Amperometric Current Research Articles

Surface-Enhanced Carboxyphenyl Diazonium Functionalized Screen-Printed Carbon Electrode for the Screening of Tuberculosis in Sputum Samples.

Curbing tuberculosis (TB) requires a combination of good strategies, including a proper prevention measure, diagnosis, and treatment. This study proposes an improvised tuberculosis diagnosis based on an amperometry approach for the sensitive detection of MPT64 antigen in clinical samples. An MPT64 aptamer specific to the target antigen was covalently attached to the carboxyphenyl diazonium-functionalized carbon electrode via carbodiimide chemistry. The electrochemical detection assay was adapted from a sandwich assay format to trap the antigen between the immobilized aptamer and horseradish peroxidase (HRP) tagged polyclonal anti-MPT64 antibody. The amperometric current was measured from the catalytic reaction response between HRP, hydrogen peroxide, and hydroquinone, which is used as an electron mediator. From the analysis, the detection limit in the measurement buffer was 1.11 ng mL−1. Additionally, the developed aptasensor exhibited a linear relationship between the current signal and the MPT64 antigen-spiked serum concentration ranging from 10 to 150 ng mL−1 with a 1.38 ng mL−1 detection limit. Finally, an evaluation using the clinical sputum samples from both TB (+) and TB (−) individuals revealed a sensitivity and specificity of 88% and 100%, respectively. Based on the analysis, the developed aptasensor was found to be simple in its fabrication, sensitive, and allowed for the efficient detection and diagnosis of TB in sputum samples.

In Situ Monitoring of Collision and Recollision Events of Single Attoliter Droplets via Single-Entity Electrochemistry.

We describe a simple method for real-time observation of collision and recollision behavior of a single aqueous attoliter droplet in an organic solvent through single-entity electrochemistry. The dynamics and morphology of the droplet after the collision event at the Au ultramicroelectrode (Au-UME) were monitored by consecutive cyclic voltammetry and amperometric current-time measurements. By sequentially applying oxidative potential and reductive potential at the Au-UME in the presence of attoliter droplets containing reversible redox species (e.g., ferrocyanide), we successfully detected the oxidative collision spike and its reductive recollision spike successively owing to the reversible redox reactions inside the droplet. Because the redox species was dissolved in a reduced form, the reductive collision spikes observed are the direct evidence that the water droplets colliding at the electrode surface are detached after the oxidation reaction. The collided droplet properties, such as size change and contact area, are also investigated and discussed.

Modified Clark Microsensors With Enhanced Sensing Current

Geometrical modification of three electrode Clark sensor is performed to enhance the sensing amperometric current. Two types of implantable microsensors are designed and characterized for measuring dissolved oxygen (DO 2 ). For type I sensor, the area of the reference electrode (RE) conventionally sandwiched between working electrode (WE) and counter electrode (CE), is optimized. In contrast to the conventional Clark sensors, the CE is sandwiched between WE and RE in type II sensor. Both type microsensors are fabricated using simple processes of silicon-based microfabrication technology. Electrochemical characterizations are performed on both sensors. For 96% DO 2 , type I and type II microsensors demonstrate a sensing current of -0.87 μA and -2.35 μA as compared to a sensing current of -0.27 μA for the conventional Clark microsensor of same size. A sensitivity of 0.0094 μA/%DO 2 and 0.024 μA/%DO 2 are achieved with type I and type II microsensor, respectively in contrast to a sensitivity of 0.0027 μA/%DO 2 of the conventional Clark microsensor of same size. The sensors show a lifetime of 48 hours. With its miniature size and enhanced sensing current the sensors have potentials for clinical and biomedical applications.

Label-free electrochemical immunosensor for sensitive HER2 biomarker detection using the core-shell magnetic metal-organic frameworks

Abstract Early diagnosis of tumors in the early stages of cancer allows for successful treatment and complete recovery. Herein, a simple and novel electrochemical immunosensor for Human Epidermal growth factor Receptor 2 (HER2) detection was constructed employing electrocatalytic activity of the magnetic framework Fe3O4@ TMU-21. The surface of the Fe3O4 nanoparticles was functionalized with methacrylic acid (MAA) to facilitate the immobilization of TMU-21. The fabrication of the immunosensor platform is based on Fe3O4@ TMU-21, and multi-walled carbon nanotubes (MWCNT). Their electrocatalytic activity towards the reduction of hydrogen peroxide is applied to signal immunosensor. In the presence of HER2 biomarker (Ag), the amperometric current of the decline of H2O2 decreased, which could be concluded that the establishment of Ag –Ab complexes on the electrode, and consequence blocking the electron transfer of reduction of H2O2 at the electrode surface. The analytical performance results of the immunosensor indicate that a linear relationship between the logarithm of the HER2 concentrations and amperometric responses is within the range of 1.0 pg mL−1-100 ng mL−1 and the detection limit was 0.3 pg mL−1. Remarkably, the detection result of HER2 in real human serum samples by the proposed immunosensor is well in correlation with HER2 spiked to human blood serum samples, therefore applies to the recognition of HER2 biomarker in clinical monitoring of tumor marker.

