Heme Protein−Clay Films:  Direct Electrochemistry and Electrochemical Catalysis

Abstract

Stable protein-clay films were fabricated by casting an aqueous dispersion of protein and clay on pyrolytic graphite electrodes. Myoglobin (Mb), hemoglobin (Hb), and horseradish peroxidase (HRP) in clay films gave a pair of well defined, quasi-reversible cyclic voltammetric peaks at about -0.28 V vs SCE in pH 5.5 buffers, characteristic of the protein heme Fe III /Fe II redox couples. Square wave voltammograms (SWV) of the protein-clay films gave good fits by nonlinear regression analysis to a model that featured thin-layer SWV and formal potential dispersion, providing average apparent heterogeneous electrontransfer rate constants, ks, and average formal potentials, E°′. UV-vis and reflectance absorption infrared spectra showed that the proteins in clay films retained near-native secondary structures. X-ray diffraction revealed that Mb-clay and Hb-clay films feature ordered layered structures with Mb and Hb intercalated between clay layers. Incorporated HRP induced disorder in the clay films. Oxygen, trichloroacetic acid, nitrite, and hydrogen peroxide were catalytically reduced by all three proteins in clay films.

Fabrication of AucoreCo3O4shell/PAA/HRP Composite Film for Direct Electrochemistry and Hydrogen Peroxide Sensor Applications

“…where Ep,a and Ep,c are the anodic and cathodic peak potentials, respectively) of HRP is about −0.31 V vs Ag/AgCl, which is similar to those obtained in some previous studies. (37)(38)(39) The peak-to-peak separation ΔEp, which is directly related to electron transfer rate, is about 50 mV. Such a small ΔEp reveals a fast and quasi-reversible electron transfer process.…”

Fabrication of Multilayers Film of Myoglobin and Glutaraldehyde on the Surface of Gold Electrode Based on Covalent Interaction and Its Application

“…2, we obviously observed an absorption peak of Mb at 410 nm, suggesting that Mb in films has a secondary structure nearly the same as the native state of Mb [26], and the absorb intensity increased linearly with the number of Mb bilayers (inset), indicting (GA/Mb) n film was successful fabricated on the surface of the glassy carbon electrode. In this work, we select (GA/Mb) 6 film for the next electrochemical experiment.…”

“…Hence, to explore methods to increase the electron transfer rate between Mb and the electrode, much effort have been devoted to the characterization of the electrochemistry of Mb using various films [4,5]. Hu's and Rusling's groups have provided a lot of good work in this area [6,7]. From the publish literature, most of work about the direct electrochemistry of Mb was performed at monolayer film.…”

Comparative electrochemistry of haemoglobin on the long and ball milling shortened carbon nanotubes

“…Therefore, one of the main challenges for the fabrication of high-performance electrochemical biosensors is to provide a suitable microenvironment for the proteins and enhance the DET capacity between the proteins and underlying electrodes. Many materials were used in order to reach this goal, such as insoluble surfactants [10], polymers [11], clay [12], egg-phosphatidylcholine [13,14], zirconium dioxide nanoparticles [15], octadecylamine [16], carbon nanotube (CNT) [17] and 11-mercaptohendecanoic acid [18]. CNTs have attracted much attention in the past decade because of their unique properties and promising applications.…”