ИСТИНА

Nowadays the sensitive and selective detection of biomarkers, especially glucose, is in the focus of intensive research. In particular, the development of novel non-invasive methods is a main purpose for painless diagnostics, avoiding potential infection and trauma of patients. A sufficient requirement for non-invasive diagnostics would be a correlation in variation rates between metabolite concentrations in the excreted liquid and the corresponding values in blood. The most progressive way to elaborate sensitive, selective, express and low cost medical tests is the use of biosensors. Prussian Blue (PB) is considered to be the most advantageous low-potential transducer for hydrogen peroxide (H2O2) over all known systems. PB possesses unique properties of the electrocatalyst allowing elaboration of sensors and biosensors with advantageous analytical characteristics [1]. Probably the only disadvantage of the PB is its inherent instability, particularly in neutral solutions. In this work PB based advanced hydrogen peroxide transducer is deposited onto screen-printed electrode structures (Rusens Ltd, Russia) and stabilized with nickel hexacyanoferrate (NiHCF), both in open circuit mode. In severe conditions under 1 mM H2O2 the developed electrodes retain the response for more than one hour. Here we confirm that operational stability of the oxidase-based biosensors can be significantly improved stabilizing the transducer used. The method describing stabilization procedure was done according to [2]. To create biosensors suspending lactate / glucose oxidase aqueous solution in isopropanol containing γ-aminopropyltriethoxysilane / Nafion analogue was deposited onto the top of iron-nickel hexacyanoferrate modified electrode. The dynamic range of PB-NiHCF based biosensors is similar to range observed for conventional PB based ones but their performance characteristics are dramatically improved. In addition, we demonstrated that stabilized Prussian Blue based glucose biosensors can be used in sweat analysis. Analysis of the sweat samples collected from 30 human volunteers has shown an average glucose concentration of 75 μM. Correlation between the changes in blood and sweat glucose concentration was investigated for 15 healthy volunteers. All work with blood and sweat was carried out in accordance with GCP regulations. [1] A. A. Karyakin, Prussian Blue and Its Analogues: Electrochemistry and Analytical Applications. Electroanalysis 2001, 13, 813-819. [2] E. V. Karpova, E. E. Karyakina, A. A. Karyakin, Accessing Stability of Oxidase-Based Biosensors via Stabilizing the Advanced H2O2 Transducer. Journal of the Electrochemical Society 2017, 164(5), B3056-B3058.