Electrocatalytic Oxidation of Glucose at Carbon Nanotubes Supported PtRu Nanoparticles and Its Detection

PtRu nanoparticles were supported on multiwall carbon nanotubes (MWNTs), which were further fabricated as an electrode for nonenzymatic glucose sensing. Transmission electron microscope and X‐ray diffraction patterns were used for characterization of the PtRu nanoparticles on MWNTs. Cyclic voltammetry and chronopotentiometry were applied to investigate the performance of the PtRu/MWNTs nanocomposite electrode for nonenzymatic oxidation of glucose. The PtRu/MWNTs electrode shows high electrocatalytic activity towards the oxidation of glucose in 0.1 M NaOH solution and thus can be used to selectively detect glucose. Under the optimal potential (+0.55 V vs. Ag/AgCl), the biosensor effectively performs a selective electrochemical analysis of glucose in the presence of common interferents, such as ascorbic acid (AA), dopamine (DP) and uric acid (UA). Wide linear calibration ranging from 1 mM to 15 mM, high sensitivity of 28.26 μA cm^?2 mM^?1, low detection limit of 2.5×10^?5 M, and fast response time of 10 s were achieved for the detection of glucose at the PtRu/MWNTs electrode.     

Electrochemical Fabrication of Cobalt Oxides/Nanoporous Gold Composite Electrode and its Nonenzymatic Glucose Sensing Performance

A nonenzymatic glucose sensor was successfully established by electrochemically decorating cobalt oxides (CoO_x) on a nanoporous gold electrode (NPG) using cobalt hexacyanoferrate (CoHCF) as a precursor. It exhibited high sensitivity and long‐term stability as well as satisfactory quantification of glucose concentration in human serum samples. The morphology and surface analysis of the resulting CoO_x/NPG were carefully characterized. Two detection methods, cyclic voltammetry and amperometry, were employed to evaluate the performance of CoO_x/NPG towards glucose sensing in alkaline solution. Using cyclic voltammetry, at ?0.5 V, the glucose partial oxidation peak current is linear to the glucose concentration up to 14 mM with a sensitivity of 283.7 µA mM^?1 cm^?2. A linear amperometric response at 0.55 V was obtained in the glucose concentration range from 2 µM to 2 mM with a sensitivity of 2025 µA mM^?1 cm^?2 and a response time <3 s.     

Highly Sensitive and Selective Determination of Dopamine in the Presence of Ascorbic Acid Using Pt@Au/MWNTs Modified Electrode

Nanoparticles containing platinum and gold supported on MWNTs (Pt@Au/MWNTs) were successfully prepared by successive reduction. A novel sensor was fabricated with Pt@Au/MWNTs nanocomposite modified glassy carbon electrode coating with nafion. Compared with the previous reports, the electrode exhibited greatly improved performance towards the oxidation and determination of dopamine in the presence of ascorbic acid. A higher sensitivity of 1.16 mA cm^?2 mM^?1 with a wider linear concentration range of dopamine up to 120 μM and a low detection limit of 8.0×10^?8 M were obtained in neutral solution. Moreover, the modified electrode presented high stability and reproducibility. The interference of ascorbic acid can be eliminated effectively. The present work provides a simple and practical approach to selective detection of dopamine in the presence of ascorbic acid.     

Single step modification of copper electrode for the highly sensitive and selective non-enzymatic determination of glucose

A non-enzymatic sensor was developed for the determination of glucose in alkaline medium by anodisation of copper in sodium potassium tartrate solution. The morphology of the modified copper electrode was studied by scanning electron microscopy, and its electrochemical behavior by cyclic voltammetry and electrochemical impedance spectroscopy. The electrode enables direct electrocatalytic oxidation of glucose on a CuO/Cu electrode at 0.7 V in 0.1 M sodium hydroxide. At this potential, the sensor is highly selective to glucose even in the presence of ascorbic acid, uric acid, or dopamine which are common interfering species. The sensor displays a sensitivity of 761.9 μA mM^?1 cm^?2, a linear detection range from 2 μM to 20 mM, a response time of <1 s, and a detection limit of 1 μM (S/N = 3). It was tested for determination of glucose level in blood serum.     

