Electrogenerated Chemiluminescence Of Luminol Research Articles

In situ growth of TiO2 nanowires on Ti3C2 MXenes nanosheets as highly sensitive luminol electrochemiluminescent nanoplatform for glucose detection in fruits, sweat and serum samples

A sensitive electrogenerated chemiluminescence (ECL) biosensor for glucose was developed based on in situ growth of TiO2 nanowires on Ti3C2 MXenes (TiO2–Ti3C2) as the nanoplatform. Via tuning the alkaline oxidation time, different amount of TiO2 nanowires can be found on MXenes. An ECL biosensor for glucose was constructed by covalent immobilization of glucose oxidase (GODx) on the glycine functional TiO2–Ti3C2 surface, with the ECL signal depending on the in-situ formation of H2O2 via the specifically catalysis of glucose by GODx, resulting in the apparent increase of ECL signal. The TiO2–Ti3C2 can also act as the catalyst for the oxidation of H2O2 into O2 to enhance the ECL of luminol. Based on this strategy, a highly sensitive ECL biosensor for glucose was obtained in wide concentration range of 20 nM-12 mM with a low detection limit of 1.2 nM (S/N = 3). The synergistic effects of large surface area, excellent conductivity, and high catalytic activity of the TiO2–Ti3C2 make the sensor highly sensitive toward glucose; the specific enzyme catalysis reaction promises excellent selectivity of the ECL sensor. The proposed biosensor has been employed to detect glucose in human serum, fruits, and sweat samples with excellent performance, providing a universal approach for glucose in various samples, which shows great prospect in clinical diagnostics and wearable sensors.

Electrogenerated chemiluminescence of luminol on a gold nanocluster-graphene-Nafion composite-modified electrode in neutral aqueous solution

The electrogenerated chemiluminescence (ECL) behavior of luminol on a glassy carbon (GC) electrode modified with gold nanocluster-graphene-Nafion composite films has been investigated in neutral aqueous solution (pH 7). In the present study, atomically well-defined gold nanoclusters of Au25(SC6H13)18, where SC6H13 is hexanethiolate, were used for the preparation of composite films. Due to the highly enhanced electrocatalytic activity of the composite towards the reduction of molecular oxygen, strong cathodic luminol ECL response related to the electrochemical oxygen reduction was observed on the composite-modified GC electrode at ca. – 1.34 V vs. Ag/AgCl (3 M NaCl) in a neutral aqueous solution, while no cathodic ECL response was observed on a bare GC electrode. The addition of hydrogen peroxide led to a decrease in the cathodic luminol ECL response related to the oxygen reduction, whereas a new ECL response related to the electrochemical reduction of hydrogen peroxide was observed at ca. – 0.01 V vs. Ag/AgCl (3 M NaCl). The possible ECL mechanisms were discussed. Under the optimum conditions, the ECL response was linear with the concentration of hydrogen peroxide in the range of 1.0 × 10−8 M ~ 4.0 × 10−6 M with a detection limit of 2.21 × 10−9 M (S/N = 3) in neutral aqueous solution.