Understanding the kinetics of catalysed reactions in microheterogeneous thin film electrodes

In this paper which is dedicated to Professor Richard Compton for his 65th birthday, we examine the problem of describing the transport and kinetics of catalytic reactions in which the catalyst is immobilized within a support matrix such as for example redox enzymes immobilized in a polymer matrix, to form a chemically modified electrode. We examine a mathematical procedure which enables a full analytical solution to the Michaelis-Menten kinetic rate equation when coupled to Ficksian diffusion in thin bounded film. This governing reaction/diffusion equation is non-linear and a full analytical solution has, up until very recently, not been developed. Analytical solutions valid for low and high substrate concentrations have been previously reported. This solution for the amperometric steady state current is accurate whatever the value of substrate concentration. The analysis is applied to diffusion/reaction in a planar slab. General analytical solutions valid for steady state conditions for both the amperometric and potentiometric sensor response are provided. We then extend this useful analysis to consider the effect of concentration polarization in the solution, and to consider the effect of competitive inhibition on the amperometric current response. Finally, the analysis is extended to a polymer modified electrode when a redox mediator is used in the polymer film. General expressions for the current are obtained which were valid for any value of the substrate concentration. Kinetic case diagrams are developed and nine approximate limiting expressions for the amperometric response at steady state when the catalytic matrix is either conducting or insulating are developed.

Electrochemical sensing platform for naphthol isomers based on in situ growth of ZIF-8 on reduced graphene oxide by a reaction-diffusion technique

Enhancing the dispersibility and conductivity is an effective solution to develop the application zeolitic imidazole frameworks (ZIF) in the electrochemical field. This work thus employs a novel reaction–diffusion framework (RDF) technique for the in situ growth of ZIF-8 crystals on graphene oxide (GO@ZIF-8) matrixes. In detail, the outer electrolyte of 2-methyl imidazole naturally diffuses into the inner agar gel matrix containing Zn2+ cations and GO nanosheets. The long reaction–diffusion makes the growth of ZIF-8 crystals controllable in a vertical gradient. After thermal treatment, the title product of ZIF-8 in situ grown on reduced graphene oxide (rGO@ZIF-8) is obtained and thus exhibits good dispersibility, high conductivity, large surface area, and more catalytic sites. The glassy carbon electrode (GCE) was modified by casting the rGO@ZIF-8 suspension. The obtained rGO@ZIF-8/GCE displays excellent catalytic activity toward naphthol (NAP) isomers. Under the optimal conditions, the amperometric currents of 1-NAP and 2-NAP demonstrate the good linear relationship in wide ranges of 0.05–12 μM and 0.02–15 μM, respectively. Their limits of detection are as low as 15 and 17 nM, respectively. The fabricated modified electrode exhibits excellent selectivity, stability, and reproducibility. The sensor is also utilized to detect NAP molecules in real water samples and indicates good accuracy and reliability.

Gold nanorods-coated reduced graphene oxide as a modified electrode for the electrochemical sensory detection of NADH

We have reported a simple chemical preparation method of gold nanorods (AuNR) incorporated reduced graphene oxide (rGO) nanocomposite. Thus, synthesized AuNR decorated rGO (AuNR@rGO) nanocomposite has directly coated on glassy carbon electrode (GCE) for the highly sensitive and selective electrochemical sensing of Dihydronicotinamide adenine dinucleotide (NADH). The electrocatalytic activity of AuNR@rGO/GCE-modified electrode towards the oxidation of NADH has elaborately discussed. From the analysis of results, the amperometric current is increased linearly while increasing the NADH concentration in the range of 1–31 μM and the small limit of detection (LoD) has estimated as 0.22 μM (S/N = 3). Furthermore, the interferent study of the AuNR@rGO/GCE-modified electrode confirms for the sensitivity and unique detection ability of the electrode when other competitive biomolecules like glucose, uric acid, ascorbic acid, and dopamine are present.

