Direct Electrochemistry Of Myoglobin Research Articles

Low band gap conductive copolymer of thiophene with p‐phenylenediamine and its magnetic nanocomposite: Synthesis, characterization and biosensing activity

Thiophene and p‐phenylenediamine were utilized as monomers to prepare low band gap copolymer and nanocomposites with core–shell construction by a simple in situ emulsion polymerization. Different devices such as Fourier transform infrared, X‐ray diffraction, scanning electron microscopy, thermal gravimetric analysis, dynamic light scattering and vibrating sample magnetometer (VSM) were used for characterizing the copolymer and nanocomposites. Band gaps were estimated from Cyclic voltammetry to be 2.1 − 1.7 eV for copolymers and nanocomposite. The results that obtained by measuring the conductivity with Four‐probe method illustrated that the electrical conductivity of the nanocomposites is considerably higher than the copolymer which is dependent on the Fe content and doping degree. The nanocomposites showed superparamagnetic behavior with high‐saturated magnetization (Ms = 10–16 emu/g). The direct electrochemistry of myoglobin (Mb) entrapped in the Nafion film on a glassy carbon electrode modified with synthesized nanocomposite had been investigated in this paper. Cyclic voltammetric results showed that a pair of well‐defined quasi‐reversible redox peaks appeared in the pH 7.0 phosphate buffer solution, which was ascribed to the direct electron transfer of Mb heme Fe(III)/Fe(II) redox couples. Also, the antioxidant activity of new nanocomposites was measured by using 2, 2‐diphenyl‐1‐picrylhydrazyl assay. POLYM. COMPOS., 40:1034–1042, 2019. © 2018 Society of Plastics Engineers

Direct Electrochemistry of Myoglobin on Three-Dimensional Graphene- Nickel Oxide Modified Electrode and Electrocatalytic Detection of Trichloroacetic Acid

Background: Graphene is easy to aggregate by π-π and Van der Waals interaction between nanosheets, which diminishes the accessible area and limits its real applications in electrochemisty. The construction of three-dimensional graphene and its related nanocomposite is an effective path to overcome this problem. Keywords: Three-dimensional graphene, nickel oxide, myoglobin, direct electron transfer, electrocatalysis, carbon ionic liquid electrode.

Effect of Carboxyl Graphene on Direct Electrochemistry of Myoglobin and Electrocatalytic Investigation

Effect of Carboxyl Graphene on Direct Electrochemistry of Myoglobin and Electrocatalytic Investigation

Direct Electrochemistry of Myoglobin on Graphene and Zinc Oxide Nanorods Composite Modified Electrode and Its Electrocatalysis

Direct Electrochemistry of Myoglobin on Graphene and Zinc Oxide Nanorods Composite Modified Electrode and Its Electrocatalysis

Direct electrochemistry of myoglobin at silver nanoparticles/myoglobin biocomposite: Application for hydrogen peroxide sensing

Herein we report a novel hydrogen peroxide (H2O2) sensor based on direct electrochemistry of myoglobin at a silver nanoparticles/myoglobin (Ag-NPs/MB) biocomposite modified electrode. The green synthesized Ag-NPs and MB were used for the fabrication of Ag-NPs/MB biocomposite. The fabricated Ag-NPs and Ag-NPs/MB biocomposite were characterized by using TEM and SEM respectively. A good direct electron transfer of MB is realized at Ag-NPs/MB biocomposite electrode rather than direct drop casting of MB onto Ag-NPs modified electrode, which indicates that the native structure of MB is retained in the biocomposite modified electrode. The apparent heterogenous electron transfer rate constant (ks) is calculated as 3.02s−1, which confirms a fast direct electron transfer of MB at the biocomposite electrode. A fast amperometric response for H2O2 (<5s) at Ag-NPs/MB biocomposite modified electrode indicates a good catalytic activity of the modified electrode. The H2O2 detection is found in the linear response range from 1μM to 3mM with the detection limit of 0.088μM. The sensitivity is calculated as 0.357μAμM−1cm−2. In addition, the fabricated biosensor shows a good consistency along with excellent precision.

