New amperometric glucose biosensor by entrapping glucose oxidase into chitosan/nanoporous ZrO_2/multiwalled carbon nanotubes nanocomposite film

A new nanocomposite material for construction of glucose biosensor was prepared. The biosensor was formed by entrapping glucose oxidase(Gox) into chitosan/nanoporous ZrO2/multiwalled carbon nanotubes nanocomposite film. In this biosensing thin film, the multiwalled carbon nanotubes can effectively catalyze hydrogen peroxide and nanoporous ZrO2 can enhance the stability of the immobilized enzyme. The resulting biosensor provides a very effective matrix for the immobilization of glucose oxidase and exhibits a wide linear response range from 8 μmol/L to 3 mmol/L with a correlation coefficient of 0.994 for the detection of glucose. And the response time and detection limit of the biosensor are determined to be 6 s and 3.5 μmol/L, respectively. Another attractive characteristic is that the biosensor is inexpensive, stable and reliable.

Amperometric Glucose Biosensor Based on Integration of Glucose Oxidase with Palladium Nanoparticles/Reduced Graphene Oxide Nanocomposite

We report on a new type of amperometric glucose biosensor that was made by integration of glucose oxidase (GOD) with palladium nanoparticles/reduce graphene oxide (Pd/RGO) nanocomposite. The Pd/RGO was prepared by a one-step reduction method in which the palladium nanoparticles and the reduced graphene oxide (RGO) were simultaneously accomplished from the reduction of dispersed solution of PdCl2 and graphite oxide (GO) with hydrazine. The asprepared nanocomposite exhibits favorable electrocatalytic activities towards the oxidation of H2O2, which makes it a good platform for the construction of the glucose biosensor. The analytical performance of the glucose biosensor is fully evaluated. It shows good analytical properties in terms of a short response time (3 s), high sensitivity (14.1 μA/mM), and low detection limit (0.034 mM). In addition, the effects of pH value, applied potential, electroactive interference and the stability of the biosensor were discussed as well.

Determination of trace mercury in compost extract by inhibition based glucose oxidase biosensor

A novel inhibition based biosensor of glucose oxidase(GOx) for environmental mercury detection was developed. An electropolymerized aniline membrane was prepared on a platinum electrode containing ferrocene as electron transfer mediator, on which GOx was cross-linked by glutaraldehyde. The response of the sensor was based on the current reduction in the electrochemical system by inhibition of mercury against GOx electrode. The detection limit of the inhibition-based sensor for mercury is 0.49 μg/L, and the linear response ranges are 0.49-783.21 μg/L and 783.21 μg/L-25.55 mg/L. The GOx membrane can be completely reactivated after inhibition, and remains 70% of the activity in more than one month. The sensor was used for mercury determination in compost extract with good results.

A Chemiluminescence Optical Fiber Glucose Biosensor Based on Co-immobilizing Glucose Oxidase and Horseradish Peroxidase in a Sol-gel Film

An optical fiber bienzyme sensor based on the luminol chemiluminescent reaction was developed and demonstrated to be sensitive to glucose. Glucose oxidase(GOD) and horseradish peroxidase(HRP) were co-immobilized by microencapsulation in a sol-gel film derived from tetraethyl orthosilicate(TEOS). The calibration plots for glucose were established by the optical fiber glucose sensor fabricated by attaching the bienzyme silica gel onto the glass window of the fiber bundle. The linear range was 0 2-2 mmol/L and the detection limit was approximately 0 12 mmol/L. The relative standard deviation was 5.3% ( n =6). The proposed biosensor was applied to glucose assay in ofloxacin injection successfully.

Simple Method for Preparing Glucose Biosensor Based on Glucose Oxidase in Nanocomposite Material of Single-Wall Carbon Nanotubes/Ionic Liquid

Based on electric conductivity and wide potential window of ionic liquid (IL) and electric property of single-wall car- bon nanotubes (SWCNTs), composite material of IL-SWCNTs was prepared, glucose sensor was built with this mate-rial for immobilizing glucose oxidase (GOx). It showed good response, sensitivity and stability for long time for glu-cose detection. Linear range for the detection of glucose was from 0.5 × 10–6 M to 12 × 10–6 M while detection limit was 6.26 × 10–8 M (S/N = 3).

