Graphene Oxide-modified Glassy Carbon Electrode Research Articles

Zirconium Phosphate-Incorporated Polyaniline-Graphene Oxide Composite Modified Electrodes for Effective and Selective Detection of Nitrite.

Nitrite contamination in food, water, and environmental samples poses a substantial health hazard, owing to its capacity for transformation into carcinogenic compounds. Given the profound ecological and physiological implications, precise and highly sensitive surveillance of nitrite has emerged as an imperative area of concern, addressing the substantial detrimental impact that it can have on both terrestrial and aquatic ecosystems. The novel electroactive polyaniline-graphene oxide composite, incorporating hexagonal zirconium phosphate discs (PGZrP), was systematically engineered as a foundation for an advanced electrochemical sensor, enabling precise nitrite detection in diverse aqueous and biological matrices. At a specific potential peak of +0.85 V, observed within a pH 7.0 phosphate buffer solution, the PGZrP-modified glassy carbon electrode (GCE) exhibited exceptional electrocatalytic proficiency in the sensing nitrite ions (NO2-), surpassing the performance of alternative electrode configurations, including the zirconium phosphate-modified GCE (ZrP/GCE), graphene oxide-modified GCE (GO/GCE), polyaniline-graphene oxide-modified GCE (PG/GCE), and the unmodified bare glassy carbon electrode. The constructed sensor demonstrated an impressive limit of detection at 80 nM along with a broad and linear detection range spanning from 124 nM to 40 mM. The synergistic effect created by the close contact between ZrP and PG, which resulted in a well-enhanced electrochemical sensing capability, was responsible for this exceptional activity. The developed sensor exhibited an enhanced electrochemical performance characterized by an extended operational range, a heightened detection threshold, and exceptional sensitivity. The PGZrP/GCE sensor, as fabricated, consistently demonstrated commendable operational stability, robust reproducibility, and remarkable repeatability in its capacity for nitrite detection. Furthermore, its successful application in the precise quantification of nitrite levels within environmental water samples and blood specimens showcased an impressive recovery rate, establishing it as a promising tool for diverse analytical applications. These findings indicate the promising potential of the PGZrP composite for integration into electrochemical devices designed to deliver rapid response times, heightened sensitivity, and sustained stability, thereby placing it as a potential candidate for the production of cutting-edge sensors, particularly those employed for the precise recognition of nitrite in aquatic and biological specimens.

Elucidation of DNA-Eltrombopag Binding: Electrochemical, Spectroscopic and Molecular Docking Techniques.

Eltrombopag is a powerful adjuvant anticancer drug used in treating MS (myelodysplastic syndrome) and AML (acute myeloid leukemia) diseases. In this study, the interaction mechanism between eltrombopag and DNA was studied by voltammetry, spectroscopic techniques, and viscosity measurements. We developed a DNA-based biosensor and nano-biosensor using reduced graphene oxide-modified glassy carbon electrode to detect DNA-eltrombopag binding. The reduction of desoxyguanosine (dGuo) and desoxyadenosine (dAdo) oxidation signals in the presence of the drug demonstrated that a strong interaction could be established between the eltrombopag and dsDNA. The eltrombopag-DNA interaction was further investigated by UV absorption and fluorescence emission spectroscopy to gain more quantitative insight on binding. Viscosity measurements were utilized to characterize the binding mode of the drug. To shed light on the noncovalent interactions and binding mechanism of eltrombopag molecular docking and molecular dynamics (MD), simulations were performed. Through simultaneously carried out experimental and in silico studies, it was established that the eltrombopag binds onto the DNA via intercalation.

An ultrasensitive electrochemical sensor for detecting porcine epidemic diarrhea virus based on a Prussian blue-reduced graphene oxide modified glassy carbon electrode