An enzymatic biosensor for hydrogen peroxide based on CeO2 nanostructure electrodeposited on ITO surface

In this study, an enzymatic biosensor for amperometric detection of hydrogen peroxide was developed based on the direct electrochemistry of myoglobin (Mb) on a porous cerium dioxide (CeO2) nanostructured film. The developed film accomplished with large surface area was electrodeposited on an indium tin oxide (ITO) substrate. Surface morphological studies revealed that the formed CeO2 film has a large specific surface area with a unique nanostructure on the ITO surface. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to demonstrate the electrochemical behavior of Mb immobilized on the fabricated film, which exhibited facile, direct electrochemistry and good electrocatalytic performance without any electron mediator. The electrode displayed a pair of quasi-reversible reduction–oxidation peaks at −0.3 and −0.2V, respectively, due to the Mb [Fe3+/Fe2+] redox couple, which is a surface-controlled electrochemical process with one electron transfer. This reagent-less biosensor showed good stability and high sensitivity for detecting H2O2 without any influence of intermediate compounds. This protein-based biosensor was capable of detecting H2O2 as low as 0.6μM with linearity up to 3mM and a response time of ~8s, compared to those of other modified electrodes. Hence, porous CeO2 is a possible candidate material for fabricating enzymatic sensors or devices.

Fabrication of graphene–platinum nanocomposite for the direct electrochemistry and electrocatalysis of myoglobin

In this paper a platinum (Pt) nanoparticle decorated graphene (GR) nanosheet was synthesized and used for the investigation on direct electrochemistry of myoglobin (Mb). By integrating GR–Pt nanocomposite with Mb on the surface of carbon ionic liquid electrode (CILE), a new electrochemical biosensor was fabricated. UV-Vis absorption and FT-IR spectra indicated that Mb remained its native structure in the nanocomposite film. Electrochemical behaviors of Nafion/Mb–GR–Pt/CILE were investigated with a pair of well-defined redox peak appeared, which indicated that direct electron transfer of Mb was realized on the underlying electrode with the usage of the GR–Pt nanocomposite. The fabricated electrode showed good electrocatalytic activity to the reduction of trichloroacetic acid in the linear range from 0.9 to 9.0mmol/L with the detection limit as 0.32mmol/L (3σ), which showed potential application for fabricating novel electrochemical biosensors and bioelectronic devices.

TiC nanoparticles-chitosan composite film for the direct electron transfer of myoglobin and its application in biosensing

We report on the direct electrochemistry of myoglobin (Mb) immobilized on a composite matrix based on chitosan (CHIT) and titanium carbide nanoparticles (TiC NPs) underlying on glassy carbon electrode (GCE). The cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the modified electrode. In deaerated buffer solutions, the cyclic voltammetry of the composite films of Mb-TiC NPs-CHIT showed a pair of well-behaved redox peaks that are assigned to the redox reaction of Mb, confirming the effective immobilization of Mb on the composite film. The electron transfer rate constant was estimated to be 3.8 (±0.2)·s−1, suggested that the interaction between the protein and certain electrode surfaces may mimic some physiological situations and may elucidate the relationship between the protein structures and biological functions. The linear dynamic range for the detection of hydrogen peroxide was 0.5–50μM with a correlation coefficient of 0.999 and the detection limit was estimated at about 0.2μM (S/N=3). The calculated apparent Michaelis–Menten constant was 0.07 (±0.01) mM, which suggested a high affinity of the redox protein–substrate. The immobilized Mb in the TiC NPs-CHIT composite film retained its bioactivity. Furthermore, the method presented here can be easily extended to immobilize and obtain the direct electrochemistry of other redox enzymes or proteins.

Direct electrochemistry of myoglobin in a layer-by-layer film on an ionic liquid modified electrode containing CeO2 nanoparticles and hyaluronic acid

We describe an ionic liquid modified electrode (CPE-IL) for sensing hydrogen peroxide (HP) that was modified by the layer-by-layer technique with myoglobin (Mb). In addition, the surface of the electrode was modified with CeO2 nanoparticles (nano-CeO2) and hyaluronic acid. UV-vis and FTIR spectroscopy confirmed that Mb retains its native structure in the composite film. Scanning electron microscopy showed that the nano-CeO2 closely interact with Mb to form an inhomogeneously distributed film. Cyclic voltammetry reveals a pair of quasi-reversible redox peaks of Mb, with the cathodic peak at −0.357 V and the anodic peak at −0.269 V. The peak separation (ΔE p) and the formal potential (E 0′) are 88 mV and −0.313 V (vs. Ag/AgCl), respectively. The Mb immobilized in the modified electrode displays an excellent electrocatalytic activity towards HP in the 0.6 to 78.0 μM concentration range. The limit of detection is 50 nM (S/N = 3), and then the Michaelis-Menten constant is 71.8 μM. We believe that such a composite film has potential to further investigate other redox proteins and in the fabrication of third-generation biosensors.