Electrochemiluminescence Imaging of Conducting Polymer Film Structures

Conducting polymers (CPs) is a class of attractive materials that, thanks to their unique properties, structures made on-demand and new composition mixtures, finds a wide variety of applications, ranging from material science to chemistry, from energy to environmental remediation and electroanalysis. Electrochemical synthesis of CPs is usually achieved by anodic oxidation, or electropolymerization, of suitable monomer species, which generally results in the formation of polymeric films deposited onto the surface of an electrode. Nevertheless, the use of this methodology makes rather difficult, or even impossible, to tune the morphology of the final CPs materials, limiting their applicability in material science. To overcome this limitation, electrosynthesis of CPs with different geometries such as brushes, films and fiber arrays has recently been achieved exploiting the unique wireless feature of bipolar electrochemistry1. In fact, this renewed technology enables electrochemical reactions at both extremities of a wireless electrode, or bipolar electrode (BPE), through the application of an external electric field generated in a low concentration of a supporting electrolyte.In this context, alternating current (AC)-bipolar electropolymerization of 3,4-ethylenedioxythiophene (EDOT) has recently been employed for the gradual in-plane growth of the corresponding poly(3,4-ethylenedioxythiophene) (PEDOT) films at the terminal of a gold BPE laid down on a glass surface2. This notable phenomenon could paved the way for the drawing of CPs on non-conductive substrates, opening up new perspectives for their potential application for circuit patterning in organic electronic devices. The possible mechanism of films formation seems to involve the generation of PEDOT fibers that propagate in an anisotropic morphology from the terminal of the BPE, in parallel to the external electric field under electrophoretic effect, resulting in colored film depositions visible at naked eye. However, very thin layers of PEDOT films underlying the main fibers are generally transparent, making their direct visualization rather difficult.In the present contribution, we propose the use of Electrogenerated Chemiluminescence (ECL) for the morphological imaging of PEDOT films synthetized by AC-bipolar electropolymerization. ECL is the emission of light at the electrode surface following an electrochemical stimulus and, nowadays, it is widely employed as an emerging microscopy technique3. The great success of ECL imaging technology is due to the electrochemical nature of light generation that allows very low background signal and the possibility to control the ECL emission both temporally and spatially by applying a suitable potential. Our approach employs the use of the well-known luminol/hydrogen peroxide ECL system for the visualization of PEDOT films grown on non-conductive substrates used as BPEs in bipolar systems. The different potential distribution on such PEDOT systems allows ECL emission only in confined areas of PEDOT films where the potential is sufficient to trigger the ECL reaction, allowing the visualization of different structural characteristics of the polymeric films (Figure 1). This technique would represent an innovative and promising tool to accurately control the morphology of the final polymer material, opening up new perspectives in the area of electrochemical synthesis of CPs. Figure 1: Schematic illustration of the bipolar setup used for ECL imaging of PEDOT films (a). Optical image of PEDOT film synthetized by AC-bipolar electropolymerization (b). Corresponding Luminol ECL images on PEDOT film working as BPE at 25 V (c) and 70 V (d).

Application of a novel electrochemiluminescence sensor based on magnetic glassy carbon electrode modified with molecularly imprinted polymers for sensitive monitoring of bisphenol A in seawater and fish samples

A highly selective molecularly imprinted electrochemiluminescence (MIECL) sensor based on molecularly imprinted Fe3O4 nanocrystals (MIP-Fe3O4/NCs) and luminol was developed for bisphenol A (BPA) determination. MIP-Fe3O4-NCs were synthesized and immobilized on the glassy carbon electrode (GCE) surface to fabricate the electrogenerated chemiluminescence (ECL) system. The GCE modified with MIP-Fe3O4-NCs could greatly promote the cathodic ECL of luminol. After incubation with the BPA solution, the imprinting sites on the surface of MIP-Fe3O4-NCs could specifically rebind BPA, resulting in selective and sensitive ECL quenching by hindering electron transfer capability. Under optimal conditions, the relative ECL intensities were proportional to the logarithm of BPA concentration ranging from 0.002 μg/L to 5.0 × 103 μg/L at a limit of detection of 2.0 × 10−4 μg/L. Satisfactory recoveries of 93.5 %–98.3 % were obtained in fish and seawater samples at a relative standard deviation of <6.1 %. The proposed MIECL sensor displayed good selectivity, high sensitivity, and excellent accuracy and precision. The results demonstrated the potential application of the MIECL sensor for BPA analysis in actual samples and for pollutant analysis.

Electrogenerated Chemiluminescence in Submicrometer Wells for Very High-Density Biosensing.

Inspired by the mechanism in stimulated emission depletion fluorescence microscopy, we established for the first time electrogenerated chemiluminescence (ECL) generated from indium tin oxide (ITO) submicrometer electrodes in submicrometer wells with aluminum walls. Aluminum is observed to have the ability to absorb ECL from luminol and, thus, removes the ECL from the diffused species away from the electrode surfaces. Accordingly, the size of the individual ECL spots is restricted to 4 μm in diameter, enabling the density of the ECL based array to be over 3 × 104/mm2. The conceptual detection of hydrogen peroxide and glucose exhibits the feasibility in the application of luminol ECL for very high-density biosensing. The realization of this ECL in submicrometer wells and the resultant biosensing offer a new strategy for high-density ECL analysis and might initiate the thought for super-resolution ECL microscopy.

