▎ 摘　　要

The main goal of this paper was to develop a biosensor containing three types of structures: graphene oxide (GO), silica nanoparticles (SNs) and gold nanoparticles (GNPs) for effective electrochemical and optical determination of dihydronicotinamide adenine dinucleotide dehydrogenase (NADH). The subsequent steps in biosensor formation, the manner of structure organization and the layer thickness were verified by different methods. Electrochemical oxidation of NADH was performed with the usage of differential pulse voltammetry method (DPV). Results show that obtained biosensor catalyzes the process of NADH electrochemical oxidation. The shift of oxidation potential toward less positive values and the increment of oxidation current were clearly noted. Additionally, the oxidized NAD form was found to exhibit an electrostatic affinity to the top layer of sensor giving a possibility to SPR detection. DPV and SPR signals registered for different amount of NADH were correlated with its concentration into linear relationship: y = 8.6388x - 0.0109; R-2 = 0.9997 and y = 1305.8x - 74.098; R-2 = 0.9913, respectively. Enhancement of the electrochemical sensitivity toward NADH, as a result of electrode modification, was proved by lower values of LOD (0.0236 mM) and LOQ (0.0707 mM) in comparison with corresponding parameters calculated for non-modified gold electrode. (C) 2016 The Electrochemical Society. All rights reserved.