Luminol Electrochemiluminescence Research Articles

An electrochemiluminescence immunosensor for myoglobin using an indium tin oxide glass electrode modified with gold nanoparticles and platinum nanowires

An electrochemiluminescence (ECL) immunosensor was fabricated to detect myoglobin in human serum. Specifically, gold nanoparticles and platinum nanowires were deposited onto indium tin oxide-coated glass with 3-aminopropyl-trimethoxysilane as the linker to fabricate a basal electrode. The gold nanoparticles had a diameter of approximately 5nm, and the platinum nanowires had diameters of approximately 2-3nm and lengths on the order of dozens of nanometers. The nanomaterials effectively enhanced the ECL of luminol and enabled it to emit strong light, even in a weakly basic environment. A myoglobin antibody was then covalently immobilized on the electrode. Upon formation of the immunocomplex, the intensity of the luminol ECL was reduced. Under the optimized experimental conditions, the intensity of the ECL linearly decreased with the logarithm of the myoglobin concentration over the range of 3.0ng·mL-1 to 0.32μg·mL-1, and the detection limit was 0.11ng·mL-1. Graphical abstract Schematic of an electrochemiluminescent immunosensor for myoglobin using gold nanoparticles and platinum nanowires as supporting matrix on indium tin oxide coated glass. It can detect myoglobin in human serum with a detection limit of 0.11ng·mL-1 and high selectivity.

Enhanced Visual Wireless Electrochemiluminescence Immunosensing of Prostate-Specific Antigen Based on the Luminol Loaded into MIL-53(Fe)-NH2 Accelerator and Hydrogen Evolution Reaction Mediation.

A sensitive prostate-specific antigen (PSA) detection method using a visual-readout closed bipolar electrode (BPE) system has been introduced by integration of hydrogen evolution reaction (HER) in cathodic pole and electrochemiluminescence (ECL) of luminol loaded within the MIL-53(Fe)-NH2 (L@MIL-53(Fe)-NH2) in the anodic pole. The cathode of the BPE was electrochemically synthesized by 3D porous copper foam, followed by decorating with nitrogen-doped graphene nanosheet and ruthenium nanoparticles. As an alternative, we employed carboxylate-modified magnetic nanoparticles (MNPs) for immobilization of the primary antibody (Ab1) and utilized the L@MIL-53(Fe)-NH2 conjugated to secondary antibody (Ab2) as a signaling probe and coreaction accelerator. After sandwiching the target PSA between Ab1 and Ab2, the MNP/Ab1-PSA-Ab2/L@MIL-53(Fe) were introduced to a gold anodic BPE. Finally, the resulting ECL of luminol and H2O2 at the anodic poles was monitored using a photomultiplier tube (PMT) or digital camera. The PMT and visual (camera)-based detections showed linear responses from 1 pg mL-1 to 300 ng mL-1 (limit of detection 0.2 pg mL-1) and 5 pg mL-1 to 200 ng mL-1 (limit of detection 0.1 pg mL-1), respectively. This strategy provides an effective method for high-performance bioanalysis and opens a new door toward the development of the highly sensitive and user-friendly device.

Enhancing Luminol Electrochemiluminescence by Combined Use of Cobalt-Based Metal Organic Frameworks and Silver Nanoparticles and Its Application in Ultrasensitive Detection of Cardiac Troponin I.

Electrochemiluminescence (ECL) has emerged as one of the most important methods for in vitro diagnosis and detection, but it is still limited in sensitivity for ultrasensitive biodetections. Fast and ultrasensitive detection of biomolecules is critical, especially for the clinical detection of cardiac troponin I (cTnI) for cardiac infarction diagnosis. In this study, an effective tactic was developed to enhance ECL efficiency of the luminol system, by combined use of Co2+-based metal organic frameworks (MOF), zeolitic imidazolate frameworks (ZIF-67), and luminol-capped Ag nanoparticles (luminol-AgNPs). The integration leads to a pronounced ∼115-fold enhancement in luminol ECL. On the basis of this fascinating sensing platform, a robust label-free ECL immunosensor was constructed for ultrasensitive detection of cTnI, the main marker of myocardial infarction, with good stability and a detection limit as low as 0.58 fg mL-1 (S/N = 3).