This study developed a novel, ultrasensitive sandwich-type electrochemical immunosensor for detecting the porcine epidemic diarrhea virus (PEDV). By electrochemical co-deposition of graphene and Prussian blue, a Prussian blue-reduced graphene oxide-modified glassy carbon electrode was made, further modified with PEDV-monoclonal antibodies (mAbs) to create a new PEDV immunosensor using the double antibody sandwich technique. The electrochemical characteristics of several modified electrodes were investigated using cyclic voltammetry (CV). We optimized the pH levels and scan rate. Additionally, we examined specificity, reproducibility, repeatability, accuracy, and stability. The study indicates that the immunosensor has good performance in the concentration range of 1 × 101.88 to 1 × 105.38 TCID50/mL of PEDV, with a detection limit of 1 × 101.93 TCID50/mL at a signal-to-noise ratio of 3σ. The composite membranes produced via co-deposition of graphene and Prussian blue effectively increased electron transport to the glassy carbon electrode, boosted response signals, and increased the sensitivity, specificity, and stability of the immunosensor. The immunosensor could accurately detect PEDV, with results comparable to real-time quantitative PCR. This technique was applied to PEDV detection and served as a model for developing additional immunosensors for detecting hazardous chemicals and pathogenic microbes.

Simultaneous Quantitation of Lead and Cadmium on an EDTA-Reduced Graphene Oxide-Modified Glassy Carbon Electrode.

Cadmium (Cd) and lead (Pb) are classified as category one toxicants. The provisional guideline values, according to the World Health Organization (WHO), for Cd and Pb are 3 and 10 ppb, respectively. An easy, quick, and cheap analytical technique is in demand for the determination of these toxic heavy metals in water. Hence, a novel electrochemical sensing platform is developed by modifying the glassy carbon electrode with ethylenediaminetetraacetic acid (EDTA)-functionalized reduced graphene oxide (ErGO) for the low-cost simultaneous quantitation of toxic heavy-metal ions, lead and cadmium, in real water samples. EDTA is grafted to the surface of graphene oxide, via amine linkage, and the oxygen functionality is reduced by a green agent, tyrosine. Various physical and electrochemical characterizations of the as-prepared electrocatalytic material were performed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), ζ-potential, ultraviolet diffuse reflectance spectroscopy (UV-DRS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), etc. The glassy carbon electrode (GCE) is modified with ErGO by a simple drop-casting method for simultaneous metal-ion quantitation by differential pulse voltammetry (DPV). EDTA functionalization of graphene oxide and its further reduction using the green agent enhance the stability and sensitivity of the electrode substrate. The limits of detection for cadmium and lead ions calculated for ErGO/GCE are 1.02 and 2.52 ppb, while the limits of quantification for lead and cadmium ions are 3.41 and 8.4 ppb, and their sensitivities are 0.8 and 0.6 nA/ppb, respectively. Real river water contains 200.2 ± 0.38 ppb of Pb2+ ions (mean ± stdev, n = 3) by the DPV technique, which is validated by ICP-OES analysis.

Electrochemical Dopamine Sensor Based on Gold Nanoparticles Electrodeposited on a Polymer/Reduced Graphene Oxide-Modified Glassy Carbon Electrode

A novel electrochemical dopamine (DA) sensor based on Au nanoparticles (AuNPs) electrochemically loaded on poly([2,2′;5′,2″]-terthiophene-3′-carbaldehyde)/reduced graphene oxide (poly(TTP)/rGO) improved glassy carbon electrode (GCE) was fabricated. The Au@poly(TTP)/rGO/GCE was evaluated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), amperometry, and electrochemical impedance spectroscopy (EIS). The optimized Au@poly(TTP)/rGO/GCE sensor had a wide electroactive surface area and exhibited good selectivity. The linear determination range of the sensor was from 0.02 to 232 µM with a sensitivity of 315 µA/mM/cm2. The limit of detection (LOD) was estimated to be 11.5 nM using signal-to-noise (S/N) ratio of 3. Additionally, the sensor displayed excellent selectivity, satisfactory response time from 4.5 to 6 s, replicability with a relative standard deviation (RSD) of 2.31%, reproducibility with a RSD of 3.67%, and storage stability with 92.57% of its initial current response for 37 days. The Au@poly(TTP)/rGO/GCE was employed to estimate DA in injection samples.

