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Multiwalled carbon nanotubes coated with cobalt(II) sulfide nanoparticles were prepared and used for immobilization of glucose oxidase (GOx) to obtain an electrochemical glucose biosensor. The nanocomposite was synthesized through an in-situ hydrothermal method and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and electrochemical impedance spectroscopy. The results show that the nanocomposite possesses a large specific surface area and apparently enhances the direct electron transfer between GOx and the surface of the electrode, best at a potential near -0.43 V (vs. SCE). The immobilized GOx retains its good bioactivity even at a high surface coverage of 30 pmol cm -2 . Under the optimum conditions. The biosensor exhibits a wide linear range (from 8 μM to 1.5 mM), a high sensitivity (15 mA M -1  cm -2 ), and a 5 μM detection limit (at S/N = 3). The sensor is selective, acceptably repeatable, specific and stable. Graphical abstractMultiwalled carbon nanotubes coated with cobalt(II) sulfide nanoparticles (CoS-MWCNTs) were synthesized through in situ hydrothermal method for the construction of a sensitive electrochemical glucose biosensor.

In this work, we reported an efficient platinum nanoparticles functionalized nitrogen doped graphene (PtNPs@NG) nanocomposite for devising novel electrochemical glucose biosensor for the first time. The fabricated PtNPs@NG and biosensor were characterized using transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, static water contact angle, UV-vis spectroscopy, electrochemical impedance spectra and cyclic voltammetry, respectively. PtNPs@NG showed large surface area and excellent biocompatibility, and enhanced the direct electron transfer between enzyme molecules and electrode surface. The glucose oxidase (GOx) immobilized on PtNPs@NG nanocomposite retained its bioactivity, and exhibited a surface controlled, quasi-reversible and fast electron transfer process. The constructed glucose biosensor showed wide linear range from 0.005 to 1.1mM with high sensitivity of 20.31 mA M(-1) cm(-2). The detection limit was calculated to be 0.002 mM at signal-to-noise of 3, which showed 20-fold decrease in comparison with single NG-based electrochemical biosensor for glucose. The proposed glucose biosensor also demonstrated excellent selectivity, good reproducibility, acceptable stability, and could be successfully applied in the detection of glucose in serum samples at the applied potential of -0.33 V. This research provided a promising biosensing platform for the development of excellent electrochemical biosensors., (Copyright © 2015 Elsevier B.V. All rights reserved.)

An electrochemical sensor based on a copolymer poly(4-vinylpyridine)-co-poly(acrylonitrile), P4VP-co-PAN, and Fe2O3 nanoparticle film modified glassy carbon electrode was developed for the determination of glucose. We studied the response of glucose with the proposed electrode, and determined the optimum conditions by changing the potential, pH and P4VP-co-PAN. The current response measurements were performed in PBS (c=0.1 M) with a potential of 0.7 V. The current response of this glucose sensor showed a linear relationship with the concentration in the range of 2.5 μM-0.58 mM (r=0.997). The experimental results demonstrate that this method has such merits as simple operation, low cost, high sensitivity, long term stability and good reproducibility, with satisfactory results., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Multi-walled carbon nanotubes (MWCNTs)-nanoflake-like SnS(2) nanocomposite were designed for immobilization of glucose oxidase (GOx). The direct electrochemistry of GOx and glucose sensing at MWCNTs-SnS(2) modified glassy carbon electrode were studied. Compared with single MWCNTs or SnS(2), the MWCNTs-SnS(2) film has larger surface area and provides a more favorable microenvironment for facilitating the electron transfer between enzyme and electrode surface. The properties of GOx/MWCNTs-SnS(2) were examined by scanning electron microscopy, UV-vis spectroscopy, Fourier transform infrared spectroscopy and cyclic voltammetry. The immobilized enzyme on MWCNTs-SnS(2) composite film retained its native structure and bioactivity and showed a surface controlled, reversible two-proton and two-electron transfer reaction with a apparent electron transfer rate constant of 3.96 s(-1). The constructed glucose biosensor exhibits wider linear range from 2.0×10(-5) M to 1.95×10(-3) M, much lower detection limit of 4.0×10(-6) M at signal-to-noise of 3 and higher sensitivity of 21.65 mA M(-1) cm(-2) than our previous nanoflake-like SnS(2)-based glucose sensor. The proposed biosensor has excellent selectivity, good reproducibility, and acceptable operational stability and can be successfully applied in the reagentless glucose sensing at -0.43 V. This MWCNTs-SnS(2) composite provides a new avenue for immobilizing proteins and fabricating excellent biosensors., (Copyright © 2012 Elsevier B.V. All rights reserved.)

