Wiring horseradish peroxidase on gold nanoparticles-based nanostructured polymeric network for the construction of mediatorless hydrogen peroxide biosensor

Gold electrodes were functionalized with an electropolymerized matrix of Au nanoparticles modified with 2-mercaptoethanesulfonic acid, 3-mercaptophenyl boronic acid and p-aminothiophenol. The resulting nanostructured electroconductive matrix was used as support for the oriented immobilization of horseradish peroxidase to construct a reagentless amperometric biosensor for H₂O₂. The electrode, poised at 0.0 mV, exhibited a rapid response within 8 s and a linear calibration range from 5 μM to 1.1 mM H₂O₂. The sensitivity of the biosensor was determined as 498 μA/M cm², and its detection limit was 1.5 μM H₂O₂ at a signal-to-noise ratio of 3. The electrode retained 95% and 72% of its initial activity after 21 and 40 days of storage at 4 °C.     

Amperometric biosensor for nitrite and hydrogen peroxide based on hemoglobin immobilized on gold nanoparticles/polythionine/platinum nanoparticles modified glassy carbon electrode

BACKGROUND: This paper describes a convenient and effective strategy to construct a highly sensitive amperometric biosensor for nitrite (NO₂^?) and hydrogen peroxide (H₂O₂). First, Pt nanoparticles (PtNPs) were electrodeposited on a glassy carbon electrode (GCE) surface, which promoted electron transfer and enhanced the loading of poly‐thionine (PTH). Subsequently, thionine (TH) was electropolymerized on the PtNPs/GCE, and gold nanoparticles (AuNPs) were assembled onto the PTH film to improve the absorption capacity of hemoglobin (Hb) and further facilitate electron transfer. Finally, Hb was immobilized onto the electrode through the AuNPs. RESULTS: Cyclic voltammetry (CV) and scanning electron microscopy (SEM) were used to characterize the fabrication process of the sensing surface. Under optimum conditions, the biosensors can be used for the determination of NO₂^? in the concentration range 70 nmol L^?1 to 1.2 mmo L^?1 and of H₂O₂ in the range 4.9 µmol L^?1 to 6.8 mmol L^?1. The detection limits (S/N = 3) were 20 nmol L^?1 and 1.4 µmol L^?1, respectively. CONCLUSION: The biosensor exhibits good analytical performance, acceptable stability and good selectivity. Copyright © 2011 Society of Chemical Industry     

Direct electrochemistry of catalase at amine-functionalized graphene/gold nanoparticles composite film for hydrogen peroxide sensor

Direct electrochemistry and electrocatalysis of catalase (Cat) was studied based on a nano-composite film consisting of amine functionalized graphene and gold nanoparticles (AuNPs) modified glassy carbon electrode. Graphene was synthesized chemically by Hummers and Offeman method and then was functionalized with amino groups via chemical modification of carboxyl groups introduced on the graphene surface. The nano-composite film showed an obvious promotion of the direct electron transfer between Cat and the underlying electrode, which attributed to the synergistic effect of graphene-NH₂ and AuNPs. The resultant bioelectrode retained its biocatalytic activity and offered fast and sensitive H₂O₂ quantification. Under the optimized experimental conditions, hydrogen peroxide was detected in the concentration range from 0.3 to 600 μM with a detection limit of 50 nM at S/N = 3. The biosensor exhibited some advantages, such as short time respond (2 s), high sensitivity (13.4 μA/mM) and good reproducibility (RSD = 5.8%).     

Fabrication of cubic PtCu nanocages and their enhanced electrocatalytic activity towards hydrogen peroxide

Cubic PtCu nanocages (NCs) were successfully synthesized through a redox reaction using cuprous oxide (Cu₂O) as a sacrificial template and reducing agent. The porous PtCu NCs were composed of amounts of PtCu nanograins with an average particle size of 2.9 nm. The electrocatalytic performance of the PtCu NC electrode towards H₂O₂ was studied by cyclic voltammetry (CV) and chronoamperometry. The prepared PtCu NC electrode exhibited excellent electrocatalytic activity towards H₂O₂, with a wide liner range from 5 μM to 22.25 mM, a relatively high sensitivity of 295.3 μA mM^-1 cm^-2, and a low detection limit of 5 μM (S/N = 3). The hollow porous nanostructure has potential applications in biosensors.     