Synthesis of Novel CuO Nanosheets with Porous Structure and Their Non‐Enzymatic Glucose Sensing Applications

Novel CuO thin films composed of porous nanosheets were in situ formed on indium tin oxide (ITO) by a simple, low temperature solution method, and used as working electrodes to construct nonenzymatic glucose sensor after calcinations. Cyclic voltammetry revealed that the CuO/ITO electrode calcinated at 200 °C exhibited better electrocatalytic activity for glucose. For the amperometric glucose detection, such prepared electrode showed low operating potential of 0.35 V and high sensitivity of 2272.64 μA mM^?1 cm^?2. Moreover, the CuO/ITO electrode also showed good stability, reproducibility and high anti‐interference ability. Thus, it is a promising material for the development of non‐enzymatic glucose sensors.     

Electrodeposition of PtCo alloy nanoparticles on inclusion complex film of functionalized cyclodextrin–ionic liquid and their application in glucose sensing

Platinum–cobalt (PtCo) alloy nanoparticles (NPs) are successfully fabricated by ultrasonic-electrodeposition method, using an inclusion complex (IC) film of functionalized cyclodextrin (CD)–ionic liquid (IL) as support. The morphology and composition of the PtCo alloy NPs are characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction, respectively. It is found that they are well-dispersed on the CD–IL surface and exhibit many unique features. The resulting modified glassy carbon electrode shows excellent catalytic activity for glucose oxidation. Under the physiological condition, the oxidation current of glucose is linear to its concentration up to 20 mM with sensitivity of 13.7 μA mM^?1 cm^?2. In addition, the interference from the oxidation of ascorbic acid and uric acid could be effectively avoided. Therefore, it is promising as a nonenzymatic glucose sensor.     

Nonenzymatic electrochemical glucose sensor based on MnO2/MWNTs nanocomposite

In this communication, an amperometric glucose biosensor based on MnO₂/MWNTs electrode was reported. MnO₂ was homogeneously coated on vertically aligned MWNTs by electrodeposition. The MnO₂/MWNTs electrode displayed high electrocatalytic activity towards the oxidation of glucose in alkaline solution, showing about 0.30 V negative shift in peak potential with oxidation starting at ca. −0.20 V (vs. 3 M KCl–Ag/AgCl) as compared with bare MWNTs electrode. At an applied potential of +0.30 V, the MnO₂/MWNTs electrode gives a linear dependence (R = 0.995) in the glucose concentration up to 28 mM with a sensitivity of 33.19 μA mM⁻¹. Meanwhile, the MnO₂/MWNTs electrode is also highly resistant toward poisoning by chloride ions. In addition, interference from the oxidation of common interfering species such as ascorbic acid, dopamine, and uric acid is effectively avoided. The MnO₂/MWNTs electrode allows highly sensitive, low-potential, stable, and fast amperometric sensing of glucose, which is promising for the development of nonenzymatic glucose sensor.     

Electrochemical Sensor for Detection of Glucose Based on Ni@Pt Core‐shell Nanoparticles Supported on Carbon

In this work, Ni@Pt core‐shell nanoparticles with diameter of 3–4 nm and thin Pt shell was synthesized by a successive reduction approach using carbon as support to develop high‐performance non‐enzymatic glucose sensor. The resulting electrochemical sensor displayed good catalytic activity toward glucose oxidation, presenting a high current density of 66.9 µA mM^?1 cm^?2 at an applied potential of ?0.1 V. It showed a wide linear range of 0.1–30.1 mM and the limit of detection was down to 30 µM (S/N=3). Notably, it was found that the proposed sensor exhibited good selectivity to avoid the interference from ascorbic acid, uric acid, fructose and acetamidophenol. Furthermore, the feasibility of the as‐prepared non‐enzymatic glucose sensor in the determination of glucose in serum samples was successfully implemented.     