A new petentiometric method to determine peroxide hydrogen and glucose had been studied. This method had been applied on the petentiometric determination of peroxide hydrogen and glucose in the total ionic strength adjustment buffer (TISAB) (pH 7.5) solution with the glassy electrode modified by the calix[4]arene. The glassy carbon electrode covered with the calix[4]arene depended on the H(2)O(2) concentration in the range of log[H(2)O(2)] from -3.3 to -1.2 in the solution of TISAB (pH 7.5) with nearly Nernstian slope of about 65.6+/-3 mV and the detection limit of peroxide hydrogen was 4.0x10(-5) mol L(-1). The glassy carbon electrode covered with the calix[4]arene depended on the glucose concentration in the range of log[glucose] from -3.6 to -2.8 in the solution of TISAB (pH 7.5) with nearly Nernstian slope of about 50.2+/-2 mV and the detection limit of glucose was 2.0x10(-5) mol L(-1). The electrode had the good selectivity, sensitivity, stability and repeatability.

In this research, dual-strategy biosensing of glucose was proposed based on multifunctional CuWO4 nanoparticles (CuWO4 NPs), which were prepared for the application of electrochemical and colorimetric sensing of glucose. CuWO4 NPs show large specific surface area and good conductivity as well as excellent peroxidase-like activity. A sensitive and selective electrochemical glucose biosensor was fabricated with the immobilization of glucose oxidase (GOx) on a CuWO4 NP modified electrode for enhancing the direct electron transfer behavior. A wide linear range of 0.005–1.8 mM with a low detection limit of 1.5 μM and a high sensitivity of 28.02 mA M−1 cm−2 were achieved by using the electrochemical biosensor. Meanwhile, a colorimetric and visual glucose biosensor was constructed based on the GOx/CuWO4 cascade nanozyme, which shows a linear range of 0.05–1.0 mM with excellent selectivity. CuWO4 NPs as a promising matrix open up a dual-strategy biosensor for sensitive and selective detection of glucose. [ABSTRACT FROM AUTHOR]

The development of flexible substrate materials and nanomaterials with high electrochemical performance is of great significance for constructing efficient wearable electrochemical sensors for real-time health monitoring. Herein, a wearable electrochemical sweat sensor based on a Ni–Co MOF nanosheet coated Au/polydimethylsiloxane (PDMS) film was prepared for continuous monitoring of the glucose level in sweat with high sensitivity. First, a stretchable Au/PDMS film based three-electrode system was prepared by chemical deposition of a gold layer on the hydrophilic treated PDMS. Then, Ni–Co MOF nanosheets with high electrocatalytic activity were synthesized by a facile solvothermal method and modified on the Au/PDMS electrode. The electrocatalytic activity of the Ni–Co MOF nanosheets synthesized under different Ni : Co ratios was investigated. The Ni–Co MOF/Au/PDMS (NCAP) film electrode showed excellent electrochemical performance for glucose detection with a wide linear range of 20 μM to 790 μM and a high sensitivity of 205.1 μA mM−1 cm−2. In addition, the flexible sensor shows high stability and a good electrochemical response to glucose when stretched and bent to different levels. Moreover, it maintained long-term stability and high selectivity for glucose monitoring. Lastly, a sweat-absorbent cloth was used to cover the working area of the sensor and was fixed with a needle and thread to form a wearable sweat glucose sensor. The sensor can be attached to the skin for stable, accurate and continuous monitoring of glucose levels in human sweat for one day. This work validates the potential of our high-performance wearable sensor for out-of-clinic health monitoring. [ABSTRACT FROM AUTHOR]

