Nonenzymatic Amperometric Sensor Research Articles

Nickel nanoparticles supported on porous silicon flour, application as a non-enzymatic electrochemical glucose sensor

Here, a non-enzymatic amperometric sensor is fabricated for glucose detection based on nickel nanoparticles supported on porous silicon flour. A facile procedure was introduced for the in-situ electroless assembling of nickel nanoparticles on porous silicon (PS) flour without using any reducing agent. Briefly, Ni@PSnanocompositewaspreparedthroughthechemicalreductionofNi2(Her)+ ions and oxidation of the surface of Si atoms in ammonium fluoride solution. The formation of the Ni@PS nanocomposite was confirmed by scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), energy dispersive spectroscopy (EDS) and FT-IR spectroscopy as well as cyclic voltammetry (CV). The synthesized nanocomposite was employed as an electrode material for non-enzymatic glucose (Gl) sensing using carbon paste electrode (CPE). The prepared amperometric sensor exhibited a wide linear range of 2.0–5000μmolL−1 with a low limit of detection (0.2μmolL−1) as well as high stability and fast response time (<3s). Also, no significant interference was observed from potentially interference species such as dopamine, ascorbic acid, uric acid and Cl− ions. The excellent applicability of the proposed sensor for determination of Gl in human blood serum with good accuracy and reproducibility made Ni@PS nanocomposite promising for the development of effective electrochemical non-enzymatic Gl sensor.

Amperometric enzyme-free glucose sensor based on the use of a reduced graphene oxide paste electrode modified with electrodeposited cobalt oxide nanoparticles

The authors describe a non-enzymatic amperometric sensor for glucose that was prepared by electrodeposition of cobalt oxide nanoparticles on a graphene paste that is readily obtained by mixing reduced graphene oxide (r-GO) nanosheets and mineral oil in a mortar. An electrode was prepared and characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Cobalt oxide nanoparticles were electrochemically deposited on the electrode, and their morphology was characterized by field emission scanning electron microscopy. Cyclic voltammetric and chronoamperometric studies showed the modified electrode to display electrocatalytic activity toward the direct oxidation of glucose, best at a working potential of 0.45 V (vs. SCE) in 0.1 M NaOH solution. The sensor exhibits a linear response in the 40 to 4000 μM glucose concentration range, has a detection limit as low as 1.4 μM (at an S/N ratio of 3), and a sensitivity of 1.21 μA∙μM−1∙cm−2. The electrode was successfully applied to the determination of glucose in (spiked) human serum where it showed recoveries between 97.2 and 103.4 %.

Ethanol electrooxidation at carbon paste electrode modified with Pd–ZnO nanoparticles

The electrocatalytic and analytical performance of palladium–zinc oxide nanoparticles modified carbon paste electrode (Pd–ZnO/CPE) for determination and oxidation of ethanol were studied in alkaline media. X-ray diffraction (XRD) and transmission electron microscopy (TEM) was used to characterize Pd–ZnO nanoparticles. The electrochemical characterizations were performed using cyclic voltammetry (CV) and chronoamperometry techniques. The results show that the electrode reveals excellent electrocatalytic characteristics for ethanol oxidation such as high catalytic activity, stability and tolerance toward poisoning effects. Also, the excellent analytical performance for ethanol determination confirms the applicability of this electrode as a nonenzymatic amperometric ethanol sensor. This sensor has the advantages of low detection limit (20.3μM), two wide linear range (1.99–490.90mM and 0.491–3.355M), and good long-term stability (more than 120 days) for ethanol determination. All results showed that palladium–zinc oxide nanoparticle is a good candidate for application in ethanol sensor and ethanol fuel cells.

Shape-selective synthesis of NiO nanostructures for hydrazine oxidation as a nonenzymatic amperometric sensor

In this work, we demonstrate the shape-dependent electrocatalytic activity of NiO NPs towards hydrazine oxidation.

