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.     

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.     

Hydrogen Peroxide Biosensor Based on Immobilization of Hemoglobin on Au@Ag Nanoparticles Modified Carbon Ionic Liquid Electrode

A hydrogen peroxide (H₂O₂) biosensor based on the combination of Au@Ag core‐shell nanoparticles with a hemoglobin‐chitosan‐1‐butyl‐3‐methyl‐imidazolium tetrafluoroborate (Hb‐CHIT‐BMIM×BF₄) composite film was prepared. UV‐vis spectroscopy and transmission electron microscopy confirmed a core‐shell nanostructure of Au@Ag nanoparticle was successfully obtained. Cyclic voltammetric results showed a pair of well‐defined redox peaks appeared with the formal potential (E^O′) of ‐0.301 V (versus Ag/AgCl reference electrode) and the peak‐to‐peak separation (ΔE_p) was 84 mV in 0.1 M phosphate buffer solutions. Due to the synergetic effect of Au@Ag core‐shell nanoparticles and Hb‐CHIT‐BMIM×BF₄, the biosensor exhibited good electrocatalytic activity to the reduction of H₂O₂ in a linear range from 1.0 × 10^?6 to 1.0 × 10^?3 M with a detection limit of 4 × 10^?7 M (S/N = 3). The apparent Michaelis‐Menten constant (K_M) was estimated to be 4.4 × 10^?4 M, showing its high affinity. Thus, the study proved that the combination of Au@Ag core‐shell nanoparticles and Hb‐CHIT‐BMIM×BF₄ is able to open up new opportunities for the design of enzymatic 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.

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 enhanced oxime-based biomimetic electrochemical sensor modified with multifunctional AuNPs–Co<Subscript>3</Subscript>O<Subscript>4</Subscript>–NG composites for dimethoate determination

An enhanced oxime-based electrochemical sensor decorated with gold nanoparticles (AuNPs) and Co₃O₄ hexagonal nanosheets coupled with nitrogen-doped graphene has been developed for dimethoate determination dramatically. The introduction of Co₃O₄ hexagonal nanosheets tackles agglomeration of AuNPs and also enhances the sensitivity of electrochemical sensors greatly. The structure and properties of the synthesized composites were characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy, confirming the successful modification of 2-(4-mercaptobutoxy)-1-naphthaldehyde oxime and Co₃O₄ supported AuNPs in a great experiment. In addition, differential pulse voltammetry further revealed that the developed electrochemical sensor exhibited excellent selectivity, sensitivity and stability in real samples analysis. Under optimal conditions, the modified sensor displayed a broad linear range from 1?×?10^?14 M to 1?×?10^?6 M with a fairly low detection limit of 8.4?×?10^?14 M (S/N?=?3) and was expected to act as a superior method for dimethoate determination.     

Sensitive and renewable picloram immunosensor based on paramagnetic immobilisation

Picloram (4-amino-3,5,6-trichloro-2-pyridincarboxylic acid) is one of the chlorinated pesticides. It is widely used for control of wood plants, wheat, barley and wide range of broadleaf weeds as a plant growth regulator. An immunosensor was developed for detection of picloram concentration in compost extracts and river water. The laccase-picloram was prepared. The magnetic core-shell (Fe₃O₄-SiO₂) nanoparticles were modified with anti-picloram-IgG and attached to the surface of carbon paste electrode (CPE) with the aid of paramagnetism. Following competitive immunoreaction with picloram and the picloram-laccase to form immunocomplex, electrochemical measurement was carried out. After immunoassay, the electrode was immersed in glycin-hydrochloric acid buffer or polished with diamond paper for regeneration. The linear range for picloram detection was 1?×?10^–4–10?µg?mL^–1 with the correlation coefficient of 0.9936, and the detection limit is 1?×?10^–4?µg?mL^–1. The laccase labelled on the picloram for competitive immunoassay showed good activity, and the current response was strong and stable in electrochemical detection. The current reached 95% of the steady-state current within about 100?s. The proposed immunosensor exhibited good precision, sensitivity, selectivity, reusability, and storage stability.     

Fabrication of Hemoglobin/Ionic Liquid Modified Carbon Paste Electrode Based on the Electrodeposition of Gold Nanoparticles/CdS Quantum Dots and Its Electrochemical Application

A novel H₂O₂ amperometric biosensor based on the electrodeposition of gold nanoparticles (AuNPs) and CdS quantum dots (CdS QDs) onto a carbon paste electrode (CPE) and immobilizing hemoglobin (Hb) with ionic liquid (IL), is presented in this article. The modification process of the electrode was monitored by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Due to synergistic effects of AuNPs, CdS QDs and IL, the biosensor exhibited high stability and good bioelectrocatalytic ability to H₂O₂ with a linear concentration range from 10 to 750 µM and a detection limit of 4.35 µM (S/N=3).     