Polyaniline-graphite composite film glucose oxidase electrode

A novel polyaniline-graphite composite film glucose oxidase （PGCF GOD） electrode was developed. The PGCF was synthesized by cyclic voitammetry method in 0.5 mol/L H2SO4 solution containing 1 g/L graphite powder and 0.2 mol/L aniline. The PGCF GOD electrode was prepared by doping GOD into the composite film. The morphology of the PGCF and the response property of the PGCF GOD electrode were investigated by scanning electron microscopy and electrochemical measurement, respectively. The results show that the PGCF has a porous and netty structure and the PGCF GOD electrode has excellent response property such as high sensitivity and short response time. Influences of pH value, temperature, glucose concentration and potential on the response current of the electrode were also discussed. The sensor has a maximum steady-state current density of 357.17μA/cm2 and an apparent Michaelis-Menten constant of 16.57 mmol/L. The maximum current response of the enzyme electrode occurs under the condition ofpH 5.5, 0.8 V and 65℃.

Direct Electron Communication Between Glucose Oxidase and Carbon Electrode Covered with Polypyrrole

Glucose oxidase can be effectively adsorbed onto the polypyrrole (PPy) thin film electrochemically formed on an anodized galssy carbon electrode (GCEa ). Direct electron communication between the redox of GOD and the modified electrode was successfully achieved, which was detected using cyclic voltammetry. GOD entrapped in PPy film still remained its biological activity and could catalyze the oxidation of glucose. As a third generation biosensor, GOD-PPy/GCEa responded linearly up to 20 mM glucose with a wider linear concentration range.

A New Amperometric Glucose Biosensor with Naphthol Green B as Mediator

Naphthol green B was used, for the first time, as a new mediator in an amperometric glucose biosensor. It is a good mediator, promoting electron transfer from glucose oxidase to graphite electrode. The biosensor shows high sensitivity to glucose at low potential with response time of 30 seconds. The linear range is from 1.5 to 18 靘ol/L glucose with detection limit of 0.5 靘ol/L glucose.

A direct electrochemical biosensor for rapid glucose detection based on nitrogen-doped carbon nanocages

Given the increasing number of diabetic patients,rapid and accurate detection of glucose in body fluids is critical.This study developed a direct electrochemical biosensor for glucose based on nitrogen-doped carbon nanocages(NCNCs).NCNCs possess a large specific surface area of 1395 m^(2)·g^(-1),a high N atomic content of 9.37%and good biocompatibility,which is favorable for enzyme loading and electron transfer.The surface average concentration of electroactive glucose oxidase on NCNCs was 2.82×10^(-10)mol·cm^(-2).The NCNC-based direct electrochemical biosensor exhibited a high sensitivity of 13.7μA·(mmol·L^(-1))^(-1)·cm^(-2),rapid response time of 5 s and an impressive electron-transferrate constant(ks)of 1.87 s^(-1).Furthermore,we investigated an NCNC-based direct electron transfer(DET)biosensor for sweat glucose detection,which demonstrated tremendous promise for non-invasive wearable diabetes diagnosis.

Development of an amperometric glucose biosensor based on the immobilization of glucose oxidase in an ormosil-PVA matrix onto a Prussian Blue modified electrode

An amperometric glucose biosensor was developed based on the immobilization of glucose oxidase in the organically modified silicate (ormosil)-polyvinyl acetate (PVA) matrix onto a Prussian Blue (PB)-modified glassy carbon electrode. A higher stability PB-modified electrode was prepared by the electrochemical deposition of FeCl3, K3[Fe(CN)6] and ethylenediamine tetraacetic acid (EDTA) under cyclic voltammetric (CV) conditions. The effects of the potential range of CV conditions, electrolyte cations, applied potential, pH, temperature and co-existing substances were investigated. The detection limit of the glucose biosensor was 8.1 μmol·L−1 (S/N = 3) with a linear range from 20 μmol·L−1 to 2 mmol·L−1 (R = 0.9965). The biosensor presented a fast response and good selectivity. Additionally, excellent reproducibility and stability of the biosensor were observed.

Nanobiocomposite Electrochemical Biosensor Utilizing Synergic Action of Neutral Red Functionalized Carbon Nanotubes

An amperometric hydrogen peroxide biosensor using a nanobiocomposite based on neutral red modified carbon nanotubes and co-immobilized glucose oxidase and horseradish peroxidase is reported. Modification of the nanobiocomposite electrode with neutral red resulted in a sensitive, low-cost and reliable H_2O_2 sensor. The use of carbon nanotubes, as the conductive part of the composite, facilitated fast electron transfer rates. The biosensor was characterized for the influence of p H, potential and temperature. A remarkable feature of the biosensor is the detection of H_2O_2 at low applied potentials where the noise level and interferences are minimal. The sensor has a fast steady-state measuring time of 10 s with a quick response(2 s). The biosensor showed a linear range from 15 n M to 45 m M of H_2O_2 and a detection limit of 5 n M. Nafion, which is used as a binder, makes the determination free from other electroactive substances. The repeatability, reproducibility,stability and analytical performance of the sensor are very good.

