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.

Novel Hydrogen Peroxide Biosensor Based on Hemoglobin Combined with Electrospinning Composite Nanofibers

A facile strategy to construct an amperometric biosensor was described for the determination of hydrogen peroxide (H₂O₂). This biosensor relied on an electrospinning gold nanoparticle-chitosan-poly(vinyl alcohol) composite nanofibers modified ITO electrode, followed by immobilization of hemoglobin (Hb) on the surface. The introduction of nanofibers and gold nanoparticles in the modification of electrode surface not only enhanced the surface area of the modified electrode for enzyme immobilization but also facilitated the electron transfer rate. Under optimum conditions, the sensor was characterized in terms of its morphology by scanning electron microscopy and its electroactivity by cyclic voltammetry and chronoamperometry. Scanning electron microscopy revealed that the obtained nanofibers were uniform. The chronoamperometric behavior of the modified electrode indicated that the immobilized Hb retained electrochemical activity inside the electrospinning fibrous membranes. The electrode responded linearly to H₂O₂ in a wider concentration range of 5.6 × 10^?7 M to 5.2 × 10^?2 M with a low detection limit (S/N = 3) of 1.98 × 10^?7 M and a short response time of ～4 s, suggesting a much better performance than that of other sensors. Moreover, the biosensor achieved bulk production and exhibited superior properties for the sensitive determination of H₂O₂, studied namely, long-term stability, good reproducibility, and high selectivity.     

A Novel NH2/ITO Ion Implantation Electrode: Preparation,Characterization, and Application in Bioelectrochemistry

A novel NH₂⁺ ion implantation‐modified indium tin oxide (NH₂/ITO) electrode was prepared. Acid‐pretreated, negatively charged MWNTs were firstly modified on the surface of NH₂⁺ ion implantation electrode, then, positively charged Mb was adsorbed onto MWNTs films by electrostatic interaction. The assembly of MWNTs and Mb was characterized with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The immobilized Mb showed a couple of quasireversible cyclic voltammetry peaks in pH 7.0 phosphate buffer solution (PBS). The apparent surface concentration of Mb at the electrode surface was 1.06×10^?9 mol cm^?2. The Mb/MWNTs/NH₂/ITO electrode also gave an improved electrocatalytic activity towards the reduction of hydrogen peroxide. The catalysis currents increased linearly to the H₂O₂ concentration in a wide range from 9×10^?7 to 9.2×10^?5 M with a correlation coefficient of 0.999. The detection limit was 9.0×10^?7 M. The experiment results demonstrated that the modified electrode provided a biocompatible microenvironment for protein and supplied a necessary pathway for its direct electron transfer.     

Determination of hemoglobin at a novel NH2/ITO ion implantation modified electrode

A novel electrode was prepared by implanting NH₂ ⁺ into an ITO film (NH₂/ITO). Gold nanoparticles were deposited on the surface of NH₂/ITO electrode. The NH₂/ITO and Au/NH₂/ITO electrodes were used to determine hemoglobin (Hb) immobilized on the electrodes surfaces. The relationship of the reductive peak current value of Hb among different electrodes was: Hb/ITO:Hb/Au/ITO:Hb/NH₂/ITO:Hb/Au/NH₂/ITO=1:1.5:2:4. The linkage between the –NH₂ implanted into ITO film and the –COOH of Hb was recognized to be the reason for the increase of active Hb coverage on NH₂/ITO electrode compared with the ITO electrode. Increase of active Hb coverage on Au/NH₂/ITO compared with Au/ITO was attributed to the different amount of gold nanoparticles deposited. The determination of Hb at an Au/NH₂/ITO electrode was optimized. Calibration curve was obtained over the range of 1.0 × 10⁻⁸ – 1.0 × 10⁻⁶ mol · L⁻¹ with a detection limit of 1.0 × 10⁻⁸ mol · L⁻¹. Results showed that the novel NH₂/ITO and Au/NH₂/ITO electrodes exhibited good stability, reproducibility besides better electrochemical performance. Correspondence: Jing Bo Hu, Department of Chemistry, Beijing Normal University, Beijing 100875, China     

