion by resonance energy transfer (RET) or competitive consumption of additional co-reactant. The choice of two suitable illuminants, application of distance-dependent RET and introduction of additional co-reactant all strongly restricted the construction of ECL ratiometric strategies. This work constructed a novel potential-regulated ECL ratiometric strategy based on an opposite effect of H2O2 on two ECL emissions from the carbonyl functioned poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) polymer nanoparticles (NPs), in which, RET and exogenous co-reactant were excluded. Impressively, for the single ECL emitter PFO NPs, two different anodic ECL emissions, namely ECL-1 and ECL-2, were detected stably at +1.25 V and +1.95 V, respectively. The strand displacement amplification (SDA) and hybridization chain reaction (HCR) were integrated to introduce a large amount of glucose oxidase (GOx). In the presence of glucose, H2O2 was generated in situ during the enzymatic reaction to quench ECL-1 and enhance ECL-2, thereby achieving an ECL ratiometric determination of microRNA-155 (miRNA-155) with a low detection limit of 17 aM. PFO NPs provide a novel potential-regulated ECL ratiometric strategy excluding RET and exogenous co-reactant, and show promising potentials for bioanalysis.