3-D periodic mesoporous nickel oxide for nonenzymatic uric acid sensors with improved sensitivity

3-D periodic mesoporous nickel oxide (NiO) particles with crystalline walls have been synthesized through the microwave-assisted hard template route toward the KIT-6 silica. It was investigated as a nonenzymatic amperometric sensor for the detection of uric acid. 3-D periodic nickel oxide matrix has been obtained by the hard template route from the KIT-6 silica template. The crystalline nickel oxide belonged to the Ia3d space group, and its structure was characterized by X-ray diffraction (XRD), N2 adsorption–desorption, and transmission electron microscopy (TEM). The analysis results showed that the microwave-assisted mesoporous NiO materials were more appropriate to be electrochemical sensors than the traditional mesoporous NiO. Cyclic voltammetry (CV) revealed that 3-D periodic NiO exhibited a direct electrocatalytic activity for the oxidation of uric acid in sodium hydroxide solution. The enzyme-less amperometric sensor used in the detection of uric acid with detection limit of 0.005μM (S/N=3) over wide linear detection ranges up to 0.374mM and with a high sensitivity of 756.26μAmM−1cm−2, and a possible mechanism was also given in the paper.

A novel nonenzymatic amperometric hydrogen peroxide sensor based on CuO@Cu2O nanowires embedded into poly(vinyl alcohol)

A new, very simple, rapid and inexpensive nonenzymatic amperometric sensor for hydrogen peroxide (H2O2) detection is proposed. It is based on the immobilization of cupric/cuprous oxide core shell nanowires (CuO@Cu2O–NWs) in a poly(vinyl alcohol) (PVA) matrix directly drop casted on a glassy carbon electrode surface to make a CuO@Cu2O core shell like NWs PVA embedded (CuO@Cu2O–NWs/PVA) sensor.CuO nanowires with mean diameters of 120–170nm and length in the range 2–5μm were grown by a simple catalyst-free thermal oxidation process based on resistive heating of pure copper wires at ambient conditions. The oxidation process of the copper wire surface led to the formation of a three layered structure: a thick Cu2O bottom layer, a CuO thin intermediate layer and CuO nanowires. CuO nanowires were carefully scratched from Cu2O layer with a sharp knife, dispersed into ethanol and sonicated. Then, the NWs were embedded in PVA matrix.The morphological and spectroscopic characterization of synthesized CuO–NWs and CuO@Cu2O–NWs/PVA were performed by transmission electron microscopy (TEM), selected area diffraction pattern (SAD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. Moreover a complete electrochemical characterization of these new CuO@Cu2O–NWs/PVA modified glassy carbon electrodes was performed by Cyclic Voltammetry (CV) and Cronoamperometry (CA) in phosphate buffer (pH=7; I=0.2) to investigate the sensing properties of this material against H2O2. The electrochemical performances of proposed sensors as high sensitivity, fast response, reproducibility and selectivity make them suitable for the quantitative determination of hydrogen peroxide substrate in batch analysis.

Nonenzymatic amperometric sensing of glucose using a glassy carbon electrode modified with a nanocomposite consisting of reduced graphene oxide decorated with Cu2O nanoclusters

We describe a simple solvothermal method for preparation of reduced graphene oxide nanosheets decorated with uniform Cu2O nanoclusters by using poly(vinyl pyrrolidone)-poly(methacrylamide)-poly(vinyl imidazole) triblock co-polymer as a shape-directing agent and L-glutamic acid as a reducing agent. The resulting nanocomposite was deposited on a glassy carbon electrode where it displays improved electrocatalytic activity toward glucose oxidation in 0.5 M NaOH. This observation was exploited to construct a non-enzymatic amperometric sensor for glucose. It has a detection limit as low as 1.0 μM, high sensitivity (23.058 μA mM−1), and a dynamic (analytical) range that extends from 5.0 to 9595 μM at a working potential of 600 mV (vs. SCE).

