Direct Electrochemistry Of Hemoglobin Research Articles

Direct Electrochemistry and Electrocatalysis of Hemoglobin Immobilized on the Functionalized Graphene-Carbon Nanotube Composite Film

The direct electrochemistry of hemoglobin (Hb) immobilized on the designed carboxyl functionalized polystyrene/graphene-carbon nanotube-Nafion modified indium tin oxide (PS/GE-CNT-Nafion/ITO) electrode and its electrocatalysis for hydrogen peroxide (H2O2) were investigated. UV-visible and Fourier-transform infrared spectra of the resulting Hb-PS/GE-CNT-Nafion composite film suggested that the immobilized Hb retained its original structure. The direct electron transfer behaviors of Hb at the Hb-PS/GE-CNT-Nafion/ITO electrode were investigated by cyclic voltammetry in which a pair of well-defined, quasi-reversible redox peaks with the formal potential (E0′) of −0.249 V (vs. SCE) in phosphate buffer solution (0.05 M, pH 7.0) was obtained. The proposed ITO modified electrode exhibited an excellent electrocatalytic activity to the reduction of H2O2, and the peak currents were linearly related to H2O2 concentration in a wider linearity range from 5.0 × 10−7 to 1.4 × 10−3 M with a correlation coefficient of 0.9983 and a detection limit of 2.0 × 10−7 M (S/N = 3). The sensitivity and the apparent Michaelis-Menten constant () were determined to be 59.1 μA·mM−1 and 8.3 × 10−5 M, respectively. It is expected that the synergetic effects of GE-CNT hybrid materials and functionalized PS provide a general platform for studying of the electron transfer of redox proteins and the design of novel biosensors.

Preparation of the Ordered Mesoporous Carbon/Fe3O4and Its Application for the Direct Electrochemistry of Hemoglobin

Preparation of the Ordered Mesoporous Carbon/Fe₃O₄and Its Application for the Direct Electrochemistry of Hemoglobin

A Hydrogen Peroxide Biosensor Based on Direct Electrochemistry of Hemoglobin in Palladium Nanoparticles/Graphene–Chitosan Nanocomposite Film

Thermally two-dimensional lattice graphene (GR) and biocompatibility chitosan (CS) act as a suitable support for the deposition of palladium nanoparticles (PdNPs). A novel hydrogen peroxide (H(2)O(2)) biosensor based on immobilization of hemoglobin (Hb) in thin film of CS containing GR and PdNPs was developed. The surface morphologies of a set of representative membranes were characterized by means of scanning electron microscopy and showed that the PdNPs are of a sphere shape and an average diameter of 50 nm. Under the optimal conditions, the immobilized Hb showed fast and excellent electrocatalytic activity to H(2)O(2) with a small Michaelis-Menten constant of 16 μmol L(-1), a linear range from 2.0 × 10(-6) to 1.1 × 10(-3) mol L(-1), and a detection limit of 6.6 × 10(-7) mol L(-1). The biosensor also exhibited other advantages, good reproducibility, and long-term stability, and PdNPs/GR-CS nanocomposites film would be a promising material in the preparation of third generation biosensor.

In-Situ Direct Electrochemistry of Hemoglobin Using Vertically Aligned Carbon Nanotube Ropes

