Covalent Immobilization of Amino-beta-Cyclodextrins on Glassy Carbon Electrode in Aqueous Media

Abstract

In the present work, the application of the amine electrooxidation method to achieve the grafting of amino beta-cyclodextrins (CD-amines) on glassy carbon electrodes (GCE) in aqueous media has been investigated. The results indicate that the electrooxidation procedure of CD-amines on GCE effects their covalent immobilization without the need of additional linkers or intermediates. Cyclic voltammograms of ferricyanide proved that the immobilized CDs cover at a large extent the GCE surface. This immobilization is due to real grafting and not the result of a weak physisorption interaction. Indeed, the presence of contributions characteristic of amide groups and the absence of peaks typical of amine groups in the XPS N 1s spectra of the modified GCE, support the evidence of the covalent bonding of the CDs to the glassy carbon surface through amide bond formation. Electrochemical experiments demonstrated that ferrocenemethanol and bentazon can be encapsulated within the cavity of the CDs immobilized on GCEs via the formation of inclusion compounds. Overall, the results of the present work show that this simple amine-electrooxidation strategy is suitable to immobilize CDs on glassy carbon surfaces while maintaining their inclusion abilities and, therefore, open the door to design cheap and simple electrochemical sensors for environmental applications. (C) The Author(s) 2019. Published by ECS.