Electrochemiluminescence Response Research Articles

Electrochemiluminescence Detecting and Imaging of Yeast Metabolism Indicated by Endogenetic Co-reactant.

Glycolysis, a pivotal step in yeast metabolism, plays an indispensable role as a carbohydrate utilization process crucial for cellular survival. Developing advanced technologies to elucidate this fundamental physiological process holds significant scientific implications. Electrochemiluminescence (ECL) imaging exhibits the advantage of negligible background interference and facilitates straightforward visualization, thereby conferring significant value in biomolecular observation. In this study, we present an ECL imaging method for investigating yeast metabolism by utilizing the endogenetic NADH as an efficient coreactant for ECL generation. The yeast glycolysis process drives the conversion of NAD+ to NADH, resulting in enhanced ECL response as well as the increased brightness of ECL images that can be used for quantification of yeast activity. There was a linear correlation between the reciprocal of both the gray value of ECL image and yeast concentration within the range of 6.25 × 106 - 6.25 × 108 CFU/mL. Due to the highly efficient coreactant behavior of NADH, our method demonstrated excellent selectivity with minimal interference. Furthermore, we employed this approach to investigate some toxic inhibitors on yeast metabolism, yielding reliable results. This ECL imaging method not only avoids the use of additional coreactants but also provides a sensitive and intuitive approach for monitoring yeast metabolism, demonstrating great potential in revealing various complex biological processes.

Analytical theoretical framework for closed bipolar electrochemical cells under homogeneous molecular catalysis: Implications for electrochemiluminescence applications

A novel analytical framework has been formulated to describe the current-potential-time response in systems with two polarized interfaces where one charge transfer process follows a catalytic mechanism, as found in co-reactant electrochemiluminescence (ECL) systems. The developed theory provides mathematical expressions for electrochemical and ECL signals, concentrations, and interfacial potentials upon the application of a constant potential pulse. Theoretical analysis reveals that the chemical regeneration of the redox reactant within the catalytic cycle has a remarkable impact on the chronoamperometric, voltammetric, and ECL responses, thereby providing means to estimate the catalytic rate constant and to optimize light emission. The system's behaviors are rationalized through the influence of catalysis on the interfacial concentrations and potentials. Also, the primary theoretical predictions have been experimentally validated using the [Ru(bpy)₃]²⁺/oxalate ECL system.

Improved Functionality of Ultrafast Responsive Electrochemiluminescent Device with DNA/Ru(bpy)3 2+ Hybrid Film and Various Electrolyte Compositions

Electrochemiluminescence (ECL), a light-emitting phenomenon induced by electrochemical redox reactions, has potential applications in lightweight and flexible light-emitting devices. Previously, an ultrafast ECL response of <100 μs was successfully achieved under application of alternating current voltage by using a DNA-modified electrode including Ru(bpy)3 2+, an orange ECL material. In this study, we investigated effect of electrolyte composition on the fast responsive ECL in the DNA/Ru(bpy)3 2+ hybrid film-based ECL device. As a result, the ECL intensity and lifetime of ECL were improved by introducing additional Ru(bpy)3 2+ into the electrolyte solution. The increase concentration of Ru(bpy)3 2+ inhibited dissolution of aggregated part formed on DNA/Ru(bpy)3 2+ hybrid film and increase in the amount of reactive charge in the aggregated part. Furthermore, we introduced blue-luminescent 9,10-diphenylanthracene (DPA) into the electrolyte solution of the ECL device consisting of DNA/Ru(bpy)3 2+ hybrid film. Consequently, blue ECL from DPA was obtained from the DNA/Ru(bpy)3 2+ hybrid electrode at lower applied voltage than that required to induce the redox reactions of DPA itself. This lower-voltage-drivable blue ECL was attributed to triplet–triplet energy transfer from Ru(bpy)3 2+ in the DNA/Ru(bpy)3 2+ hybrid electrode followed by a triplet–triplet annihilation upconversion reaction of DPA in the electrolyte solution. Moreover, ultrafast-response, electrochemically triggered blue luminescence from DPA was successfully observed.

A Dual-Ion Synergistic Catalysis Utilizing Zn2+-Regulated CdSySe1-y ECL Immunosensor Employed for the Ultrasensitive CA19-9 Detection.