Direct electrochemistry of hemoglobin (Hb) is usually implemented by immobilizing it on the electrode. In-situ determination of Hemoglobin is little bit tough due to slow electron transfer in solution phase owing to its complex structure. In this study, we report in-situ direct electrochemistry of hemoglobin using vertically aligned single walled carbon nanotubes (SWNTs) ropes on indium tin oxide (ITO) platform. Morphological characterization of aligned SWNTs is accomplished using optical surface profiler, FE-SEM and AFM. Electrochemical impedance spectroscopy (EIS) of SWNT/ITO electrode reveals reduction in 'charge transfer resistance' for SWNT/ITO electrode in comparison to ITO. Exchange current density increases tenfold (5.4 × 10-2 A cm-2 while standard rate constant increases hundred times (1.2 × 10-4 C2s-1 cm-2 after vertical alignment of SWNTs on ITO sur- face. Cyclic voltammetry (CV) of Hb demonstrates tenfold increase in the currents after SWNT immobilization. Kinetic studies using CV revel surface controlled nature of the reaction that is attributed to concentration of Hb molecules in close proximity of the electrode, which in turn is due to negatively charged carboxyl ends of aligned carbon nanotubes. Moreover, a plausible mechanism for increase of peak currents in acidic pH range is also presented that clearly demonstrates the role of oxygen containing groups at the carbon nanotube ends for direct electron transfer from hemoglobin. Sensitivity of the sensor is determined for both lyophilized Hb and that present in red blood cells (RBCs) separated from whole blood. It is found to be 21.2 μAμM-1 and 8.94 μAdLg-1 respectively. Lower detection limit of hemoglobin is found to be 10 nM. After successful demonstration of aligned carbon nanotubes (CNTs) in solution phase electrochemistry of hemoglobin, SWNT/ITO electrodes can be used for routine clinical determination of hemoglobin in whole blood samples using RBCs.

Direct Electrochemistry and Application in Electrocatalysis of Hemoglobin in a Polyacrylic Resin‐Gold Colloid Nanocomposite Film

AbstractA novel nanocomposite integrating the good biocompatibility of polyacrylic resin nanoparticles (PAR) and the good conductivity of colloidal gold nanoparticles was proposed to construct the matrix for the immobilization of hemoglobin (Hb) on the surface of a glassy carbon electrode (GCE). UV‐vis spectra demonstrated that Hb preserved its native structure after being entrapped into the composite film. The direct electrochemistry of hemoglobin (Hb) in this nanocomposite films showed a pair of well‐defined and quasi‐reversible cyclic voltammetric peaks with a formal potential of −0.307 mV and a constant electron transfer rate of 2.51±0.2 s−1. The resultant amperometric biosensor showed fast responses to the analytes with excellent detection limits of 0.2 µM for H2O2 and 0.89 µM for TCA (S/N=3), and high sensitivity of 1108.6 for H2O2 and 77.14 mA cm−2 M−1 for TCA, respectively. The linear current response was found in the range from 0.59 to 7.3 µM (R2=0.9996) for H2O2 and from 5 to 85 µM (R2=0.9996) for TCA, while the superior apparent Michaelis–Menten constant was 0.012 mM for H2O2 and 0.536 mM for TCA, respectively. Therefore, the PAR‐Au‐Hb nanocomposite as a novel matrix opens up a possibility for further study on the direct electrochemistry of other proteins.

Direct electrochemistry and electrocatalytic behavior of hemoglobin entrapped in chitosan/gold colloid/3-aminopropyl triethylene silane/Prussian blue composite film

Direct electrochemistry of hemoglobin (Hb) is achieved by immobilizing Hb–chitosan on a gold colloid/3-aminopropyl triethylene silane/Prussian blue composite film-modified glassy carbon electrode. The modified electrode exhibits a pair of well defined and quasi-reversible peaks with a formal potential of 0.205V. The immobilized Hb retains its biological activity and shows high catalytic activity to the reduction of hydrogen peroxide. Experimental conditions influencing the biosensor performances such as pH and potential are optimized and assessed. Under the optimized conditions, the catalytic currents are linear to the concentrations of H2O2 in the ranges of 2–480μM. The detection limit is 0.1μM (S/N=3). The electrochemical sensor has high stability and good reproducibility. Ultraviolet visible absorption spectra and Fourier transform infrared spectroscopy show that Hb keeps almost natural structure in the composite film. Therefore, the composite film is an alternative matrix for protein immobilization and biosensor preparation.

