Bifunctional Moderator-Powered Ratiometric Electrochemiluminescence Enzymatic Biosensors for Detecting Organophosphorus Pesticides Based on Dual-Signal Combined Nanoprobes

Abstract

The bifunctional moderator is urgently needed in the field of ratiometric electrochemiluminescence (ECL) sensing since it can mediate simultaneously two ECL signals to conveniently realize their opposite change trend. This work designed a novel dual-signal combined nanoprobe with carboxyl-functionalized poly­[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1′,3}-thiadazole)] nanoparticles (c-PFBT NPs) as the anodic ECL probe and L-cysteine capped CdS quantum dots (L-CdS QDs) as the cathodic ECL probe, which performed a dual-signal output capability without any additional coreactants. More importantly, hydrogen peroxide (H2O2) produced in situ by enzyme-catalyzed reaction was developed as a bifunctional moderator for simultaneously regulating two signals. The dual-signal combined nanoprobe (c-PFBT NPs@CdS QDs) served as the matrix to immobilize acetylcholinesterase (AChE) and choline oxidase for organophosphorus (OPs) analysis. In the absence of OPs, H2O2 was produced by catalyzing the substrate acetylthiocholine (ATCl) with enzymes and it quenched the anodic ECL signal from c-PFBT NPs and simultaneously promoted the cathodic ECL signal from L-CdS QDs. When OPs was present, the activity of AChE was inhibited, the anodic signal would increase, and the cathodic signal would accordingly decrease. The integration of the bifunctional moderator H2O2 and dual-signal combined nanoprobe c-PFBT NPs@CdS QDs not only provides an attractive ECL platform for enzymatic sensing involving the generation or consumption of H2O2 but also paves a new pathway for other ratiometric ECL systems involving enzyme catalytic amplification for detecting antigens, antibodies, DNA, RNA, etc.

Kinetics-Based Ratiometric Electrochemiluminescence Analysis for Signal Specificity: Case Studies of Piperazine Drug Discrimination with Au Nanoclusters

“…This fundamental principle is anticipated to be generalizable to other ECL luminophore–co-reactant systems for broader applications. Note that the kinetics-based ratiometric analysis differs fundamentally from classic ECL ratiometric methods where (1) either multiple ECL luminophores and/or energy transfer reagents or both cathodic and anodic reactions are necessary; and (2) the ECL signals are again almost exclusively under equilibrium or steady states, and additional recognition elements are required. − …”

Nucleic acid isothermal amplification-based soft nanoarchitectonics as an emerging electrochemical biosensing platform

“…131 In addition to dual-wavelength ratiometric ECL sensing, other types of ratiometric ECL methods include dual-potential ratiometric, bipolar-electrode (BPE) ratiometric, or internal standard ratiometric biosensors. [132][133][134] For dual-potential biosensors, two ECL emitters are generally required, which show potential-dependent features and the ratio of ECL intensities is differentiable at two excitation potentials. Thus, a pair of anodic/cathodic emitters with independent luminescence is generally employed in this type of biosensor.…”

Biosensor Based on Covalent Organic Framework Immobilized Acetylcholinesterase for Ratiometric Detection of Carbaryl

“…The following two points are of great significance for the construction of high-performance AChE inhibition-based pesticide electrochemical sensors. Firstly, choose an appropriate support material to immobilize the enzyme and maintain its activity [ 32 , 33 , 34 ]. Suitable electrode support materials should allow a large number of enzymes to be loaded and provide a good microenvironment for maintaining enzyme activity [ 35 , 36 , 37 ].…”