Direct Electron Transfer Of Myoglobin Research Articles

Carbon Nitride Nanosheet and Myoglobin Modified Electrode for Electrochemical Sensing Investigations

Background: Carbon-based nanomaterials, especially carbon nitride (C3N4) has attracted tremendous interest in biosensor applications. Meanwhile, the mechanism of redox protein sensing and related electrocatalytic reactions can provide a valid basis for understanding the process of biological redox reaction. Objective: The aim of this paper is to construct a new electrochemical enzyme sensor to achieve direct electron transfer of myoglobin (Mb) on CILE surface and display electrocatalytic reduction activity to catalyze trichloroacetic acid (TCA) and H2O2. Methods: The working electrode was fabricated based on ionic liquid modified Carbon Paste Electrode (CILE) and C3N4 nanosheets were modified on the CILE surface, then Mb solution was fixed on C3N4/CILE surface and immobilized by using Nafion film. The as-prepared biosensor displayed satisfactory electrocatalytic ability towards the reduction of TCA and H2O2 in an optimum pH 7.0 buffer solution. Results: The results indicated that C3N4 modified electrode retained the activity of the enzyme and displayed quasi-reversible redox behavior in an optimum pH 7.0 buffer solution. The electrochemical parameters of the immobilized Mb on the electrode surface were further calculated with the results of the electron transfer number (n) as 1.27, the charge transfer coefficient (α) as 0.53 and the electrontransfer rate constant (ks) as 3.32 s-1, respectively. The Nafion/Mb/C3N4/CILE displayed outstanding electrocatalytic reduction activity to catalyze trichloroacetic acid and H2O2. Conclusion: The Nafion/Mb/C3N4/CILE displayed outstanding electrocatalytic reduction, which demonstrated the promising applications of C3N4 nanosheet in the field electrochemical biosensing.

Electrodeposition of alginate–MnO2–C composite film on the carbon ionic liquid electrode for the direct electrochemistry and electrocatalysis of myoglobin

Since the direct electron transfer of myoglobin (Mb) is hardly realized on the bare electrode, the electrodeposition of the mixture of novel MnO2–C composite microsphere, sodium alginate (SA) and Mb on the surface of the carbon ionic liquid electrode (CILE) was conducted to fabricate the modified electrode, denoted as Nafion/Mb–SA–MnO2–C/CILE. The biological activity of Mb in the Mb–SA–MnO2–C composite was confirmed by FTIR and UV–Vis absorption spectra. The fabricated Nafion/Mb–SA–MnO2–C/CILE exhibited a fast electron transfer process with a pair of well-defined redox peaks attributed to the excellent electrochemical property of MnO2–C composite microsphere and good biocompatibility of SA that could provide Mb suitable microenvironment to keep its biological activity and facilitate the electron transfer. Additionally, the modified electrode also exhibited a wider linear range and a low detection limit toward the electrocatalytic reduction in trichloroacetic acid with good stability, reproducibility and accurate detection for the real samples.

Facilitated biosensing via direct electron transfer of myoglobin integrated into diblock copolymer/multi-walled carbon nanotube nanocomposites.

Nanocomposite materials were prepared by sequential drop-casting of multi-walled carbon nanotube (MWCNT) suspensions and amphiphilic polybutadiene-block-poly(2-(N,N-dimethylamino)ethyl methacrylate) (PB290-b-PDMAEMA240) diblock copolymer micellar solution on screen-printed electrodes (SPEs). These nanocomposite materials were found to be very favorable for integration of myoglobin (Mb) and facilitate direct electron transfer from the electrodes to heme proteins. In that respect, PB290-b-PDMAEMA240 was demonstrated to be a well-suited binding agent. In aqueous solutions, it forms core-corona micelles (shown by cryogenic transmission electron microscopy, cryo-TEM, and nanoparticle tracking analysis, NTA), which at pH 7 in phosphate buffer exhibit good adhesion to carbon materials (shown by atomic force microscopy, AFM, scanning electron microscopy, SEM, and scanning transmission electron microscopy, STEM) and build up uniform thin films on a hydrophobic graphite-based substrate. As demonstrated by a quartz crystal microbalance with dissipation monitoring, QCM-D, attractive interactions between Mb and PB290-b-PDMAEMA240 take place when both components are subsequently deposited onto a solid substrate. Spectroscopic studies confirmed that the absorption maximum of Mb remains unaltered, suggesting that at least some protein globules retain their tertiary structure. Cyclic voltammetry, CV, and square wave voltammetry, SWV, show a remarkable (ca. 180-fold) increase of the reductive current of Mb after its incorporation into the SPE/MWCNT/PB290-b-PDMAEMA240 matrix. The herein developed analytical approach was used for the detection of cardiac myoglobin as a very early marker of acute myocardial infarction (AMI) both in plasma of healthy donors and patients with AMI.

