Multi-walled carbon nanotubes functionalized with a new Schiff base containing phenylboronic acid residues: applicationtothe development of a bienzymatic glucose biosensor using a response surface methodology approach.

Abstract

Aninnovative supramolecular architectureis reportedfor 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 - 0.050V in the presence of 5.0 × 10-4M 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 3.0mgmL-1 and 1.50mgmL-1, respectively, while the optimum interaction time was 3.0min. The bienzymatic biosensor presented a sensitivity of (24 ± 2) × 102 µA dL mg-1 ((44 ± 4) × 102 µA M-1), a linear range between 0.06mg dL-1 and 21.6mg dL-1 (3.1µM-1.2mM) (R2 = 0.9991),and detection and quantification limits of 0.02mg dL-1 (1.0µM) and 0.06mg dL-1 (3.1µM), 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.