A novel hedgehog-shaped bismuth sulfide (HS-Bi2S3) nanostructure was for the first time explored as an electrode material for biosensing. Using cetyltrimethyl ammonium bromide (CTAB)-trimellitic acid as a composite soft template, the HS-Bi2S3 nanostructure was synthesized by a hydrothermal route. Using glucose oxidase (GOx) as the model, the HS-Bi2S3 nanostructure was employed to immobilize GOx for the development of a sensitive electrochemical glucose biosensor. The characterization of HS-Bi2S3 and the biosensor was performed by scanning electron microscopy, X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy and cyclic voltammetry. The hedgehog-shaped nanostructure of Bi2S3 has a large specific surface area to trap a large number of enzyme molecules, and at the same time greatly enhances the direct-electron-transfer action of enzymes. The HS-Bi2S3-based biosensor shows a wide linear range of 0.005–1.7 mmol L−1 and a low detection limit of 1.6 μmol L−1 for glucose at −0.37 V, which presents much better assay performance in comparison with the glucose biosensor without HS-Bi2S3. The present electrochemical biosensor displays high selectivity, good repeatability and stability, which can be used to measure blood glucose in real serum samples. [ABSTRACT FROM AUTHOR]

The authors have prepared a platinum nanoparticle-assembled nanoflake-like SnS nanocomposite of the type PtNP@SnS as a support for immobilization of glucose oxidase (GOx) to obtain an electrochemical glucose biosensor based on direct electron transfer of GOx. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy, static water contact angle measurements, and cyclic voltammetry were used to characterize the nanocomposite and the glucose biosensor. The nanocomposite has a large surface-to-volume ratio, excellent hydrophiliciy, and high electrochemical activity. This promotes the direct electron transfer between GOx and the surface of a glassy carbon electrode (GCE). The GOx immobilized on the nanocomposite displays good bioactivity, and the surface coverage of the modified electrode is 4.15 × 10 mol·cm. Under optimum conditions and at a working voltage of −0.4 V vs. SCE, the glucose biosensor exhibits a linear response in the 0.1 to 1.0 mM and 1.0 to 12 mM glucose concentration ranges, with a lower detection limit of 2.5 μM (at an S/N ratio of 3). The biosensor shows excellent selectivity and was successfully applied to the determination of glucose in human serum samples. [ABSTRACT FROM AUTHOR]

An electrochemical non-enzymatic glucose sensor was fabricated by electrodeposition of copper nanoparticles (CuNPs) onto a poly( o-phenylenediamine) (PoPD) film-modified glassy carbon electrode (CuNPs/PoPD/GCE). We had studied some factors such as the pH value of supporting electrolyte, the amount of PoPD and applied potentials and optimize the experiment conditions. Under the optimum conditions, the as-obtained sensor for glucose sensing had achieved a wide linear range, low detection limit, and fast response time. The current response of the as-obtained sensor towards electrochemical oxidation of glucose was linear with the concentration of glucose in the range of 5.0 μM to 1.6 mM ( R = 0.998) in the solution of 0.1 M NaOH at the applied potential of 0.5 V. The detection limit is 0.25 μM and the fast response achieves within 1 s. The sensor exhibits good sensitivity, selectivity, and reproducibility. The proposed non-enzymatic glucose was successfully employed to determine glucose in blood samples. [ABSTRACT FROM AUTHOR]

