In this work, the final binary SAMs composed of 11-aminoundecanethiol (AUT) domains and 10-carboxy-1- decanethiol (MUA) domains on Au(111) substrate was used for immobilizing chicken liver sulfite oxidase (CSO) to study the direct electron transfer and detect sulfite anions. Scanning tunneling microscope images clearly showed the phase separation between AUT and MUA domains in the final binary SAMs prepared by the electrochemically selective replacement method. | Vietnam Journal of Chemistry, International Edition, 54(6): 736-741, 2016 DOI: Direct electrocatalytic activity of chicken liver sulfite oxidase immobilized on binary self-assembled monolayer composed of separated domains having opposite charges Pham Hong Phong Institute of Chemistry, Vietnam Academy of Science and Technology Received 11 August 2016; Accepted for publication 19 December 2016 Abstract In this work, the final binary SAMs composed of 11-aminoundecanethiol (AUT) domains and 10-carboxy-1decanethiol (MUA) domains on Au(111) substrate was used for immobilizing chicken liver sulfite oxidase (CSO) to study the direct electron transfer and detect sulfite anions. Scanning tunneling microscope images clearly showed the phase separation between AUT and MUA domains in the final binary SAMs prepared by the electrochemically selective replacement method. The electrochemical signals of CSO appeared on the voltammogram indicated that the direct electron transfer between the enzyme and the modified electrode could be obtained without electron mediator. The electrocatalytic currents of sulfite oxidation by CSO immobilized on the final binary SAMs were linearly dependent on their concentrations in solution with R2 = , revealing a possibility in detection this anion by employing the bioelectrochemical sensor. Keywords. Binary self-assembled monolayers, sulfite oxidase, oppositely charged domains. 1. INTRODUCTION Biosensors based on the third generation, in which direct electron transfer is taken place between active sites deeply buried within enzyme and electrode, have superior selectivity because of operating in a potential window closer to the redox potential of the enzyme and therefore less prone to interfering reactions [1]. Among enzymes containing redox active sites, sulfite oxidase (SOx), an enzyme catalyzing the oxidation of sulfite to sulfate, contains the molybdenum complex cofactor (Moco) and a cytochrome b5-type (cyt b5)