Dissolved Oxygen MEMS Sensor With Enhanced Sensing Current

A new approach is proposed to enhance sensing amperometric current in three-electrode Clark dissolved oxygen (DO2) Microelectromechanical systems (MEMS) sensors. In the proposed approach, the counter electrode (CE) in a conventional concentric three-electrode sensor is modified to admit a large ratio of static electric current in an electrochemical solution. The typically large CE of a conventional sensor is replaced with an array of narrow-width electrodes. The modified CE is expected to reduce the inductive coupling and simultaneously increase the capacitive coupling of the structure. The overall changes of inductive and capacitive couplings are shown to enhance the sensing amperometric current of the sensor. Two μ-sensors are developed and fabricated based on MEMS technology including a conventional, as the reference and a new modified μ-sensors. The experimental results confirm an enhancement of 3.2:1 (0.352 μA:0.112 μA for 23% of DO2) in the sensing amperometric current of the developed MEMS μ-sensor compared to the conventional same-sized counterpart.

A robust host-guest interaction controlled probe immobilization strategy for the ultrasensitive detection of HBV DNA using hollow HP5–Au/CoS nanobox as biosensing platform

The combination of supramolecular chemistry and nanotechnology has potentially applied in the construction of biosensors, and thus improves the analytical performance and robustness of electron devices. Herein, a new sandwich-type DNA sensor was constructed for ultrasensitive determination of hepatitis B virus (HBV) DNA, a recognized marker for chronic hepatitis B. The water-soluble pillar[5]arene stabilized Pd NPs combined with reduced graphene oxide nanosheet (WP5–Pd/RGO) was synthesized and employed as supporting material for the modification of electrode surface. The probe DNA was immobilized onto the electrode surface through a new strategy based on the host-guest interaction between WP5 and methylene blue labeled DNA (MB-DNA). Moreover, MOF-derived cobalt sulfide nanobox was prepared to anchor the hydroxylatopillar[5]arene stabilized Au NPs (HP5–Au/CoS), which had superior electrocatalytic performance towards H2O2 reduction to achieve signal amplification. Under the optimized conditions, the proposed sensor displayed a linear relationship between amperometric currents and the logarithm of tDNA solution from 1 × 10−15 mol/L to 1 × 10−9 mol/L, and a low detection limit of 0.32 fmol/L. What's more, the DNA sensor had remarkable behaviors of stability, reproducibility, specificity, and accuracy, which provided a potential and promising prospect for clinical diagnosis and analysis.

A novel biosensor with the use of polypyrrole–poly(sodium-4-styrenesulphonate) as a dopant in the determination of glucose

In this paper, a new amperometric biosensor based upon a conducting polymer with anionic dopant-modified electrode was developed for use in the determination of glucose. Glucose oxidase enzyme was immobilized in polypyrrole–poly(sodium-4-styrenesulphonate) film using the entrapment method. Amperometric determination is based on the electrochemical detection of H2O2 generated in the enzymatic reaction of glucose oxidase. Glucose detection was carried out according to the oxidation of hydrogen peroxide at 0.4 V resulting from the enzymatic reaction on the biosensor surface. Some parameters that affect amperometric response current were investigated in terms of temperature, pH, and substrate concentration. The stability and reproducibility of the biosensor were analyzed. The interference effects were examined using amperometric response of the biosensor. The glucose detection ability of the biosensor was tested in a biological fluid (in blood). The film thickness, morphology, and water contact angle measurements of the polypyrrole–poly(sodium-4-styrenesulphonate) film were characterized by profilometer, atomic force microscope, and water contact angle device, respectively. For the biosensor in this study, the linear range 1 × 10−8–1 × 10−3 M, optimum temperature 25 °C, optimum pH 8, Km value 2.97 mM and Vmax value 0.097 μA was found. The results of the study show that the film can provide suitable biological application and electrochemical microenvironment for immobilization of the enzymes, making this material a perfect candidate for the production of extremely susceptible and selective glucose biosensors.

An electrochemical sensor for determination of nitrite based on Au nanoparticles decorated MoS2 nanosheets

An electrochemical sensor for the determination of nitrite was successfully fabricated via electro-depositing Au nanoparticles on a glassy carbon electrode (GCE) modified with MoS2 nanosheets. The morphology and composite of the resulted electrode were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The modified processes of the nanoAu-MoS2/GCE were monitored by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The amperometric current–time (i–t) showed that the developed electrode had excellent response for sodium nitrite under the optimum conditions, and the oxidative current of sodium nitrite was proportionally correlated with its concentration (10–2100 μM) with a limit of detection (LOD) of 0.09 μM (S/N = 3), which can be employed in the determination of nitrite in river and drinking water with the advantages of good reproducibility, anti-interference, long-term stability and satisfactory recovery rate.