Highly Sensitive Nonenzymatic Glucose Sensor Based on 3D Ultrathin NiFe Layered Double Hydroxide Nanosheets

As a promising electrode material, Ni‐based nanomaterials exhibit a remarkable electrochemical catalytic activity for nonenzymatic glucose sensors. In this paper, Nickel–Iron layered double hydroxide (NiFe‐LDH) film electrode with ultrathin nanosheets and porous nanostructures was synthesized directly on Ni foam (NF) by a one‐step hydrothermal method. The as‐obtained NiFe‐LDH electrode was adopted for glucose detection without further treatment. As an integrated binder‐free electrode for glucose sensor, the NiFe‐LDH/NF hybrid exhibits a superior sensitivity of 3680.2 μA mM⁻¹ cm⁻² with a low limit of detection (0.59 μM, S/N=3) as well as fast response time (<1 s). An excellent selectivity from potential interference species such as ascorbic acid, uric acid and Cl⁻ ions and acceptable stability were also achieved. The outstanding performance can be ascribed to the abundant electrochemistry active sites, facilitative diffusion of the electrolyte, high electron transfer rate and reliable stability architecture. Therefore, the NiFe‐LDH nanosheets demonstrate potential application in non‐enzymatic sensory of glucose.     

Nonenzymatic Electrochemical Glucose Sensor Based on Novel Copper Film

Novel copper (Cu) film composed of pillar‐like structure was synthesized on indium‐doped tin oxide (ITO) substrate by electrodeposition in acetate bath with proline as additive for the first time and used to construct nonenzymatic glucose sensor. When applied to detect glucose, such prepared electrode showed low operating potential (0.4 V), high sensitivity (699.4499 µA mM⁻¹ cm⁻²), and fast response time (<3 s) compared with other Cu‐based electrodes. In addition, the prepared electrode also offered good anti‐interference ability to ascorbic acid, uric acid and acetaminophen. Present study provides new insights into the control of Cu film morphology for sensor fabrication.     

Facile synthesis of urchin-like gold submicrostructures for nonenzymatic glucose sensing

Urchin-like gold submicrostructures (UGS) were successfully synthesized by a seed-mediated method which is quite facile and does not need any template or surfactant agent. The effect of the added silver seeds on the morphology and size of final products were investigated, and a possible growth mechanism of crystals was proposed. Electrochemical characterization indicated that these UGS have better catalytic activity for the glucose oxidation compared with flower-like gold submicrostructures (FGS), which could be ascribed to its higher surface to volume ratio. An electrochemical nonenzymatic glucose sensor was fabricated simply by casting the UGS and Nafion solution onto glass carbon electrode. This sensor displays a wide linear range from 0.2 to 13.2 mM with a high sensitivity of 16.8 μA mM⁻¹ cm⁻², and a detection limit of 10 μM. The unique properties of this sensor, such as fast response and well stability reveal the potential application of the UGS based materials in nonenzymatic detection of glucose.     

Cathodized Gold Nanoparticle‐Modified Graphite Pencil Electrode for Non‐Enzymatic Sensitive Voltammetric Detection of Glucose

A highly sensitive enzymeless electrochemical glucose sensor has been developed based on the simply prepared cathodized gold nanoparticle‐modified graphite pencil electrode (AuNP‐GPE). Cyclic voltammetry (CV) experiments show that AuNP‐GPE is able to oxidize glucose partially at low potential (around −0.27) whereas the bare GPE cannot oxidize glucose in the entire tested potential windows. Besides, fructose and sucrose cannot be oxidized at potential lower than +0.1 V at AuNP‐GPE. As a result, the glucose oxidation peak at around −0.27 V is suitable enough for selective detection of glucose in the presence of fructose and sucrose. Cathodization of AuNP‐GPE under optimum condition (‐1.0 V for 30 s) in the same glucose solution before voltammetric measurement enhanced glucose oxidation peak current around −0.27 V to achieve an efficient electrochemical sensor for glucose with a detection limit of 12 μM and dynamic range between 0.05 to 5.0 mM with a good linearity (R²= 0.999). Almost no interference effect was observed for sensing of glucose in the presence of ascorbic acid, alanine, phenylalanine, fructose, sucrose, and NaCl.     

