Nonenzymatic hydrogen peroxide sensor based on a glassy carbon electrode modified with electrospun PdO-NiO composite nanofibers

A glassy carbon electrode was modified with PdO-NiO composite nanofibers (PdO-NiO-NFs) and applied to the electrocatalytic reduction of hydrogen peroxide (H₂O₂). The PdO-NiO-NFs were synthesized by electrospinning and subsequent thermal treatment, and then characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Factors such as the composition and fraction of nanofibers, and of the applied potential were also studied. The sensor exhibits high sensitivity for H₂O₂ (583.43 μA?·?mM^?1?·?cm^?2), a wide linear range (from 5.0 μM to 19 mM), a low detection limit (2.94 μM at an SNR of 3), good long term stability, and is resistant to fouling.

Non-enzymatic hydrogen peroxide sensor based on a gold electrode modified with granular cuprous oxide nanowires

Granular nanowires with a diameter of about 60 nm were fabricated from cuprous oxide (Cu₂O) by an electrochemical method using anodic aluminium oxide as the template. A non-enzymatic sensor for hydrogen peroxide (H₂O₂) was then developed on the basis of a gold electrode modified with Cu₂O nanowires and Nafion. The resulting sensor enables the determination of H₂O₂ with a sensitivity of 745 μA?mM^?1?cm^?2, over a wide linear range (0.25 μM to 5.0 mM), and with a low detection limit (0.12 μM). The results demonstrate that the use of such granular nanowires provides a promising tool for the design of non-enzymatic chemical sensors.

A glassy carbon electrode modified with a film composed of cobalt oxide nanoparticles and graphene for electrochemical sensing of H2O2

We have prepared a graphene-based hybrid nanomaterial by electrochemical deposition of cobalt oxide nanoparticles (CoO_xNPs) on the surface of electrochemically reduced graphene oxide deposited on a glassy carbon electrode (GCE). Scanning electron microscopy and cyclic voltammetry were used to characterize the immobilized nanoparticles. Electrochemical determination of H₂O₂ is demonstrated with the modified GCE at pH 7. Compared to GCEs modified with CoO_xNPs or graphene sheets only, the new electrode displays larger oxidative current response to H₂O₂, probably due to the synergistic effects between the graphene sheets and the CoO_xNPs. The sensor responds to H₂O₂ with a sensitivity of 148.6 μA mM^?1 cm^?2 and a linear response range from 5 μM to 1 mM. The detection limit is 0.2 μM at a signal to noise ratio (SNR) of three. The method was successfully applied to the determination of H₂O₂ in hydrogen peroxide samples.

A silica-dextran nanocomposite as a novel matrix for immobilization of horseradish peroxidase, and its application to sensing hydrogen peroxide

We report on a novel matrix of solgel organic–inorganic nanocomposite that was fabricated from silica sol gel and dextran. It was used for the immobilization of horseradish peroxidase (HRP) to give a biosensor for hydrogen peroxide (H₂O₂). The sensor film was characterized by Fourier transform infrared and UV–vis spectroscopy with respect to structural features and the conformation of the enzyme. The topographies of the surface of the electrode were investigated by field emission scanning electron microscopy. The biosensor was used to determine H₂O₂ quantitatively in the presence of Methylene blue as a mediator with high electron transfer efficiency. A pair of stable and well defined quasi-reversible redox peaks of the HRP [Fe (III)]/HRP [Fe (II)] redox couple was observed at pH 7.0. The biosensor responds to H₂O₂ in the 0.5 mM to 16.5 mM concentration range, and the limit of detection is 0.5 mM.

Sensitive electrochemical sensor for hydrogen peroxide using Fe3O4 magnetic nanoparticles as a mimic for peroxidase

A sensor for hydrogen peroxide is described that is based on an indium tin oxide electrode modified with Fe₃O₄ magnetic nanoparticles which act as a mimic for the enzyme peroxidase and greatly improve the analytical performance of the sensor. The amperometric current is linearly related to the concentration of H₂O₂ in the range from 0.2 mM to 2 mM, the regression equation is y?=?-0.5–1.82x, the correlation coefficient is 0.998 (n?=?3), and the detection limit is 0.01 mM (S/N?=?3). The sensor exhibits favorable selectivity and excellent stability.