Designing and fabrication of a novel gold nanocomposite structure: application in electrochemical sensing of bisphenol A

In this article, a highly sensitive electrochemical sensor is introduced for direct electro-oxidation of bisphenol A (BPA). The novel nanocomposite was prepared based on multi-walled carbon nanotube/thiol functionalised magnetic nanoparticles (Fe₃O₄-SH) as an immobilisation platform and gold nanoparticles (AuNPs) as an amplifying electrochemical signal. The chemisorbed AuNPs exhibited excellent electrochemical activity for the detection of BPA. Some analysing techniques such as Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and energy-dispersive x-ray diffraction exposed the formation of nanocomposite. Under optimum conditions (pH 9), the sensor showed a linear range between 0.002–240 μM, with high sensitivity (0.25 μA μM^?1) along with low detection limit (6.73 × 10^?10 M). Moreover, nanocomposites could efficiently decrease the effect of interfering agents and remarkably enhance the utility of sensor at detection of BPA in some real samples.     

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).     

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.     

Electrochemistry and Electrocatalysis of Hemoglobin on 1‐Pyrenebutanoic Acid Succinimidyl Ester/Multiwalled Carbon Nanotube and Au Nanoparticle Modified Electrode

A biocompatible nanocomposite film was fabricated for hemoglobin (Hb) molecules immobilization. This film consists of multiwalled carbon nanotubes (MWNTs), 1‐pyrenebutanoic acid, succinimidyl ester (PASE), hemoglobin (Hb) and Au nanoparticles (AuNPs). Herein, PASE molecules physically adsorbed onto MWNTs, and its groups then covalently bond with Hb. AuNPs were then linked with Hb/PASE/MWNTs via electrostatic adsorption force. UV‐visible adsorption spectra, Fourier transform infrared spectra, scanning electron microscope and electrochemical impedance spectroscopy have characterized the film. Cyclic voltammetry (CV) scans showed that in the film Hb has well‐defined redox reaction, with the formal potential (E°) at about ?0.27 V (vs. Ag/AgCl). Herein, differential pulse voltammetry (DPV) was employed to electrochemically detect the Hb in the film with a detection limit of 9.3×10^?8 M. The proposed method was also succeeded for Hb detection in clinical blood samples. Furthermore, the Hb in the film showed good electrocatalytic activities to the reduction of H₂O₂, TCA, NaNO₂ and O₂.     

Direct electrochemistry and electrocatalysis of hemoglobin on a gold ion implantation-modified indium tin oxide electrode

In this paper, a gold nanoparticle-modified indium tin oxide electrode (Au/ITO) was prepared without the use of any cross-linker or stabilizer reagent. The prepared Au/ITO was used as a new platform to achieve the direct electron transfer between Hb and the modified electrode. The proposed electrode exhibited a pair of well-defined redox peaks with a formal potential of ?0.073 V (vs. Ag/AgCl). The immobilized Hb showed excellent electrocatalytic activity toward H₂O₂ and the electrocatalytic current values were linear with the increasing concentration of H₂O₂ ranging from 1.0?×?10^?6?M to 7.0?×?10^?4?M. The detection limit was 2.0?×?10^?7?M (S/N?=?3) and the Michaelis–Menten constant was calculated to be 0.2 mM. The proposed electrode also showed high selectivity, long-term stability, and good reproducibility.     

Multilayer Assembly of Hemoglobin and Colloidal Gold Nanoparticles on Multiwall Carbon Nanotubes/Chitosan Composite for Detecting Hydrogen Peroxide

Chitosan (CS) was chosen for dispersing multi‐wall carbon nanotubes (MWNTs) to form a stable CS‐MWNTs composite, which was first coated on the surface of a glassy carbon electrode to provide a containing amino groups interface for assembling colloidal gold nanoparticles (GNPs), followed by the adsorption of hemoglobin (Hb). Repeating the assembly step of GNPs and Hb resulted in {Hb/GNPs}_n multilayers. The assembly of GNPs onto CS‐MWNTs composites was confirmed by transmission electron microscopy. The consecutive growth of {Hb/GNPs}_n multilayers was confirmed by cyclic voltammetry and UV‐vis absorption spectroscopy. The resulting system brings a new platform for electrochemical devices by using the synergistic action of the electrocatalytic activity of GNPs and MWNTs. The resulting biosensor displays an excellent electrocatalytic activity and rapid response for hydrogen peroxide. The linear range for the determination of H₂O₂ was from 5.0×10^?7 to 2.0×10^?3 M with a detection limit of 2.1×10^?7 M at 3σ and a Michaelis–Menten constant K_M^app value of 0.19 mM.     

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     

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.

