Nonenzymatic electrochemical detection of glucose using well-distributed nickel nanoparticles on straight multi-walled carbon nanotubes

A nonenzymatic electrochemical sensor device was fabricated for glucose detection based on nickel nanoparticles (NiNPs)/straight multi-walled carbon nanotubes (SMWNTs) nanohybrids, which were synthesized through in situ precipitation procedure. SMWNTs can be easily dispersed in solution after mild sonication pretreatment, which facilitates the precursor of NiNPs binding to their surface and results in the homogeneous distribution of NiNPs on the surface of SMWNTs. The morphology and component of the nanohybrids were characterized by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD), respectively. Cyclic voltammetry (CV) and amperometry were used to evaluate the catalytic activity of the NiNPs/SMWNTs nanohybrids modified electrode towards glucose. It was found that the nanohybrids modified electrode showed remarkably enhanced electrocatalytic activity towards the oxidation of glucose in alkaline solution compared to that of the bare glass carbon electrode (GCE), the NiNPs and the SMWNTs modified electrode, attributing to the synergistic effect of SMWNTs and Ni²⁺/Ni³⁺ redox couple. Under the optimal detection conditions, the as-prepared sensors exhibited linear behavior in the concentration range from 1 μM to 1 mM for the quantification of glucose with a limit of detection of 500 nM (3σ). Moreover, the NiNPs/SMWNTs modified electrode was also relatively insensitive to commonly interfering species such as ascorbic acid (AA), uric acid (UA), dopamine (DA), galactose (GA), and xylose (XY). The robust selectivities, sensitivities, and stabilities determined experimentally indicated the great potential of NiNPs/SMWNTs nanohybrids for construction of a variety of electrochemical sensors.     

A novel multi-walled carbon nanotube-based biosensor for glucose detection

The bioelectrochemical characteristics of a novel multi-walled carbon nanotube (MWNT)-based biosensor for glucose detection are studied and compared with those of glassy carbon (GC)-based biosensor. The MWNT-based biosensor exhibits a strong glucose response at applied potentials of 0.65 and 0.45 V versus Ag/AgCl, respectively, while GC-based biosensor shows a weak glucose response at 0.65 V and no response at 0.45 V. Besides, the MWNT-based biosensor shows a high stability of 86.7% of the initial activity to glucose after four-month storage, much higher than 37.2%, the corresponding value for a GC-based biosensor. The detection mechanism of the MWNT-based biosensor is also discussed in detail.     

Glucose biosensor based on glucose oxidase immobilized at gold nanoparticles decorated graphene-carbon nanotubes

Biopolymer pectin stabilized gold nanoparticles were prepared at graphene and multiwalled carbon nanotubes (GR-MWNTs/AuNPs) and employed for the determination of glucose. The formation of GR-MWNTs/AuNPs was confirmed by scanning electron microscopy, X-ray diffraction, UV–vis and FTIR spectroscopy methods. Glucose oxidase (GOx) was successfully immobilized on GR-MWNTs/AuNPs film and direct electron transfer of GOx was investigated. GOx exhibits highly enhanced redox peaks with formal potential of −0.40 V (vs. Ag/AgCl). The amount of electroactive GOx and electron transfer rate constant were found to be 10.5 × 10⁻¹⁰ mol cm⁻² and 3.36 s⁻¹, respectively, which were significantly larger than the previous reports. The fabricated amperometric glucose biosensor sensitively detects glucose and showed two linear ranges: (1) 10 μM – 2 mM with LOD of 4.1 μM, (2) 2 mM – 5.2 mM with LOD of 0.95 mM. The comparison of the biosensor performance with reported sensors reveals the significant improvement in overall sensor performance. Moreover, the biosensor exhibited appreciable stability, repeatability, reproducibility and practicality. The other advantages of the fabricated biosensor are simple and green fabrication approach, roughed and stable electrode surface, fast in sensing and highly reproducible.     

