A DNAzyme-Based Dual-Stimuli Responsive Electrochemiluminescence Resonance Energy Transfer Platform for Ultrasensitive Anatoxin-a Detection

Abstract

An effective and precise electrochemiluminescence resonance energy transfer (ECL-RET), including the efficient regulation over the proximity of a donor and an acceptor and the reliable stimuli responsive as well as the avoidance of undesirable probes leakage, etc., is significant for the development of an accurate and sensitive ECL detection method; yet, the current literature in documentation involves only a limited range of such ECL-RET systems. Herein, we propose an ECL-RET strategy with dually quenched ultralow background signals and a dual-stimuli responsive, accurate signal output for the ultrasensitive and reliable detection of anatoxin-a (ATX-a). The dual quenching is accomplished by an integrated ECL-RET probe of metal organic frameworks (MOFs) encapsulated into Ru(bpy)₃²⁺ (Ru-MOF) (donor) coated with silver nanoparticles (AgNPs) shell (acceptor 1) and close proximity with DNA-ferrocene (Fc) (acceptor 2). Multistimuli responsive DNAzyme facilitated the accurate signal switch by both target ATX-a and hydrogen peroxide (H₂O₂). Because of the specific recognition of the aptamer toward ATX-a, an intricate design of the DNA sequence enabled the exposure of the Ag⁺-dependent DNAzyme sequence and H₂O₂ in situ generated Ag⁺ triggering a catalytic cleavage reaction to freely release the two ECL-RET energy acceptors, thus switching the ECL signal significantly and achieving ultrasensitive detection. It is noteworthy that AgNPs are key in this ECL-RET strategy, serving both as the gate-keepers for avoiding ECL probes leakage and also the ECL energy acceptors, and mostly importantly serving as the redox substrate for the subsequent DNAzyme catalytic signal switch. The proposed ECL-RET aptasensor for ATX-a detection displayed splendid monitoring performance with a quite low detection limit of 0.00034 mg mL^-1. This sensor not only led to the development of a dual-quenching ECL-RET system but also provided meaningful multistimuli responsive ECL biosensing platform construction, which shows a promising application prospect in complicated sample analysis.