Structural Changes in Adsorbed Cytochrome c upon Applied Potential Characterized by Neutron Reflectometry

Wood, Mary H.; Humphreys, Elizabeth; Welbourn, Rebecca J. L.

doi:10.1021/acs.langmuir.9b00691

Cited by 2 publications

(2 citation statements)

References 37 publications

(69 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous NR measurements for deposited thin films of metals, including titanium and steel alloys, have shown structural changes for the metals themselves as a function of applied potential, usually resulting from solvent inclusion when cathodically polarized. 29,30 In this instance, as the growth of the outermost carbon layer begins at positive applied potentials, it seems more likely that oxidation of the carbon to form carboxylic groups on the surface leads to weakening of the interactions between the graphitic carbon layers and hence an observed swelling of the outermost layers. 31 This was subsequently confirmed by XRR and XPS measurements (below).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Adsorption Behavior of the Coenzyme NADH at the Carbon/Electrolyte Interface Determined by Neutron Reflectometry

et al. 2022

Self Cite

View full text Add to dashboard Cite

The adsorption behavior of β-nicotinamide adenine dinucleotide (NADH) at the carbon/electrolyte interface has been studied using a combination of neutron reflectometry (NR) and solution depletion isotherms. Coupling the NR technique with an electrochemical cell allowed in situ observation of the reversible adsorption and desorption of the molecule at the electrode surface over a range of applied potentials. The overall surface coverage was low (30–50%), suggesting adsorption only at specific defect sites on the surface. Isotherms conducted over a range of temperatures were used to extract thermodynamic parameters, which implied strong physisorption via electrostatic interactions. In addition, changes in the outermost layer of the carbon electrode were observed as the applied potential was varied, which were confirmed with ex situ X-ray reflectivity measurements (XRR). X-ray photoelectron spectroscopy (XPS) measurements of the carbon surface demonstrated the majority of carbon atoms were in an sp2 state.

show abstract

Section: ■ Results and Discussionmentioning

confidence: 99%

Adsorption Behavior of the Coenzyme NADH at the Carbon/Electrolyte Interface Determined by Neutron Reflectometry

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…Chemical optimization strategies are applied to the development of protein/enzyme biosensors and facilitate fabrication of surfaces for stabilization of biomolecules in functional conformations. Previous studies highlight diverse biocompatible surfaces facilitating cytochrome c (cyt c ) electron transfer in protein/SAM electrode assemblies created to mimic the cyt c/ charged surface interactions in biological systems. − Because cyt c and other proteins function in different regions of the cell, it is important to understand how small changes in surface chemistry impact their function. Cyt c model systems provide insights into the biocompatibility of electrodes and optimization of surfaces for understanding protein immobilization; recent publications highlight biosensor applications − and the extensive electrochemistry research conducted on the protein. − …”

Section: Introductionmentioning

confidence: 99%

Tripeptide Self-Assembled Monolayers as Biocompatible Surfaces for Cytochrome c Electrochemistry

et al. 2023

View full text Add to dashboard Cite

Biocompatible tripeptide self-assembled monolayers (SAMs) are designed with a carboxylate group on the terminal amino acid (glutamate, aspartate, or amino adipate) to electrostatically attract the lysine groups around the heme crevice in horse heart cytochrome c (cyt c), creating an electroactive protein/tripeptide/Au interfacial structure. Exposing the peptide/Au electrode to cyt c resulted in an 11 ± 3 pmol/cm 2 electroactive protein surface coverage. Topographical images of the interfacial structure are obtained down to single-protein resolution by atomic force microscopy. Uniform protein monolayer assemblies are formed on the Au electrode with no major surface roughness changes. The cyt c/peptide/Au electrode systems were examined electrochemically to probe surface charge effects on the redox thermodynamics and kinetics of cyt c. Neutralization of protein surface charge due to adsorption on anionic COOH-terminated SAMs was found to change the formal potential, as determined by cyclic voltammetry. The cyt c/peptide/Au electrodes exhibit formal potentials shifted to more positive values, have a surface carboxylic acid pK a of 6 or higher, and produce effective cyt c surface charges (Z ox ) of −6 to −14. The Marcus theory is utilized to determine the protein electron transfer rates, which are ∼5 times faster for cyt c/tripeptide/Au compared to cyt c/11-mercaptoundecanoic acid SAMs of similar chain lengths.

show abstract

Structural Changes in Adsorbed Cytochrome c upon Applied Potential Characterized by Neutron Reflectometry

Cited by 2 publications

References 37 publications

Adsorption Behavior of the Coenzyme NADH at the Carbon/Electrolyte Interface Determined by Neutron Reflectometry

Adsorption Behavior of the Coenzyme NADH at the Carbon/Electrolyte Interface Determined by Neutron Reflectometry

Tripeptide Self-Assembled Monolayers as Biocompatible Surfaces for Cytochrome c Electrochemistry

Contact Info

Product

Resources

About