The Study of AA2024 De-Alloying Using Luminol Electrogenerated Chemiluminescence Imaging

This paper describes the use of luminol electrogenerated chemiluminescence (ECL) to image the re-distribution of electrochemically active copper (copper in electrical contact with the substrate) at the surface of AA2024-T351 corroding in NaCl electrolyte. AA2024 samples are thermo-mechanically treated to produce a macroscopically inhomogeneous distribution of intermetallic particles. The AA2024-T351 samples are allowed to corrode by immersion in 0.51 M aqueous NaCl and (ex-situ) ECL measurements are performed to follow copper re-distribution. Luminol ECL light emission is orders of magnitude more intense on copper than aluminum and macro and microscopic images are obtained to elucidate the re-distribution of electrochemically active copper. S phase de-alloying produces a radical re-distribution of copper on a microstructural scale (1-10 μm) but macroscopic copper distributions (1-10 mm) remain largely unchanged. In-situ experiments using the SVET show that macroscopic copper distribution directs localization of corrosive attack such that net anodic activity (pitting/intergranular attack) is concentrated in regions with lowest surface coverage of copper and net cathodic activity is concentrated in regions of highest coverage. Results are explained in terms of the role of solution chemistry and pH in influencing the transition from transient to stable pitting.

A novel aptasensor for lysozyme based on electrogenerated chemiluminescence resonance energy transfer between luminol and silicon quantum dots

In the present work, electrogenerated chemiluminescence (ECL) of luminol was investigated in neutral condition at a gold electrode in the presence of silicon quantum dots (SiQDs). The results revealed that SiQDs can not only greatly enhance luminol ECL, but also act as energy acceptor to construct a novel ECL resonance energy transfer (ECL-RET) system with luminol. As a result, strong anodic ECL signal was obtained in neutral condition at the bare gold electrode, which is suitable for biosensing application. Lysozyme exhibited apparent inhibiting effect on the ECL-RET system, based on which an ECL aptasensor was fabricated for the sensitive detection of lysozyme. The proposed method showed high sensitivity, good selectivity, and wide linearity for the detection of lysozyme in the range of 5.0×10–14−5.0×10−9gmL−1 with a detection limit of 5.8×10–15gmL−1 (3σ). The results suggested that as-proposed luminol/SiQDs ECL biosensor will be promising in the detection enzyme.

A review of electrogenerated chemiluminescent biosensors for assays in biological matrices.

Electrogenerated chemiluminescence (ECL) is the production of light via electron transfer reactions between electrochemically produced reagents. ECL-based biosensors use specific biological interactions to recognize an analyte and produce a luminescent signal. Biosensors fabricated with novel biorecognition species have increased the number of analytes detected. Some of these analytes include peptides, cells, enzymes and nucleic acids. ECL biosensors are selective, simple, sensitive and have low detection limits. Traditional methods use ruthenium complexes or luminol to generate ECL. Nanomaterials can be incorporated into ECL biosensors to improve efficiency, but also represent a new class of ECL emitters. This article reviews the application of ruthenium complex, luminol and nanomaterial-based ECL biosensors to making measurements in biological matrices over the past 4 years.

Electrogenerated chemiluminescence resonance energy transfer between luminol and CdS/graphene nanocomposites and its sensing application

Electrogenerated chemiluminescence (ECL) behaviors of luminol were comparatively studied at CdS quantum dos, graphene, and CdS/graphene (CdS/GR) nanocomposites modified gold electrodes in neutral condition. The most intense anodic ECL signal was obtained at the CdS/GR nanocomposites modified gold electrode (CdS/GR/GE). The anodic ECL of luminol (ECL-1) located at ~0.50V (vs SCE) was increased nearly 50-times compared with the bare gold electrode. Besides, two stronger anodic ECL peaks (ECL-2 and ECL-3) were observed at 1.0V and 1.4V (vs SCE), respectively. The fluorescence and the UV–vis absorption spectra revealed that resonance energy transfer between luminol and CdS/GR nanocomposites was possible. The ECL spectra further demonstrated the occurrence of ECL resonance energy transfer (ECL-RET), which resulted in strong ECL-2 and ECL-3. Cytochrome C could significantly inhibit the intensities of the anodic ECL peaks, and could be sensitively detected.