A Highly Sensitive Electrochemiluminescence Choline Biosensor Based on Poly(aniline‐luminol‐hemin) Nanocomposites

AbstractPoly(aniline‐luminol‐hemin) nanocomposites are prepared on an electrode surface through electropolymerization, and a highly sensitive electrochemiluminescence (ECL) biosensor for choline is developed based on the poly(aniline‐luminol‐hemin) nanocomposites and an enzyme catalyzed reaction of choline oxidase (CHOD). The obtained nanocomposites are characterized by scanning electron microscopy (SEM), atomic absorption spectrometry (AAS) and ECL. The results indicate that hemin can be incorporated into the poly(aniline‐luminol) nanocomposites using the facile electropolymerization method, and the poly(aniline‐luminol‐hemin) nanocomposites are rod shaped porous nanostructure. Moreover, the poly(aniline‐luminol‐hemin) nanocomposites exhibit higher ECL intensity than poly(aniline‐luminol) nanocomposites in alkaline media due to the catalytic effect of hemin on the ECL of the polymerized luminol and the electron transfer ability of hemin in the nanocomposites. CHOD is immobilized on the surface of the poly(aniline‐luminol‐hemin) nanocomposites modified electrode with glutaraldehyde, and the ECL biosensor based on poly(aniline‐luminol‐hemin)/CHOD exhibits a wider linear range for the choline detection. The enhanced ECL signals are linear with the logarithm of concentration of choline over the range of 1.0×10−11∼1.0×10−7 mol L−1 with a low detection limit of 1.2×10−12 mol L−1. Moreover, the proposed biosensor is successfully applied to the detection of choline in milk.

Codetermination of Sphingomyelin and Cholesterol in Cellular Plasma Membrane in Sphingomyelin-Depletion-Induced Cholesterol Efflux.

Quantification of multiple lipids with different contents in plasma membrane in single cells is significant, but challenging, for investigating lipid interactions and the role of dominant protein transporters. In this paper, comonitoring the alteration of low-content sphingomyelin (SM) and high-content cholesterol in plasma membrane of one living cell is realized by use of luminol electrochemiluminescence (ECL) for the first time. Concentrations of SM as low as 0.5 μM are detected, which permits the measurement of low-content membrane SM in single cells. More membrane cholesterol is observed in individual cells after depletion of membrane SM, providing direct evidence about SM-depletion-induced cholesterol efflux. The upregulation of ATP-binding cassette transporters A1 (ABCA1) and G1 (ABCG1) in SM-depleted cells induces a further increase in membrane cholesterol. These results imply that higher expression of ABCA1/G1 promotes cholesterol trafficking, which offers additional information to solve the debate about ABC transporters in cholesterol efflux. Moreover, the established approach offers a special strategy to investigate the correlation of membrane lipids and the role of transporters in cholesterol trafficking.

Simple, Fast, and Sensitive detection of artemisinin in human serum and Artemisia annua using microsensor array coupled with electrochemiluminescent imaging technique

Artemisinin is an important frontline antimalarial. Fast, accurate detection of artemisinin in human serum is of importance in monitoring its clinical pharmaceutical effect. In this work, a strategy using microsensor array coupled with electrochemiluminescence (ECL) imaging technique was developed for detection of artemisinin. The microsensor array was constructed by integrating a patterned indium tin oxide glass plate with two perforated hydrophobic paper covers. By introducing the reactant of p-aminophenylboronic acid, luminol and artemisinin into the microsensor array, artemisinin would oxidize p-aminophenylboronic acid into p-aminophenol, a product which can efficiently inhibit the ECL of luminol. ECL signals decrease linearly with the increase of artemisinin. Based on the decreased ECL signal, artemisinin can be accurately detected. A good linearity (r = 0.994) was observed for artemisinin detection. The detection sensitivity is 0.48 μM for artemisinin. The detection selectivity and stability were also investigated. Results show that the present method shows a good selectivity and stability towards artemisinin detection. To evaluate the applicability of the present strategy for detecting artemisinin in real samples, the artemisinin content in human serum and Artemisia annua samples were analyzed. Results demonstrated that the present strategy shows excellent selectivity with high sensitivity towards artemisinin detection in real samples.