Multifunctional carbon nanotubes for direct electrochemistry of glucose oxidase and glucose bioassay

Polydopamine (Pdop) has recently been shown to adsorb to a wide variety of surfaces and serves as an adhesion layer to immobilize biological molecules. In this work, the multifunctional carbon nanotube (CNT) composites were prepared though the oxidation of dopamine at room temperature and subsequent electroless silver deposition by mildly stirring. The stable immobilization and direct electron transfer of glucose oxidase were achieved on the composite film modified glassy carbon electrode. The resulting electrode gave a well-defined redox peaks with a formal potential of about −482 mV (vs. SCE) in pH 7.0 buffer. The electron transfer rate constant was estimated to be 3.6 s⁻¹, due to the combined contribution of Pdop, CNTs and Ag nanoparticles with the help of Nafion. Furthermore, the method for detecting of glucose was proposed based on the decrease of oxygen caused by the enzyme-catalyzed reaction between glucose oxidase (GOD) and glucose. The linear response to glucose ranging from 50.0 μM to 1.1 mM (R² = 0.9958), with a calculated detection limit of 17.0 μM at a signal-to-noise ratio of 3. The low calculated apparent Michaelis–Menten constant was 5.46 mM, implying the high enzymatic activity and affinity of immobilized GOD for glucose. It can reasonably be expected that this observation might hold true for other noble metal nanostructure-electroactive protein systems, providing a promising platform for the development of biosensors and biofuel cells.     

Amperometric glucose biosensor based on multilayer films via layer-by-layer self-assembly of multi-wall carbon nanotubes, gold nanoparticles and glucose oxidase on the Pt electrode

A novel amperometric glucose biosensor based on the nine layers of multilayer films composed of multi-wall carbon nanotubes (MWCNTs), gold nanoparticles (GNp) and glucose oxidase (GOD) was developed for the specific detection of glucose. MWCNTs were chemically modified with the H₂SO₄–HNO₃ pretreatment to introduce carboxyl groups which were used to interact with the amino groups of poly(allylamine) (PAA) and cysteamine via 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide cross-linking reaction, respectively. A cleaned Pt electrode was immersed in PAA, MWCNTs, cysteamine and GNp, respectively, followed by the adsorption of GOD, assembling the one layer of multilayer films on the surface of Pt electrode (GOD/GNp/MWCNTs/Pt electrode). Repeating the above process could assemble different layers of multilayer films on the Pt electrode. PBS washing was applied at the end of each assembly deposition for dissociating the weak adsorption. Film assembling and characterization were studied by transmission electron microscopy and quartz crystal microbalance, and properties of the resulting glucose biosensors were measured by electrochemical measurements. The marked electrocatalytic activity of Pt electrode based on multilayer films toward H₂O₂ produced during GOD enzymatic reactions with glucose permitted effective low-potential amperometric measurement of glucose. Taking the sensitivity and selectivity into consideration, the applied potential of 0.35 V versus Ag/AgCl was chosen for the oxidation detection of H₂O₂ in this work. Among the resulting glucose biosensors, the biosensor based on nine layers of multilayer films was best. It showed a wide linear range of 0.1–10 mM glucose, with a remarkable sensitivity of 2.527 μA/mM, a detection limit of 6.7 μM estimated at a signal-to-noise ratio of 3 and fast response time (within 7 s). Moreover, it exhibited good reproducibility, long-term stability and the negligible interferences of ascorbic acid, uric acid and acetaminophen. The study can provide a feasible approach on developing new kinds of oxidase-based amperometric biosensors, and can be used as an illustration for constructing various hybrid structures.     

Multilayer membranes for glucose biosensing via layer-by-layer assembly of multiwall carbon nanotubes and glucose oxidase

A bilayer of the polyelectrolytes poly(dimethyldiallylammonium chloride) (PDDA) and poly(sodium 4-styrenesulfonate) (PSS) was formed on a 3-mercapto-1-propanesulfonic-acid-modified Au electrode. Subsequently, multiwall carbon nanotubes (MWCNTs) wrapped by positively charged PDDA were assembled layer-by-layer with negatively charged glucose oxidase (GOx) onto the PSS-terminated bilayer. Electrochemical impedance spectroscopy and atomic force microscopy were adopted to monitor the regular growth of the PDDA-MWCNTs/GOx bilayers. Using GOx as a model enzyme, the assembled multilayer membranes showed some striking features such as the adsorbed form of GOx on individual MWCNT, uniformity, good stability, and electrocatalytic activity toward oxygen reduction. Based on the consumption of dissolved oxygen during the oxidation process of glucose catalyzed by the immobilized GOx, a sensitive amperometric biosensor was developed for the detection of glucose up to 5.0 mM with a detection limit of 58 microM. The sensitivity increased with increasing sensing layers up to five bilayers. Ascorbic acid and uric acid did not cause any interference due to the use of a low operating potential. The present method showed high reproducibility for the fabrication of carbon-nanotubes-based amperometric biosensors.     

