Electrode Electrochemiluminescence Research Articles

Spatial-Potential-Color-Resolved Bipolar Electrode Electrochemiluminescence Biosensor Using a CuMoOx Electrocatalyst for the Simultaneous Detection and Imaging of Tetracycline and Lincomycin.

A spatial-potential-color-resolved bipolar electrode electrochemiluminescence biosensor (BPE-ECL) using a CuMoOx electrocatalyst was constructed for the simultaneous detection and imaging of tetracycline (TET) and lincomycin (LIN). HOF-101 emitted peacock blue light under positive potential scanning, and CdSe quantum dots (QDs) emitted green light under negative potential scanning. CuMoOx could catalyze the electrochemical reduction of H2O2 to greatly increase the Faradic current of BPE and realize the ECL signal amplification. In channel 1, CuMoOx-Aptamer II (TET) probes were introduced into the BPE hole (left groove A) by the dual aptamer sandwich method of TET. During positive potential scanning, the polarity of BPE (left groove A) was negative, resulting in the electrochemical reduction of H2O2 catalyzed by CuMoOx, and the ECL signal of HOF-101 was enhanced for detecting TET. In channel 2, CuMoOx-Aptamer (LIN) probes were adsorbed on the MXene of the driving electrode (DVE) hole (left groove B) by hydrogen-bonding and metal-chelating interactions. LIN bound with its aptamers, causing CuMoOx to fall off. During negative potential scanning, the polarity of DVE (left groove B) was negative and the Faradic current decreased. The ECL signal of CdSe QDs was reduced for detecting LIN. Furthermore, a portable mobile phone imaging platform was built for the colorimetric (CL) detection of TET and LIN. Thus, the multiple mode-resolved detection of TET and LIN could be realized simultaneously with only one potential scan, which greatly improved detection accuracy and efficiency. This study opened a new technology of BPE-ECL sensor application and is expected to shine in microchips and point-of-care testing (POCT).

A bipolar Electrode-Electrochemiluminescence sensor for Salmonella typhimurium detection based on β-cyclodextrin Host-Guest recognition

A bipolar electrode electrochemiluminescence (BPE-ECL) with β-cyclodextrin (β-CD) host–guest recognition was constructed for the rapid detection of Salmonella typhimurium (S. typhimurium). Firstly, the sulfhydryl β-CD (SH-β-CD, with inner diameter size: 6.0–6.5 Å) was assembled on the gold-plated cathode of BPE. Ferrocene (Fc, length: 3.5 Å; width: 4.4 Å) labelled signal probe and parts Fc-aptamer complement each other to form a double-stranded DNA (dsDNA). Due to its large size, the dsDNA with a double Fc (width > 8.8 Å) could not be embedded into the cavities of β-CD. In the presence of S. typhimurium, Fc-aptamer bond specifically to S. typhimurium, and the signal probe was shed from the dsDNA. Then, the signal probe (guest) was captured by the SH-β-CD (host) on the surface of the BPE. Due to the principle of spatial matching between Fc and SH-β-CD, a stable inclusion complex could be formed, which made Fc close to the cathode surface of the BPE. When a certain driving voltage was applied, Fc was oxidized to Fc+. The cathode surface of Fc+ would promote electron transfer, causing the [Ru(bpy)3]2+ at the anode emit light, and effectively convert the electrochemical signal into an ECL signal. 101-105 CFU mL−1S. typhimurium was positively correlated with Fc+ and ECL intensity, with a detection limit of 101 CFU mL−1. Therefore, S. typhimurium can be quantitatively detected by the electron transfer rate of the BPE.

Directionally In Situ Self-Assembled Iridium(III)-Polyimine Complex-Encapsulated Metal-Organic Framework Two-Dimensional Nanosheet Electrode To Boost Electrochemiluminescence Sensing.