Light enhanced electrochemistry and electrochemiluminescence of luminol at glassy carbon electrodes

We report in this work the enhancement effect of light irradiation on the electrochemistry and electrochemiluminescence (ECL) of luminol at the bare glassy carbon electrode (GCE). Light irradiation on the GCE surface induced the formation of hot electron-hole pairs. In alkaline solutions, hot holes can oxidize hydroxide anions to hydroxyl radicals that are capable of promoting the oxidation of luminol to generate larger current and stronger ECL. Moreover, the stability of current and ECL is also significantly improved upon light irradiation. This study provides a simple method to enhance the electrochemistry and ECL of luminol that have promise in improving the sensitivity of luminol-based chemical analysis and bioanalysis.

Ultrasensitive electrochemiluminescence immunosensor with wide linear range based on a multiple amplification approach

An ultrasensitive and highly selective electrochemiluminescence (ECL) immunosensor is proposed for the detection of prostate specific antigen (PSA) based on multiple amplification via glucose oxidase (GOx) and platinum nanoparticles (Pt NPs) conjugated with polyglutamic acid (PGA). The proposed immunosensor has a wide linear range (1.0 pg/mL–150 ng/mL) and low detection limit (0.6 pg/mL) for PSA detection, which is due in part to the excellent catalytic activity of the Ab2-GOx-PGA-Pt NPs probe toward the luminol ECL reaction.

Confined electrochemiluminescence in vertically ordered silica mesochannels for the imaging of hydrogen peroxide released from single cells

Here, the confined electrochemiluminescence (ECL) of luminol and hydrogen peroxide is achieved in vertically ordered silica mesochannels (SMCs) and applied to map the efflux of hydrogen peroxide from single living cells. The vertical alignment of SMCs on indium tin oxide (ITO) slides restricts the lateral diffusion of species generated in the ECL process. Accordingly, the cross-talk of luminescence intensity from nearby microregions is minimized for higher-spatial-resolution ECL imaging. The characterization of luminol ECL on these SMC-coated slides yields a detection range of hydrogen peroxide between 5 μM and 1 mM, providing high sensitivity in imaging the efflux of hydrogen peroxide from cells. Compared with the luminescence from individual cells on bare ITO slides, ~4-fold intensity is observed for SMC-coated ITO, suggesting a better electrode surface for single-cell ECL imaging.

Label-Free Electrochemiluminescent Determination of DNA Using Luminol and Hemin Functionalized Nanoparticles

Luminol and hemin dual-functionalized silica nanoparticles were synthesized using a typical reverse water-in-oil microemulsion protocol. The obtained nanoparticles were further characterized by transmission electron microscopy, scanning electron microscopy, atomic absorption spectrometry, chemiluminescence, and electrochemiluminescence. The results indicated that the luminol and hemin dual-functionalized silica nanoparticles exhibited significantly higher chemiluminescence and electrochemiluminescence intensities than those of luminol functionalized silica nanoparticles due to the catalytic effect of hemin on the chemiluminescence and electrochemiluminescence of luminol. Furthermore, a simple and sensitive label-free electrochemiluminescence DNA biosensor was developed based on the chitosan modified luminol and hemin dual-functionalized silica nanoparticles and a single-stranded DNA probe. The chitosan modified luminol and hemin dual-functionalized silica nanoparticles were immobilized on the surface of an indium-doped tin oxide electrode and the single-stranded DNA probe was immobilized on the surface of the nanoparticles through electrostatic interactions between single-stranded DNA and chitosan, which allowed hybridization with the target DNA sequences. The hybridization events were evaluated by electrochemiluminescence, and only the complementary sequence formed double-stranded DNA with the DNA probe to give strong electrochemiluminescence signals. Finally, the electrochemiluminescence intensity was found to be linearly related to the concentration of the complementary sequence at concentrations from 1.0 × 10−12 to 1.0 × 10−6 mol·L−1 with a detection limit of 5.0 × 10−13 mol·L−1.