Multiple signal amplification electrogenerated chemiluminescence biosensors for sensitive protein kinase activity analysis and inhibition

A novel electrogenerated chemiluminescence (ECL) biosensor was built for the detection of kinase activity based on multiple signal amplification nanoprobes. In this strategy, the Xanthine oxidase (XOD) and 5′-phosphate group end DNA conjugated AuNPs was integrated with the phosphorylated peptide by Zr4+. The XOD on gold nanoparticles can catalyze dissolved oxygen to produce H2O2 in the presence of hypoxanthine (HA) which acts as a coreactor for luminol ECL reaction. In addition, due to the excellent catalytic activity of gold nanoparticle toward luminol ECL reaction and its large surface area that can accommodate large number of XOD and DNA on the surface, the ECL signal of luminol was significantly amplified, affording a highly sensitive ECL analysis of kinase activity. The as-proposed biosensor presents a low detection limit of 0.09UmL−1 for protein kinase A (PKA) activity, wide linear range (from 0.1 to 10UmL−1) and excellent stability even in serum samples. This biosensor can also be applied for quantitative kinase inhibitor evaluation. The robust ECL biosensor provides a valuable tool for the high throughput assay in the applications of clinic diagnostic and therapeutic.

Enhancement of electrogenerated chemiluminescence of luminol by ascorbic acid at gold nanoparticle/graphene modified glassy carbon electrode

Gold nanoparticle/graphene (GNP/GR) nanocomposite was one-pot synthesized from water soluble graphene and HAuCl4 by hydrothermal method and characterized by TEM, Raman spectroscopy, XRD, XPS, UV–vis spectroscopy, and electrochemical impedance spectroscopy (EIS). Electrogenerated chemiluminescence (ECL) of luminol was investigated at the GNP/GR modified glassy carbon electrode (GNP/GR/GCE) and the GNP modified glassy carbon electrode (GNP/GCE) in aqueous solution respectively. The results revealed that one strong anodic ECL peak could be observed at ∼0.8V at two modified electrodes compared with that at the bare electrode. The intensity of the anodic ECL at the GNP/GR/GCE is weaker than that at the GNP/GCE, which should be due to the synergic effect of the enhancing effect of gold nanoparticles and the inhibiting effect of graphene on anodic luminol ECL. One strong cathodic ECL peak located at ∼−0.8V could be observed at the GNP/GR/GCE but not at the GNP/GCE, which should be result from the adsorbed oxygen at the graphene film. In the presence of ascorbic acid, the anodic ECL at the GNP/GR/GCE was enhanced more than 8-times, which is more apparent than that at the GNP/GCE. Whereas, the cathodic ECL peak was seriously inhibited at the GNP/GR/GCE. The enhanced ECL intensity at the GNP/GR/GCE varied linearly with the logarithm of ascorbic acid concentration in the range of 1.0×10−8 to 1.0×10−6molL−1 with a detection limit of 1.0×10−9molL−1. The possible ECL mechanism was also discussed.

Highly sensitive electrogenerated chemiluminescence biosensor in profiling protein kinase activity and inhibition using a multifunctional nanoprobe

We presented a novel electrogenerated chemiluminescence (ECL) biosensor for monitoring the activity and inhibition of protein kinases based on signal amplification using enzyme-functionalized Au NPs nanoprobe. In this design, the biotin-DNA labeled glucose oxidase/Au NPs (GOx/Au NPs/DNA-biotin) nanoprobes, prepared by conjugating Au NPs with biotin-DNA and GOx, were bound to the biotinylated anti-phosphoserine labeled phosphorylated peptide modified electrode surface through a biotin−avidin interaction. The GOx assembled on the nanoprobe can catalyze glucose to generate H2O2 in the presence of O2 while the ECL reaction occurred in the luminol ECL biosensor. At a higher concentration of kinase, there are more nanoprobes on the electrode, which gives a higher amount of GOx at the electrode interface and thus higher electrocatalytic efficiency to the luminol ECL reaction. Therefore, the activity of protein kinases can be monitored by ECL with high sensitivity. Protein kinase A (PKA), an important enzyme in regulation of glycogen, sugar, and lipid metabolism in the human body, was used as a model to confirm the present proof-of-concept strategy. The as-proposed biosensor presents high sensitivity, low detection limit of 0.013UmL−1, wide linear range (from 0.02 to 40UmL−1), and excellent stability. Moreover, this biosensor can also be used for quantitative analysis of kinase inhibition. On the basis of the inhibitor concentration dependent ECL signal, the half-maximal inhibition value IC50 of ellagic acid, a typical PKA inhibitor, was estimated, which is in agreement with those obtained using the conventional kinase assay. The simple and sensitive biosensor is promising in developing a high-through assay of in vitro kinase activity and inhibitor screening for clinic diagnostic and drug development.