Electrochemical myoglobin biosensor based on carbon ionic liquid electrode modified with Fe3O4@SiO2 microsphere

In this paper, a Fe3O4@SiO2 core-shell structure microsphere was synthesized and used to investigate the direct electron transfer of myoglobin (Mb) with a 1-butylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE) as the substrate electrode. The mixture of Mb and Fe3O4@SiO2 microsphere could form an organic–inorganic composite, which was immobilized on the surface of CILE with a chitosan (CS) film. Cyclic voltammetric experiments indicated that a pair of well-defined quasi-reversible redox peaks appeared on CS/Mb-Fe3O4@SiO2/CILE with the formal peak potential (E0′) located at −0.31 V (vs. saturated calomel electrode), which was corresponded to the electroactive center of Mb heme Fe(III)/Fe(II) redox couples. Direct electrochemical behaviors of Mb in CS-Fe3O4@SiO2 composite film were carefully investigated with the electrochemical parameters calculated. The CS/Mb-Fe3O4@SiO2/CILE showed good electrocatalytic behaviors to the reduction of trichloroacetic acid in the concentration range from 0.2 to 11.0 mmol L−1 with the detection limit of 0.18 mmol L−1 (3σ). Based on CS/Mb-Fe3O4@SiO2/CILE, a new third-generation reagentless electrochemical biosensor was constructed with higher sensitivity and reproducibility.

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 and electrocatalysis of myoglobin-based nanocomposite membrane electrode

The direct electron transfer of myoglobin (Mb) was achieved based on the immobilization of Mb/Silver nanoparticles (AgNPs) on glassy carbon electrode by multi-wall carbon nanotubes (MWNTs)-chitosan(Chit) film. The immobilized Mb displayed a pair of well-defined and reversible redox peaks with a formal potential ( E θ′) of − 24 mV (vs. Ag/AgCl) in 0.1 M pH 7.0 phosphate buffer solution. The apparent heterogeneous electron transfer rate constants ( k s) of Mb confined to Chit-MWNTs film was evaluated as 5.47 s − 1 according to Laviron's equation. The surface concentration ( Γ ⁎) of the electroactive Mb in the Chit-MWNTs film was estimated to be (4.16 ± 0.35) × 10 − 9 mol cm − 2 . Meanwhile, the catalytic ability of Mb toward the reduction of H 2O 2 was studied. Its apparent Michaelis–Menten constant for H 2O 2 was 0.024 mM, showing a good affinity. The linear range for H 2O 2 determination was from 2.5 × 10 − 5 M to 2.0 × 10 − 4 M with a detection limit of 1.02 × 10 − 6 M (S/N = 3). Moreover, the biosensor displays rapid response to H 2O 2 and good stability and reproducibility.

Direct electron transfer of myoglobin in mesoporous silica KIT-6 modified on screen-printed electrode

A disposable hydrogen peroxide biosensor was developed based on the direct electron transfer of myoglobin (Mb) on mesopores KIT-6 modified screen-printed electrode (SPE) which was manually performed to fabricate the planar carbon electrodes. KIT-6 is a new material which can absorb abundant of Mb molecules. A mixture of Mb and KIT-6 was immobilized with nafion on electrode. The cyclic voltammetry experiment indicated that a pair of stable and well-defined reduction peaks with a formal potentials of −0.35, and −0.28 V versus saturated calomel electrode (SCE) was obtained, using the present modified electrode in phosphate buffer saline (0.05 M, pH 7.0) at scan rate of 100 mV s −1, characteristic of Mb heme Fe(III)/Fe(II) redox couple. The heterogeneous electron transfer rate constant k s was estimated to be 16.93 s −1. And the formal potential was pH-dependent, having two slopes of −54.7 and −49.3 mV/pH which illustrated one electron transfer. This modified electrode was applied to detect H 2O 2 with sensitivity of 55.68 mA M −1 cm −2. Infrared spectrum and UV–vis absorption spectra of immobilized Mb film were recorded. In conclusion, KIT-6 increases the electron transfer activity of Mb and this kind of H 2O 2 biosensor is low cost for using disposable.

