Electrografted Interfaces on Metal Oxide Electrodes for Enzyme Immobilization and Bioelectrocatalysis

Abstract

21 22 23 29 33 39 41 42 43 45 46 47 48 49 50 51 52 53 54 55 56 57 In this work, we demonstrate that diazonium electrografting of biocompatible interfaces on transparent conducting oxide indium tin oxide (ITO) can be controlled and optimized to achieve low charge transfer resistance, allowing highly efficient electron transfer to an immobilized model enzyme, the oxygen-tolerant [NiFe]-hydrogenase from Ralstonia eutropha. The use of a radical scavenger enables control of the interface thickness, and thus facilitates maximization of direct electron transfer processes between the enzyme’s active center and the electrode. Using this approach, amine and carboxylic acid functionalities were grafted on ITO, allowing enzyme immobilization both under moderate electrostatic control and covalently via amide bond formation. Despite an initial decrease in catalytic activity, covalent immobilization led to an improve-ment in current stability compared to just electrostatically immobilized enzyme. Given the superior stability of electrografted interfaces in comparison to adsorbed or self-assembled interfaces, we propose electrografting as an alternative approach for the functional immobilization of redox-active enzymes on transparent conducting oxide (TCO) electrodes in bioelectronic devices. distance from sample holder to sputter source of 75 mm. An Argon/oxygen atmosphere of 30:1 was used and the power of the RF was 200 W. A PTFE-coated O-ring was used to seal the electrochemical cell on top of the coated prism, forming a working electrode with a geometric surface area of 0.79 cm 2 in contact with the electrolyte. IR Spectra were recorded between 4000 and 1000 cm (cid:0) 1 with a spectral resolution of 4 cm (cid:0) 1 on a Bruker IFS66v/s spectrometer equipped with a liquid N 2 -cooled, photoconductive Mercury Cadmium Telluride detector. A temperature-controlled, homemade spectroelectrochemical cell was used at a controlled temperature of 25 ° C. 400 scans were averaged per IR spectrum.

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Identifiers

DOI

10.1002/CELC.202100020

Journal

ChemElectroChem

Year

2021