Non-enzymatic hydrogen peroxide biosensor based on rose-shaped FeMoO4 nanostructures produced by convenient microwave-hydrothermal method

In this work, we demonstrated a simple, rapid and reliable microwave-assisted hydrothermal approach to synthesize the uniform rose-shaped FeMoO4 within 10min. The morphologies of the synthesized materials were characterized by X-ray powder diffraction and scanning electron microscopy. Moreover, a non-enzymatic amperometric sensor for the detection of hydrogen peroxide (H2O2) was fabricated on the basis of the FeMoO4 as electrocatalysis. The resulting FeMoO4 exhibited high sensitivity and good stability for the detection of H2O2, which may be attributed to the rose-shaped structure of the material and the catalytic property of FeMoO4. Amperometric response showed that the modified electrode had a good response for H2O2 with a linear range from 1μM to 1.6mM, a detection limit of 0.5μM (S/N=3), high selectivity and short response time. Additionally, good recoveries of analytes in real milk samples confirm the reliability of the prepared sensor in practical applications.

Fabrication of a highly selective nonenzymatic amperometric sensor for hydrogen peroxide based on nickel foam/cytochrome c modified electrode

The development of an accurate, rapid, and low-cost monitoring technique for hydrogen peroxide (H2O2) is an important issue in biology, medicine, and food industry to assess human health risks. Several electrochemical sensors for H2O2 detection have been reported. Although these sensors have demonstrated low detection limits with good stability and selectivity, most of them have complicated preparation processes. Therefore, a simple design is needed for controlled development of electrochemical sensor for detecting H2O2 in real samples with high flexibility and low capital cost. In this study, a simple H2O2 sensor was developed based on 3D porous nickel foam (Ni foam) electrode functionalized with cytochrome c (Cyt.c) as an electron transfer–mediating layer between active centers of the Ni foam (i.e., nickel hydroxide) and H2O2. Our findings revealed that the combination between Ni foam and Cyt.c could enhance the sensor performance in terms of sensitivity and selectivity, and allow the detection of H2O2 over a wide linear range with a detection limit of 2×10−7M and a sensitivity of 1.95μAmM−1. The Cyt.c/Ni foam sensor did not have potentially interfering components, such as ascorbic acid, uric acid, and dopamine; hence, is applicable for analyzing environmental samples, such as apple juice. This Cyt.c/Ni foam electrode enabled H2O2 sensing system responses with revisable, selective, and sensitive recognition of a wide range of H2O2 concentrations.

Ultrasensitive nonenzymatic sensing of glucose on Ni(OH)2-coated nanoporous gold film with two pairs of electron mediators

Fabrication of new advanced nonenzymatic electrochemical nano-sensors of glucose has recently attracted intensive attention. In this work, we designed a novel ultrasensitive nonenzymatic amperometric sensor for detection of glucose by incorporating two pairs of effective electron mediators, Ni(II)/Ni(III) and Au/Au(I), into a nanoporous structure, namely a nanoporous gold film (NPGF) coated with a thin layer of nickel hydroxide about 4nm in thickness. The NPGF with high roughness was quickly prepared by anodic potential step, and the thin surface coating of Ni(OH)2 was easily obtained by electrooxidizing the electrodeposited Ni coverlayer. The incorporation of thin Ni(OH)2 coating into/on the NPGF led to mutual stabilization without changing the nanoporous structure. The Ni(OH)2/NPGF electrode fabricated totally by facile electrochemical methods at room temperature showed high electrocatalytic activity for the oxidation of glucose within a wide potential range (−0.5∼0.2V) due to co-mediating of the two pairs of electron mediators including their coupling Ni(III)+Au=Ni(II)+Au(I). The electrode also demonstrated excellent performance in sensing glucose concentration with a wide linear range (2μM∼7mM), ultrasensitivity (3529μAmM−1cm−2), low detection limit (0.73μM), good repeatability, and long-term stability (3 weeks), which was successfully applied to detect glucose in a human blood serum sample by standard addition method with satisfactory recovery. This work is expected to open a new avenue to fabricate nonenzymatic electrochemical sensors of glucose involving co-mediating.