Direct electrochemistry of myoglobin based on ionic liquid–clay composite films

The direct electron transfer of myoglobin (Mb) was realized by immobilizing Mb onto ionic liquid (1-butyl-3-methyl imidazolium tetrafluoraborate, [bmim][BF 4])–clay composite film modified glassy carbon electrode. A pair of well-defined redox peaks of Mb with a formal potential ( E o′) of −0.297 V ( vs. Ag/AgCl) was observed in 0.1 M phosphate buffer solution (pH 6.0). The ionic liquid–clay composite film showed good biocompatibility and an obvious promotion capability for the direct electron transfer between Mb and electrode. The electron transfer rate constant ( k s) of Mb was calculated to be (3.58 ± 0.12) s −1. UV–vis spectrum suggested that Mb retained its native conformation in the ionic liquid–clay system. Basal plane spacing of clay obtained by X-ray diffraction (XRD) indicated that there was an intercalation–exfoliation–restacking process, in ionic liquid and clay during the drying process of the modification, and the ionic liquid played the key role for promotion of the direct electron transfer between Mb and the ionic liquid–clay composite film modified electrode. The biocatalytic activity of Mb in the composite film was exemplified by the reduction of hydrogen peroxide. Under the optimal conditions, the reduction peak currents of Mb increased linearly with the concentration of H 2O 2 in the range of 3.90 × 10 −6 to 2.59 × 10 −4 M, with a detection limit of 7.33 × 10 −7 M. The kinetic parameter I max and the apparent Michaelis constant ( K m) for the electrocatalytic reactions were 3.87 × 10 −8 A and 17.6 μM, respectively. The proposed method would be valuable for the construction of a new third-generation H 2O 2 sensor.

Direct electron-transfer of myoglobin within a new zwitterionic gemini surfactant film and its analytical application for H 2O 2 detection

The direct electron-transfer of myoglobin in a new zwitterionic gemini surfactant film with glassy carbon electrode surface has been investigated. A pair of well-defined and quasi-reversible voltammetric peaks was observed at −0.34 and −0.30 V due to the direct electron-transfer of the redox couple of Mb (Fe III/Fe II). The voltammetric responses of myoglobin–surfactant film under different pH and scan rate conditions were obtained. The presence of hydrogen peroxide changed the typical electrochemical behaviors in terms of bioelectrocatalysis of myoglobin to hydrogen peroxide, and a higher sensitive electroanalytical method for the determination of hydrogen peroxide has been developed.

Carbon Nanotubes and Electrochemistry

Rigid carbon nanotube (CNT) polymer composites were characterized as bare electrochemical transducers and as support for (bio)functionalization. In order to accomplish that, cyclic voltammetry and impedance spectroscopy in presence of benchmark redox systems were performed. The response and sensitivity can be enhanced if the density of edges is increased in the CNT systems. Bamboo-like CNTs seem to be the best choice for composite electrodes. Additionally, the CNT electrodes result in a very robust support for chemical functionalization. Direct electron transfer of myoglobin has been verified without the need of electrochemical mediators and without compromising the biomolecule activity. Finally, some other exciting applications of CNT electrochemistry at the nanoscale regime are also highlighted.

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

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.

The Direct Electron Transfer of Myoglobin Based on the Electron Tunneling in Proteins

The electron tunneling of the protein-polypeptide interactions was observed in the study of direct electron transfer of the myoglobin (Mb) on the electrode surface. The Mb was selected as a redox active protein and gelatine was selected to couple with Mb to form an electron tunneling. The electrochemical results indicated the presence of the electron tunneling and the direct electron transfer. The circular dichroism spectra suggested that the beta-sheet chain of gelatine could interact with alpha-helical chain to form an electron tunneling to promote the protein direct electrochemistry. The SDS-PAGE results proved that the electron tunneling between Mb and gelatine was noncovalent hydrogen bonds. The immobilized Mb showed a couple of quasi-reversible redox peaks with a formal potential of -0.37V (vs SCE) in 0.1 M pH 7.0 PBS. The modified electrodes displayed a rapid amperometric response to the reduction of oxygen, H2O2, and nitrite.