ITO electrode modified by a gold ion implantation technique for direct electrocatalytic sensing of hydrogen peroxide

We report on a non-enzymatic amperometric sensor for hydrogen peroxide (H₂O₂). It was fabricated by electrodeposition of multi-wall carbon nanotubes and polyaniline along with platinum nanoparticles on the surface of a glassy carbon electrode. The modification was probed by scanning electron microscopy and cyclic voltammetry. The resulting sensor exhibits a high sensitivity (748.4?μA·mM^?1·cm^?2), a wide linear range (7.0?μM–2.5?mM), a low detection limit (2.0?μM) (S/N?=?3), a short response time (>5?s), and long-term stability, and is not interfered by common species. It was successfully applied to determine H₂O₂ in disinfectants.

Nanomolar amperometric sensing of hydrogen peroxide using a graphite pencil electrode modified with palladium nanoparticles

We report on a simple and rapid method for the preparation of a disposable palladium nanoparticle-modified graphite pencil electrode (PdNP-GPE) for sensing hydrogen peroxide (H₂O₂). The bare and PdNP-modified GPEs were characterized by cyclic voltammetry and SEM. The two electrodes displayed distinct electrocatalytic activities in response to the electrochemical reduction of H₂O₂. The amperometric detection limits were 45 nM and 0.58 mM, respectively, for the PdNP-GPE and bare-GPE, at an S/N of 3. The electrodes can be prepared simply and at low cost, and represent a promising tool for sensing H₂O₂.

Carbon nanofibers decorated with platinum nanoparticles: a novel three-dimensional platform for non-enzymatic sensing of hydrogen peroxide

We have developed a 3-dimensional (3-D) electrochemical sensor for highly sensitive detection of hydrogen peroxide (H₂O₂). Porous 3-D carbon nanofibers (CNFs), prepared by electrospinning, served as scaffold on a glassy carbon electrode. The 3-D CNFs were functionalized with platinum nanoparticles (Pt-NPs) by in-situ gas-phase decomposition of platinum salts at high temperature. The Pt-NPs act as an electrocatalyst for the decomposition of H₂O₂. TEM revealed that large amounts of Pt-NPs are deposited in the electrospun CNFs electrode even without using any stabilizer or reducing reagent. The sensor was investigated by cyclic voltammetry and amperometry and displays a good response to H₂O₂ with a linear range between 10 μM and 15 mM (R?=?0.9994), a low detection limit (3.4 μM at a signal-to-noise ratio of 3), and a response time of 3 s. The sensor shows excellent stability and selectivity.

Highly sensitive detection of hydrogen peroxide at a carbon nanotube fiber microelectrode coated with palladium nanoparticles

We report on a carbon nanotube (CNT) fiber microelectrode coated with palladium nanoparticles (PdNPs) and enabling electrochemical sensing of hydrogen peroxide (H₂O₂). The synergistic effects of the CNT fibers (good mechanical strength and large surface area) and of the PdNPs (high electrocatalytic activity) result in a microelectrode for H₂O₂ that exhibits a 2-s response time, a detection limit as low as 2 μM, a sensitivity of 2.75 A cm^?2 M^?1, and a linear response range from 2 μM to 1.3 mM (R?=?0.9994). The sensor is also selective and not interfered by potentially competing species in biological fluids, thus representing an inexpensive but highly sensitive and selective microsensor for H₂O₂.

Enhanced stability of a Prussian blue/sol-gel composite for electrochemical determination of hydrogen peroxide

We have prepared a sol–gel that incorporates Prussian Blue (PB) as a redox mediator. It is shown that the PB in the pores of the sol–gel retains its electrochemical activity and is protected from degradation at acidic and neutral pH values. TEM and EDX studies revealed the PB nanoparticles to possess a cubic crystal structure and to be well entrapped and uniformly dispersed in the pores of the matrix. The electrocatalytic activity of the materials toward hydrogen peroxide (H₂O₂) was studied by cyclic voltammetry and amperometry. The modified electrode displays good sensitivity for the electrocatalytic reduction of H₂O₂ both in acidic (pH 1.4) and neutral media. The sensor has a dynamic range from 3 to 210 μM of H₂O₂, and the detection limit is 0.6 μM (at an SNR of 3).