Solar Exfoliated Graphene Oxide: A Platform for Electrochemical Sensing of Epinephrine

Introduction: In this study, solar exfoliated graphite oxide modified glassy carbon electrode was used for the anodic oxidation of epinephrine in a phosphate buffer medium at pH7. The modified electrode showed fast response and sensitivity towards Epinephrine Molecule (EP). The electrode was characterized electrochemically through Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV). Area of the electrode enhanced three times during modification and studies reveal that the oxidation process of EP occurs by an adsorption controlled process involving two electrons. The results showed a detection limit of 0.50 ± 0.01μM with a linear range up to 100 μM. The rate constant calculated for the electron transfer reaction is 1.35 s-1. The electrode was effective for simultaneous detection of EP in the presence of Ascorbic Acid (AA) and Uric Acid (UA) with well-resolved signals. The sensitivity, selectivity and stability of the sensor were also confirmed. Methods: Glassy carbon electrode modified by reduced graphene oxide was used for the detection and quantification of epinephrine using cyclic voltammetry and differential pulse voltammetry. Results: The results showed an enhancement in the electrocatalytic oxidation of epinephrine due to the increase in the effective surface area of the modified electrode. The anodic transfer coefficient, detection limit and electron transfer rate constant of the reaction were also calculated. Conclusion: The paper reports the determination of epinephrine using reduced graphene oxide modified glassy carbon electrode through CV and DPV. The sensor exhibited excellent reproducibility and repeatability for the detection of epinephrine and also its simultaneous detection of ascorbic acid and uric acid, which coexist in the biological system.

Electrochemical Sensing of Chemical Warfare Agent Based on Hybrid Material Silver‐aminosilane Graphene Oxide

AbstractThe threat from chemical warfare agents (CWAs) imparts an alarming call for the global community not limited to human being but also extends as unprecedented environmental threat, hence, timely detection and degradation in the event of CWAs attack is very crucial. Herein, we describe a hybrid material of 3‐aminopropyltriethoxysilane (APTES) modified graphene oxide (GO) on glassy carbon (GC) electrode along with electrodeposited silver nanodendrimers (AgNDs) for the electrochemical detection and degradation of CWA sulphur mustard (HD). The AgNDs/APTES‐GO hybrid material was characterized by SEM, EDX, BET, TGA, Raman, UV‐Vis, XPS and XRD techniques. The AgNDs/APTES‐GO modified GC electrode was also characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Electrochemical studies indicated presence of electrocatalysis owing to the synergistic effect of AgNDs and GO for sensing CWA HD via reductive dehalogenation. The AgNDs/APTES‐GO modified GC electrode exhibited linearity for CWA HD from 5.3 μM to 42.4 μM. Constant potential electrolysis was performed with modified electrode and degradation products were analysed using GC‐MS, highlighting the great potential of graphene based hybrid material. This new strategy provides an opportunity for the development of “detect and destroy” system for the CWAs and other environmental toxic pollutant, which could help in mitigation of on‐ site events for first responders.

Novel electrochemical sensor using a dual-working electrode system for the simultaneous determination of glucose, uric acid and dopamine

Dual working electrodes were constructed for the simultaneous determination of three analytes. A graphene oxide-modified glassy carbon electrode (GO/GCE) was used for adsorptive anodic stripping voltammetry to detect uric acid and dopamine, while a chitosan/glucose oxidase/Prussian blue-graphite modified glassy carbon electrode (Chi/GOx/PB-G/GCE) was used for chronoamperometric glucose detection. The fabrication and operation conditions for both electrodes were optimized. Linearity was obtained in the ranges of 0.10–30 µM and 30–80 µM for dopamine, 0.20–10 µM and 10–30 µM for uric acid and 15–1,500 µM for glucose. The system provided detection limits (LOD = 3σ/S) of 0.080 µM, 0.11 µM, and 5.7 µM for dopamine, uric acid and glucose, respectively. This dual-working electrode system showed good reproducibility and excellent recovery for the simultaneous determination of dopamine, uric acid, and glucose. When used to analyze dopamine, uric acid, and glucose in blood plasma samples, the results agreed well with those from conventional methods (P > 0.05), indicating the potential of this system to simultaneously determine these three analytes in real samples.

T-T Mismatch-Based Electrochemical Aptasensor for Ultratrace Level Detection of Hg2+ Using Electrochemically Reduced Graphene Oxide-Modified Electrode.

