Copper oxide nanoparticles and ionic liquid modified carbon electrode for the non-enzymatic electrochemical sensing of hydrogen peroxide

The direct electrocatalytic reduction of hydrogen peroxide in alkaline medium at a carbon ionic liquid electrode modified with copper oxide nanoparticles was investigated. The electrode was prepared by mixing graphite particles, ionic liquid (n-octylpyridium hexafluorophosphate) and copper oxide nanoparticles. Unlike the film-modified electrode, the fabrication of this electrode is simple and highly reproducible. The combination of the good conductivity of the ionic liquid and the high catalytic activity of the nanoparticles resulted in an electrode with attractive properties for the determination of hydrogen peroxide. The concentration of NaOH and the loading of copper oxide nanoparticles were optimized. The linear range for the determination of hydrogen peroxide is from 1.0 μM to 2.5 mM, the detection limit is 0.5 μM. High stability, sensitivity, selectivity and reproducibility, fast response, the ease of preparation, and surface renewal made the electrode well suitable for the determination of hydrogen peroxide in real samples.     

Porous cuprous oxide microcubes for non-enzymatic amperometric hydrogen peroxide and glucose sensing

Using porous cuprous oxide (Cu₂O) microcubes, a simple non-enzymatic amperometric sensor for the detection of H₂O₂ and glucose has been fabricated. Cyclic voltammetry (CV) revealed that porous Cu₂O microcubes exhibited a direct electrocatalytic activity for the reduction of H₂O₂ in phosphate buffer solution and the oxidation of glucose in an alkaline medium. The non-enzymatic amperometric sensor used in the detection of H₂O₂ with detection limit of 1.5 × 10^?6 M over wide linear detection ranges up to 1.5 mM and with a high sensitivity of 50.6 μA/mM. This non-enzymatic voltammetric sensor was further utilized in detection of glucose with a detection limit of 8.0 × 10^?7 M, a linear detection range up to 500 μM and with a sensitivity of ?70.8 μA/mM.     

Electrochemical sensing of hydrogen peroxide using metal nanoparticles: a review

We are reviewing the state of electrochemical sensing of H₂O₂ based on the use of metal nanoparticles. The article is divided into subsections on sensors based on nanoparticles made from Ag, Pt, Pd, Cu, bimetallic nanoparticles and other metals. Some sensors display high sensitivity, fast response, and good stability. The review is subdivided into sections on sensors based on heme proteins and on nonenzymatic sensors. We also discussed the challenges of nanoscaled sensors and their future aspects.

A facile one-pot interfacial synthesis of Pt nanoparticles/polypyrrole composites and their application for non-enzymatic sensing hydrogen peroxide

Pt nanoparticles (PtNPs)/polypyrole (PPy) composites were successfully prepared through a facile one-pot interfacial polymerization of pyrrole by using H₂PtCl₆ as the oxidant for the first time. The as-prepared PPy was granular particles with particle size within a few hundred nanometers, on which PtNPs (1.7–3.5) nm were homogeneously dispersed. The PtNPs/PPy composites displayed excellent electrocatalytic activity toward redox of H₂O₂. The non-enzyme sensor constructed with PtNPs/PPy composites displayed good sensing ability toward H₂O₂ at ?0.1 V with a significantly high sensitivity of 6056 μAmM^?1cm^?2 and a low detection limit of 1.8 μM (S/N = 3).     

Gold nanoparticles decorated carbon fiber mat as a novel sensing platform for sensitive detection of Hg(II)

The three-dimensional fibril-like carbon fiber mat electrode (CFME) decorated with Au nanoparticles (AuNPs) was employed to construct Hg(II) sensing platform for the first time. The highly porous feature of CFME combining the high affinity of AuNPs for mercury endowed the sensing platform with high sensitivity and good reproducibility. Under optimal conditions, the prepared AuNPs/CFME was capable of sensing Hg(II) with a detection limit of 0.1 μg L^− 1 (S/N = 3) using differential pulse anodic stripping voltammetry (DPASV). Finally, the AuNPs/CFME was successfully demonstrated for the determination of Hg(II) in real water samples with satisfactory results.     