Hydrogen peroxide biosensor based on the direct electrochemistry of myoglobin immobilized on ceria nanoparticles coated with multiwalled carbon nanotubesby a hydrothermal synthetic method

A novel myoglobin-based electrochemical biosensor was developed. It is based on a nanocomposite prepared from multiwalled carbon nanotubes that were coated with ceria nanoparticles. UV-vis and electrochemical measurements displayed that the nanocomposite provides a biocompatible matrix for the immobilization of myoglobin (Mb) and also facilitates direct electron transfer between its active center and the surface of the electrode. Immobilized Mb exhibits excellent electrocatalytic activity toward the reduction of hydrogen peroxide (HP). The low apparent Michaelis-Menten constant of 63.3 μM indicates high bioactivity and enhanced affinity to HP. This study also shows that the nanocomposite is a promising support for immobilization of proteins and for the preparation of third-generation biosensors.

Direct electrochemistry of myoglobin immobilized on chitosan-wrapped rod-constructed ZnO microspheres and its application to hydrogen peroxide biosensing

Rod-constructed zinc oxide (ZnO) microspheres (RZnOMs), consisting of hundreds of needle-like ZnO nanorods, were utilized to explore a novel biosensor through coupling with myoglobin (Mb) in the presence of chitosan (Chi). Biocompatibility and electrochemical properties of the resulting ZnO-Chi-Mb composite film were studied by Fourier-transform infrared spectroscopy and cyclic voltammetry. The results revealed that the RZnOMs-based composite was a satisfying matrix for proteins to effectively retain their native structure and bioactivity. With advantages of the unique inorganic material, facilitated direct electron transfer of the metalloenzymes was acquired on the RZnOMs-based enzyme electrode. Moreover, the RZnOMs-based biosensor also displayed significant electrocatalytic activity for the reduction of hydrogen peroxide with an apparent Michaelis–Menten constant (32 µM), wide linear range (2–490 µM), and low detection limit (0.21 µM, S/N = 3). These indicated that the RZnOMs were one of the ideal candidate materials for direct electrochemistry of redox proteins and related biosensor construction.

Electrochemistry of myoglobin in Nafion and multi-walled carbon nanotubes modified carbon ionic liquid electrode

The direct electrochemistry of myoglobin (Mb) entrapped in the Nafion film on a multi-walled carbon nanotubes (MWCNTs) modified carbon ionic liquid electrode (CILE) had been investigated in this paper. By using a hydrophilic ionic liquid of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF 4) as the modifier, a high-performance basal electrode was fabricated and further modified by MWCNTs, Mb and Nafion by a step-by-step casting method. Spectroscopic results indicated that the Mb molecule on the surface of MWCNTs/CILE retained its native structure. Cyclic voltammetric results showed that a pair of well-defined quasi-reversible redox peaks appeared in the pH 7.0 phosphate buffer solution (PBS), which was attributed to the direct electron transfer of Mb heme Fe(III)/Fe(II) redox couples with the modified electrode. The Nafion/Mb/MWCNTs/CILE gave excellent electrocatalytic activity towards different substrates including trichloroacetic acid (TCA), hydrogen peroxide (H 2O 2) and sodium nitrite (NaNO 2).

Direct Electrochemistry of Myoglobin on a Room Temperature Ionic Liquid Modified Electrode and Its Application to Nitric Oxide Biosensing

AbstractMyoglobin (Myb) was successfully immobilized on a room temperature ionic liquid (RTIL), 1‐ethyl‐3‐methyl imidazolium tetrafluoroborate ([EMIM][BF4]) modified basal plane graphite (BPG) electrode. The electrochemical behavior of Myb on RTIL modified BPG electrode was explored and the results from cyclic voltammetry (CV) showed a well‐defined and quasi‐reversible CV peaks with a formal potential of −0.379 V (versus Ag/AgCl) in a phosphate buffer solution (pH 7.0). RTIL shows an obvious promotion for the direct electron‐transfer between Myb and BPG electrode. Myb adsorbed on electrode surface exhibits an obvious electrocatalytic activity for the reduction of nitric oxide (NO). The catalytic current is corresponding linearly to the NO concentration in the range of 7.0×10−7 to 7.0×10−6 M with a limit of detection of 2.0×10−7 M (three times the ratio of signal to noise, S/N=3).