Ultratrace levels of mercury ions (Hg2+) were quantified utilizing differential pulse voltammetry (DPV) in aqueous solution. This method utilized a thymine (T)-rich, methylene blue-tagged DNA (MBD) and an electrochemically-reduced graphene oxide-modified glassy carbon electrode (ERGO-GCE). The ERGO-GCE was prepared by the direct reduction of graphene oxide (GO) solution on a glassy carbon electrode (GCE) using cyclic voltammetry. The MBD, as a sensing motif, was then coated on the surface of the ERGO-GCE through π-π stacking. In the presence of Hg2+, mercury-mediated coordination of the T-Hg2+-T base pairs caused folding of the MBD, leading to a hairpin structure. This resulted in subsequent unbinding of MBD from the surface of the ERGO-GCE, which produced a change in redox current of the MB tag. DPV of the modified electrode showed that the MB signal decreased linearly with increases in Hg2+ concentrations in the range between 1 fM and 100 nM with a detection limit of 0.16 fM. This sensor also exhibited excellent selectivity for Hg2+ against interfering metal ions. In addition, the sensor could be regenerated by decoupling the T-Hg2+-T in cysteine, which unfolded the MBD.

Graphene oxide based highly sensitive electrochemical sensor for detection of environmental pollutants and biomolecules

A simple and highly sensitive electrochemical sensor based on graphene oxide modified glassy carbon electrode (GO/GCE) is reported for the detection of hydrazine (HDZ), ascorbic acid (AA) and hydrogen peroxide (H2O2). GO nanosheets were synthesized by the oxidation of natural graphite powder via a modified Hummer’s method. The structural and surface characteristics of GO were investigated by x-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, Ultraviolet-visible diffuse reflectance spectra (UV–vis DRS) spectroscopy, Raman spectroscopy and thermogravimetric analysis (TGA). The electrochemical behaviour of the GO/GCE was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and chronoamperometry. Under optimized GO concentration, GO/GCE showed stable and admirable electrocatalytic response towards the oxidation of HDZ and AA, and the reduction of H2O2 at low over potentials. GO/GCE showed promising detection ability for HDZ, AA, and H2O2 with high sensitivity, wider linear detection range and lower LOD. The obtained LOD values were 1.04, 0.5 and 4 μM for HDZ, AA, and H2O2 respectively. Furthermore, GO/GCE exhibited good stability, reusability, reproducibility and anti-interference capability. The superior electrical conductivity, strong adsorptive ability and large surface area of GO nanosheets are responsible for the excellent electrocatalytic activity of the present GO-based sensor. This study reveals that GO is a promising candidate as the electrochemical sensor.

Selective and low potential electrocatalytic oxidation of NADH using a 2,2-diphenyl-1-picrylhydrazyl immobilized graphene oxide-modified glassy carbon electrode

DPPH (2,2-diphenyl-1-picrylhydrazil), a free radical-containing organic compound, is used widely to evaluate the antioxidant properties of plant constituents. Here, we report an efficient electroactive DPPH molecular system with excellent electrocatalytic sensor properties, which is clearly distinct from the traditional free radical-based quenching mechanism. This unusual molecular status was achieved by the electrochemical immobilization of graphene oxide (GO)-stabilized DPPH on a glassy carbon electrode (GCE). Potential cycling of the DPPH adsorbed-GCE/GO between − 1 and 1 V (Ag/AgCl) in a pH 7 solution revealed a stable and well-defined pair of redox peaks with a standard electrode potential, E0′ = 0 ± 0.01 V (Ag/AgCl). Several electrochemical characterization studies as well as surface analysis of the GCE/GO@DPPH-modified electrode by transmission electron microscopy, Raman, and infrared spectroscopy collectively identified the imine/amine groups as the redox centers of the electroactive DPPH on GO. The use of different carbon-supports showed that only oxygen-functionalized GO and MWCNTs could provide major electroactivity for DPPH. This highlights the importance of a strong hydrogen-bonded network structure assisted by the concomitant π-π interactions between the organic moiety and oxygen function groups of carbon for the high electroactivity and stability of the GCE/GO@DPPH-NH/NH2-modified electrode. The developed electrode exhibited remarkable performance towards the electrocatalytic oxidation of NADH at 0 V (Ag/AgCl). The amperometric i-t sensing of NADH showed high sensitivity (488 nA μM−1 cm−2) and an extended linear range (50 to 450 μM) with complete freedom from several common biochemical/chemical interferents, such as ascorbic acid, hydrazine, glucose, cysteine, citric acid, nitrate, and uric acid.