Electrochemical determination of dioxygen and hydrogen peroxide using Fe3O4@SiO2@hemin microparticles

Iron oxide microparticles were coated with 3-aminopropyltriethoxysilane and then coated with hemin via an amidation reaction. The resulting composite particles were characterized by transmission electron microscopy. FTIR spectroscopy revealed two bands (at 1,701 and 1,634 cm^?1), which were assigned to the carboxy group and the amide linkage, respectively, resulting from the linkage between hemin and the amino-modified Fe₃O₄ particles. In addition, strong Fe-O vibrations can be observed at 563 cm^?1. An electrode was modified with these microparticles and then showed a well-defined redox behavior of the immobilized hemin, with a fast heterogeneous electron transfer process (14.5 s^?1). The electrode is capable of sensing both O₂ and H₂O₂ and displays a wide linear range, high sensitivity, and fast response. The composites reported here also may serve as a support for the immobilization of proteins, which paves the way to potential applications in novel biosensors and bioelectronic devices.

Iodide-induced adsorption of lead(II) ion on a glassy carbon electrode modified with ferroferric oxide nanoparticles

Spherical Fe₃O₄ nanoparticles (NPs) were prepared by hydrothermal synthesis and characterized by scanning electron microscopy and X-ray diffraction. A glassy carbon electrode was modified with such NPs to result in a sensor for Pb(II) that is based on the strong inducing adsorption ability of iodide. The electrode gives a pair of well-defined redox peaks for Pb(II) in pH 5.0 buffer containing 10 mM concentrations of potassium iodide, with anodic and cathodic peak potentials at ?487 mV and ?622 mV (vs. Ag/AgCl), respectively. The amperometric response to Pb(II) is linear in the range from 0.10 to 44 nM, and the detection limit is 40 pM at an SNR of 3. The sensor exhibits high selectivity and reproducibility.

New synthesis of gold nanocorals using a diazonium compound,and their application to an electrochemiluminescent assay of hydrogen peroxide

The reaction of hydrogen tetracholoroaurate, sodium borohydride and the diazonium compound prepared from 4-aminobenzoic acid results in the formation of gold nanocorals (Au-NCs) for the first time. Scanning electron microscopy images and transmission electron microscopy images show that the Au-NCs are composed of nanowires with a diameter of 5.3 nm. A glassy carbon electrode modified with Au-NCs is found to trigger intense electrochemiluminescence of the luminol/H₂O₂ system at a potential of ?0.13 V. The effect was exploited to determine H₂O₂ in the 0.1 to 100 μM concentration range with a 30 nM detection limit.

Titanium dioxide nanorod-based amperometric sensor for highly sensitive enzymatic detection of hydrogen peroxide

Titanium dioxide nanorods (TNR) were grown on a titanium electrode by a hydrothermal route and further employed as a supporting matrix for the immobilization of nafion-coated horseradish peroxidase (HRP). The strong electrostatic interaction between HRP and TNR favors the adsorption of HRP and facilitates direct electron transfer on the electrode. The electrocatalytic activity towards hydrogen peroxide (H₂O₂) was investigated via cyclic voltammetry and amperometry. The biosensor exhibits fast response, a high sensitivity (416.9 μA·mM^?1), a wide linear response range (2.5 nM to 0.46 mM), a detection limit as low as 12 nM, and a small apparent Michaelis-Menten constant (33.6 μM). The results indicate that this method is a promising technique for enzyme immobilization and for the fabrication of electrochemical biosensors.

Trans-membrane electron transfer in red blood cells immobilized in a chitosan film on a glassy carbon electrode

We have studied the trans-membrane electron transfer in human red blood cells (RBCs) immobilized in a chitosan film on a glassy carbon electrode (GCE). Electron transfer results from the presence of hemoglobin (Hb) in the RBCs. The electron transfer rate (k _s) of Hb in RBCs is 0.42 s^?1, and <1.13 s^?1 for Hb directly immobilized in the chitosan film. Only Hb molecules in RBCs that are closest to the plasma membrane and the surface of the electrode can undergo electron transfer to the electrode. The immobilized RBCs displayed sensitive electrocatalytic response to oxygen and hydrogen peroxide. It is believed that this cellular biosensor is of potential significance in studies on the physiological status of RBCs based on observing their electron transfer on the modified electrode.