Nonenzymatic glucose sensor based on ultrasonic-electrodeposition of bimetallic PtM (M = Ru, Pd and Au) nanoparticles on carbon nanotubes–ionic liquid composite film

We report here for the first time on the fabrication of highly dispersed PtM (M = Ru, Pd and Au) nanoparticles on composite film of multi-walled carbon nanotubes (MWNTs)–ionic liquid (IL, i.e., trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide) by using ultrasonic-electrodeposition method. The PtM nanoparticles are characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction, and we find that they are well-dispersed and exhibit alloy properties. Electrochemical experiments show that the PtRu(1:1, i.e., ratio of c(H₂PtCl₆)/c(RuCl₃))–MWNT–IL nanocomposite modified glassy carbon electrode (PtRu(1:1)–MWNT–IL/GCE) has smaller electron transfer resistance and larger active surface area than PtRu(1:1)/GCE, PtRu(1:1)–MWNT/GCE, PtPd(1:1)–MWNT–IL/GCE and PtAu(1:1)–MWNT–IL/GCE. The PtRu(1:1)–MWNT–IL/GCE also presents stronger electrocatalytic activity toward the glucose oxidation than other electrodes. At −0.1 V, the electrode responds linearly to glucose up to 15 mM in neutral media, with a detection limit of 0.05 mM (S/N = 3) and detection sensitivity of 10.7 μA cm⁻² mM⁻¹. Meanwhile, the interference of ascorbic acid, uric acid, acetamidophenol and fructose is effectively avoided. The as-made sensor was applied to the determination of glucose in serum and urine samples. The results agreed closely with the results obtained by a hospital. This novel nonenzyme sensor thus has potential application in glucose detection.     

Direct electrochemistry of glucose oxidase and electrochemical biosensing of glucose on quantum dots/carbon nanotubes electrodes

Because of their unique chemical, physical and electronic properties, Quantum dots (QDs) and carbon nanotubes (CNTs) are now extremely attractive and important nanomaterials in bioanalytical applications. In this work, CdTe QDs with the size of about 3 nm were prepared and a novel electrochemical biosensing platform of glucose based on CdTe/CNTs electrode was explored. This CdTe/CNTs electrode was prepared by first mixing CdTe QDs, CNTs, Nafion, and glucose oxidase (GOD) in appropriate amounts and then modifying this mixture on the glass carbon electrode (GC). Transmission electron microscopy (TEM) was used to observe the dispersion of CdTe QDs on carbon nanotubes and cyclic voltammetry (CV) was used to investigate the electrochemical behavior of the CdTe/CNTs electrode. A pair of well-defined quasi-reversible redox peaks of glucose oxidase were obtained at the CdTe/CNTs based enzyme electrode by direct electron transfer between the protein and the electrode. The immobilized glucose oxidase could retain bioactivity and catalyze the reduction of dissolved oxygen. Due to the synergy between the CdTe QDs and CNTs, this novel biosensing platform based on QDs/CNTs electrode responded even more sensitively than that based on GC electrode modified by CdTe QDs or CNTs alone. The inexpensive, reliable and sensitive sensing platform based on QDs/CNTs electrode provides wide potential applications in clinical, environmental, and food analysis.     

Fabrication and characterization of non-enzymatic glucose sensor based on ternary NiO/CuO/polyaniline nanocomposite

Novel nickel and copper oxide nanoparticle modified polyaniline (PANI) nanofibers (NiO/CuO/PANI) were fabricated and used as a non-enzymatic sensor for detecting glucose. PANI nanofibers were prepared through electrodeposition, whereas nickel and copper oxide nanoparticles were deposited on PANI nanofibers by electrodeposition and electrochemical oxidation in situ. The morphology and structure of NiO/CuO/PANI nanocomposites were characterized by field emission scanning electron microscopy (FE–SEM), X-ray diffraction (XRD), Raman spectroscopy, and Fourier transform infrared (FT–IR). The as-prepared NiO/CuO/PANI electrode was employed for non-enzymatic glucose detection in alkaline electrolyte and showed better electrocatalytic activity compared with the PANI, CuO/PANI, and NiO/PANI electrodes. Consequently, an amperometric electrode of glucose was achieved under 0.6 V versus Ag/AgCl with a wide linear range from 20 to 2500 μM (R² = 0.9978) and a low detection limit of 2.0 μM (signal/noise [S/N] = 3). This electrode can effectively analyze glucose concentration in human serum samples, avoiding interference, and is a promising non-enzymatic glucose sensor due to its low overpotential, high sensitivity, good selectivity and stability, fast response, and low cost.     