Direct Electrochemistry of Hemoglobin on Graphene Nanosheet-based Modified Electrode and Its Electrocatalysis to Nitrite

A novel amperometric nitrite (NO2 − ) sensor was developed based on immobilization of hemoglobin (Hb) on a graphene nanosheet modified electrode by chitosan-N, N-Dimethylformamide (CS-DMF) hydrogel. The surface morphologies of the modified electrode were characterized by SEM, and direct electrochemistry of Hb on the graphene nanosheet-based electrode were investigated by cyclic voltammetry. The results indicated that Hb immobilized on the surface of the graphene modified electrode could keep its bioactivity, exhibited a surface-controlled electrochemical process and had a fast heterogeneous electron transfer rate with the rate constant (ks) of 58.77 s −1 . Moreover, the resulting biosensor showed excellent electrocatalytic activities toward nitrite reduction with a low detection limit of 1.8×10 −7 M and a small apparent Michaelis-Menten constant (km) up to 12 µM. The good performance of the proposed sensor is attributed to excellent conductivity and electron mobility of graphene, and good biocompatibility of chitosan, which enhances the Hb content and promotes direct electron transfer between redox Hb and the surface of electrodes.

Direct electrochemistry of hemoglobin in a nafion and CuS microsphere modified carbon ionic liquid electrode and its electrocatalytic behavior

Direct electrochemistry of hemoglobin (Hb) was realized on a Nafion and CuS microsphere composite film modified carbon ionic liquid electrode (CILE) with N-butylpyridinium hexafluorophosphate (BPPF6) as binder. Scanning electron microscopy (SEM), UV-Vis absorption spectroscopy and cyclic voltammetry were used to characterize the fabricated Nafion/CuS/Hb/CILE. Experimental results showed that a pair of well-defined quasi-reversible redox peaks appeared with the formal potential as -0.386 V (vs. SCE) in pH 7.0 Britton-Robinson (B-R) buffer solution, which was attributed to the Hb heme Fe(III)/Fe(II) redox couples. The electrochemical parameters of Hb in the composite film were carefully investigated with the charge transfer coefficient (α), the electron transfer number (n) and the electron transfer rate constant (ks) as 0.505, 1.196 and 0.610 s -1 , respectively. The composite film provided a favorable microenvironment for retaining the native structure of Hb. The presence of CuS microspheres showed great improvement on the electron transfer rate of Hb with the CILE, which maybe due to the contribution of specific characteristics of CuS microspheres and the inherent advantages of ionic liquid on the modified electrode. The fabricated Hb modified electrode showed good electrocatalytic ability in the reduction of H2O2. The proposed bioelectrode can be used as a new third generation H2O2 biosensor.

Direct Electrochemistry of Hemoglobin in Layer‐by‐Layer Films Assembled with DNA and Room Temperature Ionic Liquid

AbstractBased on electrostatic interaction and electrodeposition, poly‐anionic deoxyribonucleic acid (DNA), room temperature ionic liquid 1‐butyl‐3‐methyl‐imidazolium tetrafluoroborate (BMIMBF4), hemoglobin (Hb) and Poly(diallyldimethylammonium chloride) (PDDA) were successfully assembled into Hb/IL/DNA/PDDA layer‐by‐layer complex films on the surface of ITO electrode. FTIR spectroscopy, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to characterize the composite film. The obtained results demonstrated that the Hb molecule in the film kept its native structure and showed its good electrochemical behavior. A pair of well‐defined redox peaks of Hb with the formal potentials (E°′) of −0.180 V (vs. SCE) was appeared in phosphate buffer solution (PBS, pH 7.0). The Hb/IL/DNA/PDDA/ITO modified electrode also showed an excellent electrocatalytic behavior to the reduction of hydrogen peroxide (H2O2). Therefore, the IL/DNA/PDDA complex film as a novel matrix open up a possibility for further study on the direct electrochemistry of other proteins and the fabrication of the third‐generation electrochemical biosensors.