Direct growth of MnOOH nanorod arrays on a carbon cloth for high-performance non-enzymatic hydrogen peroxide sensing

Novel MnOOH nanorod arrays directly growing on a flexible carbon cloth substrate (MnOOH/CC) is first synthesized through a facile hydrothermal technique and utilized as an electrocatalyst for non-enzymatic detection of hydrogen peroxide. The as-prepared MnOOH nanorods are uniformly distributed on the carbon cloth with a 3D porous network structure, which provides a high specific surface area and numerous electroactive sites. The electrode based on the carbon cloth-supported MnOOH nanorod arrays exhibits a higher sensitivity (692.42 μA mM⁻¹ cm⁻²) and a wider linear range (20 μm–9.67 mM) with a detection limit of 3.2 μM (S/N = 3) compared with the electrode based on the rigid graphite substrate supported the random distributed MnOOH nanorods. Further, the MnOOH/CC possesses an outstanding flexibility and can conveniently be assembled into the required shape for a specific use, thus the arc-shaped MnOOH/CC electrodes are fabricated whose electrocatalytic activity toward the hydrogen peroxide reduction remains nearly unchanged in comparison with the unbent state. Due to its excellent sensitivity, reproducibility, anti-interference and stability, the electrode based on the carbon cloth-supported MnOOH nanorod arrays is believed to be promising for applications in high efficiency flexible hydrogen peroxide sensing.     

Carbon nanofibers decorated with poly(furfuryl alcohol)-derived carbon nanoparticles and tetraethylorthosilicate-derived silica nanoparticles

The present paper introduces a novel method to functionalize nanofiber surfaces with carbon or silica nanoparticles by dip coating. This novel approach holds promise of significant benefits because dip coating of electrospun and carbonized nanofiber mats in poly(furfuryl alcohol) (abbreviated as PFA) is used to increase surface roughness by means of PFA-derived carbon nanoparticles produced at the fiber surface. Also, dip coating in tetraethylorthosilicate (abbreviated as TEOS) is shown to be an effective method for decorating carbon nanofibers with TEOS-derived silica nanoparticles at their surface. Furthermore, dip coating is an inexpensive technique which is easier to implement than the existing methods of nanofiber decoration with silica nanoparticles and results in a higher loading capacity. Carbon nanofiber mats with PFA- or TEOS-decorated surfaces hold promise of becoming the effective electrodes in fuel cells, Li-ion batteries and storage devices.     

Hydrothermal and plasma nitrided electrospun carbon nanofibers for amperometric sensing of hydrogen peroxide

Microchimica Acta - A fluorometric method is presented for sensitive deternination of microRNA. It is making use of carbon dots (C-dots) loaded with a DNA probe as fluorophore and MnO2 nanosheets...     

Non-enzymatic hydrogen peroxide sensor based on a nanoporous gold electrode modified with platinum nanoparticles

A novel non-enzymatic electrochemical sensor based on a nanoporous gold electrode modified with platinum nanoparticles was constructed for the determination of hydrogen peroxide (H₂O₂). Platinum nanoparticles exhibit good electrocatalytic activity towards hydrogen peroxide. The nanoporous gold (NPG) increases the effective surface area and has the capacity to promote electron-transfer reactions. With electrodeposition of Pt nanoparticles (NPs) on the surface of the nanoporous gold, the modified Au electrode afforded a fast, sensitive and selective electrochemical method for the determination of H₂O₂. The linear range for the detection of H₂O₂ was from 1.0 × 10^?7 M to 2.0 × 10^?5 M while the calculated limit of detection was 7.2 × 10^?8 M on the basis of the 3σ/slope (σ represents the standard deviation of the blank samples). These findings could lead to the widespread use of electrochemical sensors to detect H₂O₂.     

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.