Electrochemiluminescence-based Monitoring of Activated Human Neutrophils Using Luminol Derivative Immobilized onto Screen-printed Electrodes

Electrochemiluminescence (ECL) of luminol is used to develop biosensors for detection of reactive oxygen species (ROS). Rapid and reagentless measurement of ROS is required for medical diagnosis an...

Electrochemiluminescence detection of human breast cancer cells using aptamer modified bipolar electrode mounted into 3D printed microchannel

In the present manuscript, a closed bipolar electrode system integrated with electrochemiluminescence (ECL) detection has been introduced for sensitive diagnosis of human breast cancer cells (MCF-7). For sensitive and selective detection, the anodic pole of the bipolar electrode was modified with the AS1411 aptamer, a specific aptamer for the nucleolin, and treated by the secondary aptamer modified gold nanoparticles. The electrochemiluminescence of luminol was followed in the presence of hydrogen peroxide on the anode pole of bipolar electrode (BPE) as an analytical signal. Moreover, 3D printed microchannels were used for the fabrication of BPE systems to minimize the required amounts of sample. The present aptasensor offers low cost, sensitive and selective cancer cell detection with two acceptable linear ranges. The first linear section appears within 10–100 cells and the latter is found to be within 100–700 cells. The limit of detection was about 10 cells.

Sensitive Nonenzymatic Electrochemiluminescence Determination of Hydrogen Peroxide in Dental Products using a Polypyrrole/Polyluminol/Titanium Dioxide Nanocomposite

A layer-by-layer assembled of a polypyrrole and polyluminol was synthesized through the electrodeposition of pyrrole and luminol in acidic medium on a graphite electrode. The electrode was then modified by casting titanium dioxide (TiO2) nanoparticles on its surface for enhancing electrochemiluminescence of luminol. The properties of this electrochemiluminescence sensor were studied by cyclic voltammetry, electrochemical impedance spectroscopy, field emission scanning electron microscopy, and energy dispersive X-ray spectroscopy. The results demonstrated that the modification of this electrochemiluminescence sensor shows sensitive response for the determination of hydrogen peroxide. Figures of merit include broad linearity from 1 pmol L−1 to 4 µmol L−1 (R2 = 0.996) with a limit of detection as low as 0.40 pmol L−1 at a signal-to-noise ratio of three and good reproducibility with relative standard deviation of 4% for the determination of a 400 nmol L−1 hydrogen peroxide solution (n = 4), along with favorable long-term stability. The presence of glucose, citric acid, uric acid, dopamine, and ascorbic acid at concentrations as high as 100 nmol L−1 of H2O2 did not produce any electrochemiluminescence signals, which demonstrates the selective nature of this modified electrode. The sensor was also used for the determination of H2O2 in mouthwash formulations and dental whitelight gels.

An enzymatic calculation system based on electrochemiluminescence and fluorescence of luminol and cyclic voltammetry of ferrocene methanol

In this work, a biomolecular calculation system was developed based on electrochemiluminescence (ECL) and fluorescence emission (FL) of luminol and cyclic voltammetry (CV) of ferrocene methanol (FMA). When triethylamine (TEA) was added in luminol solution as a coreactant, a great ECL peak at 1.1 V was observed. While the further addition of enzymatic system, esterase/ethyl butyrate (EB), would significantly lower the ECL response. On the other hand, TEA could quench the FL signal of luminol at 430 nm, while the injection of esterase/EB in the luminol solution could enhance the FL signal. Furthermore, FMA exhibited a CV peak pair at 0.2 V and could decrease the ECL signal greatly in the luminol/TEA solution. Based on these interesting results, a 3-input and 5-output biomolecular logic gate was established with TEA, FMA and esterase/EB as inputs and the ECL, CV and FL signals as outputs. Moreover, some nonarithmetic logic devices, such as an encoder, a decoder, a 3-input keypad lock and two dual transfer gates were elaborately designed on the same platform. This work presented a new example of how the complexity of biocomputing system could be enhanced either by increasing the number of outputs of traditional logic gates or by fabricating some nonarithmetic logic devices based on the same simple electrochemical system.

Enhancing the Electrochemiluminescence of Luminol by Chemically Modifying the Reaction Microenvironment.

