Faraday-Cage-Type Electrochemiluminescence Immunoassay: A Rise of Advanced Biosensing Strategy

Abstract

Electrochemiluminescence immunoassays are usually carried out through "on-electrode" strategy, i.e., sandwich-type immunoassay format, the sensitivity of which is restricted by two key bottlenecks: (1) the number of signal labels is limited and (2) only a part of signal labels could participate in the electrode reaction. In this Perspective, we discuss the development of an "in-electrode" Faraday-cagetype concept-based immunocomplex immobilization strategy. The biggest difference from the traditional sandwich-type one is that the designed "in-electrode" Faraday-cage-type immunoassay uses a conductive two-dimensional (2-D) nanomaterial simultaneously coated with signal labels and a recognition component as the detection unit, which could directly overlap on the electrode surface. In such a case, electrons could flow freely from the electrode to the detection unit, the outer Helmholtz plane (OHP) of the electrode is extended, and thousands of signal labels coated on the 2-D nanomaterial are all electrochemically "effective." Thus, then, the above-mentioned bottlenecks obstructing the improvement of the sensitivity in sandwich-type immunoassay are eliminated, and as a result a much higher sensitivity of the Faraday-cage-type immunoassay can be obtained. And, the applications of the proposed versatile "in-electrode" Faraday-cage-type immunoassay have been explored in the detection of target polypeptide, protein, pathogen, and microRNA, with the detection sensitivity improved tens to hundreds of times. Finally, the outlook and challenges in the field are summarized. The rise of Faraday-cage-type electrochemiluminescence immunoassay (FCT-ECLIA)-based biosensing strategies opens new horizons for a wide range of early clinical identification and diagnostic applications.

Switching the Photoluminescence and Electrochemiluminescence of Liposoluble Porphyrin in Aqueous Phase by Molecular Regulation

“…This is mainly due to the insuffi-cient lifetimes of the electrogenerated radical species in the vicinity of the electrode that would be requisite for ECL. The addition of co-reactant often enhances ECL, as the coreactant and luminophore-based radicals required for producing excited state can be electrogenerated at similar potentials.F igure 3A compares the CV along with the ECLpotential curve for different samples in the presence of K 2 S 2 O 8 (0.1 M) in 0.1 MPBS (pH 7.5) with 0.1 MKCl as the supporting electrolyte.Evidently,the ATPP-TPE displays the most intense ECL among the studied systems and the maximum ECL intensity is 6-fold increased by comparison with pure ATPP (the maximum ECL intensities are 18 000 au and 3000 au for ATPP-TPE and ATPP,r espectively), indicating ATPP-TPE has bright prospect for generating ECL in the aqueous phase.A lthough the TPE-PAs hows aggregated ECL ( Figure S13, Supporting Information), the motions of propeller-like TPE structure could be greatly suppressed in the aggregated state,w hich blocked the nonradiative decay channel and favor the resonance energy (electron) transfer from TPE moiety (donor) to ATPP core (acceptor) and thus provides ATPP-TPE adduct with inherent ECL characteristic of ATPP core.W hile the ACQe ffect makes the pure ATPP with lower ECL activity.T he mechanism of generating AIECL of ATPP-TPE is proposed in Equations (1)- (4). Theo nset of AIECL for ATPP-TPE was observed at about À1.2 V(red, Figure 3A), where the ATPP-TPE anion radical [ATPP-TPEC À ,Eq.…”

“…[3] Kannan et al discussed an ew kind of "in electrode" Faraday-cage-type ECL immunoassay capable of am uch higher (ten to hundreds of times) sensitivity than common sandwich-type immunoassay format, opening new horizons for early clinic identification and diagnostic aspects. [4] Zhang and co-workers successfully monitored the highly electrochemical dynamic redox processes with millisecond temporal resolution by using ECL imaging strategy and closed bipolar microelectrodes. [5] Nevertheless,t he design and synthesis of robust electrochemiluminophores are the most important part for application of ECL based techniques.T od ate,i norganic metal (Ru, Pt, Ir,e tc.)…”

Switching the Photoluminescence and Electrochemiluminescence of Liposoluble Porphyrin in Aqueous Phase by Molecular Regulation

“…Kannan et al. discussed a new kind of “in electrode” Faraday‐cage‐type ECL immunoassay capable of a much higher (ten to hundreds of times) sensitivity than common sandwich‐type immunoassay format, opening new horizons for early clinic identification and diagnostic aspects [4] . Zhang and co‐workers successfully monitored the highly electrochemical dynamic redox processes with millisecond temporal resolution by using ECL imaging strategy and closed bipolar microelectrodes [5] .…”

Core-shell gold-nickel nanostructures as highly selective and stable nonenzymatic glucose sensor for fermentation process

“…Therefore, the addition of a second metal, i.e. to generate bimetallic nanoparticles or nanocomposites [28][29][30][31][32][33][34][35] , is often used to improve the sensor performance. In principle, the second metal can effectively manipulate the electronic and geometric properties of the nanoparticles, leading to their higher selectivity and reactivity.…”