Manufacturing electrochemiluminescence (ECL) electrodes to detect analytes with high performance in the aqueous phase for water-insoluble metal complexes is a great challenge. Here, a directional self-assembling avenue for in situ fabricating iridium(III)-polyimine complex-encapsulated metal-organic framework (MOF) two-dimensional electrode Hf-MOF/Ir2PD/APS/ITO is developed. The electrode displayed bright red ECL emission with high stability in the aqueous phase and specific adsorption toward ssDNA against dsDNA and mNs. That is to say, a "high-performance and multifunctional ECL electrode" is presented and explored for sensitive detection of acetamiprid (Ace) with a limit of detection of 0.0025 nM, where Ace-aptamer recognition-switched Exonuclease III-mediated digestion to make large numbers of Fc-labeled ssDNA transform into Fc-mNs. Furthermore, the proposed method was triumphantly employed to monitor the change in the residual concentration of Ace in pakchoi. This work breaks through the bottleneck of metal complex-based ECL emission in organic solvents and provides a novel strategy to develop high-performance ECL sensors.

Atomically Fe‐anchored MOF‐on‐MOF nanozyme with differential signal amplification for ultrasensitive cathodic electrochemiluminescence immunoassay

AbstractThe successful application of electrochemiluminescence (ECL) in immunoassays for clinical diagnosis requires stable electrodes and high‐efficient ECL signal amplification strategies. Herein, the authors discovered a new class of atomically dispersed peroxidase‐like nanozymes with multiple active sites (CoNi‐MOF@PCN‐224/Fe), which significantly improved the catalytic performance and uncovered the underlying mechanism. Experimental studies and theoretical calculation results revealed that the nanozyme introduced a Fenton‐like reaction into the catalytic system and the crucial synergistic effects of definite active moieties endow CoNi‐MOF@PCN‐224/Fe strong electron‐withdrawing effect and low thermodynamic activation energy toward H2O2. Benefiting from the high peroxidase‐like activity of the hybrid system, the resultant ECL electrode exhibited superior catalytic activity in the luminol‐H2O2 system and resulted in an ≈17‐fold increase in the ECL intensity. In addition, plasmonic Ag/Au core‐satellite nanocubes (Ag/AuNCs) were designed as high‐efficient co‐reactant quenchers to improve the performance of the ECL immunoassay. On the basis of the differential signal amplification strategy (DSAS) proposed, the immunoassay displayed superior detection ability, with a low limit of detection (LOD) of 0.13 pg mL−1 for prostate‐specific antigen (PSA). The designed atomically anchored MOF‐on‐MOF nanozyme and DSAS strategy provides more possibilities for the ultrasensitive detection of disease markers in clinical diagnosis.

Microfluidic Gradient Culture Arrays for Cell Pro-oxidation Analysis Using Bipolar Electrochemiluminescence.

A microfluidic gradient array is a widely used screening and analysis device, which has characteristics of high efficiency, high automation, and low consumption. Bipolar electrode electrochemiluminescence (BPE-ECL) has special value in microfluidic array chips. The combination of the microfluidic gradient and BPE arrays has potential for high-throughput screening. In this article, a microfluidic BPE array chip for gradient culture and conditional screening of cancer cells was designed. The generation of concentration gradients, continuous culture of cancer cells with high throughput, and drug screening through BPE-ECL of the Ru(bpy)32+/TPrA system can be performed in one chip. We tested gradient pro-oxidation of MCF-7 by ascorbic acid and the synergistic effect of pro-oxidation on doxorubicin. The method achieves high analysis efficiency through a BPE array while simplifying the tedious procedures required by cell culture methods.

Assembled Photonic Crystal/Gold Nanoparticle Interface: A Dual Amplifying Electrochemiluminescent Aptasensor for the Ultrasensitive Detection of an Amyloid-β Monomer.

