Avidin and glucose oxidase-non-covalently functionalized multi-walled carbon nanotubes: A new analytical tool for building a bienzymatic glucose biosensor

Abstract

We report an innovative supramolecular architecture for bienzymatic glucose biosensing based on the non-covalently functionalization of multi-walled carbon nanotubes (MWCNTs) with two proteins, glucose oxidase (GOx) (to recognize glucose) and avidin (to allow the specific anchoring of biotinylated horseradish peroxidase (b-HRP)). The optimum functionalization was obtained by sonicating for 10 min 0.50 mg mL−1 MWCNTs in a solution of 2.00 mg mL−1 GOx+1.00 mg mL−1avidin prepared in 50 : 50 v/v ethanol/water. The sensitivity to glucose for glassy carbon electrodes (GCE) modified with MWCNTs-GOx-avidin dispersion and b-HRP (GCE/MWCNTs-GOx-avidin/b-HRP), obtained from amperometric experiments performed at −0.100 V in the presence of 5.0×10−4 M hydroquinone, was (4.8±0.3) μA mM−1 (r2=0.9986) and the detection limit was 1.2 μM. The reproducibility for 5 electrodes using the same MWCNTs/GOx-avidin dispersion was 4.0 %, while the reproducibility for 3 different dispersions and 9 electrodes was 6.0 %. The GCE/MWCNT-GOx-avidin/b-HRP was successfully used for the quantification of glucose in a pharmaceutical product and milk.