Electrochemical Characteristics of a DNA Modified Electrode as a Function of Percent Binding.

Electrochemical characteristics of immobilized double-stranded DNA (dsDNA) on a Au electrode were studied as a function of coverage using a home-built optoelectrochemical method. The method allows probing of local redox processes on a 6 μm spot by measuring both differential reflectivity (SEED-R) and interferometry (SEED-I). The former is sensitive to redox ions that tend to adsorb to the electrode, while SEED-I is sensitive to nonadsorbing ions. The redox reaction maxima, Rmax and Δmax from SEED-R and SEED-I, respectively, are linearly proportional to amperometric peak current, Imax. The DNA binding is measured by a redox active dye, methylene blue, that intercalates in dsDNA, leading to an Rmax. Concomitantly, the absence of Δmax for [Fe(CN)6]4-/3- by SEED-I ensures that there is no leakage current from voids/defects in the alkanethiol passivation layer at the same spot of measurement. The binding was regulated electrochemically to obtain the binding fraction, f, ranging about three orders of magnitude. A remarkably sharp transition, f = fT = 1.25 × 10-3, was observed. Below fT, dsDNA molecules behaved as individual single-molecule nanoelectrodes. Above the crossover transition, Rmax, per dsDNA molecule dropped rapidly as f-1/2 toward a planar-like monolayer. The SEED-R peak at f ∼ 3.3 × 10-4 (∼270 dsDNA molecules) was (statistically) robust, corresponding to a responsivity of ∼0.45 zeptomoles of dsDNA/spot. Differential pulse voltammetry in the single-molecule regime estimated that the current per dsDNA molecule was ∼4.1 fA. Compared with published amperometric results, the reported semilogarithmic dependence on target concentration is in the f > fT regime.

Organic solvent free in situ growth of flower like Co-ZIF microstructures on nickel foam for glucose sensing and supercapacitor applications

Flower like microstructures of cobalt zeolitic imidazolate framework (FLCo-ZIF) was grown on flexible nickel foam (NF) when water was used as a solvent using Co-salt and imidazole as precursors. No such flower like microstructures was formed when ethanol or methanol was used as a solvent. Interestingly, no microstructures were grown on NF in the presence of DMF or DMSO. The microstructure growth was optimized with respect to the mole ratio of 2-methylimidazole (2-MI) and Co salt, solvent and immersion time. The scanning electron microscopy (SEM) images confirmed the formation of FLCo-ZIF on NF with an average framework size of 5 μm from 1:2 mole ratio in water at an immersion time of 3 h. Here, water acted as a green solvent and structure-directing agent to favour Co2+ nuclei to interact with the smaller building units of 2-MI to form FLCo-ZIF microstructures on NF. The cyclic voltammogram of FLCo-ZIF showed two redox waves corresponding to Co and Ni. Further, the FLCo-ZIF fabricated on NF was directly used as a binder free electrocatalyst for glucose oxidation and supercapacitor electrode. When the concentration of glucose increases the amperometric current was increased linearly from 2 μM to 1 mM in 0.1 M NaOH and the limit of detection (LOD) was found to be 0.42 μM (S/N = 3) with a sensitivity of 2.981 mA/(mM cm2). The clinical application of the present method was evaluated by determining glucose in human blood serum samples and the results were validated with the commercial glucometer. Besides, NF modified with FLCo-ZIF was also used for supercapacitor application. It showed a specific capacitance (C) of 87 F g−1 at the current density of 0.5 A g−1 and good stability for 2000 cycles. Thus, the FLCo-ZIF formed on NF from a green solvent shown here is a potential candidate for not only non-enzymatic sensing of glucose but also supercapacitor application.