Lighting Up Redox Propulsion with Luminol Electrogenerated Chemiluminescence

The development of systems at different scales that are remotely controlled or actuated in a wireless fashion is becoming a fast-developing area at the interface between chemistry and physics. In that framework, self-propelled macro-, microand nano-objects that are able to move in liquids when submitted to external physical fields or chemical fuels have recently been designed. In the latter case, the motion is induced by the conversion of locally available chemicals into mechanical energy via the production of gas bubbles. The mainstream strategy involves a metallic moiety which is able to catalyze the decomposition of hydrogen peroxide, resulting in the interfacial generation of oxygen bubbles. In contrast to this chemically-induced locomotion, physical methods involving electric fields have also been demonstrated. Bipolar electrochemistry (BPE) has recently encountered an important renewal thanks to the development of new applications in the fields of analytical chemistry and chemical sensing, surface science and generation of chemical gradients, catalysis and materials synthesis. The behaviour of a bipolar electrode (BE) is atypical with respect to conventional electrochemistry because it acts as an anode and a cathode at the same time. This asymmetric redox reactivity can also be advantageously used to set in motion conductive particles. The very first example of translational motion was proposed on the basis of an electrochemical self-regeneration with a zinc dendrite. Alternatively, water splitting at both reactive extremities of a BE is responsible for a spatially separated bubble production. This overall reaction generates twice more hydrogen bubbles at the cathodic pole when compared to oxygen at the anodic end. Here, the intrinsic stoichiometry controls the directionality of the resulting motion from the feeder anode to the feeder cathode. Enhancing the speed of motion can be achieved by introducing additive sacrificial redox compounds such as quinone or hydroquinone. In the latter case, the anodic counter reaction is not useful and simply allows to produce bubbles at only one pole of the BE. Interestingly, this recent approach allows as well the addition of new functionalities to dynamic systems like for example the emission of electrogenerated chemiluminescence (ECL). ECL is the light emission resulting from an initial electrochemical reaction. A model ECL system is based on the oxidation of luminol (5-Amino-2,3-dihydro-1,4-phthalazine-dione) in alkaline solution in the presence of hydrogen peroxide in order to promote blue light emission. Luminol and its derivatives are widely used in biochemical and clinical analysis such as enzymatic assays and immunoassays. For example, luminol ECL coupled to oxidasecatalysed reactions generating hydrogen peroxide constitutes a sensitive and versatile analytical strategy. ECL has not only been exploited in combination with BPE for analytical purposes, but also to design the first light emitting electrochemical swimmer involving [Ru(bpy)3] 2+ and tripropylamine (TPrA). The present contribution will show that this methodology can be generalized with another ECL system based on luminol, allowing to tune the wavelength of light emission. Moreover, all previously described BPE-driven motions were reported in neutral or acidic aqueous solutions with cathodic bubbles generation. In contrast, this first example in an alkaline solution proceeds through an alternative mechanism based on H2O2 oxidation and allowing the light emission at the same pole (anode) than the bubble production (Scheme 1). Simultaneous generation of gas bubbles and of ECL could be theoretically achieved when the interfacial difference of potential alongside a BE becomes sufficiently high. Preliminary

