Electrochemical behaviour of horse‐heart cytochrome‐c

Schreurs, Jpgm Jan; Veugelers, P Peter-Paul; Wonders, AH Ad; Barendrecht, E Embrecht

doi:10.1002/recl.19841030904

Cited by 9 publications

(3 citation statements)

References 30 publications

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“…As expected, the lowest binding affinity of Cyt-C was observed when the glass surface was functionalized with ITO/APTES. Such low affinity is predictable due to the weak interaction between Cyt-C and APTES, as both APTES and Cyt-C are positively charged at neutral pH. , We quantified a clear increase in the K eq for the bare ITO, (when compared to ITO/APTES interface), which is attributed to the favorable adsorption based on the electrostatic attraction between positively charged amino acid residues (lysine) and the −OH groups of ITO; these results are in good agreement with previously reported work of Cyt-C adsorption onto glass surface . Whereas, the highest value in K eq was measured when the glass surface was functionalized with ITO/APTES/Cyt-C Ab, which confirms that the presence of a capturing Cyt-C Ab highly increases the affinity of the specific binding events of the Cyt-C protein adsorption, even though concurrent and partial nonspecific modes of adsorption might also be present.…”

Section: Resultssupporting

confidence: 90%

Electroactive Interface for Enabling Spectroelectrochemical Investigations in Evanescent-Wave Cavity-Ring-Down Spectroscopy

et al. 2020

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In this study, we report the development of an electrically active solid−liquid interface for the evanescent-wave cavity-ring-down spectroscopic (EW-CRDS) technique to enable spectroelectrochemical investigations of redox events. Because of a high-quality transparent conductive electrode film of indium tin oxide (ITO) coated on the interface of total internal reflection of the EW-CRDS platform, a cavity ring-down time of about 900 ns was obtained allowing spectroelectrochemical studies at solid− liquid interfaces. As a proof-of-concept on the capabilities of the developed platform, measurements were performed to address the effects of an applied electric potential to the adsorption behavior of the redox protein cytochrome c (Cyt-C) onto different interfaces, namely, bare-ITO, 3-aminopropyl triethoxysilane (APTES), and Cyt-C antibody. For each interface, the adsorption and desorption constants, the surface equilibrium constant, the Gibbs free energy of adsorption, and the surface coverage were optically measured by our electrically active EW-CRDS tool. Optical measurements at a set of constant discrete values of the applied electric potential were acquired for kinetic adsorption analysis. Cyclic voltammetry (CV) scans under synchronous optical readout were performed to study the effects of each molecular interface on the redox process of surface-adsorbed protein species. Overall, the experimental results demonstrate the ability of the electro-active EW-CRDS platform to unambiguously measure electrode-driven redox events of surface-confined molecular species at low submonolayer coverages and at a single diffraction-limited spot. Such capability is expected to open several opportunities for the EW-CRDS technique to investigate a variety of electrochemical phenomena at solid−liquid interfaces.

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Section: Resultssupporting

confidence: 90%

Electroactive Interface for Enabling Spectroelectrochemical Investigations in Evanescent-Wave Cavity-Ring-Down Spectroscopy

et al. 2020

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“…It is noted that the presence of a capturing Cyt-C Ab dramatically increased the binding affinity of Cyt-C to the surface even though concurrent and partial nonspecific modes of adsorption might be present. Also, the lowest binding affinity of Cyt-C was observed when the EA-IOW was functionalized with APTES, presumably due to the electrostatic repulsion between Cyt-C and APTES, which both have overall positive charges at neutral pH 44,45 . When compared to ITO/APTES interface a clear increase in the equilibrium constant for the bare ITO is seen, this may be attributed to the favorable adsorption based on the electrostatic attraction between positively charged amino acid residues (lysine) and the −OH groups of ITO; these results are agree well with reported work of Cyt-C adsorption onto ITO surface 39,46 .…”

Section: Iii(b))mentioning

confidence: 99%

Adsorption Properties and Electron-transfer Rates of a Redox Probe at Different Interfaces of an Immunoassay Assembled on an Electro-active Photonic Platform

et al. 2021

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Physical and chemical properties of a redox protein adsorbed to different interfaces of a multilayer immunoassay assembly were studied using a single-mode, electro-active, integrated optical waveguide (SM-EA-IOW) platform. For each interface of the immunoassay assembly (indium tin oxide, 3-aminopropyl triethoxysilane, recombinant protein G, antibody, and bovine serum albumin) the surface density, the adsorption kinetics, and the electron-transfer rate of bound species of the redox-active cytochrome c (Cyt-C) protein were accurately quantified at very low surface concentrations of redox species (from 0.4 % to 4 % of a full monolayer) using a highly sensitive optical impedance spectroscopy (OIS) technique based on measurements obtained with the SM-EA-IOW platform. The technique is shown here to provide quantitative insights into an important immunoassay assembly for characterization and understanding of the mechanisms of electron transfer rate, the affinity strength of molecular binding, and the associated bioselectivity. Such methodology and acquired knowledge are crucial for the development of novel and advanced immuno-biosensors.

