Interaction ofd-Amino Acid Oxidase with Carbon Nanotubes: Implications in the Design of Biosensors

Abstract

We have investigated the interaction of D-amino acid oxidase (DAAO) with single walled carbon nanotubes (CNT) by spectroscopic ellipsometry. Dynamic adsorption experiments were performed at different experimental conditions. In addition, the activity of the enzyme adsorbed at different conditions was studied. Our results indicate that DAAO can be adsorbed to CNT at different pH values and concentrations by a combination of hydrophobic and electrostatic interactions. Considering that the highest enzymatic activity was obtained by adsorbing the protein at pH 5.7 and 0.1 mg.mL−1, our results indicate that DAAO can adopt multiple orientations on the surface; which are ultimately responsible for significant differences in catalytic activity.

Recent applications of carbon-based nanomaterials in analytical chemistry: Critical review

“…The authors stated that BSA molecules arriving at the CNT surface may adopt a preferred orientation with the positive and non-polar patches of the protein facing the hydrophobic sorbent surface, resulting in an attachment-controlled adsorption process. Later, Mora et al investigated the relationship between the interaction phenomena (adsorption/desorption kinetics and amount) and the activity of adsorbed D-amino acid oxidase (DAAO) [173]. They found that the adsorption of DAAO to CNT is controlled by a combination of hydrophobic and electrostatic forces, and observed that the activity of the sensor was influenced not only by the adsorbed amount but also by the conformation adopted by the enzyme on the CNT surface.…”

Immobilization of Genetically-Modified d-Amino Acid Oxidase and Catalase on Carbon Nanotubes to Improve the Catalytic Efficiency

“…It has been proposed that evolved H 2 O 2 is eliminated during the production of 7ADCA [6]. DAAOs can also be used to catalyze the production of α-keto acids from essential D-amino acids [7,8], resolution of racemic mixtures of amino acids [9], and quantification of the D-amino acid content in biological fluids [10][11][12][13][14][15]. Cooperating with other enzymes, DAAOs promote the catalysis processes [16,17].…”

An amperometric glucose biosensor based on layer-by-layer GOx-SWCNT conjugate/redox polymer multilayer on a screen-printed carbon electrode

“…Recent studies reported that incorporation of SWCNTs [26] or MWCNTs [27] into LBL films containing glucose oxidase (GOx) increases sensor response by enhancing electron diffusion through the films and/or the electrochemical surface area. Further, physical adsorption of the enzyme onto nanotubes for biosensor development has also attracted substantial research attention [28][29][30]; GOx adsorbed onto CNTs has been reported to reduce the distance between the FAD center and the electrode surface. CNTs may also penetrate closer to the FAD center due to their small diameter which allows improved access to the FAD center via redox mediator [31,32].…”