Super-Paramagnetic Nanoparticles by Surface Imprinting on Graphene Oxide Modified Iron (II,III) with Application for the Determination of Ovalbumin by Absorption Spectroscopy

Protein surface imprinting produces materials capable of selective recognition and capture of proteins. Herein, a protein surface imprinted polymer on graphene oxide modified super-paramagnetic Fe₃O₄ nanoparticles is reported. The molecularly imprinted polymer was synthesized by ultrasound-assisted suspension polymerization, using ovalbumin as the template molecule, 3-aminophenylboronie acid as the functional monomer, and methylene-bis-acrylamide as the cross-linking agent. The nanoparticles were approximately 40 nanometers in size and super-paramagnetic. Moreover, these particles demonstrated considerably high adsorption capacity, fast adsorption kinetics, and selective binding affinities toward the template protein ovalbumin. The calibration curve of ovalbumin was linear from 5.0 × 10^?11 to 1.0 × 10^?10 molar. The limit of detection of ovalbumin was 2.0 × 10^?11 M. These results show that this super-paramagnetic material has potential for biological macromolecule separation and determination.     

Organophosphorus pesticides detection using acetylcholinesterase biosensor based on gold nanoparticles constructed by electroless plating on vertical nitrogen-doped single-walled carbon nanotubes

An acetylcholinesterase (AChE) biosensor was constructed based on gold nanoparticles (AuNPs) using electroless plating on vertical nitrogen-doped single-walled carbon nanotubes (VNSWCNTs) for detecting organophosphorus pesticides (OPs). AChE was immobilised on AuNPs via Au–S bonding, and VNSWCNTs were produced by spontaneous chemical adsorption of NSWCNTs on gold electrode, also via Au–S bonding. This modified electrode exhibited excellent electron transfer capacity due to the synergy between AuNPs and VNSWCNTs. The developed biosensor showed good linear relations at concentrations of 10^?5 – 1 ppb, and the detection limits were 3.04 × 10^?6 ppb for methyl parathion, 1.96 × 10^?6 ppb for malathion and 2.06 × 10^?6 ppb for chlorpyrifos, respectively. The AChE biosensor revealed satisfactory stability, excellent sensitivity and good repeatability. These results suggest that this biosensor has good application prospects and can function as a sensitive device in OPs analysis.     

A Novel Sensitive Biosensor for Ca2+ Ion Based on Gold Nanoparticles Modified Electrode by Pulsed Electrodeposition

The work demonstrates a simple method for sensitive detection of Ca²⁺ ion by electrochemical response of alizarin red S (ARS) and Ca-ARS at a gold nanoparticle modified glassy carbon electrode (GCE). In the 0.1 M KOH, a sensitive reduction peak was observed at ?0.795 V at the gold nanoparticles modified electrode. The peak currents were proportional to the concentrations of Ca²⁺ ion in the range of 2.0 × 10^?7 M–1.2 × 10^?4 M. For the different pulse voltammetry (DPV) methods, the detection limit was 2.57 × 10^?8 M. The reaction mechanism was primarily determined by cyclic voltammetry, and the experimental results showed that the electrode processes were quasireversible responses of ARS and irreversible responses of ARS-Ca. In addition, the method was simple, fast, precise, and was used in the determination of calcium in blood serum with satisfactory results.     

Direct Electrochemistry of Glucose Oxidase Immobilized on Titanium Carbide‐Au Nanoparticles‐Fullerene C60 Composite Film and Its Biosensing for Glucose

The direct electrochemistry of glucose oxidase (GOD) immobilized on the designed titanium carbide‐Au nanoparticles‐fullerene C₆₀ composite film modified glassy carbon electrode (TiC‐AuNPs‐C₆₀/GCE) and its biosensing for glucose were investigated. UV‐visible and Fourier‐transform infrared spectra of the resulting GOD/TiC‐AuNPs‐C₆₀ composite film suggested that the immobilized GOD retained its original structure. The direct electron transfer behaviors of immobilized GOD at the GOD/TiC‐AuNPs‐C₆₀/GCE were investigated by cyclic voltammetry in which a pair of well‐defined, quasi‐reversible redox peaks with the formal potential (E^0′) of ‐0.484 V (vs. SCE) in phosphate buffer solution (0.05 M, pH 7.0) at the scan rate of 100 mV·s^?1 were obtained. The proposed GOD modified electrode exhibited an excellent electrocatalytic activity to the reduction of glucose, and the currents of glucose reduction peak were linearly related to glucose concentration in a wider linearity range from 5.0 × 10^?6 to 1.6 × 10^?4 M with a correlation coefficient of 0.9965 and a detection limit of 2.0 × 10^?6 M (S/N = 3). The sensitivity and the apparent Michaelis‐Menten constant (K_M^app) were determined to be 149.3 μA·mM^?1·cm^?2 and 6.2 × 10^?5 M, respectively. Thus, the protocol will have potential application in studying the electron transfer of enzyme and the design of novel electrochemical biosensors.