Cerium oxide–graphene as the matrix for cholesterol sensor

A simple and sensitive electrogenerated chemiluminescence (ECL) cholesterol biosensor was prepared based on cerium oxide–graphene (CeO2–graphene) composites as an efficient matrix. CeO2–graphene composites were prepared by depositing CeO2 onto graphene and were characterized by scanning electron microscopy. The experimental results demonstrated that CeO2–graphene could catalyze the ECL of a luminol–H2O2 (hydrogen peroxide) system to amplify the luminol ECL signal greatly. In addition, the use of CeO2–graphene provided a better biocompatible microenvironment for the immobilized enzyme, resulting in excellent stability and a long lifetime of the ECL biosensor. The surface assembly process, ECL behaviors, and electrochemistry of the biosensor were investigated in detail. The quantity of cholesterol was in the linear range from 12μM to 7.2mM with a detection limit of 4.0μM (signal/noise=3). In addition, the biosensor exhibited outstanding reproducibility, long-term stability, and selectivity. Moreover, this cholesterol biosensor offers an alternative analytical method with low cost and high speed.

Electrogenerated chemiluminescence of luminol at a polyaniline/graphene modified electrode in neutral solution

Polyaniline (PANI) was in situ electrochemical polymerized on an electrochemical reduced graphene oxide (GO) modified glassy carbon electrode (GCE) to prepare PANI-graphene (GR) composite modified GCE (PANI-GR-GCE). The modified electrode was characterized by atomic force microscopy, IR and electrochemical techniques. The results showed that the multi-layer of PANI and graphene could be formed on a bare electrode. The electrochemical signal was improved greatly compared with the PANI or the GR modified electrodes, respectively. Electrogenerated chemiluminescence (ECL) of luminol was comparatively investigated at the PANI-GCE, the GR-GCE, and the PANI-GR-GCE in neutral phosphate buffer solution (PBS). The anodic luminol ECL was inhibited greatly and the cathodic luminol ECL was enhanced at the GR-GCE. Extremely weak luminol ECL peaks were obtained at the PANI-GCE except one strong ECL obtained at high potential range. The PANI-GR composite exhibited apparent electrocatalytical effect on luminol oxidation, and as a result, the intensity of anodic ECL located at 0.50V was enhanced two magnitudes compared with other two modified electrodes. Several impact factors, such as the supporting electrolytes, the pH, the potential scan rate, and the different atmosphere, were studied. The mechanism of luminol ECL was also proposed.

Electrogenerated chemiluminescence of luminol at a gold nanoparticle–carbon nanotube–graphene composite modified glassy carbon electrode in neutral solution

In this paper, a graphene modified glassy carbon electrode (GR-GCE), a carbon nanotube modified glassy carbon electrode (CNT-GCE), a carbon nanotube–graphene modified glassy carbon electrode (CNT–GR-GCE), and a gold nanoparticle–carbon nanotube–graphene modified glassy carbon electrode (GNP–CNT–GR-GCE) were prepared and characterized by FT-IR, atomic force microscopy (AFM), and electrochemical methods respectively. Electrogenerated chemiluminescence (ECL) of luminol was comparatively studied at these modified electrodes in neutral solution. The results revealed that carbon nanotube could intercalate into the graphene film and improve the conductivity of the CNT–GR composite significantly. The CNT–GR composite is an ideal matrix for the deposition of gold nanoparticles. At the GNP–CNT–GR-GCE, the effect of GR on luminol ECL is more predominant than that of CNT while the electrocatalytic effect of GNP on luminol ECL is well preserved. These nanomaterials exhibit a good synergic effect towards luminol ECL, which is more efficient than that of the sole material. The volume ratio of GR and CNT, the amount of modified suspension, the presence of N2 and O2, and the supporting electrolytes could affect luminol ECL. Finally, the mechanisms of luminol ECL at the modified electrodes were proposed.