Direct Electrochemistry of Hemoglobin in Chitosan/Multiwalled Carbon Nanotubes/Ionic Liquid–Modified Carbon-Paste Electrode

The direct electrochemistry of hemoglobin (Hb) was realized on chitosan and multiwalled carbon nanotubes (MWCNTs)–modified carbon ionic liquid electrode (CILE). The CILE was fabricated first and further modified by MWCNTs to get an electrode as MWCNTs/CILE. The Hb was immobilized on the surface of MWCNTs/CILE with the help of chitosan film. Ultraviolet–visible (UV-vis) and Fourier transform–infrared (FT-IR) spectra indicated that Hb kept its native structure in the modified film. A pair of well-defined quasi-reversible redox peaks of heme Fe(III)/Fe(II) couple appeared with the formal potential (E0′) as −0.314 V (vs. SCE) in pH 7.0 phosphate buffer solution (PBS). The modified electrode showed good electrocatalytic ability for the reduction of trichloroacetic acid.

Graphitized macroporous carbon microarray with hierarchical mesopores as host for the fabrication of electrochemical biosensor

A novel graphitized ordered macroporous carbon (GMC, pore size ∼380 nm) with hierarchical mesopores (2–30 nm) and high graphitization degree was prepared by nickel-catalyzed graphitization of polystyrene arrays. The obtained GMC possessed high specific surface area, large pore volume, and good electrical conductivity, which was explored for the enzyme entrapment and biosensor fabrication by a facile method. With advantages of novel nanostructure and good electrical conductivity, direct electrochemistry of hemoglobin (a model protein) was observed on the GMC-based biocomposite with a formal potential of −0.36 V (vs. Ag/AgCl) and an apparent heterogeneous electron transfer rate constant ( k s ) of 1.2 s −1 in pH 7.0 buffer. Comparative studies revealed that GMC offered significant advantages over carbon nanotubes (CNTs) in facilitating direct electron transfer of entrapped Hb. The fabricated biosensor exhibited good sensitivity (101.6 mA cm −2 M −1) and reproducibility, wide linear range (1–267 μM), low detection limit (0.1 μM), and good long-term stability for H 2O 2 detection. GMC proved to be a promising matrix for enzyme entrapment and biosensor fabrication, and may find wide potential applications in biomedical detection and environmental analyses.

Direct Electrochemistry of Hemoglobin and its Electrocatalysis Based on a Carbon Nanotube Paste Electrode

AbstractA new hemoglobin (Hb) and carbon nanotube (CNT) modified carbon paste electrode was fabricated by simply mixing the Hb, CNT with carbon powder and liquid paraffin homogeneously. To prevent the leakage of Hb from the electrode surface, a Nafion film was further applied on the surface of the Hb‐CNT composite paste electrode. The modified electrode was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Direct electrochemistry of hemoglobin in this paste electrode was easily achieved and a pair of well‐defined quasi‐reversible redox peaks of a heme Fe(III)/Fe(II) couple appeared with a formal potential (E0′) of −0.441 V (vs. SCE) in pH 7.0 phosphate buffer solution (PBS). The electrochemical behaviors of Hb in the composite electrode were carefully studied. The fabricated modified bioelectrode showed good electrocatalytic ability for reduction of H2O2 and trichloroacetic acid (TCA), which shows potential applications in third generation biosensors.

Direct electrochemistry of hemoglobin at vertically-aligned self-doping TiO 2 nanotubes: A mediator-free and biomolecule-substantive electrochemical interface