Enhanced nonenzymatic sensing of hydrogen peroxide released from living cells based on Fe3O4/self-reduced graphene nanocomposites

A novel, sensitive, nonenzymatic amperometric sensor for the reliable detection of extracellular H2O2 released from living cells was fabricated based on Fe3O4/reduced graphene oxide (Fe3O4/rGO) nanocomposites, which were prepared using a simple and cost-effective one-pot approach. Electrochemical performances of the Fe3O4/rGO nanocomposites modified glassy carbon electrode (GCE) were studied. The results demonstrated that this H2O2 sensor exhibited excellent electrocatalytic performance towards the reduction of H2O2 at a potential of −0.3 V in the wide linear concentration range from 0.001 to 20 mM with a high sensitivity of 387.6 μA mM−1 cm−2 and a detection limit as low as 0.17 μM (S/N = 3), which was lower than certain enzymes and noble metal nanomaterials-based biosensors. Moreover, good anti-interference property, reproducibility, and long-term stability of the enzymeless sensor were achieved. Because of these remarkable analytical advantages, a novel, effective approach for the detection of extracellular H2O2 released from HeLa cells stimulated by CdTe quantum dots (QDs) was established by the constructed sensor. Since H2O2 is a byproduct of several oxidative biological reactions, this work could be applied to study the downstream biological effects of various stimuli in pathophysiology, and may expand the application of Fe3O4-based nanomaterials in the field of electrochemical sensing and bioanalysis.

Silver nanoparticle impregnated mesoporous silica as a non-enzymatic amperometric sensor for an aqueous solution of hydrogen peroxide

Silver nanoparticles (AgNPs) were impregnated in amine functionalized mesoporous silica (NH2-SBA-15) particles, by in situ chemical reduction, for making a hydrogen peroxide (H2O2) sensor. AgNPs formed were isolated and well dispersed in hydrophilic NH2-SBA-15 at a loading of 17.2wt.%, with mean particle diameter 4.5nm and standard deviation 0.4nm. AgNP impregnated NH2-SBA-15 was used as a modifier of glassy carbon electrode (GCE) for an enzyme-less amperometric sensor. It showed good electrocatalytic activity towards H2O2. Optimum composition of the modifier on the GCE surface (12.2µg Ag in AgNP-NH2-SBA-15/cm2 surface area of GCE) resulted in a high sensitivity of 171.3μAcm−2mM−1 and a wide linearity range (5.3–124.5mM H2O2), due to the high loading of electrically conductive AgNPs in NH2-SBA-15 host. The sensor was selective to only H2O2, even in presence of high concentrations of both reducible and oxidizable interfering agents, like, sodium nitrate, sodium nitrite, urea, glucose or ascorbic acid. The response time was also less than 3s. Therefore, it achieved the desirable sensor-characteristics, like linearity, sensitivity, selectivity and speed of response. Our results are better than other reported H2O2 sensors with impregnated AgNPs (in terms of linear range and sensitivity), compared to even those with good conducting hosts (like carbon nanotube, graphene oxide). Therefore, performance of any sensor can be improved by ensuring uniform dispersion of isolated NPs at a high loading, when impregnated in a hydrophilic host.

Nitrogen-Doped Carbon-Copper Nanohybrids as Electrocatalysts in H2O2and Glucose Sensing

Invited for this month′s cover is Prof. Huan Pang from Anyang Normal University. The image represents a non-enzymatic amperometric sensor detecting H2O2. The sensor was fabricated and investigated for the detection of both H2O2 and glucose oxidation. It is revealed that the as-prepared sensor based on N-doped nanoporous carbon–copper nanohybrid plates has a high sensitivity, low detection limit, and excellent selectivity. Read the full text of the article at 10.1002/celc.201300211.