Self-assembly electrode based on silver nanoparticle toward electrogenerated chemiluminescence analysis of glucose

Electrogenerated Chemiluminescence (ECL) involves applying a certain electric potential to a chemical reaction, resulting in the oxidation or reduction of the substance which reacts to produce light. We determined the amount of glucose by its reaction to glucose oxidase (GOX) on the surface of the proposed modified electrode, which results hydrogen peroxide (H2O2) as side product. After that the reactions between luminol and H2O2 under oxidizing conditions generate dependent light which can be used to analyze. In the current article at first we proposed a convenient method to obtaining a self-assembly modified electrode. A nano based modified glassy carbon (GC) electrode (Glucose oxidase/Ag nanoparticles/cysteamine (CA)/p-aminobenzene sulfonic acid/GC electrode) was prepared, and the ECL behavior of luminol in the presence of glucose was examined. Compared to the bare GC electrode, the modified electrode incorporating glucose oxidase significantly enhanced the response of the ECL biosensor to glucose due to the enhanced specificity of the modified surface to enzymatic reaction, and the sensitivity of the luminol ECL reaction. Under optimal conditions, the electrode was established to respond linearly to glucose in the concentration range 5.0×10−7 to 8.0×10−3 mol/L, and the detection limit was established to be a glucose concentration of 4.0×10−8 mol/L.

Enhanced Cathodic Electrogenerated Chemiluminescence of Luminol at a Graphene Modified Electrode in Neutral Solution

Graphene oxide (GO) and electrochemically reduced graphene (ERG) modified glassy carbon electrodes (GCE) were prepared and characterized by FT-IR, scanning electron microscopy (SEM), and electrochemical techniques, respectively. Electrogenerated chemiluminescence (ECL) of luminol was studied on the modified electrodes in neutral phosphate buffer solution (PBS). Either at the GO modified electrode or at the ERG modified electrode, the anodic ECL emission of luminol was inhibited greatly and only one cathodic ECL peak was obtained. The intensity of the cathodic ECL emission at the ERG modified electrode increased 123 times compared with that of the GO modified electrode or the bare electrode, which is due to the strong adsorption of dissolved oxygen by ERG film. Several impact factors of luminol ECL, such as the electrochemical reduction potential, the duration of the applied reduction potential, the pH values, the supporting electrolytes, and the potential scan rate were studied and the mechanism of the cathodic luminol ECL emission on the ERG modified electrode was proposed.

Detection of hydrogen peroxide with luminol electrogenerated chemiluminescence at mesoporous platinum electrode in neutral aqueous solution

Electrogenerated chemiluminescence (ECL) behavior of luminol on a mesoporous platinum (H1-ePt) electrode has been studied in a neutral aqueous solution of phosphate buffer at pH 7. ECL behavior of luminol on a mesoporous Pt electrode was quite different from that observed on a bare Pt electrode. Since the highly enlarged surface area of Pt electrode (roughness factor=220) exhibited much larger electrochemical response for reductions of PtO and molecular oxygen, strong luminol ECL responses related to those electrochemical reactions were observed at ca. +0.1V and −0.5V vs. Ag/AgCl (3M NaCl) even in a neutral solution pH. The presence of hydrogen peroxide led to further increase in the luminol ECL response. Under the optimum conditions, the ECL response of luminol was linear with the concentration of hydrogen peroxide in the range of 10−8–10−3–M with a detection limit of 2.62nM (S/N=3). The reproducibility of the ECL measurements for 1.0mM hydrogen peroxide was quite good (relative standard deviation=3.4%, n=10).

Electrogenerated chemiluminescence of luminol at a carbon nanotube-perfluorosulfonate polymer (Nafion) modified gold electrode

A multi-wall carbon nanotube/Nafion modified gold electrode (CNT/Nafion/GE) was fabricated by casting the composite film on the electrode surface. Electrogenerated chemiluminescence (ECL) of luminol at the modified gold electrode was studied under conventional cyclic voltammetry in alkaline Na 2CO 3–NaHCO 3 buffer solution. Three ECL peaks were obtained. The most strong ECL peak (ECL-1) was enhanced about 20-fold at the CNT/Nafion modified gold electrode compared with that at the bare gold electrode. The emitter of all the ECL peaks was indentified as 3-aminophthalate. The intensities of ECL peaks were found to depend on the ratio of CNT/Nafion, the electrolytes, the pH, and the presence of O 2 and N 2. The mechanisms of all ECL peaks have been proposed. The results indicate that carbon nanotubes have a significantly catalytic effect on luminol ECL, which might further expand the analytical application of nanomaterial-modified electrode in the field of electrogenerated chemiluminescence.