In this study, graphite rod (GR) electrodes were electrochemically modified by dendritic gold nanostructures (DGNs) followed by immobilization of glucose oxidase (GOx) in the presence of mediator phenazine methosulfate (PMS). Modified with polyaniline (PANI) or polypyrrole (Ppy), GOx/DGNs/GR electrodes were used in glucose biosensor design. Different electrochemical methods were applied for the registration of glucose concentration, and constant potential amperometry (CPA) was chosen as the best one. PANI and Ppy layers synthesized enzymatically on the GOx/DGNs/GR electrodes extended the linear glucose determination range, the width of which depended on the duration of PANI- and Ppy-layers formation. Enzymatically formed polypyrrole was determined as the most suitable polymer for the modification and formation of the glucose biosensor instead of polyaniline, because it was 1.35 times more sensitive and had a 2.57 times lower limit of detection (LOD). The developed glucose biosensor based on the Ppy/GOx/DGNs/GR electrode was characterized by appropriate sensitivity (59.4 μA mM-1 cm-2), low LOD (0.070 mmol L-1), wide linear glucose determination range (up to 19.9 mmol L-1), good repeatability (8.01%), and appropriate storage stability (33 days). The performance of the developed glucose biosensor was tested in biological samples and beverages.
Keywords: biomedical samples and beverages; dendritic gold nanostructures; electrochemical methods; glucose oxidase; polyaniline; polypyrrole.