Electrochemistry, Surface Plasmon Resonance, and Quartz Crystal Microbalance: An Associative Study on Cytochrome c Adsorption on Pyridine Tail-Group Monolayers on Gold

Abstract

Quartz crystal microbalance (QCM), surface plasmon resonance (SPR), and electrochemistry techniques were used to study the electron-transfer (ET) reaction of cytochrome c (Cyt c) on gold surfaces modified with thionicotinamide, thioisonicotinamide, 4-mercaptopyridine, 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol, 5-phenyl-1,3,4-oxadiazole-2-thiol, 4,4'-bipyridine, and 4,4'-dithiopyridine. The electrochemical results showed that the ET process is complex, being chiefly diffusional with steps depending on the orientation of the pyridine or phenyl tail group of the modifiers. The correlation between the electrochemical results and those acquired by SPR and QCM indicated the presence of an adlayer of Cyt c adsorbed on the thiolate SAMs. This adlayer, although being not electroactive, is essential to assess the ET reaction of Cyt c in solution. The results presented in this work are consistent with the statement (Feng, Z. Q.; Imabayashi, S.; Kakiuchi, T.; Niki, K. J. Electroanal. Chem. 1995, 394, 149-154) that the ET reaction of Cyt c can be explained in terms of the through-bond tunneling mechanism.

Efficiency of Enzymatic O2 Reduction by Myrothecium verrucaria Bilirubin Oxidase Probed by Surface Plasmon Resonance, PMIRRAS, and Electrochemistry

“…On the basis of the knowledge that a hydrophilic pocket composed of positively charged amino acid residues surrounds the T1 Cu, many other studies also reported that carboxylate groups on the surface of electrodes allow fast electron transfer for adsorbed Mv BOD. ,− Although this observation is commonly accepted to be related to a suitable orientation of the enzyme on the surface, the proof of such an orientation and the way in which the conformation and amount of adsorbed proteins evolved in relation to the catalytic activity have only seldom been reported. , Coupled methods were used to get further insights into the relation between the enzymatic activity and the immobilized enzyme amount and conformation. , Quartz crystal microbalance measurements coupled with electrochemistry (e-QCM) was especially carried out to study Mv BOD activity on negatively charged interfaces. , It was shown that electroactivity loss did not correlate with enzyme leaching but with structural rearrangements. , Surface plasmon resonance (SPR) is another method that can be coupled with electrochemistry in order to obtain information about adsorbed species at the electrochemical interface . Any perturbation at the surface induces change in the refractive index of the adsorbed layer that is monitored through the modification in the resonant angle of light as a result of light adsorption by surface plasmons. , Electrochemistry coupled with SPR (e-SPR) has been used in the past to study electron transfer on cytochrome c as a function of SAM chemistry on a gold electrode, redox state induced immobilization of ferrocene-modified proteins, effects of nanostructuration of materials on the activity per bound glucose oxidase molecule, and assemblies of various nanomaterials and enzymes for biosensor applications …”

“…35 Any perturbation at the surface induces change in the refractive index of the adsorbed layer that is monitored through the modification in the resonant angle of light as a result of light adsorption by surface plasmons. 36,37 Electrochemistry coupled with SPR (e-SPR) has been used in the past to study electron transfer on cytochrome c as a function of SAM chemistry on a gold electrode, 38 redox state induced immobilization of ferrocene-modified proteins, 39 effects of nanostructuration of materials on the activity per bound glucose oxidase molecule, 40 and assemblies of various nanomaterials and enzymes for biosensor applications. 41 In this work, we perform e-SPR to study for the first time the relationship between the loading and activity of Mv BOD adsorbed on two different SAMs.…”

Real-Time Dynamic Adsorption Processes of Cytochrome c on an Electrode Observed through Electrochemical High-Speed Atomic Force Microscopy

“…To understand the correlation between molecular dynamic behavior and the electrochemical response of proteins adsorbed on the electrode, numerous studies have used spectro-electrochemical techniques that combine electrochemical measurements and various spectroscopy techniques, such as surface-enhanced resonance Raman (SERRS) [ 1 – 3 ] and surface-enhanced infrared absorption (SEIRA) [ 4 – 6 ]. Electrochemical quartz crystal microbalance (EQCM) and surface plasmon resonance (SPR) measurements also have been used to study dynamic molecular adsorption processes [ 7 – 9 ]. These techniques provide excellent opportunities to study redox protein mechanisms and provide overall information concerning the interface between proteins and an electrode; however, the local structure is not obtained, due to a lack of spatial resolution.…”

“…It is well known that cyt c electrostatically immobilizes on SAMs of carboxylic acid-terminated alkanethiols via lysine residues surrounding the cyt c heme crevice and exhibits a reversible voltammetric response [ 22 – 27 ]. Numerous studies on direct electrochemistry of cyt c adsorbed on a SAM-modified [ 25 ] electrode have employed various surface analysis techniques [ 5 , 9 , 11 , 28 – 33 ]. Until now, however, cyt c molecules adsorbed on electrodes have not been directly observed through real-time imaging using microscopy techniques.…”

Concanavalin A–Polysaccharides binding affinity analysis using a quartz crystal microbalance

“…QCMs have been proven to be reliable in the field of electrochemistry (Paulo Tde et al, 2013; Sun et al, 2013a, 2013b), in petroleum characterization (Pejcic et al, 2011; Ueyama et al, 2002), in environmental chemistry (Nicolini et al, 2012), material science (Pei et al, 2010) and more interestingly in the development of biosensors (Bouchet-Spinelli et al, 2013; Eom et al, 2013; Guntupalli et al, 2013; Wangchareansak et al, 2013) which are valuable for disease diagnosis. QCMs also found a great interest in the monitoring of the affinity constants defining a given substrate-ligand interaction (Lebed et al, 2006; Li et al, 2013; Mori et al, 2009; Tan et al, 2013).…”