Amyloid-β (Aβ) protein is considered to be a key biomarker that is closely associated with Alzheimer's disease (AD). The level of Aβ, particularly its subtle fluctuation, indicates early neuropathological changes, which poses a considerable challenge in predicting AD, considering the detection limit of sensing technologies. Herein, a new label-free sensor based on luminol electrochemiluminescence (ECL) was proposed by developing a close-packed monolayered-SiO2 array with gold (Au) nanoparticles (NPs) entrapped in their gaps as the basal electrode. The well-organized SiO2 NPs with a quasiphotonic crystal structure amplified the ECL signal via light scattering, while Au NPs amplified the signal by directly catalyzing luminol oxidation. Owing to the dual signal amplification, the proposed electrode furnished an ∼64-fold-intensified ECL signal of luminol as the sensing background. Further, the as-prepared ECL electrode served as the substrate to develop an aptasensor for the sensitive detection of Aβ. The inhibition of the ECL signal due to the suppressed diffusion of luminol to the sensor surface acts as an indicator to quantify the amount of Aβ. The transfer dynamics mechanism provides a label-free sensing strategy and facilitates the high sensitivity of the aptasensor for Aβ detection. Under optimal conditions, the developed aptasensor exhibits an ultrasensitive performance for Aβ with a very low limit of detection of 5 fM, providing a new prospect for clinical research on Aβ and a promising approach in the field of ECL sensing.

Paper-Based Bipolar Electrode Electrochemiluminescence Platform Combined with Pencil-Drawing Trace for the Detection of M.SssI Methyltransferase.

Herein, a hand-drawing paper-based bipolar electrode (BPE) electrochemiluminescence (ECL) platform for M.SssI methyltransferase (M.SssI MTase) assay was proposed via employing high electrocatalytic Pt@CeO2 as an ECL co-reaction accelerator and pencil-drawing graphite electric circuits as wires and electrodes. Notably, the introduction of pencil-drawing trace not only simplified the manufacturing process but also reduced the cost and saved fabricating time. Meanwhile, Pt@CeO2 with good electrocatalytic activity and satisfactory chemical stability was used at the anode of the closed BPE-ECL device to accelerate the oxidation rate of uric acid. Due to the balanced charges of the bipolar electrode, the ECL response of the MnS: CdS@ZnS/S2O82- system emitted on the cathode was enhanced. In situ growth of gold nanoparticles in the two electrode areas was convenient for DNA immobilization. With the above points in mind, the specific DNA double strands functionalized via Pt@CeO2 were employed to identify M.SssI MTase. The unmethylated DNA double strands were cut by HpaII endonuclease, resulting in the quenching of the ECL signal. Under the optimal conditions, sensitive detection of M.SssI MTase in a wide linear range of 0.01-100 U·mL-1 with a satisfactory detection limit of 0.008 U·mL-1 was realized. The reliable and versatile BPE-ECL tool for the determination of M.SssI MTase with easy-to-operate pencil-drawing traces and independent solution systems provides a new opportunity to develop paper-based devices applied in early disease diagnosis and pathogenesis research.

Laser Ablated Reduced Graphene Oxide on Paper to Realize Single Electrode Electrochemiluminescence Standalone Miniplatform Integrated With a Smartphone

Paper-based microfluidic devices are widely employed in diverse applications, including medical diagnostics and point-of-care testing, since they have key characteristics, such as inherent capillary action and superior biological compatibility. Herein, for the first time, reduced graphene oxide (rGO) has been successfully embedded over the paper-based substrate by ablating a blue laser with optimized speed (100&#x0025;) and power (10&#x0025;) as an electrode for electrochemiluminescence (ECL) applications. Thus, a paper-based single electrode ECL (P-SE-ECL) device was successfully fabricated and effectively utilized for glucose and lactate sensing. Furthermore, wax printing was employed to form a microfluidic channel (hydrophilic zone) on the paper patterned with an rGO electrode. A 3-D printed handy black box, integrated with a smartphone and a buck&#x2013;boost converter, was proficiently utilized to capture ECL signals. The smartphone was purposefully utilized to execute a variety of functions, including capturing ECL signals, calculating ECL signal intensity, and powering the P-SE-ECL device. Moreover, the performance of the fabricated P-SE-ECL device was validated by performing luminol-/H₂O₂-based chemical reactions. Glucose and lactate were detected in a linear range of 100&#x2013;1000 and 100&#x2013;5000 <inline-formula> <tex-math notation="LaTeX">$\mu \text{M}$ </tex-math></inline-formula> with a limit of detection (LOD) values of 2.14 and 3.84 <inline-formula> <tex-math notation="LaTeX">$\mu \text{M}$ </tex-math></inline-formula>, respectively. Finally, the fabricated disposable rGO-based P-SE-ECL has the prospective to be employed in a range of applications such as food control management, clinical diagnostics, and point-of-care.