In this work, the fabrication and performances of a glucose biosensor based on the electrodeposited gold nanoparticle–polyvinylpyrrolidone–polyaniline (AuNP–PVP–PANI) nanocomposites have been demonstrated. The nanocomposites were electrodeposited on a glassy carbon electrode (GCE) in a homogeneous three-component solution consisting of aniline, PVP and AuNPs. Glucose oxidase (GOx) was subsequently immobilized on the as-prepared AuNP–PVP–PANI nanocomposites using Nafion as the preventing layer. The electrochemical and electrocatalytic properties of the Nafion/GOx/AuNP–PVP–PANI modified GCE were researched. It exhibited good electrocatalytic performances with a large linear range from 0.05 mM to 2.25 mM, a low detection limit of 1.0 × 10 − 5 M (S/N = 3), and a high sensitivity of 9.62 μA mM − 1 cm − 2 . This sensor with excellent stability and reproducibility was also allowed for the detection of glucose in human serum samples with satisfactory results. [ABSTRACT FROM AUTHOR]

A tetragonal columnar-shaped TiO2 (TCS-TiO2) nanorods are synthesized via a facile route for the immobilization of glucose oxidase (GOx). A novel electrochemical glucose biosensor is constructed based on the direct electrochemistry of GOx at TCS-TiO2 modified glassy carbon electrode. The fabricated biosensor is characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, electrochemical impedance spectra and cyclic voltammetry. The immobilized enzyme molecules on TCS-TiO2 nanorods retain its native structure and bioactivity and show a surface controlled, quasi-reversible and fast electron transfer process. The TCS-TiO2 nanorods have large surface area and provide a favorable microenvironment for enhancing the electron transfer between enzyme and electrode surface. The constructed glucose biosensor shows wide linear range from 5.0×10−6 to 1.32×10−3 M with a high sensitivity of 23.2mAM−1 cm−2. The detection limit is calculated to be 2.0×10−6 M at signal-to-noise of 3. The proposed glucose biosensor also exhibits excellent selectivity, good reproducibility, and acceptable operational stability. Furthermore, the biosensor can be successfully applied in the detection of glucose in serum sample at the applied potential of −0.50V. The TCS-TiO2 nanorods provide an efficient and promising platform for the immobilization of proteins and development of excellent biosensors. [ABSTRACT FROM AUTHOR]

Abstract: An electrochemical sensor based on a copolymer poly(4-vinylpyridine)-co-poly(acrylonitrile), P4VP-co-PAN, and Fe2O3 nanoparticle film modified glassy carbon electrode was developed for the determination of glucose. We studied the response of glucose with the proposed electrode, and determined the optimum conditions by changing the potential, pH and P4VP-co-PAN. The current response measurements were performed in PBS (c=0.1M) with a potential of 0.7V. The current response of this glucose sensor showed a linear relationship with the concentration in the range of 2.5μM–0.58mM (r=0.997). The experimental results demonstrate that this method has such merits as simple operation, low cost, high sensitivity, long term stability and good reproducibility, with satisfactory results. [Copyright &y& Elsevier]

A novel glucose electrochemical biosensor was constructed based on the immobilization of glucose oxidase (GOx) in cage-like PbS nanostructure. The fabricated biosensor was characterized by scanning electron microscopy, UV–vis spectroscopy, Fourier transform infrared spectroscopy and cyclic voltammetry, respectively. The direct electrochemistry of GOx at cage-like PbS nanostructure modified glassy carbon electrode was for the first time studied. The cage-like PbS nanostructure has larger surface area and provides a favorable microenvironment for facilitating the direct electron transfer between enzyme and electrode surface. The immobilized enzymes on PbS cage-like nanostructure retains its native structure and bioactivity and shows a surface controlled, reversible two-proton and two-electron transfer reaction with a apparent electron transfer rate constant of 2.85s−1. The biosensor shows wide linear range for glucose from 5.0×10−5 M to 1.45×10−3 M with high sensitivity of 11.02mAM−1 cm−2. The detection limit was calculated to be 1.0×10−5 M at signal-to-noise of 3. Moreover, the proposed glucose biosensor displays excellent selectivity, good reproducibility, and acceptable operational stability and can be successfully applied in the detection of glucose in serum sample. The cage-like PbS nanostructure provides a promising approach for immobilizing proteins and fabricating excellent biosensors. [ABSTRACT FROM AUTHOR]