Direct electrochemistry of myoglobin in a room temperature ionic liquid aqueous solution and its catalysis to H2O2

Using 1-ethyl-2-methylimidazolium trifluoroacetate (EMImTfa) as the supporting electrolyte, a couple of well-defined and reversible redox peaks of Myb could be observed at the basal plane graphite (BPG) electrode through direct electron transfer between the protein and the BPG electrode, whose anodic and cathodic peak potentials were at −0.098 V and −0.144 V vs. Ag | AgCl, respectively. Both anodic and cathodic peak currents increased linearly with the potential scan rates. Compared with the supporting electrolyte of phosphate buffer solution, EMImTfa played an important role for the direct electron transfer between Myb and the BPG electrode. Further investigation suggested that Myb was adsorbed tightly on the surface of the BPG electrode in the presence of EMImTfa to form a stable, approximate monolayer Myb film. Myb adsorbed on the BPG electrode surface could retain its biological activity and showed a remarkable electrocatalytic activity for the reduction of H2O2 in an EMImTfa aqueous solution. Based on these, a third-generation biosensor could be constructed to directly detect the concentration of H2O2 in EMImTfa aqueous solution with a limit of detection of 3.24 × 10−8 M.

Clay–chitosan–gold nanoparticle nanohybrid: Preparation and application for assembly and direct electrochemistry of myoglobin

A biocompatible nanohybrid material (clay/AuCS) based on clay, chitosan and gold nanoparticles was explored. The material could provide a favorable microenvironment for proteins to realize the direct electron transfer on glassy carbon electrodes (GCE). Myoglobin (Mb), as a model protein to investigate the nanohybrid, was immobilized between the clay/AuCS film and another clay layer. Mb in the system exhibited a pair of well-defined and quasi-reversible redox peaks at −0.160 V (vs. saturated Ag/AgCl electrode) in 0.1 M PBS (pH 7.0), corresponding to its heme Fe III/Fe II redox couples. UV–vis spectrum suggested that Mb retained its native conformation in the system. Basal plane spacing of clay obtained by X-ray diffraction (XRD) indicated that there was an intercalation–exfoliation–restacking process among Mb, AuCS and clay during the modified film drying. Excellent biocatalytic activity of Mb in the modified system was exemplified by the reduction of hydrogen peroxide and nitrite. The linear range of H 2O 2 determination was from 3.9 × 10 −5 to 3.0 × 10 −3 M with a detection limit of 7.5 μM based on the signal to noise ratio of 3. The kinetic parameters such as α (charge transfer coefficient), k s (electron transfer rate constant) and K m (Michaelis–Menten constant) were evaluated to be 0.55, 2.66 ± 0.15 s −1 and 5.10 mM, respectively.

Controllable fabrication and characterization of biocompatible core-shell particles and hollow capsules as drug carrier

SiO 2@CdSe core-shell particles were fabricated by controllable deposition CdSe nanoparticles on silica colloidal spheres. Step-wise coating process was tracked by the TEM and XRD measurements. In addition, SiO 2@CdSe/polypyrrole(PPy) multi-composite particles were synthesized based on the as-prepared SiO 2@CdSe particles by cationic polymerization. The direct electrochemistry of myoglobin (Mb) could be performed by immobilizing Mb on the surface of SiO 2@CdSe particles. Immobilized with Mb, SiO 2@CdSe/PPy-Mb also displayed good bioelectrochemical activity. It confirmed the good biocompatible property of the materials with protein. CdSe hollow capsules were further obtained as the removal of the cores of SiO 2@CdSe spheres. Hollow and porous character of CdSe sub-meter size capsules made them becoming hopeful candidates as drug carriers. Doxorubicin, a typical an antineoplastic drug, was introduced into the capsules. A good sustained drug release behavior of the loading capsules was discovered via performing a release test in the PBS buffer (pH 7.4) solution at 310 k. Furthermore, SiO 2@CdSe/PPy could be converted to various smart hollow capsules via selectively removal of their relevant components.