A highly sensitive nonenzymatic glucose sensor based on NiO-modified multi-walled carbon nanotubes

A highly sensitive and selective glucose biosensor has been constructed by using highly dispersed NiO nanoparticles supported on well-aligned MWCNTs (NiO/MWCNTs) as sensing interface. The NiO/MWCNTs nanocomposite was synthesized by magnetron sputtering deposition of NiO nanoparticles on vertically aligned carbon nanotubes. The nanocomposite electrode showed high electrochemical activity towards the oxidation of glucose in 0.20 M NaOH solution. At an applied potential of +0.50 V, it gives a fast response time (< 5 s) and a linear dependence (R?=?0.997) on the glucose concentration up to 7.0 mM with an extraordinarily high sensitivity of 1.77 mA mM^-1 cm^-2 and a detection limit of 2 μM. The interference by the oxidation of common interfering species such as ascorbic acid, dopamine, uric acid, lactose, and fructose is effectively avoided. The electrode was used to analyze glucose concentration in human serum samples. It allows highly sensitive, stable, and fast amperometric sensing of glucose, which is promising for the development of nonenzymatic glucose sensors.     

Nonenzymatic Electrochemical Glucose Sensor Based on Pt Nanoparticles/Mesoporous Carbon Matrix

A nonenzymatic amperometric sensor for sensitive and selective detection of glucose has been constructed by using highly dispersed Pt nanoparticles supported onto mesoporous carbons (MCs). The Pt nanoparticles/mesoporous carbons (Pt/MCs) composites modified electrode displayed high electrocatalytic activity towards the oxidation of glucose. At an applied potential of 0.1 V, the Pt/MCs electrode has a linear dependence (R=0.996) in the glucose concentration up to 7.5 mM with a sensitivity of 8.52 mA M^?1 cm^?2. The Pt/MCs electrode has also shown highly resistant toward poisoning by chloride ions and without interference from the oxidation of common interfering species.     

Commercial Copper Foam as an Effective 3D Porous Electrode for Nonenzymatic Glucose Detection

Commercially available copper foam (CF) was used as a 3D porous electrochemical sensing platform for nonenzymatic glucose detection. CF shows high electrocatalytic activity towards glucose oxidation and can be used directly for glucose electrochemical sensing without any pretreatment. The sensor exhibits high performance towards glucose in 0.1 M NaOH solution with the linear range from 1 μM to 0.5 mM, the sensitivity of 5.85 mA mM^?1 cm^?2 and the detection limit of 0.5 μM (S/N=3) simultaneously. Furthermore, the sensor shows a high selectivity for glucose against the common interferences and good reliability for glucose detection in human serum samples.     

Glucose biosensor based on glucose oxidase immobilized on a nanofilm composed of mesoporous hydroxyapatite, titanium dioxide, and modified with multi-walled carbon nanotubes

We report on a highly sensitive glucose biosensor that was fabricated from a composite made from mesoporous hydroxyapatite and mesoporous titanium dioxide which then were ultrasonically mixed with multi-walled carbon nanotubes to form a rough nanocomposite film. This film served as a platform to immobilize glucose oxidase onto a glassy carbon electrode. The morphological and electrochemical properties of the film were examined by scanning electron microscopy and electrochemical impedance spectroscopy. Cyclic voltammetry and chronoamperometry were used to characterize the electrochemical performances of the biosensor which exhibited excellent electrocatalytic activity to the oxidation of glucose. At an operating potential of 0.3?V and pH 6.8, the sensor displays a sensitivity of 57.0?μA?mM^?1?cm^?2, a response time of <5?s, a linear dynamic range from 0.01 to 15.2?mM, a correlation coefficient of 0.9985, and a detection limit of 2?μM at an SNR of 3. No interferences are found for uric acid, ascorbic acid, dopamine and most carbohydrates. The sensor is stable and was successfully applied to the determination of glucose in real samples.

NiMoO4 nanofibres designed by electrospining technique for glucose electrocatalytic oxidation

Electrochemical oxidation of glucose is the guarantee to realize nonenzymatic sensing of glucose, but greatly hindered by the slow kinetics of its oxidation process. Herein, various nanomaterials were designed as catalysts to accelerate glucose oxidation reaction. However, how to effectively build an excellent platform for promoting the glucose oxidation is still a great challenge. In our work, 1D CaMoO₄ and NiMoO₄ nanofibres with same morphologies and sub-microstructures were fabricated by electrospinning technique in the first time, and explored to modify the detection electrodes of nonenzymatic glucose sensors. The electrochemical results indicated that the NiMoO₄ based sensor exhibited a good catalytic activity toward glucose including the low response potential (0.5 V), high sensitivity(193.8 μA mM⁻¹ cm⁻²) with a linear response region of 0.01–8 mM, low detection limit (4.6 μM) and fast response time (2 s), all of which are superior to the corresponding values of CaMoO₄ nanofibres and even higher than those of most reported NiO and Co₃O₄ catalysts, which is due to the NiMoO₄ nanofibres are not only advantageous to electron transfer, but can mediated the electrocatalytic reaction of glucose. This work should provide a new pathway for the design of advanced glucose catalysts for nonenzymatic sensor.     

