Composite Films of Surfactants, Nafion, and Proteins with Electrochemical and Enzyme Activity

Abstract

Stable, functional composite films were made from the ionomer Nafion, water-insoluble surfactants, and heme proteins or the enzyme alcohol dehydrogenase. Rates of electron transfer between myoglobin (Mb) and hemoglobin (Hb) and edge plane pyrolytic graphite (PG) electrodes in these composite films were much larger than those for Hb and Mb in solution on Nafion-coated or bare PG electrodes. Films containing Nafion, didodecydimethylammonium bromide (DDAB), and hemoglobin or myoglobin retained about 90% of the initial redox activity during 4 weeks of storage at 4°C. DDAB is arranged in lamellar liquid crystal bilayers in these films at 25°C, which were more stable than films of the proteins and DDAB alone. Films of Nafion-lecithin-Cyt c on edge plane PG also had good electrochemical properties but were much less stable. Electronic and vibrational spectra indicate that the heme proteins are not denatured in the composite films, but conformational differences from the native state may exist. Linear dichroism suggests that the proteins are specifically oriented in these films. After treatment with a cross-linking agent, Nafion-lipid films containing the enzyme alcohol dehydrogenase retained twice the activity of the enzyme in solution (4°C) when stored for 2 days at room temperature.

Electrocatalytic Properties of Heme Proteins in Layer‐by‐Layer Films Assembled with SiO2 Nanoparticles

“…These values are also quite large and all in the same order of magnitude, and close to those of cast heme protein films obtained by CV data and the same method [42,77]. However, these k s values are about one order smaller than those obtained by SWV (Table 2).…”

Direct Electrochemistry of Myoglobin in a Nafion‐Ionic Liquid Composite Film Modified Carbon Ionic Liquid Electrode

“…Then a composite material based on Nafion and a hydrophobic 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF 6 ) was explored to form a stable film on the CILE surface. Nafion is a perfluorosulfonate linear ion-exchange polymer with good proton conductivity and has been used as an immobilization matrix to entrap proteins due to its good film forming ability and biocompatibility [20,21]. Combined the advantages of CILE and ILs composite film, the direct electrochemistry of myoglobin (Mb) was achieved in this new platform.…”

Highly Sensitive and Selective Uric Acid Biosensor Based on Direct Electron Transfer of Hemoglobin-encapsulated Chitosan-modified Glassy Carbon Electrode

“…1b), showing the potential characteristic of a heme redox couple of the proteins. 41 The anodic and cathodic peak currents are of similar magnitude, with an ipa/ipc ratio of about unity. They are linearly proportional to the scan rates at 20 -500 mV s -1 , suggesting that this quasi-reversible reaction is a surface-controlled process, as expected for immobilized systems.…”