Recent advances in electrochemical sensing for hydrogen peroxide: a review

Due to the significance of hydrogen peroxide (H(2)O(2)) in biological systems and its practical applications, the development of efficient electrochemical H(2)O(2) sensors holds a special attraction for researchers. Various materials such as Prussian blue (PB), heme proteins, carbon nanotubes (CNTs) and transition metals have been applied to the construction of H(2)O(2) sensors. In this article, the electrocatalytic H(2)O(2) determinations are mainly focused on because they can provide a superior sensing performance over non-electrocatalytic ones. The synergetic effect between nanotechnology and electrochemical H(2)O(2) determination is also highlighted in various aspects. In addition, some recent progress for in vivo H(2)O(2) measurements is also presented. Finally, the future prospects for more efficient H(2)O(2) sensing are discussed.     

Determination of hydrogen peroxide and glucose using a novel sensor platform based on Co0.4Fe0.6LaO3 nanoparticles

We report on a novel nonenzymatic sensor platform for the determination of hydrogen peroxide and glucose. It is based on a carbon paste electrode that was modified with Co_0.4Fe_0.6LaO₃ nanoparticles synthesized by the sol–gel method. The structure and morphology of Co_0.4Fe_0.6LaO₃ nanoparticles were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The electrochemical performance of this sensor was evaluated by cyclic voltammetry and amperometry, and the results demonstrated that it exhibits strong electrocatalytical activity towards the oxidation of H₂O₂ and glucose in an alkaline medium. The sensor has a limit of detection as low as 2.0 nM of H₂O₂ and a linear range that extends from 0.01 to 800 μM. The response to glucose is characterized by two analytical ranges of different slope, viz. from 0.05 to 5 μM and from 5 to 500 μM, with a 10 nM limit of detection. The glucose sensor has a fast response and good long term stability.

Glassy carbon electrode modified with gold nanoparticles and hemoglobin in a chitosan matrix for improved pH-switchable sensing of hydrogen peroxide

Hemoglobin (Hb) has been demonstrated to endow electrochemical sensors with pH-switchable response because of the presence of carboxyl and amino groups. Hb was deposited in a chitosan matrix on a glassy carbon electrode (GCE) that was previously coated with clustered gold nanoparticles (Au-NPs) by electrodeposition. The switching behavior is active (“on”) to the negatively charged probe [Fe(CN)₆ ³⁻] at pH 4.0, but inactive (“off”) to the probe at pH 8.0. This switch is fully reversible by simply changing the pH value of the solution and can be applied for pH-controlled reversible electrochemical reduction of H₂O₂ catalyzed by Hb. The modified electrode was tested for its response to the different electroactive probes. The response to these species strongly depends on pH which was cycled between 4 and 8. The effect is also attributed to the presence of pH dependent charges on the surface of the electrode which resulted in either electrostatic attraction or repulsion of the electroactive probes. The presence of Hb, in turn, enhances the pH-controllable response, and the electrodeposited Au-NPs improve the capability of switching. This study reveals the potential of protein based pH-switchable materials and also provides a simple and effective strategy for fabrication of switchable chemical sensors as exemplified in a pH-controllable electrode for hydrogen peroxide.

A pH “on-off” switchable nanobiosensor was fabricated by casting a chitosan-hemoglobin biocomposite onto nano-gold electrode. This composite film exhibits not only excellent pH-responsive on (pH 4.0)-off (pH 8.0) behavior but also excellent pH-tunable on-off bioelectrocatalysis of H₂O₂.

     

A glassy carbon electrode modified with SnO2 nanofibers,polyaniline and hemoglobin for improved amperometric sensing of hydrogen peroxide

Microchimica Acta - The authors describe a glassy carbon electrode (GCE) modified with a multiporous nanofibers prepared from SnO2, polyaniline and hemoglobin, and its application to the...     