Analysis of the relationship between preoperative serum tumor marker levels and tumor immune scores in patients with colorectal cancer based on nano-electrochemiluminescence

Surgery can be used to remove tumors from patients with colon cancer, but some patients have recurrence a short time after the tumor is surgically removed, and the disease-free survival (DFS) period is short. Therefore, if these high-risk patients can be identified as early as possible, appropriate treatment strategies can be formulated to reduce their postoperative recurrence rate. Tumor immune scores have been proven to be effective in predicting the prognosis of patients, but the scoring can only be performed after the tumor has been removed from the patient. There is still urgency to find indicators that can predict the prognosis of patients before surgery. We used electrochemiluminescence electrodes modified with nanomaterials to detect the expression of serum markers. After comparison, it was found that the contents of CEA, AFP, CA19-9, and CA125 in patients with CRC were substantially higher than those with benign colonic disease. Pearson correlation analysis showed that CEA, AFP, CA19-9, and CA125 contents are positive correlated to the patient’s tumor immune score. Further investigation found that patients with high expression of CEA, AFP, CA19-9, and CA125 had a three-year DFS rate, which was substantially lower than those with low expression. Therefore, our findings suggest that the use of the composite nano-modified electrode electrochemiluminescence method to detect the content of CEA, AFP, CA19-9, and CA125 in patients with colorectal cancer can predict DFS after surgery to a certain extent. Additionally, the perioperative data plan can be adjusted in time according to the expression of tumor markers before surgery.

Light Scattering and Luminophore Enrichment-Enhanced Electrochemiluminescence by a 2D Porous Ru@SiO2 Nanoparticle Membrane and Its Application in Ultrasensitive Detection of Prostate-Specific Antigen.

Electrochemiluminescence (ECL) by virtue of its controllability and versatility has emerged as a significant tool in bioassay, but how to integrate it with other (nano)materials and further break the limit of sensitivity for ultrasensitive detection still possess tremendous potential. Herein, a close-packed Ru@SiO2 NP nanomembrane that serves as an enhanced substrate and luminophore enricher simultaneously was constructed by the liquid-liquid interface self-assembly method and applied for ECL-enhanced bioassay. The developed ECL electrode obtained ∼600-fold enhancement on ECL intensity compared with the bare ITO electrode and ∼21-fold enhancement compared with the SiO2 NP nanomembrane electrode due to the dramatic light scattering of the 2D SiO2 NPs and the enrichment of Ru(bpy)32+ molecules on the surface of the Ru@SiO2 NP nanomembrane electrode. Based on the fascinating Ru@SiO2 NP nanomembrane platform, we further constructed a label-free immunosensor for the detection of prostate-specific antigen (PSA). The as-fabricated Ru@SiO2-nanomembrane ECL immunosensor exhibited good stability and performed ultrasensitive detection with an utmost low detection limit of 0.169 fg·mL-1 (signal/noise = 3). Our work puts forward an effective solution benefiting for further improving ECL performance for ultrasensitive bioassays.

Direct-laser-writing of electrochemiluminescent electrode on glassy carbon for iodide sensing in aqueous solution

Abstract Simple and scalable construction of high-efficient solid-state electrochemiluminescence (ECL) electrode has attracted a lot of attention. Herein, using CdS as a model ECL emitter, one-step laser-scribing technique was successfully explored as an in situ and straightforward solid-phase-transition approach for the facile construction of binder-free ECL electrode. The suitable laser-scanning of Cd2+-doped polyethersulfone film on glassy carbon (GC) leads to the synchronous generation of laser-induced graphene (LIG) and laser-induced CdS (LI-CdS) hybrids anchored on GC surface (LI-CdS-G@GC). The cathodic ECL properties of LI-CdS-G@GC electrodes before and after an ultrasonication process (LI-CdS-G@GCUS) were investigated using peroxodisulfate as co-reactant. Notably, 60-fold higher ECL emission with excellent stability and reproducibility was obtained from the resultant LI-CdS-G@GCUS as compared to untreated LI-CdS-G@GC due to the ultrasonication-assisted removal of blackbody effect of LIG. Ultimately, the as-prepared LI-CdS-G@GCUS electrode with rapid and reliable ECL response was employed to construct an ECL sensor for the detection of iodide ions, showing a wide linear range of 10.0 nM–2500 nM and a low detection limit of 4.0 nM with acceptable selectivity. This work not only expands the application range of LIG but also provides a guideline for the facile design and scalable fabrication of sensitive ECL sensing interface.