Electrocatalysis of Horseradish Peroxidase Immobilized on Cobalt Nanoparticles Modified ITO Electrode

Abstract

It is the first time that Horseradish peroxidase (HRP) was successively immobilized on the magnetic cobalt nanoparticles modified ITO (indium tin oxide) electrode. Morphologies of electrode surface were featured by the field emission‐scanning electron microscope (FSEM). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the modified process of electrode. Direct electrochemistry and electrocatalysis of HRP immobilized on nano‐Co/ITO were investigated. The biosensor exhibited high sensitivity, good stability, and excellent electrocatalytic activity to the reduction of H₂O₂. Under the optimized experimental conditions, a calibration curve over 2.0×10^?9～2.0×10^?8 mol l^?1 and 2.0×10^?7～2.0×10^?6 mol l^?1, with a limit of detection of 1.9×10^?9 mol l^?1 was obtained. The apparent Michaelis‐Menten constant (K _M ^app ) for HRP/nano‐Co/ITO electrode was calculated to be 0.79 mmol l^?1, indicating a higher affinity of HRP attached on the modified electrode.     

A conductive crosslinked graphene/cytochrome c networks for the electrochemical and biosensing study

The direct electrochemistry of catalytically active cytochrome C (Cyt c) adsorbed together with a 3-dimensional network of chemically synthesized graphene on glassy carbon electrode has been readily obtained in aqueous phosphate buffer. Direct electrical communication between the redox center of Cyt c and the modified graphene-based electrode was established. The modified electrode was employed as a high-performance hydrogen peroxide (H₂O₂) biosensor. The Cyt c present in modified electrode exhibited a pair of quasi-reversible redox peaks with a midpoint potential of ?0.380 and ?0.2 V, cathodic and anodic, respectively. Investigations into the electrocatalytic activity of the modified electrode upon hydrogen peroxide exposure revealed a rapid amperometric response (5 s). Under optimized conditions, the linear range of response to H₂O₂ concentration ranged from 5 × 10^?7 to 2 × 10^?4 M with a detection limit of 2 × 10^?7 M at a signal-to-noise ratio of 3. The stability, reproducibility, and selectivity of the proposed biosensor are discussed in relation to the morphology and composition of the modified electrode.     

Non-enzymatic amperometric sensor for hydrogen peroxide based on a biocomposite made from chitosan, hemoglobin, and silver nanoparticles

We report on a novel non-enzymatic sensor for hydrogen peroxide (HP) that is based on a biocomposite made up from chitosan (CS), hemoglobin (Hb), and silver nanoparticles (AgNPs). The AgNPs were prepared in the presence of CS and glucose in an ultrasonic bath, and CS is found to act as a stabilizing agent. They were then combined with Hb and CS to construct a carbon paste biosensor. The resulting electrode gave a well-defined redox couple for Hb, with a formal potential of about ?0.17?V (vs. SCE) at pH?6.86 and exhibited a remarkable electrocatalytic activity for the reduction of HP. The sensor was used to detect HP by flow injection analysis, and a linear response is obtained in the 0.08 to 250?μM concentration range. The detection limit is 0.05?μM (at S/N?=?3). These characteristics, along with its long-term stability make the sensor highly promising for the amperometric determination of HP.

Direct electrochemistry of hemoglobin on graphene/Fe3O4 nanocomposite-modified glass carbon electrode and its sensitive detection for hydrogen peroxide

Graphene/Fe₃O₄ nanocomposite was prepared for the immobilization of hemoglobin (Hb) to improve the electron transfer between Hb and glass carbon electrode (GCE). The characterization of nanocomposites was described by transmission electron microscopy, Fourier transform infrared, Raman spectroscopy, and X-ray photoelectron spectroscopy, respectively. The electrochemistry of Hb on the graphene/Fe₃O₄-based GCE was investigated by cyclic voltammetry and amperometric measurement. The modified electrode showed a wide linear range from 0.25 μmol/L to 1.7 mmol/L with a correlation coefficient of 0.9967. The detection limit of the H₂O₂ biosensor was estimated at 6.0?×?10^?6?mol/L at a signal-to-noise ratio of 3.     