Carbohydrate antigen 19-9 is a well-known malignancy biomarker, and its sensitive detection is particularly crucial in the diagnosis and assessment of pancreatic cancer. In this study, an ultrasensitive CA19-9 immunosensor was constructed using the Zn2+-regulated CdSySe1-y (Zn-CdSySe1-y) nanospheres (NSs) as the electrochemiluminescence (ECL) emitter and FeCoS2 nano octahedrons (NOs) as a coreactant enhancer. The microstructure of ternary transition metal chalcogenide CdSySe1-y was precisely tuned by Zn2+ doping to avoid aggregation and thus enable stable and efficient cathodic ECL responses. The bimetallic sulfide FeCoS2 was synthesized using a metal organic framework (MOF) as the template by ion permeation. It was able to catalyze the coreactant efficiently due to the synergistic effect of the Fe2+ and Co2+. The immunosensor exhibited low detection limit (7.6 × 10-5 U mL-1) in the wide linear range of 0.0001-100 U mL-1, offering a sensitive CA19-9 detection method.

Strong Electrochemiluminescence Response Derived from Ionic Chiral Covalent Organic Frameworks for Enantioselective Discrimination of Amino Acid Enantiomers via an Electrostatic Attraction Effect.

Porous chiral materials accompanied by electrochemiluminescence (ECL) activity are rarely reported for enantioselective discrimination because of the big challenges to integrate the stereogenic center and ECL-active unit in the backbone. In the present study, ionic chiral covalent organic frameworks (iCCOFs) consisting of the pyridinium unit as the ECL-active species were prepared by a facile strategy. We were amazed that such iCCOFs could display strong cathodic ECL responses. Meanwhile, the as-prepared ECL-active iCCOFs performed enantioselective ECL quenching toward amino acid enantiomers, attributed to the enhanced photoinduced electron transfer process derived from the formed complex between the iCCOFs and amino acids via an electrostatic attraction effect. The iCCOF with an (S)-configuration was prone to interact with l-amino acids, producing a lower ECL intensity. The maximum intensity ratio between the d- and l-enantiomers was 33.0. Finally, the enantiomeric compositions of the measured amino acids presented a good linear relation with the obtained ECL intensity, which was fit for the determination of samples with unknown enantiomeric purity. In brief, the obtained results convince us that this study advances a new generation of ECL-active iCCOFs and displays great potential in enantioselective sensing.

Dual-mode electrochemical and electrochemiluminescence detection of dopamine based on perylene diimide self-assembly material.

The self-assembly materialN,N-bis-(3-dimethyl aminopropyl)-3,4,9,10-perylene tetracarboxylic acid diimide (PDI) isreported to show electrochemical (EC)/electrochemiluminescence (ECL) property for designing new dual-mode dopamine (DA) sensors. K2S2O8 significantly improved the EC reduction current at -0.346V and ECL intensity at -0.25V of thePDI self-assembly material. DA largely decreased the EC reduction current and ECL intensity of this homogeneous EC/ECL material due to the competitive consumption of K2S2O8 in theoxidization process of DA and the low electron conductivity of polyDA formed through the oxidization of DA by K2S2O8. In addition, the ECL quenching mechanism involved an energy-transfer process resulting from the collision between the produced o-benzoquinone species (oxidization of DA) and the excited state of PDI, which decreased the ECL intensity. This homogeneous EC/ECL material showed linear EC current response for DA from 5.0 nM to 50.0 µM with a detection of limit of 2.7 nM and linear ECL response for DA from 1.0 nM to 100.0 µM with a detection of limit of 0.41 nM. Theproposed dual-mode EC/ECL sensors also showed good feasibility in urine sample analysis.

Photoluminescent and Electrochemiluminescent Detection of Fe3+ Using Cyclometalated Iridium Complexes via Fe3+-Catalyzed Hydrolysis.

Ferric ion (Fe3+) is a biologically abundant and important metal ion. We developed several cyclometalated iridium complex-based molecular sensors (1, ppy-1, 1-phen, 1 a, and 1_OMe) for the detection of Fe3+ using an acetal moiety as the reaction site. The acetal moiety in iridium complexes undergoes Fe3+-catalyzed hydrolysis and subsequent formation of a formyl group, resulting in turn-off photoluminescent and electrochemiluminescent responses. Sensor 1 showed excellent selectivity toward Fe3+ over other biologically important metal ions. Furthermore, we compared the performance of the sensors based on the structural differences of the iridium complexes, and revealed a relationship between the structure and chemical properties through electrochemical experiments and computational calculations.