Direct Electrochemistry of Myoglobin in Titanate Nanotubes Film

Titanate nanotubes (TNT) were proven to be efficient support matrixes for the immobilization of myoglobin (Mb). A comparative study was performed using the corresponding analogue, nanocrystalline anatase TiO2 (TNP). UV-visible absorption and FT-IR spectra show that Mb was not obviously denatured in TNT film in contrast to the significant denaturation of Mb in TNP film. Cyclic voltammetry and square wave voltammetry measurements were carried out using the Mb-TNT or Mb-TNP cast film-covered basal plane pyrolytic graphite electrode. The Mb-TNT film gave a well-defined, nearly reversible redox couple with the apparent formal peak potential (Ep) of -0.239 V (vs Ag/AgCl) in pH 5.5 buffer, whereas a relatively smaller, quais-reversible redox pair with Ep of -0.263 V was observed for the Mb-TNP film. The amounts of electroactive Mb in TNT film and TNP film were 15 and 10%, respectively. Moreover, the Mb-TNT film exerted facile direct electron transfer with the apparent heterogeneous electron-transfer rate constant (kET) of 86+/-7 s-1, almost 4 times the 22+/-5 s-1 value for the Mb-TNP membrane and higher than other Mb-entrapped films reported. Additionally, the Mb-TNT film demonstrates good electrocatalytic reduction of hydrogen peroxide with a detection limit of 0.6 microM, much lower than the 3.0 microM value for the Mb-TNP electrode and other Mb-related film-modified electrodes reported so far. The Mb-TNT film exhibits higher peroxidase-like activity with the apparent Michaelis-Menton constant (KM) of 140 microM, significantly lower than the 1300 microM value for the Mb-TNP film. The functional hydroxyl group and the surface charge as well as tubular morphology of TNT are important factors to stabilize the bound protein.

Direct Electrochemistry and Raman Spectroscopy of Sol−Gel-Encapsulated Myoglobin

The direct electrochemistry of myoglobin (Mb) has been observed at a glassy carbon (GC) electrode coated with silica sol-gel-encapsulated Mb film. A well-behaved cyclic voltammogram is observed with a midpoint potential (E(1/2)) of -0.25 V vs Ag/AgCl in a pH 7.0 phosphate buffer. This potential, which is pH-dependent, is 70-90 mV more negative than the formal potential values obtained by using the spectroeletrochemical titration method at the same pH. Square wave voltametry (SWV) also shows a peak potential of -0.25 V for the reduction of Mb under the same experimental conditions. Both cathodic and anodic peak currents have a linear relationship with the scan rate. The midpoint potential decreases with pH, having a slope of -30 mV/pH. UV-vis and resonance Raman spectroscopic studies reveal that the sol-gel provides a bio-compatible environment where Mb retains a structure similar to its solution form, a 6-coordinated aquomet myoglobin. These results suggest that the silica sol-gel is a useful matrix for studying direct electrochemistry of other heme proteins.

Electrochemical Investigation of Redox Thermodynamics of Immobilized Myoglobin: Ionic and Ligation Effects

In this study, we investigated redox thermodynamics of myoglobin as well as the ionic (phosphate ions) and ligation (imidazole) effects via a dynamic electrochemical approach. We employed a previously established system that features nonmediated, direct electrochemistry of myoglobin and myoglobin in an immobilized state (i.e., diffusionless electrochemistry). Thermodynamics parameters were obtained by measuring redox potential (E degrees ') of myoglobin at varied temperature (T), in the presence and in the absence of specific ions or axial ligands. As a step further, we evaluated contributions from allosteric effect and axial iron ligation by partitioning E degrees ' changes into entropic and enthalpic terms. Compensation phenomena between the entropic and enthalpic changes were observed in all these cases. On the basis of these studies, we also correlated these phenomena to possible structural variations.

Direct electrochemistry and electrocatalysis of myoglobin immobilized on a hexagonal mesoporous silica matrix

The direct electrochemistry of myoglobin (Mb) immobilized on a hexagonal mesoporous silica (HMS)-modified glassy carbon electrode was described. The interaction between Mb and HMS was investigated by using Fourier transfer infrared spectroscopy, nitrogen adsorption isotherm, and cyclic voltammetry. Two couples of redox peaks corresponding to Fe(III) to Fe(II) conversion of the Mb intercalated in the mesopores and adsorbed on the surface of the HMS were observed with the formal potentials of −0.167 and −0.029 V in 0.1 M, pH 7.0, phosphate buffer solution, respectively. The electrode reaction showed a surface-controlled process with one proton transfer. The immobilized Mb displayed good electrocatalytic responses to the reduction of both hydrogen peroxide (H 2O 2) and nitrite (NO 2 −), which were used to develop novel sensors for H 2O 2 and NO 2 −. The apparent Michaelis–Menten constants of the immobilized Mb for H 2O 2 and NO 2 − were 0.065 and 0.72 mM, respectively, showing good affinity. Under optimal conditions, the sensors could be used for the determinations of H 2O 2 ranging from 4.0 to 124 μM and NO 2 − ranging from 8.0 to 216 μM. The detection limits were 6.2 × 10 −8 and 8.0 × 10 −7 M at 3 σ, respectively. The HMS provided a novel matrix for protein immobilization and the construction of biosensors via the direct electron transfer of immobilized protein.