A DNAzyme-Based Dual-Stimuli Responsive Electrochemiluminescence\nResonance Energy Transfer Platform for Ultrasensitive Anatoxin‑a\nDetection

Abstract

An\neffective and precise electrochemiluminescence resonance energy\ntransfer (ECL-RET), including the efficient regulation over the proximity\nof a donor and an acceptor and the reliable stimuli responsive as\nwell as the avoidance of undesirable probes leakage, etc., is significant\nfor the development of an accurate and sensitive ECL detection method;\nyet, the current literature in documentation involves only a limited\nrange of such ECL-RET systems. Herein, we propose an ECL-RET strategy\nwith dually quenched ultralow background signals and a dual-stimuli\nresponsive, accurate signal output for the ultrasensitive and reliable\ndetection of anatoxin-a (ATX-a). The dual quenching is accomplished\nby an integrated ECL-RET probe of metal organic frameworks (MOFs)\nencapsulated into Ru­(bpy)₃²⁺ (Ru-MOF) (donor)\ncoated with silver nanoparticles (AgNPs) shell (acceptor 1) and close\nproximity with DNA-ferrocene (Fc) (acceptor 2). Multistimuli responsive\nDNAzyme facilitated the accurate signal switch by both target ATX-a\nand hydrogen peroxide (H₂O₂). Because of the\nspecific recognition of the aptamer toward ATX-a, an intricate design\nof the DNA sequence enabled the exposure of the Ag⁺-dependent\nDNAzyme sequence and H₂O₂ in situ generated\nAg⁺ triggering a catalytic cleavage reaction to freely\nrelease the two ECL-RET energy acceptors, thus switching the ECL signal\nsignificantly and achieving ultrasensitive detection. It is noteworthy\nthat AgNPs are key in this ECL-RET strategy, serving both as the gate-keepers\nfor avoiding ECL probes leakage and also the ECL energy acceptors,\nand mostly importantly serving as the redox substrate for the subsequent\nDNAzyme catalytic signal switch. The proposed ECL-RET aptasensor for\nATX-a detection displayed splendid monitoring performance with a quite\nlow detection limit of 0.00034 mg mL^–1. This sensor\nnot only led to the development of a dual-quenching ECL-RET system\nbut also provided meaningful multistimuli responsive ECL biosensing\nplatform construction, which shows a promising application prospect\nin complicated sample analysis.