Paper-based closed Au-Bipolar electrode electrochemiluminescence sensing platform for the detection of miRNA-155

This paper introduces a paper-based closed Au-bipolar electrode (BPE) biosensing system for the rapid and sensitive electrochemiluminescence (ECL) detection of miRNA-155. This microfluidic paper-based sensing platform is formed by wax-printing technology, screen printing method and in-situ Au nanoparticles (NPs) growth to form hydrophilic cells, hydrophobic boundaries, water proof electronic bridge, driving electrode regions and bipolar electrode regions. For rapid and sensitive detection, the cathode of bipolar electrode was modified with the prepared DNA (S1)–AuPd NPs by hybridization chain reaction, in which the target could initiate multiple cycles reaction to load more AuPd NPs which catalyzed H2O2 reduction. In addition, a classical ECL system tris (2,2′-bipyridine) ruthenium (II)- tripropylamine (Ru(bpy)32+/TPrA) exists at the anode of the bipolar electrode. Due to the charge balance between the anode and the cathode of BPE, the ECL signal response of Ru(bpy)32+/TPrA system was enhanced in the reporting cell. The intensity of ECL was quantitatively correlated with the concentration of miRNA-155 in the range of 1 pM–10 μM with the detection limit 0.67 pM. Moreover, this method paves a novel way for highly sensitive detection of miRNA-155 in clinical application.

Combination of area controllable sensing surface and bipolar electrode-electrochemiluminescence approach for the detection of tetracycline

A novel area controllable biosensing interface is designed on glassy carbon bead (GCB) and used for measurement of tetracycline (TET) in closed bipolar electrode-electrochemiluminescence (ECL) device. One face of GCB is modified with Au particles and the covered area is varied from 0 to 45.3% by tuning the external voltage during bipolar electrodeposition process in a home-made open bipolar electrochemical cell. It enables the conjugation of various amounts of biomolecules on Au/GCB. Then DNA walker and methylene blue (MB) labeled DNA (MB-DNA) are conjugated on Au surface for the following combination of aptamer. In the presence of target, aptamer partially hybridized with DNA walker will be released from Au surface, leading to the formation of dsDNA between DNA walker and MB-DNA. As a result, MB-DNA with recognition site for nicking endonuclease (Nb.BbvCI) in dsDNA is cleft into two segments by Nb.BbvCI. Meanwhile, the liberated DNA walker is triggered to continue the degradation of many MB-DNA. Due to the excellent electrochemical performance of MB, it is reduced at the cathode of BPE to amplify the ECL signal at the anode of BPE in a closed BPE-ECL platform. When the covered area of GCB by Au particles is enlarged from 10.1 to 45.3%, the change of ECL intensity could be increased 2.7-fold. The linear range for the detection of tetracycline is from 1 × 10−12 to 1 × 10−5 M with the detection limit of 6.0 × 10−13 M. Hence, controllable sensing area on a single glassy carbon bead, the amplification effect of DNA walker and MB make this approach possess many advantages over traditional biosensor.

Nanoengineered Metasurface Immunosensor with over 1000-Fold Electrochemiluminescence Enhancement for Ultra-sensitive Bioassay.