Ionic Covalent-Organic Frameworks Composed of Anthryl-Extended Viologen as a Kind of Electrochemiluminescence Luminophore.

Nowadays, covalent-organic frameworks (COFs) integrated with the electrochemiluminescence (ECL) behavior are highly desired owing to the significant advantages including multifunctionality, high sensitivity, and low background noise. Here, two ionic COFs (iCOFs) consisting of the anthryl-extended viologen as the backbone were designed and synthesized via the Zincke reaction. It is found for the first time that the as-prepared iCOFs accompanied by potassium persulfate as the coreactant can provide a clear ECL response in a water-bearing medium. The maximum ECL emissions of the iCOFs were in agreement with the photoluminescence spectra. Besides, cyclic voltammetry and electron paramagnetic resonance measurements reveal that the pyridinium unit was electrochemically reduced to afford the free radical. Then, it reacted with SO4·- to generate the excited-state [iCOF]*. Finally, [iCOF]* quickly returned to its ground state coupled with a clear ECL emission, yielding a maximum ECL quantum efficiency of 23.4% compared with tris(2,2'-bipyridyl) ruthenium(II) as the benchmark. In brief, the current study opens a way to develop a kind of ECL emitter that holds great potential in sensing, imaging, and light-emitting devices.

A novel multimodal aptasensor for Patulin detection in fruit products based on high-performance RuMOF@hydrogel and versatile pericarp-derived carbonized polymer dots

Patulin (PAT) is a widespread fruit toxin. Trace-level PAT exposure can cause serious harm to human health. Herein, a multimodal PAT aptasensor was designed based on Ru(bpy)32+-based metal organic framework composited hydrogel (RuMOF@hydrogel) and versatile banana peel-derived carbonized polymer dots (BPPDs). RuMOF@hydrogel modified magnetic-electrode exhibited excellent anodic and cathodic electrochemiluminescence (ECL) emission and stability. Meanwhile, the BPPDs could enhance anodic ECL of RuMOF@hydrogel, and also show excellent fluorescence (FL) and photothermal (PT) properties. With the aid of PAT-triggered hybridization chain reaction and magnetic separation, ECL, FL, and PT responses could be recorded concurrently. The detection limit can reach as low as 0.25 fg mL−1. The ratiometric ECL quantitation ensured the sensitivity and accuracy of this assay. And visual FL and portable PT modes contributed to the utility. Furthermore, this aptasensor demonstrated better performances than HPLC in fruit products and the protocol can be extended to determine various contaminants in foods.

Confinement-enhanced electrochemiluminescence of copper nanoclusters on 3D layered double hydroxide for ultrasensitive detection of GFAP

In this work, the copper nanoclusters (Cu NCs) were confined on 3D layered double hydroxide (3D-LDH) to form Cu NCs@3D-LDH with outstanding electrochemiluminescence (ECL) for constructing ultrasensitive biosensor to detect of glial fibrillary acidic protein (GFAP) implicated in Alzheimer's Disease (AD). More importantly, compared to the individual Cu NCs, Cu NCs@3D-LDH presented strong and stable ECL response, since 3D-LDH could not only gather more Cu NCs but also limit the intramolecular free motion to reduce nonradiative transition for obtaining high ECL intensity. In addition, the improved cascade amplification method combining proximity ligation assay (PLA) with DNAzyme could transform tiny amount of target protein into a large amount of output DNA to improve sensitivity of biosensor. The ECL biosensor realized ultrasensitive detection of GFAP with the detection limit of 2 ag/mL and it had been successfully applied to the evaluation of GFAP in the serum of patients with neurological diseases. This research offered a general and facile method to improve ECL performance of Cu NCs for sensitive detection of biomarkers for disease diagnosis.

Cu Single-Atom Nanozyme-Mediated Electrochemiluminescence Biosensor for Highly Sensitive Detection of MicroRNA-622.