A hydrogen peroxide sensor based on electrochemically roughened silver electrodes

Silver (Ag) electrodes were roughened by electrochemical oxidation-reduction cycles (ORC) in a KCl solution. The roughened Ag electrode exhibited a powerful electrocatalytic activity for the reduction of hydrogen peroxide (H₂O₂). Atomic force microscopy and electrochemical experiments confirmed that the electrocatalytic ability mainly resulted from the Ag nanoparticles produced in the process of ORC on the roughened Ag electrode. The electrochemical behaviors of the roughened Ag electrodes toward the reduction of H₂O₂ and the factors related to that reduction were investigated in detail.     

A hydrogen peroxide sensor based on a horseradish peroxidase/polyaniline/carboxy-functionalized multiwalled carbon nanotube modified gold electrode

We have developed a polyaniline/carboxy-functionalized multiwalled carbon nanotube (PAn/MWCNTCOOH) nanocomposite by blending the emeraldine base form of polyaniline (PAn) and carboxy-functionalized multiwalled carbon nanotubes (MWCNT) in dried dimethyl sulfoxide (DMSO) at room temperature. The conductivity of the resulting PAn/MWCNTCOOH was 3.6 × 10⁻³ S cm⁻¹, mainly as a result of the protonation of the PAn with the carboxyl group and the radical cations of the MWCNT fragments. Horseradish peroxidase (HRP) was immobilized within the PAn/MWCNTCOOH nanocomposite modified Au (PAn/MWCNTCOOH/Au) electrode to form HRP/PAn/MWCNTCOOH/Au for use as a hydrogen peroxide (H₂O₂) sensor. The adsorption between the negatively charged PAn/MWCNTCOOH nanocomposite and the positively charged HRP resulted in a very good sensitivity to H₂O₂ and an increased electrochemically catalytical current during cyclic voltammetry. The HRP/PAn/MWCNTCOOH/Au electrode exhibited a broad linear response range for H₂O₂ concentrations (86 μM–10 mM). This sensor exhibited good sensitivity (194.9 μA mM⁻¹ cm⁻²), a fast response time (2.9 s), and good reproducibility and stability at an applied potential of −0.35 V. The construction of the enzymatic sensor demonstrated the potential application of PAn/MWCNTCOOH nanocomposites for the detection of H₂O₂ with high performance and excellent stability.     

A nonenzymatic hydrogen peroxide sensor based on Pt/PPy hollow hybrid microspheres

The surface of silica particles was NH₂? functionalized by 3‐aminopropyltrimethoxysilane, then the platinum/polypyrrole hybrid hollow microspheres were prepared by treating the SiO₂ template decorated by the H₂PtCl₆ via the NH₂? group with pyrrole vapor and developed as hydrogen peroxide (H₂O₂) sensor. The platinum/polypyrrole hybrid hollow sphere materials were characterized by transmission electron microscopy and infrared spectroscopy, and the catalytic electrodes were investigated by electrochemical method. The results showed that the nonenzymatic sensor displayed a good electro‐catalytic response and high sensitivity to the oxidation of H₂O₂, and the resulting sensor showed a wide linear range from 1.9 to 9.7 mM H₂O₂. The obvious response could be still observed in i–t curve when the concentration of H₂O₂ was as low as 1.0 μM. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A hydrogen peroxide electrochemical sensor based on silver nanoparticles decorated silicon nanowire arrays

The ordered H-terminated Si nanowire (SiNW) arrays via electroless etching method are capable of reducing silver ions, leading to the deposition of Ag nanoparticles (AgNPs) on SiNW. The AgNPs decorated SiNW arrays are directly fabricated into a novel sensor for the detection of hydrogen peroxide in phosphate buffered solutions. The results of electrochemical experiments reveal that such constructed sensor has a fast amperometric sensing, low detection limit and wide linear responding range as well as high sensitivity. Our results indicate that the AgNPs decorated SiNW arrays with favorable electrocatalytic performance are very promising for the future development of non-enzymatic hydrogen peroxide sensors.     