SummaryEnhancing electrochemiluminescence (ECL) with plasmonic materials is promising but still a long-standing barrier to improve its sensitivity for ultrasensitive bioassays, due to the lack of comprehensive understanding and effective strategies to fully utilize plasmonic effects for ECL enhancement. Herein, by insulating gold nanoparticles with silica shells (Au@SiO2 NPs), and finely tuning their core/shell sizes and controlling interparticle spacing via assembling them into a dense nanomembrane, we develop a novel 2D metasurface. Due to well-controlled high density “hot spots” and 2D ordered arrangement of the unit NPs in the nanomembrane, the metasurfaced ECL electrode shows over 1,000-fold plasmonic ECL enhancement for the classical Ru(bpy)32+-tripropylamine system, which is two orders of magnitude higher than ever reported (<30-fold). Such fabricated ECL biosensor demonstrates superior detection performance for prostate-specific antigen with a detection limit of 3 fg mL−1. Our results provide understanding of plasmonic effects for ECL enhancement and will benefit for biosensor construction for ultrasensitive bioassays.

Switches-controlled bipolar electrode electrochemiluminescence arrays for high-throughput detection of cancer biomarkers

Switches-controlled electrochemiluminescence chip has been easily fabricated on indium tin oxide electrode for high throughput screening cancer biomarkers, based on the closed bipolar electrode arrays with concentric circles structure. The ECL reporting cell located at the centre of the circle. And the sensing cells located at the circle with the same radius. The general sandwich-structured immunosensors were designed in the sensing cells and Ru(bpy)32+/(NH4)2C2O4 was used as ECL system in the reporting cell. The electrochemiluminescence chip provided not only a controllable, simple, and high-throughput detection but also the possibility of multi-assays.

Bipolar electrode-electrochemiluminescence (ECL) biosensor based on a hybridization chain reaction.

A novel electrochemiluminescence (ECL) closed bipolar electrode (BPE) chip was designed based on a hybridization chain reaction (HCR)-induced ECL amplification strategy for the detection of both DNA and H2O2. Without the utilization of a patterned ITO bipolar electrode (BPE), this chip platform consisted of an ITO glass coated with two layers of PDMS slices. The ITO cathode was modified with Au nanoparticles for further functionalization of biomolecules, which could also amplify the ECL signal at the anode of the BPE. Based on the specific hybridization and hybridization chain reaction (HCR), DNA sequences were greatly extended, leading to a significant increase in the resistance of the cathode. The reduction of H2O2 was inhibited on the cathode of the BPE, resulting in a quenching effect on the ECL intensity on the anode of the BPE. The designed biosensor displayed a satisfactory linear relationship for the detection of both DNA and H2O2. Therefore, the biosensor could not only be employed for DNA assays but also used in enzyme reactions based on the generation of H2O2.

Graphite paper-based bipolar electrode electrochemiluminescence sensing platform

In this work, aiming at the construction of a disposable, wireless, low-cost and sensitive system for bioassay, we report a closed bipolar electrode electrochemiluminescence (BPE-ECL) sensing platform based on graphite paper as BPE for the first time. Graphite paper is qualified as BPE due to its unique properties such as excellent electrical conductivity, uniform composition and ease of use. This simple BPE-ECL device was applied to the quantitative analysis of oxidant (H2O2) and biomarker (CEA) respectively, according to the principle of BPE sensing―charge balance. For the H2O2 analysis, Pt NPs were electrodeposited onto the cathode through a bipolar electrodeposition approach to promote the sensing performance. As a result, this BPE-ECL device exhibited a wide linear range of 0.001–15mM with a low detection limit of 0.5µM (S/N=3) for H2O2 determination. For the determination of CEA, chitosan-multi-walled carbon nanotubes (CS-MWCNTs) were employed to supply a hydrophilic interface for immobilizing primary antibody (Ab1); and Au@Pt nanostructures were conjugated with secondary antibody (Ab2) as catalysts for H2O2 reduction. Under the optimal conditions, the BPE-ECL immunodevice showed a wide linear range of 0.01–60ngmL−1 with a detection limit of 5.0pgmL−1 for CEA. Furthermore, it also displayed satisfactory selectivity, excellent stability and good reproducibility. The developed method opened a new avenue to clinical bioassay.

Paper-Based Bipolar Electrode Electrochemiluminescence Switch for Label-Free and Sensitive Genetic Detection of Pathogenic Bacteria.