Direct electron transfer of glucose oxidase promoted by carbon nanotubes

A stable suspension of carbon nanotubes (CNT) was obtained by dispersing the CNT in a solution of surfactant, such as cetyltrimethylammonium bromide (CTAB, a cationic surfactant). CNT (dispersed in the solution of 0.1% CTAB) has promotion effects on the direct electron transfer of glucose oxidase (GOx), which was immobilized onto the surface of CNT. The direct electron transfer rate of GOx was greatly enhanced after it was immobilized onto the surface of CNT. Cyclic voltammetric results showed a pair of well-defined redox peaks, which corresponded to the direct electron transfer of GOx, with a midpoint potential of about -0.466 V (vs SCE (saturated calomel electrode)) in the phosphate buffer solution (PBS, pH 6.9). The electrochemical parameters such as apparent heterogeneous electron transfer rate constant (ks) and the value of midpoint potential (E1/2) were estimated. The dependence of E1/2 on solution pH indicated that the direct electron transfer reaction of GOx is a two-electron-transfer coupled with a two-proton-transfer reaction process. The experimental results also demonstrated that the immobilized GOx retained its bioelectrocatalytic activity for the oxidation of glucose, suggesting that the electrode may find use in biosensors (for example, it may be used as a bioanode in biofuel cells). The method presented here can be easily extended to immobilize and obtain the direct electrochemistry of other redox enzymes or proteins.     

A sensitive nonenzymatic glucose sensor in alkaline media with a copper nanocluster/multiwall carbon nanotube-modified glassy carbon electrode

Copper (Cu) nanoclusters were electrochemically deposited on the film of a Nafion-solubilized multiwall carbon nanotube (CNTs)-modified glassy carbon electrode (CNTs-GCE), which fabricated a Cu-CNTs composite sensor (Cu-CNTs-GCE) to detect glucose with nonenzyme. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used for the characterization of the distribution of the Cu nanoclusters on the CNTs matrix. The composite of the Cu-CNTs was investigated by the electrochemical characterization of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The preliminary study shows that the nonenzymatic sensor has synergistic electrocatalytic activity to the oxidation of glucose in alkaline media. A well applicable sensor was constructed to use for the analysis of the glucose in real blood serum samples due to the large number of electrons taking part in the oxidation process, the high apparent kinetic rate constant, and the stable operation of the electrode. The linear range for the detection of the glucose is 7.0 x 10(-7) to 3.5 x 10(-3) M with a high sensitivity of 17.76 microA mM(-1), a low detection limit of 2.1 x 10(-7) M, and a fast response time of within 5s. Experiment results also showed that the sensor has good reproducibility and long-term stability and is interference free.     

Amperometric glucose biosensor based on single-walled carbon nanohorns

The biosensing application of single-walled carbon nanohorns (SWCNHs) was demonstrated through fabrication of an amperometric glucose biosensor. The biosensor was constructed by encapsulating glucose oxidase in the Nafion-SWCNHs composite film. The cyclic voltammograms for glucose oxidase immobilized on the composite film displayed a pair of well-defined and nearly symmetric redox peaks with a formal potential of -0.453 V. The biosensor had good electrocatalytic activity toward oxidation of glucose. To decrease detection potential, ferrocene monocarboxylic acid was used as a redox mediator. The mediated glucose biosensor shows a linear range from 0 to 6.0 mM. The biosensor shows high sensitivity (1.06 microA/mM) and stability, and can avoid the commonly coexisted interference. Because of impressive properties of SWCNHs, such as high purity and high surface area, SWCNHs and their composites are expected to be promising material for biomolecular immobilization and biosensing applications.     

Enzymes immobilized on carbon nanotubes

Enzyme immobilizations on carbon nanotubes for fabrication of biosensors and biofuel cells and for preparation of biocatalysts are rapidly emerging as new research areas. Various immobilization methods have been developed, and in particular, specific attachment of enzymes on carbon nanotubes has been an important focus of attention. The method of immobilization has an effect on the preservation of the enzyme structure and retention of the native biological function of the enzyme. In this review, we focus on recent advances in methodology for enzyme immobilization on carbon nanotubes.     