Direct Electrochemistry and Electrocatalysis of Hemoglobin/ZnO‐Chitosan/nano‐Au Modified Glassy Carbon Electrode

The highly efficient H₂O₂ biosensor was fabricated on the basis of the complex films of hemoglobin (Hb), nano ZnO, chitosan (CHIT) dispersed solution and nano Au immobilized on glassy carbon electrode (GCE). Biocompatible ZnO‐CHIT composition provided a suitable microenvironment to keep Hb bioactivity (Michaelis‐Menten constant of 0.075 mmol L^?1). The presence of nano Au in matrix could effectively enhance electron transfer between Hb and electrode. The electrochemical behaviors and effects of solution pH values were carefully examined in this paper. The (ZnO‐CHIT)‐Au‐Hb/GCE demonstrated excellently electrocatalytical ability for H₂O₂. This biosensor had a fast response to H₂O₂ less than 4 s and excellent linear relationships were obtained in the concentration range from1.94×10^?7 to 1.73×10^?3 mol L^?1 with the detection limit of 9.7×10^?8 mol L^?1 (S/N=3) under the optimum conditions. Moreover, the stability and reproducibility of this biosensor were evaluated with satisfactory results.     

Direct Electrochemistry and Electrocatalysis of Hemoglobin Based on Nafion‐Room Temperature Ionic Liquids‐Multiwalled Carbon Nanotubes Composite Film

A robust and effective composite film combined the benefits of Nafion, room temperature ionic liquid (RTIL) and multi‐wall carbon nanotubes (MWNTs) was prepared. Hemoglobin (Hb) was successfully immobilized on glassy carbon electrode surface by entrapping in the composite film. Direct electrochemistry and electrocatalysis of immobilized Hb were investigated in detail. A pair of well‐defined and quasi‐reversible redox peaks of Hb was obtained in 0.10 mol·L^?1 pH 7.0 phosphate buffer solution (PBS), indicating that the Nafion‐RTIL‐MWNTs film showed an obvious promotion for the direct electron transfer between Hb and the underlying electrode. The immobilized Hb exhibited an excellent electrocatalytic activity towards the reduction of H₂O₂. The catalysis current was linear to H₂O₂ concentration in the range of 2.0×10^?6 to 2.5×10^?4 mol·L^?1, with a detection limit of 8.0×10^?7 mol·L^?1 (S/N=3). The apparent Michaelis‐Menten constant (K_m^app) was calculated to be 0.34 mmol·L^?1. Moreover, the modified electrode displayed a good stability and reproducibility. Based on the composite film, a third‐generation reagentless biosensor could be constructed for the determination of H₂O₂.     

Synergetic effect of Prussian blue film with gold nanoparticle graphite–wax composite electrode for the enzyme-free ultrasensitive hydrogen peroxide sensor

