Reagentless D-Tagatose Biosensors Based on the Oriented Immobilization of Fructose Dehydrogenase onto Coated Gold Nanoparticles- or Reduced Graphene Oxide-Modified Surfaces: Application in a Prototype Bioreactor

• Published in: Biosensors (Basel) 2021-11, Vol.11 (11), p.466
• Main Authors: Šakinytė, Ieva, Butkevičius, Marius, Gurevičienė, Vidutė, Stankevičiūtė, Jonita, Meškys, Rolandas, Razumienė, Julija
• Format: Article
• Language: English
• Subjects: Arabinose; Arabinose isomerase; Au nanoparticles; Biocatalysts; Bioconversion; bioelectrocatalysis; Bioreactors; Biosensing Techniques; Biosensors; Biosynthesis; Carbohydrate Dehydrogenases; Chemical synthesis; Coated electrodes; Coatings; Conformation; Correlation coefficient; Correlation coefficients; D-Galactose; D-tagatose; Dairy industry; Dehydrogenase; Dehydrogenases; Design modifications; direct electron transfer; Electrical measurement; Electrodes; Enzymes; Enzymes, Immobilized; Ethanol; Fructose; Galactose; Gluconobacter - enzymology; Gold; Graphene; Graphite; Hexoses - analysis; Immobilization; L-Arabinose; L-Arabinose isomerase; Metal Nanoparticles; Methods; Nanomaterials; Nanoparticles; Nanotechnology; Oxidation; Prototypes; Selectivity; Sensitivity; Spectrophotometry; Substrates; thermally reduced graphene oxide
• ISSN: 2079-6374; 2079-6374
• DOI: 10.3390/bios11110466

As electrode nanomaterials, thermally reduced graphene oxide (TRGO) and modified gold nanoparticles (AuNPs) were used to design bioelectrocatalytic systems for reliable D-tagatose monitoring in a long-acting bioreactor where the valuable sweetener D-tagatose was enzymatically produced from a dairy by-product D-galactose. For this goal D-fructose dehydrogenase (FDH) from immobilized on these electrode nanomaterials by forming three amperometric biosensors: AuNPs coated with 4-mercaptobenzoic acid (AuNP/4-MBA/FDH) or AuNPs coated with 4-aminothiophenol (AuNP/PATP/FDH) monolayer, and a layer of TRGO on graphite (TRGO/FDH) were created. The immobilized FDH due to changes in conformation and spatial orientation onto proposed electrode surfaces catalyzes a direct D-tagatose oxidation reaction. The highest sensitivity for D-tagatose of 0.03 ± 0.002 μA mM cm was achieved using TRGO/FDH. The TRGO/FDH was applied in a prototype bioreactor for the quantitative evaluation of bioconversion of D-galactose into D-tagatose by L-arabinose isomerase. The correlation coefficient between two independent analyses of the bioconversion mixture: spectrophotometric and by the biosensor was 0.9974. The investigation of selectivity showed that the biosensor was not active towards D-galactose as a substrate. Operational stability of the biosensor indicated that detection of D-tagatose could be performed during six hours without loss of sensitivity.