Nonenzymatic amperometric sensor for ascorbic acid based on hollow gold/ruthenium nanoshells

We report a new nonenzymatic amperometric detection of ascorbic acid (AA) using a glassy carbon (GC) disk electrode modified with hollow gold/ruthenium (hAu–Ru) nanoshells, which exhibited decent sensing characteristics. The hAu–Ru nanoshells were prepared by the incorporation of Ru on hollow gold (hAu) nanoshells from Co nanoparticle templates, which enabled AA selectivity against glucose without aid of enzyme or membrane. The structure and electrocatalytic activities of the hAu–Ru catalysts were characterized by spectroscopic and electrochemical techniques. The hAu–Ru loaded on GC electrode (hAu–Ru/GC) showed sensitivity of 426μAmM−1cm−2 (normalized to the GC disk area) for the linear dynamic range of <5μM to 2mM AA at physiological pH. The response time and detection limit were 1.6s and 2.2μM, respectively. Furthermore, the hAu–Ru/GC electrode displayed remarkable selectivity for ascorbic acid over all potential biological interferents, including glucose, uric acid (UA), dopamine (DA), 4-acetamidophenol (AP), and nicotinamide adenine dinucleotide (NADH), which could be especially good for biological sensing.

Bimetallic PdCu nanoparticle decorated three-dimensional graphene hydrogel for non-enzymatic amperometric glucose sensor

A bimetallic PdCu nanoparticle (NP) decorated three-dimensional graphene hydrogel (PdCu/GE) was developed by a simple one-step hydrothermal method. The PdCu/GE hybrids exhibited an interconnected microporous framework with PdCu NPs dispersed and encapsulated within the GE layers. The PdCu/GE hybrids showed significant electrocatalytic activity toward glucose oxidation due to the synergistic effect of PdCu NPs and GE sheets in the alkaline solution containing chloride ions, presenting a substantial increase in the oxidation current and decrease in the onset potential of oxidation compared to the monometallic modified GE hybrids. At an applied potential of −0.4V, the PdCu/GE modified electrode with optimized bimetallic ratio presented quick respond to glucose oxidation with a wide linear range up to 18mM and a reproducible sensitivity of 48μA(mgmM)−1 in the presence of chloride ions. Furthermore, the PdCu/GE modified electrode exhibited high selectivity to glucose and resistance against poisoning by commonly interfering species such as dopamine, ascorbic acid, uric acid, acetamidophenol and some monosaccharides. The PdCu/GE hybrid hydrogels with 3D micropores were therefore promising for the future development of non-enzymatic amperometric glucose sensors with improved electrochemical performances.

Direct electrodeposion of reduced graphene oxide and dendritic copper nanoclusters on glassy carbon electrode for electrochemical detection of nitrite

We have developed an effective strategy to fabricate a novel non-enzymatic nitrite sensor. Copper nanodendrites (Cu-NDs) and reduced graphene oxide (RGO) were successively deposited on glassy carbon electrode (GCE) via a simple and two-step electrodeposition method. The fabricated sensor showed an excellent electrocatalytic activity for nitrite reduction. Moreover, the effects of electrodeposition circles, Cu2+ concentration, pH value and detection potential on the current responses of Cu-NDs/RGO/GCE toward nitrite were optimized to obtain the maximal sensitivity. Under optimal experimental conditions, Cu-NDs/RGO/GCE demonstrated the low detection limit of 0.4μM nitrite (signal-to-noise ratio, S/N=3), the high sensitivity of 214μAmM−1cm−2, and the wide linear range from 1.25×10−3 to 13mM. The superior response of the sensor to nitrite was mainly attributed to the enlarged surface-to-volume ratio with more electroactive sites and the synergistic effect of Cu-NDs and RGO. This work presented a feasible approach for future research in non-enzymatic amperometric sensors and other surface functionalizing.