Enzyme-free amperometric ultrasensitive determination of hydrogen peroxide (H₂O₂) was investigated using a Prussian blue (PB) film-modified gold nanoparticles (AuNPs) graphite–wax composite electrode. A stable PB film was obtained on graphite surface through 2-aminoethanethiol (AET)-capped AuNPs by a simple approach. Field emission scanning electron microscope studies results in formation of PB nanoparticle in the size range of 60–80 nm. Surface modification of PB film on AET–AuNPs–GW composite electrode was confirmed by Fourier transform infrared attenuated total reflection (FTIR-ATR) spectroscopy studies. Highly sensitive determination of H₂O₂ at a peak potential of ?0.10 V (vs. SCE) in 0.1 M KCl PBS, pH?=?7.0) at a scan rate of 20 mVs^?1 with a sensitivity of 23.58 μA/mM was observed with the modified electrode using cyclic voltammetry. The synergetic effect of PB film with AuNPs has resulted in a linear range of 0.05 to 7,800 μM with a detection limit of 0.015 μM for H₂O₂ detection with the present electrode. Chronoamperometric studies recorded for the successive additions of H₂O₂ with the modified electrode showed an excellent linearity (R ²?=?0.9932) in the range of 4.8?×?10^?8 to 7.4?×?10^?8 M with a limit of detection of 1.4?×?10^?8 M. Selective determination of H₂O₂ in presence of various interferents was successfully demonstrated. Human urine samples and stain remover solutions were also investigated for H₂O₂ content.     

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.

A Sensitive Hydrogen Peroxide Sensor Based on Hemoglobin Immobilized on Gold Nanoparticles and 1,6-hexanedithiol Modified Gold Electrode

Hemoglobin (Hb) was successfully immobilized on a gold electrode modified with gold nanoparticles (AuNPs) via a molecule bridge 1,6-hexanedithiol (HDT). The AFM images suggested that the HDT/gold electrode could adsorb more AuNPs. UV-vis spectra indicated that Hb on AuNPs/HDT film retained its near-native secondary structures. The electrochemical behaviors of the sensor were characterized with cyclic voltammetric techniques. The resultant electrode displayed an excellent electrocatalytical response to the reduction of hydrogen peroxide (H₂O₂). The linear relationship existed between the catalytic current and the H₂O₂ concentration ranging from 5.0 × 10^?8 to 1.0 × 10^?6 mol · L^?1. The detection limit (S/N = 3) was 1.0 × 10^?8 mol · L^?1.     

A Novel Hydrogen Peroxide Biosensor Based on the PDDA‐GNPs/MWNTs Nanocomposite Matrix

A novel nanocomposite designed by the assembly of the positively charged poly(diallyldimethylammonium chloride) protected gold nanoparticles (PDDA‐GNPs), and the negatively charged multi‐walled carbon nanotubes (MWCNTs) on ITO electrode via electrostatic interaction, was used as a supporting matrix for immobilizing hemoglobin (Hb) to develop a high‐performance hydrogen peroxide (H₂O₂) biosensor. The cyclic voltammetrys of immobilized Hb showed a pair of well‐defined and quasi‐reversible redox peaks with the formal potential of ‐0.205V (vs. SCE) and the peak‐to‐peak potential separation of 44 mV at a scan rate of 100 mV×s^?1 in 0.1 mol×L^?1 pH 7.0 PBS. Under the optimized experimental conditions, a linearity range for determination of H₂O₂ was from 2.0 × 10^?6 to 5.2 × 10^?4 mol×L^?1 with a correlation coefficient of 0.9994 (n = 37) and a detection limit of 8.4 × 10^?7 mol×L^?1. The biosensor displayed excellent electrochemical and electrocatalytic response to the reduction of H₂O₂, high sensitivity, long‐term stability, good bioactivity and selectivity.     

Direct Electrochemistry of Hemoglobin in Cerium Dioxide/Carbon Nanotubes/Chitosan for Amperometric Detection of Hydrogen Peroxide

Abstract

A novel hemoglobin (Hb) biosensor based on the remarkable synergistic effects of cerium dioxide (CeO₂) and multiwalled carbon nanotubes (MWNTs) for detection of hydrogen peroxide (H₂O₂) is presented. The Hb/CeO₂/MWNTs/CHIT nanocomposite was nanoengineered by selected matched material components and optimized composition ratio to produce a superior H₂O₂ sensor. The preparation method is quite simple and practical. This composite matrix combined the advantages of MWNTs, CeO₂ nanoparticles, and chitosan (CHIT), with good electron-transfer ability, attractive biocompatibility, and fine film-forming ability, which could increase Hb attachment quantity and H₂O₂ detection sensitivity. In the optimum pH 7.0 phosphate buffer, the electrocatalytic response exhibited a linear dependence on H₂O₂ concentration in a wide range from 5.0 × 10^?6 to 4.6 × 10^?4 mol L^?1 with a detection limit of 6.5 × 10^?7 mol/L (3σ).     