As one of the most efficient and commonly used electrochemiluminescence (ECL) reagents, luminol has been paid much attention by the analysts due to its low excitation potential, simple dissolved oxygen-based coreactant ECL reaction requirement, and the widely analytical applications. However, the ECL performances of luminol on most electrode materials suffered from the lower ECL quantum yield, which limited its analytical applications. Herein, it was first found that, compared to that of the bare gold electrode, the ECL quantum yield of luminol on the 1,6-hexanedithiol hydrophobic pinhole film modified gold electrode was 3 times increased. This higher ECL quantum yield of luminol was related to the hydrophobic microenvironment on the surface of the modified electrode, which was formed from the hydrophobic carbon chains on the basis of their supramolecular interaction. On the basis of this new finding as well as the cap effect of gold nanoparticle to these pinhole gates, a highly sensitive ECL sensing scheme for microRNA was also developed.

Highly sensitive luminol electrochemiluminescence immunosensor based on platinum-gold alloy hybrid functionalized zinc oxide nanocomposites for catalytic amplification

A highly sensitive sandwiched luminol electrochemiluminescence (ECL) immunosensor has been constructed based on the double catalysis effect and multiamplification strategy of platinum-gold alloy hybrid functionalized zinc oxide nanocomposites (Pt-Au@ZnONPs). First, the improved surface area and excellent biocompatibility of Pt-Au@ZnONPs were used for binding the secondary antibody (Ab2) and glucose oxidase (GOD) to obtain the novel bioconjugate Pt-Au@ZnONPs-GOD-Ab2. Pt-Au@ZnONPs and the loaded GOD amplified luminol ECL signals and promoted the luminol ECL response by efficiently catalyzing glucose to produce hydrogen peroxide (H2O2) in situ as a coreactant of luminol. Then, Pt-Au@ZnONPs catalyzed H2O2 to generate various reactive oxygen species (ROSs) that accelerated the ECL reaction of luminol, thus enhanced the ECL intensity of luminol and improved the sensitivity of the immunosensor. Second, gold nanoparticles decorated reduced graphene sheets (AuNPs@GS) with large specific surface area, good biocompatibility, high conductivity, and high catalytic activity were prepared and used as substrate of the immunosensor to capture the primary antibody (Ab1). Experimental results demonstrated that the proposed ECL immunosensor showed a sensitive response for the detection of α-1-fetoprotein (AFP) from 0.1 pg mL−1 to 200 ng mL−1 with detection limit of 0.03 pg mL−1 (S/N = 3). The as-proposed luminol ECL immunosensor has excellent sensitivity, stability, and specificity, which makes it very promising for clinical applications.

Chemically Regulated ROS Generation from Gold Nanoparticles for Enzyme-Free Electrochemiluminescent Immunosensing.

In the present work, we report on an enzyme-free electrochemiluminescent (ECL) immunosensing scheme utilizing the catalytic generation of reactive oxygen species (ROS) from gold nanoparticles (AuNPs) (diameter ≥5 nm) dispersed in aqueous solutions of trishydroxymethylaminomethane (Tris). First, to examine this catalytic pathway in detail, the effects of various factors such as the AuNP size and concentration, dispersant type and concentration, and dissolved oxygen were investigated using the electrochemiluminescence (ECL) of luminol. It was found that the catalytic generation of ROS from AuNPs can be regulated chemically by altering conditions such as the type, concentration, and pH of the solution that the AuNPs are dispersed in. Under the best conditions studied in this work, the AuNPs displayed high catalytic activity toward ROS generation, with an estimated apparent turnover number per AuNP of 0.1 s-1, comparable to those of several common peroxide-producing enzymes. Following these studies, this phenomenon was applied to develop a one-step enzyme-free ECL immunosensor based on sandwiching the target analyte using antibody-conjugated magnetic beads (MB) and AuNPs. Using IgA as a model analyte, the developed immunosensor was able to detect the target in the range of 1 ng/mL to 10 μg/mL, with the lower detection limit being comparable to those of commercial assays for the same target. Altering the antibodies used to modify the MB and AuNPs could further improve the detection limit as well as expand the applicability of this immunoassay to the detection of other analytes.