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“…It can be noticed that the presence of a capturing Cyt-C Ab increases the binding affinity and the equilibrium rate constants of Cyt-C to the functionalized electrode surface. Furthermore, the lowest binding affinity of Cyt-C was observed when the SM-EA-IOW was functionalized with APTES, such low affinity is due to the weak interaction between Cyt-C and APTES, as APTES as well as Cyt-C have positive charges at neutral pH[91,92].Moreover, in comparison to the ITO/APTES/ProG/Cyt-C Ab immunolayer one can notice the small change in the overall equilibrium constant when a blocking buffer -BSAwas used. This small change may indicate the homogeneous morphology of the functionalized immunolayers on the SM-EA-IOW device surface, such hypothesis is also supported by the adsorption measurements of Cyt-C where only a small effect on the surface coverage of Cyt-C was observed when BSA was used(Figure 2-5).…”

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confidence: 99%

Photonic tools for advanced sensing and imaging at the nanoscale.

Ghithan¹

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This dissertation reports a novel bio-sensing strategy based on single-mode, electro-active, integrated optical waveguide (SM-EA-IOW) platforms. It also reports the development of a super-resolved far-field optical imaging tool to enable optical, electronic, and spectroelectrochemical investigations at the nanoscale. SM-EA-IOW platforms with its outstanding sensitivity for spectroelectrochemical interrogation was combined with a sandwich bioassay for the development of a novel immunosensing based strategy for label-free detection of infectious pathogens. The strategy begins with the functionalization of the electroactive waveguide surface with a capturing antibody aimed at a specific target analyte. Once the target analyte is bound to the photonic interface, it promotes the binding of a secondary antibody that has been labeled with a redox active reporter. This labeled antibody reporter forms the analytical signal, which is linked uniquely to both the spectral and electrochemical properties of the redox probe designed to specifically recognize a target analyte. Based on this novel detection strategy experimental results in the interrogation of influenza A (H5N1) HA protein have reached an outstanding level of detection in the picomolar range. In vii addition, the novel label-free SM-EA-IOW bio-sensing strategy was successfully demonstrated for detection of gram-negative bacteria in present authentic clinical eye samples. Such demonstration has also shown the flexibility and ability of the new strategy to probe samples in in the microliter volume range, without any prior processing or pre-enrichment steps. As the groundwork towards the optimal operation of the novel sensing strategy, the effects of the adsorption process and the rate of electron transfer of redox bound species to the electrode surface were thoroughly studied. For each interface of a multilayer immunoassay assembly the surface density, the adsorption kinetic, and the electron-transfer rate of bound species of a redox-active protein were investigated using an optical impedance spectroscopy (OIS) technique based on measurements obtained with the SM-EA-IOW platform. Such methodology and acquired knowledge are crucial for the rational development of novel and advanced immuno-biosensors. Electrochemically modulated fluorescent molecules to be conjugated with relevant antibodies for creating an electroactive probe at the nanoscale was also investigated. Such capability has the potential to enable the development of an arrayed immunosensing technology. Fluorescence emission at the nanoscale suffers from two main restrictions, diffraction limit and photobleaching effects. To address these hinders, a modulated stimulated emission depletion microscope (STED) that is capable of achieving far-field super-resolved images was developed and used to reduce the power of the applied excitation and depletion laser beams diminish photobleaching effects in single-molecule sub-diffraction STED imaging. viii These two photonic devices provide new approaches for bio-sensi...

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Electrochemical behaviour of horse‐heart cytochrome‐c

Cited by 9 publications

References 30 publications

Electroactive Interface for Enabling Spectroelectrochemical Investigations in Evanescent-Wave Cavity-Ring-Down Spectroscopy

Electroactive Interface for Enabling Spectroelectrochemical Investigations in Evanescent-Wave Cavity-Ring-Down Spectroscopy

Adsorption Properties and Electron-transfer Rates of a Redox Probe at Different Interfaces of an Immunoassay Assembled on an Electro-active Photonic Platform

Photonic tools for advanced sensing and imaging at the nanoscale.

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