MicroRNA (miRNA) detection is a critical aspect of disease diagnosis, and recent studies indicate that miRNA-622 could be a potential target for lung cancer. Herein, Cu single atoms were anchored on graphitic carbon nitride (Cu SAs@CN) as a coreaction accelerator applied in luminol-H2O2 system, thereby establishing an efficient and sensitive electrochemiluminescence (ECL) biosensor for miRNA-622 detection. Cu SAs@CN was explored to possess excellent enzyme-like activities that promote the generation of abundant reactive oxygen species, which amplified ECL emission. Meanwhile, in order to improve the accuracy and sensitivity for miRNA-622 detection, the highly specific trans-cleavage ability of CRISPR/Cas12a was combined with a catalytic hairpin assembly strategy. Therefore, an ECL biosensor for miRNA-622 detection was systematically constructed as a proof of concept, achieving an ultralow limit of detection of 1.09 fM, and the feasibility was demonstrated in human serum samples. The findings of this research provide a promising strategy to enhance the ECL response using versatile single-atom catalysts, thus advancing the development of ECL biosensing applications.

Conductivity-Regulated Bipolar Electrochemiluminescence Sensing Platform for Indicator-Free Homogeneous Bioassay.

Electrochemiluminescence (ECL) sensors have been widely developed because of their high sensitivity and low background. However, most of them suffered from tedious probe modification on the electrode and cross-interferences within the sensing and reporting reactions. The bipolar electrode based ECL (BPE-ECL) can effectively eliminate interference by physically separating the sensing and reporting cells, but there is still a need for exogenous electroactive indicators to transduce the variations between two poles of a BPE. Herein, based on the discovery that conductivity can be regulated in aqueous medium by homogeneous bioreaction, we showed a novel BPE-ECL sensing platform that combined the conductivity-based biosensing technology with ECL reporting system for the first time. Compared to many short nucleic acids, the target induced a hybridization chain reaction to produce the long nucleic acid aggregates, resulting in a conductivity decrease of the sensing cell and finally reducing the ECL response in the reporting cell. The BPE-ECL platform has already been applied to detect microRNA-21 for a demonstration. This innovative system not only separates the target sensing and reporting reactions but also avoids the use of electrochemical indicators for measurement. The BPE-ECL biosensing platform can be developed to detect different targets by changing the probe used.

Highly Specific Aptamer-Antibody Birecognized Sandwich Module for Ultrasensitive Detection of a Low Molecular Weight Compound.

Herein, the aptamer-antibody sandwich module was first introduced to accurately recognize a low molecular weight compound (mycotoxin). Impressively, compared with the large steric hindrance of a traditional dual-antibody module, the aptamer-antibody sandwich with low Gibbs free energy and a low dissociation constant has high recognition efficiency; thus, it could reduce false positives and false negatives caused by a dual-antibody module. As a proof of concept, a sensitive electrochemiluminescence (ECL) biosensor was constructed for detecting mycotoxin zearalenone (ZEN) based on an aptamer-antibody sandwich as a biological recognition element and porous ZnO nanosheets (Zn NSs) supported Cu nanoclusters (Cu NCs) as the signal transduction element, in which the antibody was modified on the vertex of a tetrahedral DNA nanostructure (TDN) with a rigid structure to increase the kinetics of target recognition for promoting the detection sensitivity. Moreover, the Cu NCs/Zn NSs exhibited an excellent ECL response that was attributed to the aggregation-induced ECL enhancement through electrostatic interactions. The sensing platform achieved trace detection of ZEN with a low detection limit of 0.31 fg/mL, far beyond that of the enzyme-linked immunosorbent assay (ELISA, the current rapid detection method) and high-performance liquid chromatography (HPLC, the national standard detection method). The strategy has great application potential in food analysis, environmental monitoring, and clinical diagnosis.

Nanoconfined Silver Nanoclusters Combined with X-Shaped DNA Recognizer-Triggered Cascade Amplification for Electrochemiluminescence Detection of APE1.