An Electrochemiluminescent Platform for Living Cell Oxygen Metabolism Monitoring

This study has developed a novel sensing platform for the investigation of cell oxygen metabolism. With chitosan@TiO2 nanocomposites as supporting matrix which was decorated on the surface of indium tin oxide glass, it can effectively absorb A549 cells and sensitize the electrochemiluminescence (ECL) of luminol. On this platform, the ECL output is dependent on the level of reactive oxygen species (ROSs), which was evidenced by the intervening of resveratrol, a typical ROSs’ scavenger. The results indicated that the ECL signal was quenched by the resveratrol within its concentration range from 0.10 nM to 2.97 µM. Thus, it is believable that the ECL of luminol sensitively responded upon oxygenic matters on this living cell platform would be powerful for cell oxygen metabolism monitoring.

A novel “dual-potential” ratiometric electrochemiluminescence DNA sensor based on enhancing and quenching effect by G-quadruplex / hemin and Au-Luminol bifunctional nanoparticles

An ultrasensitive and stable “dual-potential” ratiometric electrochemiluminescence (ECL) sensor is reported for specific DNA, the femtomolar detection limit (0.12 fM, S/N = 3) and high selectivity insure its potential applications in cancer biomarkers searching or monitoring. The excellent performance of the sensor comes from simultaneously fabricated layer by layer structure “target DNA + Hemin / Au-Luminol NPs / DNA* / sl DNA / TGA / QDs / MWNTs / GCE” mode which was based on the enhancing effect of luminol by G-quadruplex / hemin and Au nanoparticles and the quenching effect of CdSe/ZnS by G-quadruplex / hemin. (i) DNA-SH could combine with Au-Luminol NPs via S-Au bond to solve the problem of poor solubility and weak ECL intensity of luminol in neutral medium. (ii) Target DNA and Hemin formed the G-quadruplex / hemin peroxidase mimicking DNAzyme could enhance the ECL of luminol and quench the ECL of CdSe/ZnS simultaneously. (iii) DNA* was employed to increase a certain distance between CdSe/ZnS and Au-Luminol for enhancing the CdSe/ZnS QDs initial ECL intensity. The dual-potential ratiometric mode lower the influence of background and side reaction of the ECL sensor which were the most important factors in trace sensing.

Colorimetric and Electrochemiluminescence Dual-Mode Sensing of Lead Ion Based on Integrated Lab-on-Paper Device.

A highly selective two-point separation strategy was designed based on a cross-like all-in-one lab-on-paper analytical device. The stable and cleavable enzyme-coated reduced graphene oxide (rGO)-PdAu probe was fabricated as the signal reporter to enable the visualization and electrochemiluminescence (ECL) dual-mode sensing of Pb2+. Concretely, the experimental workflow consists of the following process: (i) fabrication of the lab-on-paper device and growth of Au nanoparticles on ECL detection zone, (ii) immobilization of Pb2+-specific DNAzyme, and (iii) hybridization between DNAzyme and rGO-PdAu-glucose oxidase (GOx) labeled oligonucleotide to form the double-stranded DNA. Upon addition of Pb2+ into the prepared system, the double-helix structure of the DNA was destroyed, resulting in the release of cleaved rGO-PdAu-GOx probe to visualization bar to promote the effective oxidation and color change of 3,3',5,5'-tetramethylbenzidine. As a consequence, the color change can be recognized by naked eye, meanwhile GOx on an uncleaved signal probe can oxidize glucose along with the H2O2 production. As a co-reaction reagent for luminol ECL system, the concentration of H2O2 is proportional to the ECL intensity, which constitutes a new mechanism for colorimetric and ECL dual mode to detect Pb2+. With the method developed here, the concentration of Pb2+ could be easily determined by the naked eye within a linear range from 5 to 2000 nM, as well as by monitoring the decreased ECL intensity of luminol in a linear range of 0.5-2000 nM. This work not only constructs a simple and versatile platform for on-site visible monitoring of Pb2+ in tap water and river water but also furnishes a strategy for designing a dual-mode sensing toward different heavy metal ions based on specific DNAzyme in the fields of environmental monitoring-related technologies.