Graphene wrapped Cu2O nanocubes: Non-enzymatic electrochemical sensors for the detection of glucose and hydrogen peroxide with enhanced stability

In this study, a sensor for the detection of glucose and hydrogen peroxide was developed on the basis of Cu2O nanocubes wrapped by graphene nanosheets (Cu2O/GNs) as electrocatalysts. Cubic Cu2O nanocrystals/graphene hybrid has been successfully fabricated by a chemical reduction method at low temperature. The morphologies of the synthesized materials were characterized by scanning electron microscopy (SEM) and powder X-ray diffraction measurements (XRD). As a non-enzymatic amperometric sensor, the resulting Cu2O/graphene composite exhibited high sensitivity for the detection of glucose and H2O2. Moreover, the graphene coating was found to be able to effectively improve the electrochemical cycling stability of the fabricated sensor. With the Cu2O/GNs modified electrode, amperometric sensing of glucose was realized with a linear response over the concentration range from 0.3 to 3.3mM, a detection limit of 3.3μM (S/N=3), high selectivity and short response time (<9s). Compared to unsupported Cu2O nanocubes, the graphene-wrapped Cu2O nanocubes exhibited higher catalytic activity for glucose oxidation with higher sensitivity and lower detection limit. The enzymeless sensor also exhibited good response toward H2O2, with the linear response ranging from 0.3 to 7.8mM at −0.4V and the detection limit of 20.8μM. Moreover, because the surface is covered by graphene nanosheets, the as-synthesized Cu2O/GNs exhibited improved electrochemical stability. Such novel graphene nanosheets wrapped Cu2O nanocubes represent promising enzyme-free glucose and hydrogen peroxide sensors with high sensitivity and selectivity, improved stability and fast amperometric response.

Simple synthesis of macroporous carbon–graphene composites and their use as a support for Pt electrocatalysts

Macroporous carbon–graphene (MC–GR) composites were synthesized by a casting method using silica nanoparticles-graphene oxide (SiO2-GO) as the template and sucrose as the carbon precursor. The MC–GR composites combine the porous structure of MC with the excellent electrical and mechanical properties of GR. When used as a support for Pt electrocatalysts, Pt nanoparticles with an average diameter of 3.1±0.7nm are distributed onto the MC–GR. The MC on the surface of GR is beneficial for decreasing the aggregation of GR sheets and improving the diffusion of molecules through the GR sheets. Nonenzymatic amperometric sensor of glucose based on the Pt/MC–GR composites is developed. The Pt/MC–GR responds very rapidly to the changes in the level of glucose, producing steady-state signals within 3s. Due to the low potential, no obvious interference is observed with the addition of ascorbic acid, acetaminophen, dopamine, and uric acid. The Pt/MC–GR also exhibits significant catalytic activity for the oxidation of methanol. The maximum peak value of oxidation current density at Pt/MC–GR is 81.6mAmg−1, higher than that of Pt/GR (34.7mAmg−1) and Pt/MC (65.8mAmg−1).

A Nonenzymatic Hydrogen Peroxide Sensor Based on Silver Nanowires and Chitosan Film

AbstractA nonenzymatic amperometric electrochemical sensor for the detection of hydrogen peroxide (H2O2) was fabricated based on highly dense silver nanowires (Ag NWs) and chitosan (CS) film. Ag NWs were synthesized by a poly(vinyl pyrrolidone) (PVP)‐mediated polyol process in the presence of manganese chloride (MnCl2), and were characterized by scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDS), and X‐ray diffraction (XRD). Under the optimal conditions, the proposed nonenzymatic sensor exhibited good electrocatalytic activity towards the reduction of H2O2, and could detect H2O2 in the linear range of 0.008–1.35 mM, with a detection limit of 2 µM (S/N=3).

Amperometric non-enzymatic bimetallic glucose sensor based on platinum tellurium microtubes modified electrode

A non-enzymatic amperometric sensor for glucose detection based on a Pt electrode modified with Te microtubes (Te-MTs), by direct drop casting of Te-MTs dispersed in ethanol, is proposed. The spectroscopic characterization of as synthesized Te-MTs and Pt/Te-MTs modified electrodes was performed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Moreover electrochemical characterization of Pt/Te-MTs modified electrodes was performed by Cyclic Voltammetry (CV) and Cronoamperometry (CA) in phosphate buffer (pH=7 I=0.2). Electrochemical results indicate that the proposed sensor exhibits very strong and sensitive amperometric responses to glucose and explains a good anti-interference ability.