Selective Detection of Ascorbic Acid Using Octacyanomolybdate‐Doped‐Glutaraldehyde‐Cross‐Linked Poly‐L‐Lysine Film Modified Glassy Carbon Electrode

The present work describes oxidation of ascorbic acid (AA) at octacyanomolybdate‐doped‐glutaraldehyde‐cross‐linked poly‐L ‐lysine (PLL‐GA‐Mo(CN) film modified glassy carbon electrode in 0.1 M H₂SO₄. The modified electrode has been successfully prepared by means of electrostatically trapping Mo(CN) mediator in the cationic film of glutaraldehyde‐cross‐linked poly‐L ‐lysine. The dependence of peak current of modified electrode in pure supporting indicates that the charge transfer in the film was a mixed process at low scan rates (5 to 200 mV s^?1), and kinetically restrained at higher scan rates (200 to 1000 mV s^?1). Cyclic voltammetry and rotating disk electrode (RDE) techniques are used to investigate the electrocatalytic oxidation of ascorbic acid and compared with its oxidation at bare and undoped PLL‐GA film coated electrodes. The rate constant of catalytic reaction k obtained from RDE analysis was found to be 9.5×10⁵ cm³ mol^?1 s^?1. The analytical determination of ascorbic acid has been carried out using RDE technique over the physiological interest of ascorbic acid concentrations with a sensitivity of 75 μA mM^?1. Amperometric estimation of AA in stirred solution shows a sensitivity of 15 μA mM^?1 over the linear concentration range between 50 and 1200 μM. Interestingly, PLL‐GA‐Mo(CN) modified electrode facilitated the oxidation of ascorbic acid but not responded to other electroactive biomolecules such as dopamine, uric acid, NADH, glucose. This unique feature of PLL‐GA‐Mo(CN) modified electrode allowed for the development of a highly selective method for the determination of ascorbic acid in the presence of interferents.     

Amperometric Biosensor for Choline Based on Gold Screen‐Printed Electrode Modified with Electrochemically‐Deposited Silica Biocomposite

A mediator‐free choline biosensor was developed using the electrochemically assisted sol‐gel deposition on gold screen‐printed electrodes. The addition of 12 mM of cationic surfactant CTAB in silica sol allowed enhancing the stability of the sensor. The modified electrode demonstrated catalytic activity and stable amperometric response to choline for over 3 weeks of exploitation with the sensitivity of 6 µA mM^?1 and LOD of 6 µM. The interference of ascorbic acid was reduced by pretreating the analyzed solution with MnO₂ powder. The application of the sensor with the purpose of identifying choline in the baby milk demonstrated satisfactory metrological characteristics.     

Nonenzymatic glucose sensor based on glassy carbon electrode modified with a nanocomposite composed of nickel hydroxide and graphene

We report on a nonenzymatic glucose sensor based on a glassy carbon electrode that was electrochemically modified with a nanocomposite prepared from nickel hydroxide and graphene. Scanning electron microscopy revealed that the nickel hydroxide in the nanocomposite was present in the form of a nanostructure of three-dimensional spheres that were assembled by many densely arranged nanosheets. The electrocatalytic activity of the electrode toward the oxidation of glucose was investigated by chronoamperometry. The current response was linearly related to the glucose concentration in the range from 1 to 10?μM, with a sensitivity of 494?μA?mM^–1?cm^–2 and a correlation coefficient of 0.9990, and a second range (from 10 to 1000?μM with a sensitivity of 328?μA?mM^–1?cm^–2 and a correlation coefficient of 0.9990). The detection limit was 0.6?μM at a signal-to-noise ratio of 3, and the response time was as short as 2?s.