Amperometric glucose biosensor based on adsorption of glucose oxidase at platinum nanoparticle-modified carbon nanotube electrode

A new amperometric biosensor, based on adsorption of glucose oxidase (GOD) at the platinum nanoparticle-modified carbon nanotube (CNT) electrode, is presented in this article. CNTs were grown directly on the graphite substrate. The resulting GOD/Pt/CNT electrode was covered by a thin layer of Nafion to avoid the loss of GOD in determination and to improve the anti-interferent ability. The morphologies and electrochemical performance of the CNT, Pt/CNT, and Nafion/GOD/Pt/CNT electrodes have been investigated by scanning electron microscopy, cyclic voltammetry, and amperometric methods. The excellent electrocatalytic activity and special three-dimensional structure of the enzyme electrode result in good characteristics such as a large determination range (0.1-13.5mM), a short response time (within 5s), a large current density (1.176 mA cm(-2)), and high sensitivity (91mA M(-1)cm(-2)) and stability (73.5% remains after 22 days). In addition, effects of pH value, applied potential, electrode construction, and electroactive interferents on the amperometric response of the sensor were investigated and discussed. The reproducibility and applicability to whole blood analysis of the enzyme electrode were also evaluated.     

Layer-by-layer fabrication and direct electrochemistry of glucose oxidase on single wall carbon nanotubes

Layer-by-layer assembly of glucose oxidase (GOx) with single-wall carbon nanotubes (SWCNTs) is achieved on the electrode surface based on the electrostatic attraction between positively charged GOx in pH 3.8 buffer and negatively charged carboxylic groups of CNTs. The cyclic voltammetry and electrochemical impedance spectroscopy are used to characterize the formation of multilayer films. In deaerated buffer solutions, the cyclic voltammetry of the multilayer films of {GOx/CNT}_n shows two pairs of well-behaved redox peaks that are assigned to the redox reactions of CNTs and GOx, respectively, confirming the effective immobilization of GOx on CNTs using the layer-by-layer technique. The redox peak currents of GOx increase linearly with the increased number of layers indicating the uniform growth of GOx in multilayer films. The dependence of the cyclic voltammetric response of GOx in multilayer films on the scan rate and pH is also studied. A linear decrease of the reduction current of oxygen at the {GOx/CNT}-modified electrodes with the addition of glucose suggests that such multilayer films of GOx retain the bioactivity and can be used as reagentless glucose biosensors.     

Development of biofuel cells based on gold nanoparticle decorated multi-walled carbon nanotubes

This study focused on developing the synthesis of Au nanoparticle-decorated functionalized multi-walled carbon nanotubes (Au-NPs/f-MWCNTs) for monosaccharide (bio-fuel) oxidation reactions and practical application in air-biofuel cells. We developed a scalable and straightforward method to synthesize Au-NPs/f-MWCNTs which allow us to control the loading and size of the Au-NPs. The Au-NPs/f-MWCNTs exhibited better catalytic activities and stability than the Au sheet and subsequently resulted in a threefold increase in the power density of the air-glucose fuel cell with an exceptionally high open circuit voltage (∼1.3 V). The catalytic efficiency was confirmed by high performance liquid chromatography with the superior of the Au-NPs/f-MWCNTs over a bare gold electrode. In addition, the application of this advanced catalyst to other monosaccharide oxidation reactions figured out that the configuration of –OH groups at C₂ and C₃ of the reactants plays an important role in the initial adsorption process, and thus, affects the required activation energy for further oxidation. The different monosaccharides lead to significantly different fuel cell performances in terms of power density, which coherently corresponds to the difference in the configuration of C₂ and C₃. Because two small air-glucose fuel cells using Au-NPs/f-MWCNTs can run a LED lamp, further applications of other monosaccharides as fuel in biofuel cells for equivalent required power devices may be possible.     

Amperometric sensor based on ferrocene-modified multiwalled carbon nanotube nanocomposites as electron mediator for the determination of glucose

A kind of nanocomposite with good dispersion in water was prepared through covalent adsorption of ferrocenecarboxaldehyde on multiwalled carbon nanotubes (MWNTs) for electrical communication between glucose oxidase (GOD) and electrode. The ferrocene-modified multiwalled carbon nanotube nanocomposites (MWNTs-Fc) could be conveniently cast on electrode surfaces. With the aid of chitosan, GOD was then immobilized on the nanostructure film to form a reagentless amperometric sensor for glucose determination. FTIR spectra and cyclic voltammetry were used to characterize the nanocomposites. The presence of both ferrocene as mediator of electron transfer and MWNTs as conductor enhanced greatly the enzymatic response to the oxidation of glucose. The novel biosensor exhibited a fast response toward glucose with a detection limit of 3.0 × 10⁻⁶ mol/L and the linear range extended up to 3.8 × 10⁻³ mol/L.     

