Comparative Electrochemical Behavior of Proteins; Cytochrome c, Agaricus Bisporus Laccase, and Glucose Oxidase, Immobilized onto Gold-Thiol Self-Assembled Monolayer via Electrostatic, Covalent, and Covalent Coordinate Bond Methods

• Immobilization of proteins via EDC/NHS, electrostatic and Zr(IV) routes are compared.
• Cyt c, Lacasse and glucose oxidase model proteins are practically and comparatively studied.
• Characteristics studied include Γprotein, electrochemical activities and storage stabilities.
• Large activity & Γ are found for Cyt c & LacAB via Zr(IV), but EDC/NHS is better for GOx.
• Overall, regarding storage stabilities and regeneration/repairing, Zr(IV) route is excellent.

Comparative electrochemical behavior of three types of proteins; cytochrome c (Cyt c), Agaricus Bisporus laccase (LacAB) and glucose oxidase (GOx) immobilized on gold mercaptopropionic acid self-assembled monolayer via three different methods, including (a) covalent attachment by using EDC/NHS organic activators, (b) electrostatic interactions, and (c) covalent-coordinate binding by using Zr(IV) ion glue is investigated. Immobilization steps and electrochemical behavior of the immobilized proteins are traced by means of cyclic and differential pulse voltammetry (CV and DPV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). The results indicate that characteristics of the immobilized systems including; surface coverage, electrocatalytic activity and stability of the proteins are considerably affected by type of the bond formed between electrode and protein (the immobilization method), and nature of the protein. Immobilization via Zr(IV) ion resulted in higher activities for metalloproteins, i.e. Cytc with Heme active center and LacAB with T copper active center, while EDC/NHS method was more efficient for GOx having FAD cofactor. The experimental data will be presented and discussed from which the efficient immobilizing method for each case is introduced.

Immobilization methods: (A) covalent attachment via EDC/NHS activators, (B) electrostatic interaction, and (C) covalent coordinate interaction using Zr(IV) ion glue.Figure optionsDownload as PowerPoint slide