A glucose biosensor based on direct electrochemistry of glucose oxidase immobilized onto platinum nanoparticles modified graphene electrode

The platinum nanoparticles were adsorbed on graphene oxide sheets and played an important role in catalytic reduction of graphene oxide with hydrazine, leading to the formation of graphene-Pt nanoparticles. Because of their good electronic properties, biocompatibility and high surface area, graphene-Pt based composites achieved the direct electron transfer of redox enzyme and maintained their bioactivity well. The graphene-Pt nanocomposites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED). The amperometric biosensor fabricated by depositing glucose oxidase over Nafion-solubilized graphene-Pt electrode retained its biocatalytic activity and has offered fast and sensitive glucose quantification.

A New Application of Carbon Nanotubes Constructing Biosensor

Carbon nanotubes used for constructing biosensor was described for the first time. Single-wall carbon nanotubes (SWNTs) functionalized with carboxylic acid groups were used to immobilize glucose oxidase forming a glucose biosensor. The biosensor response can be determined by amperometric method at a low applied potential (0.40 V).

Direct electrochemistry of glucose oxidase on the hydroxyapatite/Nafion composite film modified electrode and its application for glucose biosensing

A novel glucose biosensor was constructed by immobilizing the glucose oxidase(GOD) on a hydroxyapatite(HAp)/Nafion composite film modified glassy carbon electrode(GCE) and applied to the highly selective and sensitive determination of glucose.With the cooperation of HAp and Nafion,the composite film played an important role in enhancing the stability and sensitivity of the biosensor.The results demonstrate that the GOD adsorbed onto the HAp/Nafion composite film exhibits a pair of welldefined nearly reversible redox peaks and fine catalysis to the oxidation of glucose companied with the consumption of dissolved oxygen.On the basis of the decrease of the reduction current of dissolved oxygen at the applied potential of -0.80 V(vs.SCE) upon the addition of glucose,the concentration of glucose could be detected sensitively and selectively.The decreased reduction current was linear with the concentration of glucose in the range of 0.12―2.16 mM.The detection limit and sensitivity were 0.02 mM(S/N=3) and 6.75 mA·M-1,respectively.All the results demonstrate that HAp/Nafion composite film provides a novel and efficient platform for the immobilization of enzymes and realizes the direct electrochemistry.The composite materials should have potential applications in the fabrication of third-generation biosensors.

Bird nest-like zinc oxide nanostructures for sensitive electrochemical glucose biosensor

In this research,a novel bird nest-like zinc oxide(BN-ZnO)nanostructures were prepared by a simple solvothermal method.A sensitive electrochemical glucose biosensor was for the first time developed based on the immobilization of glucose oxidase(GOx)on nanostructured BN-ZnO modified electrode.The BN-ZnO nanostructure and the resultant biosensor were characterized by scanning electron microscope,X-ray diffraction spectroscopy,Fourier transform infrared spectroscopy,and electrochemical impedance spectroscopy.BN-ZnO nanostructures have large specific surface area and can load large amounts of GOx molecules.Meanwhile,BN-ZnO provides an excellent microenvironment to retain the native bioactivity of enzymes and to promote direct electron transfer between GOx and electrode surface.The proposed biosensor shows a wide linear range of 0.005–1.6 mmol/L,high sensitivity of15.6 mA L mol^(-1)cm^(-2)with a low detection limit of 0.004 mmol/L.The resulting biosensor also shows excellent selectivity,acceptable stability and reproducibility,and can be successfully applied in the detection of glucose in human serum samples at-0.37 V.

Facile Fabrication of a Graphene-based Electrochemical Biosensor for Glucose Detection

A simple and effective glucose biosensor based on immobilization of glucose oxidase （GOD） in graphene （GR）/Nafion film was constructed. The results indicated that the immobilized GOD can maintain its native structure and bioactivity, and the GR/Nafion film provides a favorable microenvironment for GOD immobilization and promotes the direct electron transfer between the electrode substrate and the redox center of GOD. The electrode reaction of the immobilized GOD shows a reversible and surface-controlled process with the large electron transfer rate constant （ks） of 3.42±0.08 s-1. Based on the oxygen consumption during the oxidation process of glucose catalyzed by the immobilized GOD, the as-prepared GOD/GR/Nafion/GCE electrode exhibits a linear range from 0.5 to 14mmol·L-1 with a detection limit of 0.03 mmol·L-1. Moreover, it displays a good reproducibility and long-term stability.