The present work is dedicated to making the best of vertically-aligned TiO 2 nanotubes (TNTs) array to serve as a prospectively ideal “vessel” for protein immobilization and biosensor applications. The TNTs fabricated by electrochemical anodizing possess the advantageous of perpendicular alignment and tailored tubular architecture, as well as the good biocompatibility and hydrophilicity. But the electron-transfer resistance of the as-grown (AG-) TNTs is too large for the direct electron transfer and electrochemical biosensing. A simple strategy on controllable electrochemical reduction treatment of TNTs is adopted on it, leading TNTs in situ self-doped with Ti(III), which makes the Ti(III)–TNTs much better conductivity while the tubular and crystal structure of TNTs array still well maintained. Results show that the TNTs can be used as a super vessel for rapid and substantive immobilization of hemoglobin (Hb), with a large surface electroactive Hb coverage ( Γ*) of 1.5 × 10 −9 mol cm −2. The enhanced direct electron transfer of Hb is commendably observed on the Ti(III)–TNTs/Hb biosensor with a couple of well-defined redox peaks compared with the AG-TNTs/Hb. The biosensor further exhibits fast response, high sensitivity and stability for the amperometric biosensing of H 2O 2 with the detection limit of 1.5 × 10 −6 M, and the apparent Michaelis–Menten constant of 1.02 mM.

Electrochemistry and electrocatalysis of hemoglobin on multi-walled carbon nanotubes modified carbon ionic liquid electrode with hydrophilic EMIMBF 4 as modifier

The direct electrochemistry of hemoglobin (Hb) on multi-walled carbon nanotubes (MWCNTs) modified carbon ionic liquid electrode (CILE) was achieved in this paper. By using a hydrophilic ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF 4) as the modifier, a new CILE was fabricated and further modified with MWCNTs to get the MWCNTs/CILE. Hb molecules were immobilized on the surface of MWCNTs/CILE with polyvinyl alcohol (PVA) film by a step-by-step method and the modified electrode was denoted as PVA/Hb/MWCNTs/CILE. UV–vis and FT-IR spectra indicated that Hb remained its native structure in the composite film. Cyclic voltammogram of PVA/Hb/MWCNTs/CILE showed a pair of well-defined and quasi-reversible redox peaks with the formal potential ( E 0′) of −0.370 V (vs. SCE) in 0.1 mol/L pH 7.0 phosphate buffer solution (PBS), which was the characteristic of the Hb heme Fe III/Fe II redox couples. The redox peak currents increased linearly with the scan rate, indicating the direct electron transfer was a surface-controlled process. The electrochemical parameters of Hb in the film were calculated with the results of the electron transfer coefficient ( α) and the apparent heterogeneous electron transfer rate constant ( k s ) as 0.49 and 1.054 s −1, respectively. The immobilized Hb in the PVA/MWCNTs composite film modified CILE showed excellent electrocatalytic activity to the reduction of trichloroacetic acid (TCA) and hydrogen peroxide. So the proposed electrode showed the potential application in the third generation reagentless biosensor.

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

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).

Direct electrochemistry of hemoglobin in poly(acrylonitrile- co-acrylic acid) and its catalysis to H 2O 2

Hemoglobin (Hb) was successfully immobilized in poly(acrylonitrile- co-acrylic acid) (PAN- co-PAA) film modified glassy carbon electrode (GCE). The Hb-PAN- co-PAA film exhibited a pair of well-defined and quasi-reversible cyclic voltammetric peaks for Hb Fe(III)/Fe(II) redox couple in a pH 7.0 phosphate buffer. The formal potential of Hb heme Fe(III)/Fe(II) couple varied linearly with the increase of pH in the range of 4.0–8.0 with a slope of −53.5 mV pH −1, implying that one proton was accompanied with one electron transferred in the electrochemical reaction. Position of Soret absorption band of Hb-PAN- co-PAA film suggested that the Hb kept its secondary structure similar to its native state in the PAN- co-PAA matrix. The protein in PAN- co-PAA matrix acted as a biologic catalyst to catalyze reduction of hydrogen peroxide. The electrocatalytic response showed a linear dependence on the H 2O 2 concentration ranging from 9.2 × 10 −6 to 2 × 10 −3 M with a detection limit of 4.5 × 10 −6 M at 3 σ.