A Facile Electrochemical Fabrication of Reduced Graphene Oxide-Modified Glassy Carbon Electrode for Simultaneous Detection of Dopamine, Ascorbic Acid, and Uric Acid

A Facile Electrochemical Fabrication of Reduced Graphene Oxide-Modified Glassy Carbon Electrode for Simultaneous Detection of Dopamine, Ascorbic Acid, and Uric Acid

A Facile Electrochemical Fabrication of Reduced Graphene Oxide-Modified Glassy Carbon Electrode for Simultaneous Detection of Dopamine, Ascorbic Acid, and Uric Acid

This paper describes the simple fabrication of an electrode modified with electrochemically reduced graphene oxide (ERGO) for the simultaneous electrocatalytic detection of dopamine (DA), ascorbic acid (AA), and uric acid (UA). ERGO was formed on a glassy carbon (GC) electrode by the reduction of graphene oxide (GO) using linear sweep voltammetry. The ERGO/GC electrode was formed by subjecting a GO solution (1 mg mL-1 in 0.25 M NaCl) to a linear scan from 0 V to −1.4 V at a scan rate of 20 mV s-1. The ERGO/GC electrode was characterized by Raman spectroscopy, Fourier transform infrared spectroscopy, contact angle measurements, electrochemical impedance spectroscopy, and cyclic voltammetry. The electrochemical performance of the ERGO/GC electrode with respect to the detection of DA, AA, and UA in 0.1M PBS (pH 7.4) was investigated by differential pulse voltammetry (DPV) and amperometry. The ERGO/GC electrode exhibited three well-separated voltammetric peaks and increased oxidation currents during the DPV measurements, thus allowing for the simultaneous and individual detection of DA, AA, and UA. The detection limits for DA, AA, and UA were found to be 0.46, 77, and 0.31 μM respectively, using the amperometric i-t curve technique, with the S/N ratio being 3. Keywords: Dopamine, Graphene, Reduced graphene oxide, Electrochemical sensor

Effect of different copper salts on the electrochemical determination of Cu(II) by the application of the graphene oxide-modified glassy carbon electrode

In this study, graphene oxide and reduced graphene oxide nanoparticles were synthesized by Hummers method and characterized Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, scanning electron microscopy and thermogravimetric analysis. Then, glassy carbon electrode surfaces were modified with synthesized and characterized graphene oxide (GO) and reduced graphene oxide (red-GO) using physical immobilization. Bare and modified surfaces were characterized by cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. Application of graphene oxide (GO/GC) and reduced graphene oxide-modified glassy carbon (red-GO/GC) surfaces for the electrochemical determination of copper(II) using different copper salts such as CuSO4·5H2O, Cu(NO3)2·3H2O and CuCI2 were performed by differential pulse voltammetry. The GO/GC surface was found to be suitable for selective determination of Cu(II) in the solutions containing the mixture of heavy metal ions (Zn(II), Pb(II), Cd(II), Fe(III) and Mn(II)) and showed high stability and reproducibility. The GO/GC surface was treated with CuSO4·5H2O, Cu(NO3)2·3H2O and CuCI2 salts solution in optimum conditions and afterward SEM images were measured 10 µm in size and radius of these ions in Cu(II)/GO/GC surfaces. Thus the determination of copper ions on the GO/GC surface was made for the first time by comparing the effect of the types of copper salts. When it was evaluated in terms of inorganic theory, the results were found to be in harmony.