Apurinic/apyrimidinic endonuclease 1 (APE1), as a vital base excision repair enzyme, is essential for maintaining genomic integrity and stability, and its abnormal expression is closely associated with malignant tumors. Herein, we constructed an electrochemiluminescence (ECL) biosensor for detecting APE1 activity by combining nanoconfined ECL silver nanoclusters (Ag NCs) with X-shaped DNA recognizer-triggered cascade amplification. Specifically, the Ag NCs were prepared and confined in the glutaraldehyde-cross-linked chitosan hydrogel network using the one-pot method, resulting in a strong ECL response and exceptional stability in comparison with discrete Ag NCs. Furthermore, the self-assembled X-shaped DNA recognizers were designed for APE1 detection, which not only improved reaction kinetics due to the ordered arrangement of recognition sites but also achieved high sensitivity by utilizing the recognizer-triggered cascade amplification of strand displacement amplification (SDA) and DNAzyme catalysis. As expected, this biosensor achieved sensitive ECL detection of APE1 in the range of 1.0 × 10-3 U·μL-1 to 1.0 × 10-10 U·μL-1 with the detection limit of 2.21 × 10-11 U·μL-1, rendering it a desirable approach for biomarker detection.

Highly Electroactive Co2+-Based Metal-Organic Frameworks as an Efficient Coreaction Accelerator for Amplifying Near-Infrared Electrochemiluminescence of Gold Nanoclusters in Biomarkers Immunoassay.

Metal nanoclusters (NCs) as a new kind of luminophore have acquired sufficient interest, but their widespread application is restricted on account of their relatively low electrochemiluminescence (ECL) efficiency. Then, aqueous metal NCs with high ECL efficiency were strongly anticipated, especially for the ultrasensitive analysis of biomarkers. Herein, a near-infrared (NIR) ECL biosensing strategy for the test of neuron-specific enolase (NSE) was proposed by utilizing N-acetyl-l-cysteine (NAC)- and cysteamine (Cys)-stabilized gold NCs (NAC/Cys-AuNCs) as ECL emitters with the NIR ECL emission around 860 nm and a metal-organic framework/palladium nanocubes (ZIF-67/PdNCs) hybrid as the coreaction accelerator through their admirable electrocatalytic activity. The NIR emission would reduce photochemical injury to the samples and even realize nondestructive analysis with highly strong susceptibility and suitability. Furthermore, the utilization of ZIF-67/PdNCs could improve the ECL response of NAC/Cys-AuNCs by facilitating the oxidation of the coreactant triethylamine (TEA), leading to the production of a larger quantity of reducing intermediate radical TEA•+. Consequently, NAC/Cys-AuNCs with ZIF-67/PdNCs displayed 2.7 fold enhanced ECL emission compared with the single NAC/Cys-AuNCs using TEA as the coreactant. In addition, HWRGWVC (HWR), a heptapeptide, was introduced to immobilize antibodies for the specially binding Fc fragment of the antibodies, which improved the binding efficiency and sensitivity. As a result, a "signal-on" immunosensor for NSE analysis was obtained with an extensive linear range of 0.1 to 5 ng/mL and a low limit of detection (0.033 fg/mL) (S/N = 3). This study provides a wonderful method for the development of an efficient nondestructive immunoassay.

A novel electropolymerized molecularly imprinted dual-mode sensor for bisphenol AF detection in pond mud

Recently, bisphenol AF (BPAF) as most commonly used bisphenol A analogs had the increasing higher level in the environment with unknown risks. Herein, a synchronous dual-mode sensor had been established based on differential pulse voltammetry (DPV) and electrochemiluminescence (ECL) for the detection of BPAF in pond mud. Firstly, the sensing molecularly imprinted polymer (MIP) films were prepared by electrochemical polymerization procedure with 3,4-ethoxylene dioxy thiophene (EDOT) as the functional monomer, BPAF as the template molecule and MXene as the supporting electrolyte. Due to unique characters of PEDOT and MXene, the constructed MIP films were stable and highly conductive. Meanwhile, zinc-doped bismuth sulfide quantum dots (Zn-Bi2S3 QDs) were synthesized as a nano-emitter to generate strong ECL signals in the MIP film. In the sensing process, a pulsed voltage applied to the PEDOT/MXene MIP film to generate both DPV and ECL signals for simultaneous dual-mode detection. Additionally, the liquid-liquid extraction with deep eutectic solvent (menthol: octanol 1:1) was used for the pre-concentration of the BPAF in the pond mud. Based on the sensing system, the ECL and DPV response showed the good linear relationships with the concentration of BPAF with the ranges of 0.01 μM–50 μM and 0.1 μM–50 μM and the detection limits of 0.0060 μM and 0.059 μM, respectively.