Non-enzymatic hydrogen peroxide detection using gold nanoclusters-modified phosphorus incorporated tetrahedral amorphous carbon electrodes

Sensitive electrochemical electrodes for hydrogen peroxide (H₂O₂) detection were developed using gold nanoclusters (NCs) to modify phosphorus incorporated tetrahedral amorphous carbon films (ta-C:P/Au). Au oxide covered Au NCs were electrodeposited on ta-C:P surfaces, and the size of Au/AuO_x NCs ranged between 50 nm and 91 nm, depending on the deposition time. The ta-C:P/Au electrodes exhibited higher electrocatalytic activity towards H₂O₂ oxidation compared to ta-C:P electrodes. This is due to the three-dimensional island structure of Au/AuO_x NCs, which accelerates electron exchange between ta-C:P and H₂O₂ in phosphate buffered solution. We also found that ta-C:P/Au electrodes with Au/AuO_x NCs of a smaller size and moderate coverage exhibited larger current response to H₂O₂ oxidation. The results obtained from amperometric response curves indicated that the use of Au/AuO_x NCs as microelectrodes directly favored H₂O₂ oxidation through hemispherical diffusion. The linear detection range of H₂O₂ at the non-enzymatic ta-C:P/Au electrodes was identified to be between 0.2 μM and 1 mM with a detection limit of 80 nM under optimized conditions. These ta-C:P/Au electrodes have potential applications in H₂O₂ sensing due to their high sensitivity, fast response and long-term stability.     

Electrocatalytic reduction of hydrogen peroxide at nanostructured copper modified electrode

The electrocatalytic reduction of hydrogen peroxide (H₂O₂) has been studied at nanostructured copper (Cu_nano) modified glassy carbon (GC/Cu_nano) electrode in phosphate buffer (pH 7.2). The electrical properties of GC/Cu_nano modified electrodes were studied by electrochemical impedance spectroscopy (EIS). Surface and electrochemical characterization were carried out by using atomic force microscopy (AFM) and cyclic voltammetry. A well-defined H₂O₂ reduction signal, which is due to mediation of a surface active site redox transition exhibits at the GC/Cu_nano electrode. The Cu_nano is acting as a bridge without the aid of any other electron mediator, which enables the direct electron transfer between the modified electrode and the substrate. The results are compared with bulk copper macroelectrode and emphasized the efficiency of the Cu_nano modified electrode. Systematic investigations were made to optimize the experimental parameter, such as applied potential (E_app) for copper electrodeposition. The calibration curve obtained from chronoamperometric studies was found to be linear in the range 0.5 to 8.0 μM H₂O₂ with a detection limit of ca.10 nM (S/N = 3) at the GC/Cu_nano electrode. The modified electrode is stable for 1 week in phosphate buffer after repetitive measurements.     

Magnetite–graphene for the direct electrochemistry of hemoglobin and its biosensing application

Magnetite–graphene (Fe₃O₄–GE) was prepared via a simple effective chemical precipitation method, followed by the chemical reduction with hydrazine. Fe₃O₄–GE was characterized by Raman spectroscopy, transmission electron microscope, X-ray powder diffraction and electrochemical methods. A hydrogen peroxide (H₂O₂) biosensor was structured by immobilizing hemoglobin (Hb) into Fe₃O₄–GE for the first time. UV–vis and Fourier transform infrared spectra were employed to characterize Hb retained original structure in the resulting Hb–Fe₃O₄–GE membrane. Electrochemical investigation of the biosensor showed a pair of well-defined, quasi-reversible redox peaks with E_pa = −0.285 V and E_pc = −0.363 V (vs. SCE) in phosphate buffer solution (0.1 mol/L, pH 7.0) at the scan rate of 100 mV/s. The Hb–Fe₃O₄–GE showed a better synergistic electrochemical effect for the reduced process of H₂O₂. The biosensor displayed a fast response time (<3 s) and broad linear response to H₂O₂ in the range from 1.50 to 585 μmol/L with a relatively low detection limit of 0.5 μmol/L (S/N = 3). Moreover, the biosensor could be applied in practical analysis and exhibit good reproducibility and long-term stability.     

Direct synthesis of hydrogen peroxide from H2 and O2 using zeolite-supported Au-Pd catalysts

The direct synthesis of hydrogen peroxide from H₂ and O₂ using zeolite-supported Au-Pd catalysts is described using two zeolites, ZSM-5 and zeolite Y, using an impregnation method of preparation. The addition of Pd to Au for these catalysts significantly enhances the productivity for hydrogen peroxide. The use of zeolites as a support for Au-Pd gives higher rates of hydrogen peroxide formation when compared with alumina-supported Au catalysts prepared using a similar method. The addition of metals other than Pd is also investigated, but generally Au-Pd catalysts give the highest activity for the synthesis of hydrogen peroxide. The addition of Ru and Rh have no significant effect, but the addition of Pt does enhance the activity for the selective formation of hydrogen peroxide.     