Direct Electrochemistry of Hemoglobin on Single‐Walled Carbon Nanotubes Modified Carbon Ionic Liquid Electrode and Its Electrocatalysis

AbstractIn this article we report on the fabrication of a carbon ionic liquid electrode (CILE) by using a room temperature ionic liquid of 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIMPF6) as binder. It was further modified by single‐walled carbon nanotubes (SWCNTs) to get a SWCNTs modified CILE denoted as SWCNTs/CILE. The redox protein of hemoglobin (Hb) was further immobilized on the surface of SWCNTs/CILE with the help of Nafion film. UV‐vis and FT‐IR spectra indicated that the immobilized Hb retained its native conformation in the composite film. The direct electrochemistry of Hb on the SWCNTs/CILE was carefully studied in pH 7.0 phosphate buffer solution (PBS). Cyclic voltammetric results indicated that a pair of well‐defined and quasireversible voltammetric peaks of Hb heme Fe(III)/Fe(II) was obtained with the formal potential (E°') at −0.306 V (vs. SCE). The electrochemical parameters such as the electron transfer coefficient (α), the electron transfer number (n) and the apparent heterogeneous electron transfer rate constant (ks) were calculated as 0.34, 0.989 and 0.538 s−1, respectively. The fabricated Hb modified electrode showed good electrocatalytic ability to the reduction of trichloroacetic acid (TCA) in the concentration range from 20.0 to 150.0 mmol/L with the detection limit of 10.0 mmol/L (3σ).

Direct Electrochemistry of Hemoglobin and Its Electrocatalysis Based on Hyaluronic Acid and Room Temperature Ionic Liquid

AbstractA biocomposite material of hyaluronic acid (HA) and room temperature ionic liquid, 1‐butyl‐3‐methyl‐imidazolium tetrafluoroborate (BMIMBF4) was fabricated and characterized by voltammetry and electrochemical impedance spectroscopy. Hemoglobin (Hb), as a model protein, was immobilized in this biocomposite on glassy carbon electrode to investigate its direct electrochemistry. A pair of well‐defined, quasireversible cyclic voltammetric peaks appeared with the formal potentials (E°′) at −0.360 V (vs. SCE). The Hb modified electrode exhibited an excellent electrocatalytic activity to the reduction of H2O2 with a wide linear range, good selectivity, sensitivity and reproducibility, which had potential application to fabrication the third‐generation biosensor.

Hemoglobin Modified Carbon Paste Electrode: Direct Electrochemistry and Electrocatalysis

A new hemoglobin (Hb) modified carbon paste (CP) electrode was fabricated by simply mixing the hemoglobin with carbon powder and paraffin homogeneously. To prevent the leakage of Hb from the electrode surface, a Nafion film was further applied on the surface of Hb-carbon composite paste electrode. Direct electrochemistry of hemoglobin in the paste electrode was easily achieved, and a pair of well-defined quasi-reversible redox peak of heme Fe(III)/Fe(II) couple appeared with the formal potential (E0′) as −0.335 V (vs. Saturated calomel electrode; CE) in pH 7.0 phosphate buffer solution (PBS). The fabricated Hb modified electrode showed good electrocatalytic ability to the reduction of trichloroacetic acid (TCA) and H2O2.

Direct electrochemistry and electrocatalysis of hemoglobin immobilized by methacrylic acid

The direct electrochemistry of hemoglobin (Hb) incorporated in methacrylic acid (MAA) film on a paraffin-impregnated graphite electrode (PIGE) was described. A pair of well-defined and quasi-reversible cyclic voltametric peaks are obtained. The formal potentials (E 0′) linearly depend on the pH of solution, indicating that the electron transfer was proton-coupled. Ultraviolet-visible (UV-Vis) spectra showed that the secondary structure of Hb in the MAA film was similar to individual Hb. The immobilized Hb retained its biological activity well and exhibited a nice response to the reduction of both NO 2 − , and H2O2, on the basis of which a new biosensor has been developed.