Abstract

We report for the first time a sensitive and selective glucose biosensor based on the immobilization at glassy carbon electrodes (GCE) of a new hybrid nanomaterial consisting of gold nanoparticles functionalized with 3-mercaptophenyl boronic acid (AuNPs-B(OH)(2)) and bamboo-like multiwall carbon nanotubes (bMWCNT) dispersed in hyperbranched polyethyleneimine (PEI). The presence of boronic acid residues allowed the supramolecular immobilization of glucose oxidase (GOx) as a model glycoenzyme while the hybrid nanomaterial Au(NP)-bMWCNT produces a synergistic effect on the catalytic detection of the enzymatically generated hydrogen peroxide. The resulting functionalized nanomaterials were characterized by TEM, FT-IR and electrochemical techniques. The sensitivity at 0.700 V was (3.26 + 0.03) mA M-1 (28.6 mAM(-1) cm(-2)), with a linear range between 2.50 x 10(-4)M and 5.00 x 10(-3) M, a detection limit of 0.8 p,M and a quantification limit of 2.4 p,M. The biocatalytic layer demonstrated to be highly reproducible with R.S.D. values of 8.6% for 10 successive amperometric calibrations using the same surface, and 4.5% for ten different bioelectrodes. The sensitivity of the biosensor after 14 days of storage at 4 degrees C remained at 86.1% of its original value. The combination of the excellent dispersing properties of PEI, the stability of the bMWCNT-PEI dispersion, the synergistic effect of AuNPs-B(OH)(2) and bMWCNT towards the electrooxidation of hydrogen peroxide, and the robust immobilization of GOx at AuNP-B(OH)(2) allowed building a sensitive, reproducible and stable amperometric biosensor for the quantification of glucose in beverages and milk samples. (C) 2015 Published by Elsevier B.V.