Glucose biosensor based on new carbon nanotube–gold–titania nano-composites modifed glassy carbon electrode

In this paper, a novel biosensor was prepared by immobilizing glucose oxidase （GOx） on carbon nanotube-gold-titania nanocomposites （CNT/Au/TiO2） modified glassy carbon electrode （GCE）. SEM was initially used to investigate the surface morphology of CNT/Au/TiO2 nanocomposites modified GCE, indicating the formation of the nano-porous structure which could readily facilitate the attachment of GOx on the electrode surface. Cyclic voltammogram （CV） and electrochemical impedance spectrum （EIS） were further utilized to explore relevant electrochemical activity on CNT]Au/TiO2 nanocomposites modified GCE. The observations demonstrated that the immobilized GOx could efficiently execute its bioelectrocatalytic activity for the oxidation of glucose. The biosensor exhibited a wider linearity range from 0.1 mmol L-1 to 8 mmol L^-1 glucose with a detection limit of 0.077 mmol L^- 1.

Photoelectrochemical glucose biosensor incorporating CdS nanoparticles

A novel photoelectrochemical biosensor incorporating nanosized CdS semiconductor crystals with enzyme to enhance photochemical reaction has been investigated. CdS nanoparticles were synthesized by using dendrimer PAMAM as inner templates. The CdS nanoparticles and glucose oxidase （GOD） were immobilized on Pt electrode via layer-by-layer （LbL） technique to fabricate a biological-inorganic hybrid system. Under ultraviolet light, the photo-effect of the CdS nanoparticles showed enhancement of the biosensor to detect glucose. Pt nanoparticles were mixed into the Nation film to immobilize the CdS/enzyme composites and to improve the charge transfer of the hybrid. Experimental results demonstrate the desirable characteristics of this biosensing system, e,g. a sensitivity of 1.83 μA/（mM cm^2）, lower detection limit （1 μM）, and acceptable reproducibility and stability,

A mediator-free self-powered glucose biosensor based on a hybrid glucose/MnO_(2) enzymatic biofuel cell

Self-powered glucose biosensor(SPGB)is of great interest due to the advantages including single configuration,good stability and particularly no need of external power sources.Herein,a mediator-free SPGB with high sensitivity and good selectivity is constructed based on a hybrid enzymatic biofuel cell(EBFC)composed of a glucose oxidase/cobalt phthalocyanine/1-pyrenebutyric acid/buckypaper(GOD/CoPc/PBA/BP)bioanode and a MnO_(2)/PBA/BP capacitive cathode.The efficient electron transfer from GOD to electrodes is achieved successfully through the anode oxidation of hydrogen peroxide(H_(2)O_(2)),one nature product of glucose oxidation catalyzed by GOD,thus avoiding the potential drawbacks posed by the use of redox mediators.CoPc servers as an efficient catalyst to lower the anode potential required by the reaction of H_(2)O_(2) to 0.17 V.The MnO_(2)/PBA/BP capacitive cathode is utilized because it can not only provide a high discharge potential and adequate capacitance to match the bioanode well,but also exhibit no potential interference to the anodic reaction.The concentration of glucose can be detected simply by measuring the output of the SPGB and a wide linear detection range from 0.5 to 8 mM has been obtained with high sensitivities of 48.66 and 32.12μA·cm^(−2)·mM^(−1) with and without stirring,respectively.The recoveries of glucose in grape juice and human serum are in the range from 99.5%to 101.2%with the relative standard deviation(RSD)less than 8%,indicating the good promise of the SPGB in sensing glucose in real samples.

Preparation of glucose oxidase electrode containing hydrophobic silica nanoparticles by the sol-gel method

The influences of hydrophobic SiO_2 nanoparticles and the contents of glucose oxidase(GOD) upon the response current of enzyme electrode have been investigated by using the sol-gel method,in which polyvinylbutyryl(PVB)was used as a matrix.The influenoe of enzymatic activity was measured by electrochemical method.Experimental data demonstrated that hydrophobic SiO_2 particles can immobilize enzyme well,providing a good and simple method for preparing high quality GOD biosensor.The mechanism has been discussed.