Ultrashort-Distance Internal Light Source-Integrated ECL-PEC Dual-Mode Molecular-Sensing Device for Highly Sensitive and Accurate Detection

High sensitivity and accuracy are pivotal for advancing photoelectrochemical (PEC) bioanalysis. However, the concurrent improvement of the two is difficult at present. In this work, by coupling an internal electrochemiluminescence (ECL) light source integrated ECL-PEC dual-mode detection with an enzyme-assisted target recycling amplification strategy, we developed a novel compact molecular-sensing device that achieves the concurrent enhancement of sensitivity and accuracy. Specifically, the luminol-Au NPs, as an internal ECL light source, were introduced onto Bi2WO6 photoelectrode via a duplex-specific nuclease-assisted target recycling and hybridization process. This internal ECL light source could efficiently trigger the photoactivity of Bi2WO6 photoelectrode in an ultrashort distance of ≤8.16 nm. In-depth research has shown that this device, with an internal ECL light source, can increase the PEC property by over 20 times, which is conducive to improving sensitivity. Meanwhile, the simultaneous output of the ECL signal from luminol-Au NPs and the PEC signal from Bi2WO6 can be used for cross-validation to improve accuracy. This novel design ultimately realized the highly sensitive and accurate detection of microRNA-21 and its successful application in human serum samples. This work may open up a new prospect for the concurrent improvement of sensitivity and accuracy, as well as trace bioanalysis.