One-step preparation of a composite consisting of graphene oxide, Prussian blue and chitosan for electrochemical sensing of hydrogen peroxide

We report on the single-step preparation of a composite consisting of graphene oxide (GO), Prussian blue (PB) and chitosan (Chit) that was deposited on a glassy carbon electrode and then used to determine hydrogen peroxide. The composite was obtained by mixing GO, Chit, potassium ferricyanide and ferric chloride and keeping it at 90 °C for 1 h. This method is simple and inexpensive, and does not require purification, centrifugation or sedimentation. Scanning electron microscopy, UV-vis spectroscopy, Fourier transform IR spectroscopy and X-ray diffraction were used to characterize the GO-PB-Chit composites and revealed that PB nanoparticles were formed and uniformly distributed on the surfaces of the GO due to the integrating effects of Chit and GO. The composite displayed electrocatalytic activity in the reduction of hydrogen peroxide to which it responded with good linear relationship in the 1.0 μM to 1.0 mM concentration range, with a detection limit of 0.1 μM (at S/N?=?3).

Direct electrochemistry and electrocatalysis of myoglobin using an ionic liquid-modified carbon paste electrode coated with Co3O4 nanorods and gold nanoparticles

A nanohybrid biomaterial was fabricated by mixing Co₃O₄ nanorods, gold nanoparticles (Au-NPs) and myoglobin (Mb), and depositing it on the surface of a carbon paste electrode containing the ionic liquid N-hexylpyridinium hexafluorophosphate as the binder. UV–vis and FT-IR revealed the Mb in the composite film to have remained in its native structure. A pair of well-defined redox peaks appears in cyclic voltammograms and indicates direct electron transfer from the Mb to the underlying electrode. The results are attributed to the favorable orientation of Mb in the composite film, to the synergistic effects of Co₃O₄ nanorods and Au-NPs. The modified electrode shows excellent electrocatalytic ability towards the reduction of substrates such as trichloroacetic acid and nitrite, and displays good stability and reproducibility.

Hydrogen peroxide biosensor based on direct electrochemistry of hemoglobin immobilized on gold nanoparticles in a hierarchically porous zeolite

Highly dispersed gold nanoparticles (AuNPs) were introduced into a hierarchically porous zeolite of the MFI type that contains mesopores and an inherently microporous structure. These represent a novel matrix for the immobilization of biomolecules. The composites were characterized by FTIR, X-ray diffraction, UV–vis spectroscopy, transmission electron microscopy, nitrogen sorption measurements, and electrochemical impedance spectroscopy. The crystallinity and morphology of the zeolite is not compromised by incorporating the AuNPs with their size of 3–20 nm. A sensor for hydrogen peroxide (H₂O₂) was fabricated by incorporating hemoglobin into the matrix and placing it on the surface of a glassy carbon electrode. The resulting biosensor exhibits excellent bioelectrocatalytic capability for the reduction of H₂O₂. The amperometric response at ?0.4 V linearly depends on H₂O₂ in the 1.0 μM to 18 mM concentration range. The detection limit is 0.8 μM (at an S/N of 3). Its good sensitivity, stability and reproducibility make the modified hierarchically porous zeolite a promising new matrix material for protein immobilization and the construction of biosensors.

Self-assembly of ultra-small gold nanoparticles on an indium tin oxide electrode for the enzyme-free detection of hydrogen peroxide

A novel enzyme-free electrochemical sensor for H₂O₂ was fabricated by modifying an indium tin oxide (ITO) support with (3-aminopropyl) trimethoxysilane to yield an interface for the assembly of colloidal gold. Gold nanoparticles (AuNPs) were then immobilized on the substrate via self-assembly. Atomic force microscopy showed the presence of a monolayer of well-dispersed AuNPs with an average size of ~4 nm. The electrochemical behavior of the resultant AuNP/ITO-modified electrode and its response to hydrogen peroxide were studied by cyclic voltammetry. This non-enzymatic and mediator-free electrode exhibits a linear response in the range from 3.0?×?10^?5 M to 1.0?×?10^?3 M (M?=?mol?·?L^?1) with a correlation coefficient of 0.999. The limit of detection is as low as 10 nM (for S/N?=?3). The sensor is stable, gives well reproducible results, and is deemed to represent a promising tool for electrochemical sensing.