A novel gaseous dimethylamine sensor utilizing cataluminescence on zirconia nanoparticles

A novel cataluminescence (CTL) sensor using ZrO₂ nanoparticles as the sensing material was developed for the determination of trace dimethylamine in air samples based on the catalytic chemiluminescence (CL) of dimethylamine on the surface of ZrO₂ nanoparticles. The CTL characteristics and the different factors on the signal intensity for the sensor, including nanomaterials, working temperature, wavelength and airflow rate, were investigated in detail. The CL intensity on ZrO₂ nanoparticles was the strongest among the seven examined catalysts. This novel CL sensor showed high sensitivity and selectivity to gaseous dimethylamine at optimal temperature of 330°C. Quantitative analysis was performed at a wavelength of 620 nm. The linear range of CTL intensity vs concentration of gaseous dimethylamine was 4.71 × 10^?3 to 7.07 × 10^?2 mg L^?1 (r = 0.9928) with a detection limit (3σ) of 6.47 × 10^?4 mg L^?1. No or only very low levels of interference were observed while the foreign substances such as benzene, hydrochloric acid, methylbenzene, chloroform, n‐hexane and water vapor were passing through the sensor. The response time of the sensor was less than 50 s, and the sensor had a long lifetime of more than 60 h. The sensor was successfully applied to the determination of dimethylamine in artificial air samples, and could potentially be applied to analysis of nerve agents such as Tabun (GA). Copyright © 2009 John Wiley & Sons, Ltd.     

A novel nanobiocomposite based glucose biosensor using neutral red functionalized carbon nanotubes

The performance of a new glucose biosensor based on the combination of biocatalytic activity of glucose oxidase (GOx) with the electrocatalytic properties of CNTs and neutral red (NR) for the determination of glucose is described. This sensor is comprised of a multiwalled carbon nanotubes (MWNTs) conduit functionalized with NR and Nafion (Nf) as a binder and glucose oxidase as a biocatalyst. Neutral red was covalently immobilized on carboxylic acid groups of the CNTs via carbodiimide reaction. The functionalized MWNTs were characterized by microscopic, spectroscopic and thermal methods. The MWNT-NR-GOx-Nf nanobiocomposite was prepared by mixing the GOx solution with NR functionalized CNTs followed by mixing homogeneously with Nafion. The performance of the MWNT-NR-GOx-Nf nanobiocomposite modified electrode was examined by electrochemical impedance spectroscopy and cyclic voltammetry. The catalytic reduction of hydrogen peroxide liberated from the enzymatic reaction of glucose oxidase upon glucose with NR functionalized CNTs leads to the selective detection of glucose. The excellent electrocatalytic activity and the influence of nanobiocomposite film result in good characteristics such as low potential detection of glucose with a large determination range from 1 x 10(-8) to 1 x 10(-3)M with a detection limit of 3 x 10(-9)M glucose, a short response time (with 4s), good stability and anti-interferent ability. The improved electrocatalytic activity and stability made the MWNT-NR-GOx-Nf nanobiocomposite biosensor system a potential platform to immobilize different enzymes for other bioelectrochemical applications.     

A novel glucose biosensor based on the immobilization of glucose oxidase onto gold nanoparticles-modified Pb nanowires

A novel glucose biosensor was developed, based on the immobilization of glucose oxidase (GOD) with cross-linking in the matrix of bovine serum albumin (BSA) on a Pt electrode, which was modified with gold nanoparticles decorated Pb nanowires (GNPs-Pb NWs). Pb nanowires (Pb NWs) were synthesized by an l-cysteine-assisted self-assembly route, and then gold nanoparticles (GNPs) were attached onto the nanowire surface through –SH–Au specific interaction. The morphological characterization of GNPs-Pb NWs was examined by transmission electron microscopy (TEM). Cyclic voltammetry and chronoamperometry were used to study and to optimize the electrochemical performance of the resulting biosensor. The synergistic effect of Pb NWs and GNPs made the biosensor exhibit excellent electrocatalytic activity and good response performance to glucose. The effects of pH and applied potential on the amperometric response of the biosensor have been systemically studied. In pH 7.0, the biosensor showed the sensitivity of 135.5 μA mM⁻¹ cm⁻², the detection limit of 2 μM (S/N = 3), and the response time <5 s with a linear range of 5–2200 μM. Furthermore, the biosensor exhibits good reproducibility, long-term stability and relative good anti-interference.