Abstract: Multi-walled carbon nanotubes (MWCNTs)–nanoflake-like SnS2 nanocomposite were designed for immobilization of glucose oxidase (GOx). The direct electrochemistry of GOx and glucose sensing at MWCNTs–SnS2 modified glassy carbon electrode were studied. Compared with single MWCNTs or SnS2, the MWCNTs–SnS2 film has larger surface area and provides a more favorable microenvironment for facilitating the electron transfer between enzyme and electrode surface. The properties of GOx/MWCNTs–SnS2 were examined by scanning electron microscopy, UV–vis spectroscopy, Fourier transform infrared spectroscopy and cyclic voltammetry. The immobilized enzyme on MWCNTs–SnS2 composite film retained its native structure and bioactivity and showed a surface controlled, reversible two-proton and two-electron transfer reaction with a apparent electron transfer rate constant of 3.96s−1. The constructed glucose biosensor exhibits wider linear range from 2.0×10−5 M to 1.95×10−3 M, much lower detection limit of 4.0×10−6 M at signal-to-noise of 3 and higher sensitivity of 21.65mAM−1 cm−2 than our previous nanoflake-like SnS2-based glucose sensor. The proposed biosensor has excellent selectivity, good reproducibility, and acceptable operational stability and can be successfully applied in the reagentless glucose sensing at −0.43V. This MWCNTs–SnS2 composite provides a new avenue for immobilizing proteins and fabricating excellent biosensors. [Copyright &y& Elsevier]

Abstract: An electrochemical sensor based on a self-made electrode from recordable CDs was developed for the non-enzymatic detection of glucose by chronoamperometry. We discussed the amperometric current response of glucose with the change of potential, pH and electrode area, and determined the optimum detection conditions. The current response measurements were performed in a phosphate buffered solution (pH 6.5) with a potential of −0.50V, and presented a linearity over the range of 0.5–13mmol/L (r =0.996). The experimental results of the designed sensor demonstrate that this method has merits such as simple operation, low cost and rapid responses. The results of detecting glucose in blood samples were satisfactory. [Copyright &y& Elsevier]

Abstract: In this paper, a facile electrochemical alloying–dealloying technique was performed in aqueous media to prepare a nanoporous platinum (Pt) electrode with high sensitivity for glucose sensing. A homogeneous Pt–Cu alloy was electrochemically deposited on a glassy carbon electrode at room temperature, and then Cu in the alloy was selectively dissolved by electrochemical method from the Pt–Cu alloy resulting in the nanoporous platinum film with a higher surface area. A roughness factor of the electrode was determined from the ratio of the true area to the geometric area, and it was up to 184. This nanoporous platinum exhibits high stability and remarkable catalytic activity for glucose oxidation in pH 7.0 PBS. It is also resistant toward poisoning by some common interfering species such as uric acid and p-acetamidophenol. Under the optimal experimental conditions, the nanoporous platinum film responded to glucose with a good linear dependence in the range from 1.00×10−5 to 8.14×10−3 M and the detection limit was 7.75×10−6 M (S/N=3). [Copyright &y& Elsevier]

Abstract: A novel urchin-like In2O3–chitosan modified glassy carbon electrode (GCE) is for the first time prepared. The direct electrochemistry of glucose oxidase (GOD) immobilized on the surface of modified GCE and biosensing are studied. The urchin-like In2O3 nanostructure-based matrix has large specific surface area and provides a favorable and biocompatible microenvironment for promoting the direct electron transfer between proteins and electrode surface. The properties of different modified electrode are characterized by scanning electron microscopy (SEM), electrochemical impedance spectra (EIS), UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and cyclic voltammetry, respectively. The constructed glucose biosensor shows wide linear range (5.0×10−6 to 1.3×10−3 M), low detection limit (1.9×10−6 M), a Michaelis–Menten constant of 0.37mM. The proposed biosensor has good sensitivity, excellent selectivity, good reproducibility and stability. This urchin-like In2O3–chitosan matrix provides a new approach and efficient matrix for the direct electrochemistry of proteins and developing novel types of biosensors. [Copyright &y& Elsevier]