Direct Electrochemistry and Raman Spectroscopy of Sol−Gel-Encapsulated Myoglobin

Abstract

The direct electrochemistry of myoglobin (Mb) has been observed at a glassy carbon (GC) electrode coated with silica sol-gel-encapsulated Mb film. A well-behaved cyclic voltammogram is observed with a midpoint potential (E(1/2)) of -0.25 V vs Ag/AgCl in a pH 7.0 phosphate buffer. This potential, which is pH-dependent, is 70-90 mV more negative than the formal potential values obtained by using the spectroeletrochemical titration method at the same pH. Square wave voltametry (SWV) also shows a peak potential of -0.25 V for the reduction of Mb under the same experimental conditions. Both cathodic and anodic peak currents have a linear relationship with the scan rate. The midpoint potential decreases with pH, having a slope of -30 mV/pH. UV-vis and resonance Raman spectroscopic studies reveal that the sol-gel provides a bio-compatible environment where Mb retains a structure similar to its solution form, a 6-coordinated aquomet myoglobin. These results suggest that the silica sol-gel is a useful matrix for studying direct electrochemistry of other heme proteins.

Electrocatalysis of Hemoglobin in ZnO Nanoparticle/Ionic Liquid Composite Film Modified Glassy Carbon Electrode

“…The film can provide an excellent microenvironment for the proteins to keep their structure and facilitate the electron transfer between the active center and the underlying electrode. Many immobilization methods for proteins have been proposed such as covalent attachments, 4 sol-gels, 5,6 polymers 7,8 and layer-by-layer. [9][10][11] Recently, nanoparticles had also been used in the field of protein electrochemistry.…”

Direct Electrochemistry of Hemoglobin Immobilized on Hydrophilic Ionic Liquid-chitosan-ZrO2 Nanoparticles Composite Film with Carbon Ionic Liquid Electrode as the Platform

“…[2][3][4] So proteins are often incorporated into different thin film-modified electrodes, which can enhance the direct electron transfer rate between the proteins or enzymes and the underlying electrodes. A variety of materials, such as surfactants, [5][6][7][8][9][10] sol-gels, [11][12][13] polymers, 14-17 composite films, [18][19][20][21] carbon nanotubes, [22][23][24][25][26][27] and nanoparticles [28][29][30][31][32] have been employed to immobilize enzymes. Recently, nanoparticles have attracted increasing attention in electrochemical studies for the protein electrochemistry and protein immobilization because of some noticeable advantages of nanoparticles, such as large surface area, high thermal and chemical stability, tunable porosity and biocompatibility.…”

Encapsulating Cytochrome <em>c</em> in Silica Aerogel Nanoarchitectures without Metal Nanoparticles while Retaining Gas-phase Bioactivity

“…c being encapsulated in sol-gels that have been kept wet or that have been dried ambiently [24][25][26][27][28][29][30] . Reports of encapsulating biomolecules in sol-gels that are then dried supercritically to form aerogels are rarer due to the necessary processing that can be detrimental to the structure of many proteins.…”