Electrochemical Determination of Carbendazim in Food Samples Using an Electrochemically Reduced Nitrogen-Doped Graphene Oxide-Modified Glassy Carbon Electrode

Nitrogen-doped graphene oxide (NGO) was synthesized via pyrolysis of graphene oxide and urea and was characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). An electrochemically reduced nitrogen-doped graphene oxide-modified glassy carbon electrode (ERNGO/GCE) was developed for the determination of carbendazim (CBZ) in food samples. The surface morphology of the modified electrode was characterized by scanning electron microscopy (SEM). Cyclic voltammetry and electrochemical impedance spectroscopy were employed to demonstrate the large electrode surface and fast electron transfer of the ERNGO/GCE. Electrochemical behaviors of CBZ at different electrodes were studied by voltammetry. Experimental results showed that the ERNGO/GCE achieved better performance for the electrochemical oxidation of CBZ than either the bare glassy carbon electrode (GCE) or the nitrogen-doped graphene oxide-modified GCE (NGO/GCE). Under optimized conditions, the ERNGO/GCE exhibited a wide linearity of 5.0~850 μg/L with a detection limit of 1.0 μg/L (signal-to-noise ratio = 3). Application of our proposed method in food products was shown to be practical and reliable.

Electrochemiluminescene Resonance Energy Transfer Between Traditional Luminescent Reagents and Nanomaterials and Their Biosensing Application

Luminescence resonance energy transfer (LRET) is a powerful technique for probing changes in the distance between energy donors and acceptors, which has often been used in bioassays.1 Electrochemiluminescence (ECL) technique has been widely used in sensing applications, however, it has been seldom reported in LRET due to the difficulty in finding suitable energy donor/acceptor pair. In order to expand its application, it is very important to establish more suitable ECL resonance energy transfer (ECL-RET) pairs. Recently, we found that some traditional ECL reagents, such as luminol, Ru(bpy)3 2+, and lucigenin, can transfer their ECL energy to nanomaterials including semiconductor quantum dots and graphene. The obtained ECL-RET signals are usually stronger than the original ECL signals, which makes the ECL-RET more suitable for biosensing application. Electrochemluminescence resonance energy transfer (ECL-RET) between luminol as a donor and CdSe@ZnS quantum dots (QDs) as an acceptor can be obtained in neutral condition. CdSe@ZnS quantum dots modified on a glassy carbon electrode can catalyze the luminol oxidation to promote the anodic luminol ECL without coreactant. The intensity of anodic luminol ECL (0.60 V) at the CdSe@ZnS/GCE was enhanced more than one magnitude compared with that at the bare GCE. Another strong anodic ECL peak observed at more positive potential (1.10 V) could be assigned to the ECL-RET between the excited state of luminol and the QDs. A label-free ECL aptasensor for the detection of thrombin was fabricated based on the synergic effect of the electrocatalysis and the ECL-RET. The approach showed high sensitivity, good selectivity, and wide linearity for the detection of thrombin in the range of 10 fM-100 pM with a detection limit of 1.4 fM (S/N=3). The energy transfer between lucigenin and CdSe QDs was investigated. Strong anodic ECL can be obtained in neutral lucigenin solution at a CdSe quantum dots modified glassy carbon electrode in the presence of bromide. Electrochemical results suggested that CdSe quantum dots can catalyze the oxidation of lucigenin and bromide, which can generate the anodic ECL. The fluorescence and the ECL spectra revealed that the ECL-RET can occur between lucigenin and CdSe quantum dots. The oxidation product of bromide can promote the ECL-RET and increase the anodic ECL signal significantly. Cytochrome c exhibited apparent inhibiting effect on the anodic ECL emission, based on which a sensitive ECL sensor for the detection of cytochrome c was established.3 The ECL-RET can also occur between Ru(bpy)3 2+ ECL and gold nanoparticles/graphene oxide nanocomposite. Strong anodic Ru(bpy)3 2+ ECL was observed at a graphene oxide modified glassy carbon electrode (GO/GCE) in the absence of coreactants. The catalytical effect of GO on the oxidation of Ru(bpy)3 2+ suggested that GO itself can act as the coreactant of Ru(bpy)3 2+ ECL. Thiol group terminated adenosine triphosphate (ATP) aptamer was immobilized on the GO film via DNA hybridization. When gold nanoparticles/graphene oxide (AuNPs/GO) nanocomposites were modified on the aptamer through S-Au bond to form sandwich-like structure, the ECL-RET could occur between Ru(bpy)3 2+and AuNPs/GO nanocomposites, resulting in apparent decrease of ECL signal. After the ECL sensor was incubated in ATP solution, the AuNPs/GO nanocomposites were released from the electrode due to the specific interaction between aptamer and ATP, leading to the increased ECL signal. Based on these results, an ECL aptasensor was fabricated and could be used in the sensitive and selective detection of ATP in the range of 0.02-200 pM with a detection limit of 6.7 fM (S/N=3). The above results suggested that the ECL-RET between the traditional luminescent reagents and nanomaterials can be used to fabricate different kinds of biosensors for the detection of protein and DNA, which will sufficiently expand the application of ECL technique in biosensing field.

