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(-1)avidin 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 5.0x10(-4) M hydroquinone, was (4.8 +/- 0.3) mu A mM(-1) (r(2)=0.9986) and the detection limit was 1.2 mu M. 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.