Direct synthesis of hydrogen peroxide from H2 and O2 using zeolite-supported Au catalysts

The direct synthesis of hydrogen peroxide from H₂ and O₂ using zeolite-supported Au catalysts is described and their activity is contrasted with silica- and alumina-supported Au catalysts. Two zeolites were investigated, ZSM-5 and zeolite Y. The effect of calcination of these catalysts is studied and it is found that for uncalcined catalysts high rates of hydrogen peroxide formation are observed, but these catalysts are unstable and lose Au during use. Consequently, reuse of these catalysts leads to lower rates of hydrogen peroxide formation. However, catalysts calcined at 400 °C are more stable and can be reused without loss of gold. The use of zeolites as a support for Au gives comparable rates of hydrogen peroxide formation to alumina-supported Au catalysts and higher rates when compared with silica-supported catalysts. prepared using a similar method. Zeolite Y-supported catalysts are more active than ZSM-5-supported catalysts for the stable calcined materials. It is considered that the overall activity of these supported catalysts may be related to the aluminium content as the activity increases with increasing aluminium content.     

Catalytic reduction of hydrogen peroxide at metal hexacyanoferrate composite electrodes and applications in enzymatic analysis

The electrocatalytic activity of various metal hexacyanoferrates (Mhcfs) (i) immobilized on graphite electrodes, and (ii) as components of a composite electrode was investigated with respect to the reduction of hydrogen peroxide. The flow-through working electrode was a thin layer consisting of a composite of Mhcf, graphite, and polymethylmetacrylate (PMMA) as a binder, sandwiched between two Plexiglas plates. Among the pure Mhcfs immobilized on a graphite electrode, iron(III) hexacyanoferrate (Prussian blue) exhibits the highest electrocatalytic effect, whereas in the composite electrodes chromium(III) hexacyanoferrate (Crhcf) shows the highest activity and best performance and reproducibility for the electrochemical reduction of H₂O₂. The Crhcf electrode provides a linear dependence on H₂O₂ concentration in the range 2.5 × 10⁻⁶ mol L⁻¹ (LOD) to 1 × 10⁻⁴ mol L⁻¹ (phosphate buffer, pH 7). The sensor was applied for the detection of H₂O₂ enzymatically produced by glucose oxidase. The optimal conditions for the peroxide injection were 2 min after the beginning of the reaction and 25 °C with a detection limit of 7.0 × 10⁻⁶ mol L⁻¹ for glucose.     

Electrochemical oxidation of hydrogen peroxide at nanoporous platinum electrodes and the application to glutamate microsensor

The electrochemical behavior of hydrogen peroxide (H₂O₂) at nanoporous platinum (Pt) thin film was investigated and the reaction of the enzymes immobilized on the electrode was examined. The nanoporous Pt underlying the enzyme layer was electrochemically deposited on Pt-Ir alloy microelectrodes in the solution consisting of hexachloroplatinic acid and a non-ionic surfactant, octaethylene glycol monohexadecyl ether (C₁₆EO₈). Glutamate oxidases were entrapped during electro-polymerization of 1,3-phenylenediamine on the nanoporous Pt microelectrodes to form a glutamate oxidase layer. The glutamate microsensors as made were compared with flat Pt-based one in terms of the performance and characteristics.     

Electrocatalytic oxidation and simultaneous determination of uric acid and ascorbic acid on the gold nanoparticles-modified glassy carbon electrode

A new gold nanoparticles-modified electrode (GNP/LC/GCE) was fabricated by self-assembling gold nanoparticles to the surface of the l-cysteine-modified glassy carbon electrode. The modified electrode showed an excellent character for electrocatalytic oxidization of uric acid (UA) and ascorbic acid (AA) with a 0.306 V separation of both peaks, while the bare GC electrode only gave an overlapped and broad oxidation peak. The anodic currents of UA and AA on the modified electrode were 6- and 2.5-fold to that of the bare GCE, respectively. Using differential pulse voltammetry (DPV), a highly selective and simultaneous determination of UA and AA has been explored at the modified electrode. DPV peak currents of UA and AA increased linearly with their concentration at the range of 6.0 × 10⁻⁷ to 8.5 × 10⁻⁴ mol L⁻¹ and 8.0 × 10⁻⁶ to 5.5 × 10⁻³ mol L⁻¹, respectively. The proposed method was applied for the detection of UA and AA in human urine with satisfactory result.     