Highly sensitive nonenzymatic glucose sensor based on nickel nanoparticle–attapulgite-reduced graphene oxide-modified glassy carbon electrode

In this article, a fast and sensitive nonenzymatic glucose sensor is reported utilizing a glassy carbon electrode modified by synthesizing nanocomposites of nickel nanoparticle–attapulgite-reduced graphene oxide (Ni NPs/ATP/RGO). A facile one-step electrochemical co-deposition approach is adopted to synthesize Ni NPs-ATP-RGO nanocomposites via electrochemical reduction of mixed precursor solution containing graphene oxide (GO), attapulgite (ATP) and nickel cations (Ni2+) at the cathode potentials. This strategy results in simultaneous depositions of ATP, cathodic reduction of Ni2+ into nickel nanoparticles under acidic conditions, and in situ reduction of GO. The as-prepared NiNPs/ATP/RGO-based glucose sensor exhibits outstanding performance for enzymeless glucose sensing with sensitivity (1414.4 μAmM−1cm−2), linear range (1–710μM) and detection limit (0.37μM). What is more, the sensor has excellent stability and selectivity against common interferences in real sample.

Electrogenerated Chemiluminescence Resonance Energy Transfer between Ru(bpy)3(2+) Electrogenerated Chemiluminescence and Gold Nanoparticles/Graphene Oxide Nanocomposites with Graphene Oxide as Coreactant and Its Sensing Application.

In the present work, strong anodic electrogenerated chemiluminescence (ECL) of Ru(bpy)3(2+) was observed at a graphene oxide modified glassy carbon electrode (GO/GCE) in the absence of coreactants. The electrocatalytical effect of GO on the oxidation of Ru(bpy)3(2+) suggested that GO itself can act as the coreactant of Ru(bpy)3(2+) ECL, which can be used to fabricate the ECL biosensor. Thiol group terminated adenosine triphosphate (ATP) aptamer was immobilized on the GO film via DNA hybridization. When gold nanoparticles/graphene oxide (AuNPs/GO) nanocomposites were modified on the aptamer through the S-Au bond to form a sandwich-like structure, the ECL resonance energy transfer (ECL-RET) could occur between Ru(bpy)3(2+) and AuNPs/GO nanocomposites, resulting in an apparent decrease of ECL signal. After the ECL sensor was incubated in ATP solution, the AuNPs/GO nanocomposites were released from the electrode due to the specific interaction between aptamer and ATP, leading to the increased ECL signal. On the basis of these results, an ECL aptasensor was fabricated and could be used in the sensitive and selective detection of ATP in the range of 0.02-200 pM with a detection limit of 6.7 fM (S/N = 3). The proposed ECL aptasensor can be applied in the detection of ATP in real samples with satisfactory results.

Determination of Rutin by a Graphene-Modified Glassy Carbon Electrode

A reduced graphene oxide-modified glassy carbon electrode for sensitive detection of rutin is reported. The modified electrode was obtained by one-step electrochemical reduction of graphene oxide on the bare glassy carbon electrode. In the presence of graphene, an enhanced electrochemical response for rutin appeared with a pair of well-defined anodic and cathodic peaks in pH 3.0 phosphate buffer. Under the optimized conditions, the anodic peak currents exhibited a linear relationship with rutin concentration from 0.1 to 2.0 µM with a detection limit of 23.2 nM. The modified electrode was employed to the analysis of tablets (with satisfactory recovery of 19.96 mg/per tablet) and Flos Sophorae. The graphene-modified electrode exhibited high sensitivity, good stability, and selectivity for the determination of rutin.

A Label-free Electrochemical Biosensor for Acrylamide Based on DNA Immobilized on Graphene Oxide-Modified Glassy Carbon Electrode

A Label-free Electrochemical Biosensor for Acrylamide Based on DNA Immobilized on Graphene Oxide-Modified Glassy Carbon Electrode