Highly Sensitive and Selective Detection of L-Tryptophan by ECL Using Boron-Doped Diamond Electrodes.

L-tryptophan is an amino acid that is essential to the metabolism of humans. Therefore, there is a high interest for its detection in biological fluids including blood, urine, and saliva for medical studies, but also in food products. Towards this goal, we report on a new electrochemiluminescence (ECL) method for L-tryptophan detection involving the in situ production of hydrogen peroxide at the surface of boron-doped diamond (BDD) electrodes. We demonstrate that the ECL response efficiency is directly related to H2O2 production at the electrode surface and propose a mechanism for the ECL emission of L-tryptophan. After optimizing the analytical conditions, we show that the ECL response to L-tryptophan is directly linear with concentration in the range of 0.005 to 1 µM. We achieved a limit of detection of 0.4 nM and limit of quantification of 1.4 nM in phosphate buffer saline (PBS, pH 7.4). Good selectivity against other indolic compounds (serotonin, 3-methylindole, tryptamine, indole) potentially found in biological fluids was observed, thus making this approach highly promising for quantifying L-tryptophan in a broad range of aqueous matrices of interest.

Preparation and sensing performance of chiral carbon Dot@MOF electrode material

Abstract Chirality is a ubiquitous phenomenon in nature. The identification of chiral compounds has important theoretical significance and application prospects in many fields such as biology, medicine, and food. This paper proposes an innovative approach to differentiate enantiomers by using the synergistic effect of chiral MOFs and CDs through electrochemiluminescence. The results demonstrate that CDs@[Zn(D-cam)(phen)(H2O)]n exhibit higher electrochemiluminescent response towards L/D-Trp, enabling the detection of Trp enantiomers. This research suggests that selective recognition of amino acid enantiomers can be achieved through ECL-based nanocomposites of CDs and porous MOFs.

MoS2/MXene Van der Waals heterojunction-based electrochemiluminescence sensor for triple negative breast cancer detection

The van der Waals heterojunction is able to combine the advantages of different materials and has potential to be used in biosensing researches. In this study, we developed a novel van der Waals heterojunction by combining MXene and MoS2 nanosheets for the electrochemiluminescence (ECL) sensing applications. This van der Waals heterojunction material not only possessed the superior conductivity of MXene, but also regulated the electron transport. Additionally, the incorporation of MoS2 nanosheets into the MXene interlayers significantly enhances the material stability. Meanwhile, nitrogen-rich quantum dots (N dots) were synthesized as ECL tags with an impressive nitrogen content of up to 75 %. By integrating the ECL response of N dots within the van der Waals heterojunction, we established a highly efficient sensing system for miRNA-373, which overexpressed in triple negative breast cancer tissues. The van der Waals heterojunction-based biosensor can enhance the ECL signal of N dots effectively to detect miRNA-373 from 1 fM to 1 μM. Consequently, the developed sensing system holds promise for the early detection of metastasis of the triple-negative breast cancer, paving the way for the effective clinical interventions.

A molecularly imprinted electrochemiluminescence sensor based on ZnO@CdTe for the detection of mevastatin

In this paper, CdTe quantum dots with near-infrared fluorescence (NIR) and hexagonal prism-shaped ZnO were synthesized, and the composites were characterized for their performance. A sensitive molecularly imprinted electrochemiluminescence (ECL) sensor for the determination of mevastatin was constructed based on ZnO@CdTe and molecularly imprinted polymer (MIP). The highest ECL intensity of the system was obtained by ZnO@CdTe as the main luminophores reacted with the co-reactant K2S2O8. The ECL response generated by the reaction of ZnO@CdTe and K2S2O8 was used as the basic signal detection platform. The MIP was prepared by the electropolymerization process on the above platform, which laid the foundation for forming the mevastatin cavities with specific recognition sites. In addition, the response mechanism was investigated, and the determination conditions were optimized. The ECL intensity change values (ΔI) of the sensor showed a good linear relationship with the logarithm of mevastatin concentration in the range of 2.0 × 10−11 to 2.0 × 10−6 mol L−1, and the limit of detection was 6.7 × 10−12 mol L−1 (S/N = 3). This method obtained satisfactory results in the detection of mevastatin in tablets.