A non-enzymatic sensor for hydrogen peroxide based on polyaniline, multiwalled carbon nanotubes and gold nanoparticles modified Au electrode

We describe the construction of a polyaniline (PANI), multiwalled carbon nanotubes (MWCNTs) and gold nanoparticles (AuNPs) modified Au electrode for determination of hydrogen peroxide without using peroxidase (HRP). The AuNPs/MWCNT/PANI composite film deposited on Au electrode was characterized by Scanning Electron Microscopy (SEM) and electrochemical methods. Cyclic voltammetric (CV) studies of the electrode at different stages of construction demonstrated that the modified electrode had enhanced electrochemical oxidation of H(2)O(2), which offers a number of attractive features to develop amperometric sensors based on split of H(2)O(2). The amperometric response to H(2)O(2) showed a linear relationship in the range from 3.0 μM to 600.0 μM with a detection limit of 0.3 μM (S/N = 3) and with high sensitivity of 3.3 mA μM(-1). The sensor gave accurate and satisfactory results, when employed for determination of H(2)O(2) in milk and urine.     

Integration of a nanoporous platinum thin film into a microfluidic system for non-enzymatic electrochemical glucose sensing.

In this paper, we describe an amperometric-type enzymeless glucose sensing system based on a nanoporous platinum (Pt) electrode embedded in a microfluidic chip. This microchip system is comprised of a microfluidic transport channel network and a miniaturized electrochemical cell for nonenzymatic glucose sensing. Sample and buffer solutions were transferred to the cell by programmed electroosmotic flow (EOF). A nanoporous Pt electrode with the roughness factor of 200.6 was utilized to determine glucose concentrations in phosphate buffered saline (PBS) by the direct oxidation of glucose, without any separation process. The sensitivity of the developed system is 1.65 microA cm-2 mM-1 in the glucose concentration range from 1-10 mM in PBS.     

Highly sensitive hydrogen peroxide sensor based on a glassy carbon electrode modified with platinum nanoparticles on carbon nanofiber heterostructures

We are presenting a sensor for hydrogen peroxide (H₂O₂) that is based on the use of a heterostructure composed of Pt nanoparticles (NPs) and carbon nanofibers (CNFs). High-density Pt NPs were homogeneously loaded onto a three-dimensional nanostructured CNF matrix and then deposited in a glassy carbon electrode (GCE). The resulting sensor synergizes the advantages of the conducting CNFs and the nanoparticle catalyst. The porous structure of the CNFs also favor the high-density immobilization of the NPs and the diffusion of water-soluble molecules, and thus assists the rapid catalytic oxidation of H₂O₂. If operated at a working voltage of −0.2 V (vs. Ag/AgCl), the modified GCE exhibits a linear response to H₂O₂ in the 5 μM to 15 mM concentration range (total analytical range: 5 μM to 100 mM), with a detection limit of 1.7 μM (at a signal-to-noise ratio of 3). The modified GCE is not interfered by species such as uric acid and glucose. Its good stability, high selectivity and good reproducibility make this electrode a valuable tool for inexpensive amperometric sensing of H₂O₂.

The Pt NPs/CNF heterostructure-based H₂O₂ sensor synergizes the advantages of both the conducting carbon nanofibers and the nanoparticle catalyst. The 3D structure of the nanofibers favor high density immobilization of the nanoparticles and penetration by water-soluble molecules, which assists the catalyic oxidation of H₂O₂. The sensor shows outstanding performance in terms of detection range, detection limit, response time, stability and selectivity.

     

Preparation and characterization of size-controlled silver nanoparticles decorated multi-walled carbon nanotubes and their electrocatalytic reduction properties for hydrogen peroxide

The well dispersed and size-controlled Ag nanoparticles decorated multi-walled carbon nanotubes (MWCNT) were synthesized by a simple chemical plating method. The oxidized MWCNT surfaces could get a more controlled and specific nucleation of Ag nanoparticles. The as-prepared nanocomposites were characterized by transmission electron microscopy, X-ray diffraction and cyclic voltammetry. Randles-Sevcik plot suggested that the reaction of the nanocomposites in alkaline solution was a diffusion-controlled process. The electrocatalytic reduction property toward H₂O₂ was also studied.