Langmuir-Blodgett Assembly of Carboxylic Multiwalled Carbon Nanotubes-Nafion for Amperometric Sensing of Codeine

In this work, Langmuir−Blodgett (LB) technique was proposed to assemble the homogeneous and controlled films of carboxylic multiwalled carbon nanotubes-Nafion (c-MWCNTs-Nafion). Microstructure and electrochemical performance of LB films of c-MWCNTs-Nafion were characterized by AFM, SEM and electrochemical experiments. Moreover, the LB film of c-MWCNTs-Nafion was transferred to the surface of glassy carbon (GC) electrode to fabricate the electrochemical voltametric and amperometric sensor for codeine. The fabricated sensor showed enhanced electrocatalytic behavior for the oxidation of codeine. The amperometric currents for codeine are proportional to its concentration in a range from 1.0 × 10−7 to 1.0 × 10−5 mol L−1 with a detection limit of 3.0 × 10−8 mol L−1. And the proposed method exhibited good repeatability, stability, selectivity and accuracy.

The graphitic carbon nitride/polyaniline/silver nanocomposites as a potential electrocatalyst for hydrazine detection

The preparation of electrodes with a new nanocomposite material obtained by silver (Ag) nanoparticle deposition on fluorine doped tin oxide/polyaniline/graphitic‑carbon nitride film (PANI/g-C3N4/AgNPs) is developed. The PANI/g-C3N4/AgNPs nanocomposite material is characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), X-Ray diffraction (XRD) patterns, Brunauer-Emmett-Teller (BET), energy dispersive X-ray diffraction (EDX), Fourier-transform infrared (FT-IR) spectroscopy, and atomic absorption spectrophotometry (AAS). An amperometric sensing platform is constructed for electrochemical detection of hydrazine using PANI/g-C3N4/AgNPs and exhibits a wide linear range of 5–300mM with a limit of detection (LOD) of 300μM (S/N=3). Moreover, the amperometric currents are highly stable in the presence of interfering species. These results demonstrate that PANI/g-C3N4/AgNPs nanocomposites have great potential in hydrazine electrooxidation.

Sensitive Flow-Injection Electrochemical Determination of Hydrogen Peroxide at a Palladium Nanoparticle-Modified Pencil Graphite Electrode

A novel flow-injection amperometric method was proposed for the sensitive and enzymeless determination of hydrogen peroxide based on its electrocatalytic reduction at a palladium nanoparticle-modified pretreated pencil graphite electrode in a laboratory-constructed electrochemical flow cell. Cyclic voltammograms of the unmodified and modified electrodes were recorded in pH 7.0 phosphate buffer containing 0.10 M KCl at a scan rate of 50 mV s−1 for the investigation of electrocatalytic reduction of hydrogen peroxide at the palladium nanoparticle-modified pretreated pencil graphite electrode. Cyclic voltammograms of the pretreated pencil graphite electrode revealed an irreversible oxidation peak and a weak reduction peak of hydrogen peroxide at +1100 mV and –450 mV vs. an Ag/AgCl/KCl saturated reference electrode. However, the reduction of hydrogen peroxide was observed at –100 mV with an increase in current in the cyclic voltammograms of the palladium nanoparticle-modified pretreated pencil graphite electrode compared to the unmodified electrode. These results indicate that the palladium nanoparticle-modified pretreated pencil graphite electrode exhibits efficient electrocatalytic activity for the reduction of hydrogen peroxide. A linear concentration range was obtained between .01 and 10.0 mM hydrogen peroxide with a detection limit of 3.0 µM from flow injection amperometric current–time curves recorded in pH 7.0 phosphate buffer at –100 mV and a 2.0 mL min−1 flow rate. The novelty of this work relies on its use of a laboratory-constructed flow cell constructed for the pencil graphite electrode using these inexpensive, disposable, and electrochemically reactive modified electrodes for the amperometric determination of hydrogen peroxide in a flow injection analysis system.

Estimating amperometric spike parameters resulting from quantal exocytosis using curve fitting seeded by a matched-filter algorithm

BackgroundQuantal exocytosis of oxidizable neurotransmitters can be detected as spikes of amperometric current using electrochemical microelectrodes. Measurements of spike parameters indicate the maximal transmitter flux, flux duration, and amount of transmitter released from individual vesicles. Automated analysis algorithms need to reject spikes that overlap in time. In addition, many spikes are preceded by small amplitude “foot” signals, attributed to slow release of transmitter through a fusion pore. Accurate pre-spike baseline determination is essential for estimating fusion-pore duration and the amount of transmitter released through the fusion pore. New MethodWe developed an estimation approach that is based on fitting a multi-exponential function to the data. Our previously described matched-filter algorithm is used to identify the sections of data to fit and provides seed values to facilitate convergence of the iterative fit. The new estimation algorithm includes overlap rejection, a two-step fitting procedure and a novel baseline estimation procedure. ResultsHistograms of spike parameters demonstrate excellent agreement of the new approach with manually computed parameters. Comparison with Existing MethodsParameter estimates generated using the new approach are closer to blind manual estimates than commonly used existing methods. The improved performance is due to better detection of valid spikes and rejection of overlapping spikes. Moreover, since the complete time course of the spike is fit to a function, more complete information about the spike time course is captured. ConclusionsThe matched-filter seeded algorithm reliably rejects overlaps and estimates spike and foot signal parameters in a fully automated manner.