A novel amperometric sensor for peracetic acid based on a polybenzimidazole–modified gold electrode

We have developed a peracetic acid (PAA) sensor based on a polybenzimidazole–modified gold (PBI/Au) electrode. Fourier transform infrared and X-ray photoelectron spectroscopy indicated that PAA oxidized 69.4% of the imine in PBI to form PBI N-oxide, increasing the electrochemical reduction current during cyclic voltammetry. The chemical oxidation of the PBI/Au electrode by PAA, followed by its electrochemical reduction, allowed PAA to be detected directly and consecutively by assessing its reduction current. The PAA sensor had a broad linear detection range (3.1 μM–1.5 mM) and a rapid response time (3.9 s) at an applied potential of −0.3 V. Potentially interfering substances, such as hydrogen peroxide, acetic acid, and oxygen, had no effect on the ability of the probe to detect PAA, indicating high selectivity of the probe. Furthermore, the detection range, response time, and sensitivity of the sensor could all be improved by modification of the smooth planar electrode surface to a porous three-dimensional configuration. When compared to the analytical characteristics of other PAA sensors operating under optimal conditions, the three-dimensional PBI/Au electrode offers a rapid detection time, a usable linear range, and a relatively low detection limit.     

Amperometric hydrogen peroxide biosensor based on the immobilization of horseradish peroxidase on core-shell organosilica@chitosan nanospheres and multiwall carbon nanotubes composite

The application of the composites of multiwall carbon nanotubes (MWNTs) and core-shell organosilica@chitosan crosslinked nanospheres as an immobilization matrix for the construction of an amperometric hydrogen peroxide (H₂O₂) biosensor was described. MWNTs and positively charged organosilica@chitosan nanospheres were dispersed in acetic acid solution (0.6 wt%) to achieve organosilica@chitosan/MWNTs composites, which were cast onto a glass carbon electrode (GCE) surface directly. And then, horseradish peroxidase (HRP), as a model enzyme, was immobilized onto it through electrostatic interaction between oppositely charged organosilica@chitosan nanospheres and HRP. The direct electron transfer of HRP was achieved at HRP/organosilica@chitosan/MWNTs/GCE, which exhibited excellent electrocatalytic activity for the reduction of H₂O₂. The catalysis currents increased linearly to H₂O₂ concentration in a wide range of 7.0 × 10⁻⁷ to 2.8 × 10⁻³ M, with a sensitivity of 49.8 μA mM⁻¹ cm⁻² and with a detection limit of 2.5 × 10⁻⁷ M at 3σ. A Michaelies-Menten constant value was estimated to be 0.32 mM, indicating a high-catalytic activity of HRP. Moreover, the proposed biosensor displayed a rapid response to H₂O₂ and possessed good stability and reproducibility. When used to detect H₂O₂ concentration in disinfector samples and sterilized milks, respectively, it showed satisfactory results.     

Bioelectrocatalytic and biosensing properties of horseradish peroxidase covalently immobilized on (3-aminopropyl)trimethoxysilane-modified titanate nanotubes

Titanate nanotubes (TiNT) surface modified with (3-aminopropyl)trimethoxysilane were employed as a support for covalent immobilization of horseradish peroxidase (HRP) by using 1,4-benzoquinone as a coupling agent. Composite film-electrodes consisting of HRP-modified TiNT embedded into the porous carbon powder/Nafion matrix were fabricated and their applicability in direct bioelectrocatalytic reduction of H₂O₂ and H₂O₂ biosensing were investigated. An efficient direct electron transfer between the immobilized HRP molecules and the electrode was observed in the presence of H₂O₂ at potentials lower than 600 mV (vs. Hg/Hg₂Cl₂/3.5 M KCl). For the HRP–TiNT-modified electrodes polarized at 0 mV, a linear dependence of the bioelectrocatalytic current on the concentration of H₂O₂ was observed up to the concentration of H₂O₂ equal to 10 μM, with the sensitivity of (1.10 ± 0.01) AM⁻¹ cm⁻² and the detection limit of 35 nM.