As electrode nanomaterials, thermally reduced graphene oxide (TRGO) and modified gold nanoparticl... more 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 Gluconobacter industrius 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–1cm–2 was achieved using TRGO/FDH. The TRGO/FDH was applied in a prototype bioreactor for the quantitative evalu...
Thermally reduced graphene oxide (TRGO) is a graphene-based nanomaterial that has been identified... more Thermally reduced graphene oxide (TRGO) is a graphene-based nanomaterial that has been identified as promising for the development of amperometric biosensors. Urease, in combination with TRGO, allowed us to create a mediator-free amperometric biosensor with the intention of precise detection of urea in clinical trials. Beyond simplicity of the technology, the biosensor exhibited high sensitivity (2.3 ± 0.1 µA cm−2 mM−1), great operational and storage stabilities (up to seven months), and appropriate reproducibility (relative standard deviation (RSD) about 2%). The analytical recovery of the TRGO-based biosensor in urine of 101 ÷ 104% with RSD of 1.2 ÷ 1.7% and in blood of 92.7 ÷ 96.4%, RSD of 1.0 ÷ 2.5%, confirmed that the biosensor is acceptable and reliable. These properties allowed us to apply the biosensor in the monitoring of urea levels in samples of urine, blood, and spent dialysate collected during hemodialysis. Accuracy of the biosensor was validated by good correlation (R ...
Proceedings of the 9th International Joint Conference on Biomedical Engineering Systems and Technologies, 2016
The idea of developing multi-parameter urea analyser comprising urea, Na + and K + selective elec... more The idea of developing multi-parameter urea analyser comprising urea, Na + and K + selective electrodes has been considered. For this purpose the urea biosensors based on urease and recombinant urease working in amperometric and potentiometric way were developed. The working parameters of both urea biosensors were studied and optimized. Possibilities of real samples analysis using the developed biosensors were shown by measuring urea concentrations in blood dialysate taken from patients with renal failure. Both the potentiometric and the amperometric biosensors demonstrated high degree of signal reproducibility (the relative standard deviation of responses did not exceed 5 %). Change of sodium and potassium concentrations during blood hemodialysis is dangerous life-threatening condition and their monitoring is an important feature of point-of-care analyser. For this purpose high integrity commercial Na + and K + selective electrodes were analysed and our own signal amplification and processing system proposed.
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Papers by Ieva Sakinyte