Sensitive and Programmable Signal-Off Electrochemiluminescence Sensing Platform Based on Cascade Amplification and Multiple Quenching Mechanisms

A versatile and sensitive quantum dot (QD)-based signal-off electrochemiluminescence (ECL) sensing system was constructed using target-initiated dual Mg2+-dependent DNAzyme (MNAzyme) recycling and catalytic hairpin assembly (CHA) amplification strategies. After the cascade amplification, numerous ferrocene-labeled Y-shaped DNA complexes generated on the QD-modified electrode surface. In the presence of hemin, moreover, the terminal sequence of the formed complex could assemble into hemin/G-quadruplex. Therefore, the highly efficient ECL quenching was achieved due to the multiple quenching mechanisms, including electron/energy transfer between ferrocene and QDs, the steric hindrance effects, and the horseradish peroxidasemimicking activity of hemin/G-quadruplex. Furthermore, owing to the flexibility in regulating the recognition sequences of MNAzyme, the assaying targets can be programmed. Based on the cascade amplification and multiple ECL quenching mechanisms, the developed programmable signal-off' ECL sensing platform demonstrates excellent sensitivity and the detection limits of 35.00 aM, 3.71 fM, and 0.28 pM (S/N = 3) for target DNA, aptamer substrate (ATP as a model), and ion (Ag+ as a model), respectively.

Automated summary

A versatile and sensitive quantum dot-based signal-off electrochemiluminescence sensing system was constructed using target-initiated dual Mg2+-dependent DNAzyme recycling and catalytic hairpin assembly amplification strategies. The developed programmable signal-off ECL sensing platform demonstrates excellent sensitivity with detection limits for target DNA, aptamer substrate, and ion.