Abstract

An innovative supramolecular architecture is reported for bienzymatic glucose biosensing based on the use of a nanohybrid made of multi-walled carbon nanotubes (MWCNTs) non-covalently functionalized with a Schiff base modified with two phenylboronic acid residues (SB-dBA) as platform for the site-specific immobilization of the glycoproteins glucose oxidase (GOx) and horseradish peroxidase (HRP). The analytical signal was obtained from amperometric experiments at ? 0.050 V in the presence of 5.0 × 10?4 M hydroquinone as redox mediator. The concentration of GOx and HRP and the interaction time between the enzymes and the nanohybrid MWCNT–SB-dBA deposited at glassy carbon electrodes (GCEs) were optimized through a central composite design (CCD)/response surface methodology (RSM). The optimal concentrations of GOx and HRP were 3.0 mg mL?1 and 1.50 mg mL?1, respectively, while the optimum interaction time was 3.0 min. The bienzymatic biosensor presented a sensitivity of (24 ± 2) × 102 µA dL mg?1 ((44 ± 4) × 102 µA M?1), a linear range between 0.06 mg dL?1 and 21.6 mg dL?1 (3.1 µM–1.2 mM) (R2 = 0.9991), and detection and quantification limits of 0.02 mg dL?1 (1.0 µM) and 0.06 mg dL?1 (3.1 µM), respectively. The reproducibility for five sensors prepared with the same MWCNT–SB-dBA nanohybrid was 6.3%, while the reproducibility for sensors prepared with five different nanohybrids and five electrodes each was 7.9%. The GCE/MWCNT–SB-dBA/GOx-HRP was successfully used for the quantification of glucose in artificial human urine and commercial human serum samples. Graphical Abstract: (Figure presented.) © The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature 2024.