Amperometric Biosensor for Hydrogen Peroxide Based on Myoglobin Doped Multiwalled Carbon Nanotube Enhanced Grafted Collagen Matrix

Abstract

A reagentless H₂O₂ sensor based on the direct electron transfer of myoglobin (Mb) doped in multiwalled carbon nanotubes enhanced grafted collagen matrix is proposed. The formal potential of the immobilized Mb was ?0.358 V with a surface coverage of 4.0×10^?10 mol cm^?2. The electrode process was surface‐controlled with an electron transfer rate constant of 9.7 s^?1. The proposed biosensor displayed an excellent electrocatalytic response to the reduction of H₂O₂ with a linear range from 0.6 to 39.0 µM. Owing to the good biocompatibility and high enzyme loading of the matrix the biosensor exhibited acceptable stability and reproducibility.     

Biosensor for Hydrogen Peroxide Based on Chitosan and Nanoparticle Complex Film–Modified Glassy-Carbon Electrodes

Abstract

A biosensor for hydrogen peroxide was fabricated by co-immobilizing cadmium telluride (CdTe) nanoparticles, chitosan, and hemoglobin (Hb) matrix. There was a pair of nearly reversible redox peaks around ?0.360 V, and the electrochemical behavior of Hb was a surface-controlled process, with an electron-transfer rate constant of 1.36 s^?1 and surface coverage of 2.62 × 10^?10 mol cm^?2. Fourier transform infrared (FT-IR) spectra and ultraviolet–visible (UV-vis) spectra indicated that Hb sustained its natural conformation. It was demonstrated that Hb in the matrix kept its bioactivity and exhibited catalytic ability toward H₂O₂, with a response ranging from 7.44 × 10^?6 to 6.95 × 10^?4 M and a detection limit of 2.23 × 10^?6 M.     

An Organic Sol‐Gel Film as Modifier to Construct Biosensor

A new amperometric biosensor for hydrogen peroxide (H₂O₂) was developed by adsorbing hemoglobin (Hb) on an organic sol‐gel film. The organic sol‐gel was prepared using resorcinol and formaldehyde as monomers. This sol‐gel film shows a biocompatible microenvironment for retaining the native activity of the adsorbed Hb. The direct electron transfer between Hb and electrode is achieved. Hb adsorbed on the film shows an enzyme‐like catalytic activity for the reduction of H₂O₂. The reduction peak currents are proportional linearly to the concentration of hydrogen peroxide in the range of 6×10^?8 to 3.6×10^?6 M, with a detection limit of 2.4×10^?8 M (S/N=3). This research enlarges the applications of organic sol‐gel materials in biosensor field.     

Amperometric Biosensors Based on Platinum Nanowires

Abstract

Platinum nanowires (PtNW) were prepared by an electrodeposition strategy using nanopore alumina template. The nanowires prepared were dispersed in chitosan (CHIT) solution and stably immobilized onto the surface of glassy carbon electrode (GCE). The electrochemical behavior of PtNW‐modified electrode and its application to the electrocatalytic reduction of hydrogen peroxide (H₂O₂) are investigated. The modified electrode allows low potential detection of hydrogen peroxide with high sensitivity and fast response time. As an application example, the glucose oxidase was immobilized onto the surface of PtNW‐modified electrode through cross‐linking by glutaric dialdehyde. The detection of glucose was performed in phosphate buffer at –0.2 V. The resulting glucose biosensor exhibited a short response time (<8 s), with a linear range of 10^?5?10^?2 M and detection limit of 5×10^?6 M.     

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.