Genetic analysis is of great importance for the detection of pathogenic bacteria. Bacterial identification must become simpler, less expensive, and more rapid than the traditional methods. In this study, a low-cost, label-free, and wireless paper-based bipolar electrode electrochemiluminescence (pBPE-ECL) analysis system was constructed for the rapid and sensitive genetic detection of pathogenic bacteria. Wax-screen printing was used to form hydrophilic channels on filter paper, and a carbon ink-based bipolar electrode and driving electrodes were screen-printed into the channels. The "light-switch" molecule [Ru(phen)2dppz]2+ (phen = 1,10-phenanthroline; dppz = dipyridophenazine) was used to intercalate into the base pairs of the double-stranded DNA PCR amplification products, and the complexs were then applied to the paper-based bipolar electrode to perform the ECL assays; the ECL of [Ru(phen)2dppz]2+ is quenched in aqueous solution, but this molecule displays intense ECL when intercalated into double-stranded DNA. Under optimized experimental conditions, as little as 10 copies/μL of the genomic DNA of Listeria monocytogenes could be detected. Additionally, the system could also specifically distinguish Listeria monocytogenes from Salmonella, Escherichia coli O157:H7, and Staphylococcus aureus. This label-free, simple, and rapid method has potential in point-of-care applications for pathogen detection.

A robust electrochemiluminescence immunoassay for carcinoembryonic antigen detection based on a microtiter plate as a bridge and Au@Pd nanorods as a peroxidase mimic.

The common drawbacks of most traditional electrochemiluminescence (ECL) immunoassays are the strict storage conditions for the ECL electrode and the steric hindrance caused by bovine serum albumin and antigen. The strict storage conditions require that the modified electrode must be stored at 4 °C before measurement, which may cause the degradation of protein molecules and low reproducibility as the time goes by. The steric hindrance can hinder electron transfer between the electrode and the electrochemical active substance unable to transmit proteins on the electrode surface. The current study takes a 96-well microtiter plate (MTP) as a bridge for analyte pre-treatment and Au@Pd nanorods as a peroxidase mimic to assemble a simple and robust ECL immunoassay. Advantages of such assay include not only high sensitivity but also robust detection circumstance. We demonstrated the method by detecting carcinoembryonic antigen from human serum and obtained a good detection limit of 3 fg mL(-1).

Electrochemical reduction and in-situ electrochemiluminescence detection of nitroaromatic compounds

An integrative method based on the combination of electrochemical reduction (ECR) and in-situ electrochemiluminescence (ECL) detection was developed for the sensitive detection of the nitroaromatic compounds (NACs), including 4-nitrotoluene (4-NT), 2,4-dinitrotoluene (2,4-DNT), 2,4,6-trinitrotoluene (TNT). An electrochemical flow cell including two working electrodes was fabricated with poly(dimethylsiloxane) (PDMS) to achieve the dual functions. The first one is a copper mesh electrode, acting as the reductor to convert the NACs to aminoaromatic compounds (AACs). Electrochemical deposition of copper nanoparticles on the surface of the copper mesh was conducted to further increase the reduction efficiency. The second one is an ECL electrode, which was used for in-situ detection of the reduced products. The ECL electrode was fabricated by the immobilization of Ru(bpy)32+ on a glassy carbon electrode (GCE) with the Nafion/the multi-wall carbon nanotubes (MWCNTs) composite film. The copper mesh electrode was arranged directly underneath the ECL electrode to ensure the reduced products could be immediately detected in-situ. An electrolytic solution consists of 33.3mmol/L Na2SO4 and 16.7mmol/L phosphate buffer solution (PBS, pH7.0) was found to be optimum for both the electrochemical reduction of the NACs and the ECL detection. The ECL intensities were proportional to the concentrations of 4-NT, 2,4-DNT and TNT in the range from 1.0×10−9 to 1.0×10−5, 3.5×10−9 to 1.0×10−5 and 7.5×10−9 to 1.0×10−5mol/L respectively. The limit of detections (LOD) were 4.0×10−10, 1.7×10−9 and 3.1×10−9mol/L respectively for 4-NT, 2,4-DNT and TNT. The reduction mechanism was preliminarily investigated and it was found that the presence of oxygen was critical for the reduction process, suggesting that the reductive oxygen species O2−,OH could be involved in the NACs reduction process.