Synthesis of albumin capped gold nanoparticles and their direct attachment on glassy carbon electrode for the determination of nitrite ion

Development of a facile method for the detection of nitrite ion is very important due to its huge impact on environment. In the present study, water soluble bovine serum albumin capped gold nanoparticles (BSA-AuNPs) were directly attached on glassy carbon (GC) electrode for the sensitive determination of nitrite ion. The BSA-AuNPs were synthesized and HR-TEM images showed that the average size was ~5 nm. The BSA-AuNPs were then directly attached on GC electrode without any external linker and confirmed by SEM, EDS, XPS, DRS and CV. The appearance of peak at 286 eV (C-N) in XPS confirmed that BSA-AuNPs were attached on GC substrate through Michaeli's nucleophilic addition. The GC/BSA-AuNPs electrode showed an excellent catalytic activity towards nitrite by not only shifting its oxidation potential towards less positive potential by 150 mV but also enhanced its oxidation current by 3-fold compared to bare GC electrode. The amperometric current was increased linearly while increasing nitrite concentration from 10 × 10−9 to 1 × 10−6 M (R2 = 0.9917) and the limit of detection (LOD) by amperometry was found to be 2 × 10−9 M (S/N = 3). The real-time application of the present electro-catalyst was evidenced by determining nitrite in water samples.

Impedimetric gene assay for BCR/ABL transcripts in plasmids of patients with chronic myeloid leukemia.

A label-free impedimetric biosensor was developed for determination of BCR/ABL transcripts. Specific DNA primers were covalently immobilized on a gold electrode modified with carboxylated multiwalled carbon nanotubes (cMWCNTs) and zinc oxide nanoparticles (ZnO-NPs). Aggregation of the ZnO-NPs is prevented by the introduction of an amino-modified silica coating, which also allows a subsequent covalent linkage to cMWCNTs. The impedimetric biosensor was typically operated at a working voltage of +10mV vs. Ag/AgCl, in a frequency range from 100 mHz to 100kHz. Studies on the surface morphology and electrochemical properties of the electrode demonstrated improved bioactivity. Amperometric currents and impedimetric parameters, such as charge transfer resistance, varied significantly throughout the construction of the biosensor. The hybridization process was also evidenced by changes in the topography of the surface after exposure to samples containing BCR/ABL. The gene sensor has a linear concentration range for the target gene of 6.94 aM to 694 fM with a limit of detection as low as 0.039 aM. Also, the biosensor is selective and reproducible with a standard deviation of 4.1%. Three replicates for each experimental condition were used. Hence, it is perceived to be a viable tool for early-stage diagnosis of the BCR/ABL fusion gene and monitoring of major molecular remission in clinical samples. Graphical abstract Schematic of a highly sensitive hybridization assay for theBCR/ABL fusion gene. It is based on ZnO nanoparticle functionalized with 3-(aminopropyl)triethoxysilane.

Electrochemical Determination of Hydrogen Peroxide Using a Glassy Carbon Electrode Modified with Three-Dimensional Copper Hydroxide Nanosupercages and Electrochemically Reduced Graphene Oxide

ABSTRACTThree-dimensional copper hydroxide nanosupercages and electrochemically reduced graphene oxide were used to modify the glassy carbon electrode for the selective determination of hydrogen peroxide. The morphology and electrochemistry properties of copper hydroxide nanosupercage/electrochemically reduced graphene oxide/glassy carbon electrode were characterized using transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectra, Raman spectra, cyclic voltammetry, and electrochemical impedance spectroscopy. The resulting copper hydroxide nanosupercage/electrochemically reduced graphene oxide/glassy carbon electrode showed favorable performance for the electrocatalytic reduction of hydrogen peroxide. The amperometric current–time curve of the electrochemical sensor exhibited a wide linear range from 0.5 to 1030 µM with a limit of detection of 0.23 µM at a signal-to-noise ratio of three. Moreover, the sensor provided favorable selectivity, reproducibility, and stability and was used for the determination of H2O2 in tap water.