ИСТИНА

The concept of ‘self-powered’ electrochemical (bio)sensors is becoming increasingly popular nowadays. However, despite an attractive title, ‘self-powered’ (bio)sensors are able to generate sufficient power only in highly concentrated solutions and, thus, are hardly applicable in complete absence of external power supply. Besides, large potential difference between the electrodes forces operation of the working electrode far from its optimal potential, which dramatically affects analytical performance characteristics of such sensors. We report on the operation principle of Prussian Blue-based (bio)sensors in power generation mode providing improved analytical performance characteristics compared to conventional three-electrode approach [1]. Prussian Blue (PB) is known to be the most advantageous low-potential hydrogen peroxide transducer for both hydrogen peroxide detection and oxidases-based biosensors [2]. The PB-based amperometric sensors are commonly operated at the working potential of 0.00 V (vs. Ag/AgCl/0.1 M KCl) [3]. Short-circuiting the PB-modified working electrode with the silver chloride reference electrode (through the ammeter), it is possible to adjust the working electrode potential to 0.00 V without a potentiostat. Current generated by the sensor linearly depends on hydrogen peroxide concentration in the range from 2•10-7 to 1•10-3 M. The sensors display advantageous performance characteristics in terms of high sensitivity – 0.65 A•M-1•cm-2. Sensor selectivity in power generation mode exceeds two orders of magnitude allowing detection of H2O2 by its reduction in the presence of oxygen. Besides, Prussian Blue-based sensors in power generation mode retain high selectivity relatively to reductants (ascorbate, paracetamol), practically avoiding their influence on analysis. Moreover, the noise of Prussian Blue-based sensors in power generation mode is an order of magnitude lower compared to it in a conventional three-electrode regime, as soon as in three-electrode constant potential experiments the output noise is generated by operational amplifiers enhancing noises from their inputs (inc. voltage generator and feedback control amplifier). The principle was adapted for the Prussian Blue-based glucose and lactate biosensors. Prussian Blue-based glucose test-strips operated in power-generation mode with coulometric detection were shown to be applicable for the whole blood glucose analysis. Concluding, Prussian Blue-based (bio)sensors successfully operate without a potentiostat by a simple short-circuiting the working and the reference electrodes. The proposed energy harvesting technique, providing improved analytical performance, would have a potential for low voltage read-out methods, for example for printable electronics or wearable smart devices. Financial support through Russian Science Foundation grant # 16-13-00010 is greatly acknowledged and Russian Foundation for Basic Research grant # 18-33-00392 is greatly acknowledged. References: [1] Komkova M.A., E.E. Karyakina and A.A. Karyakin, Noiseless Performance of Prussian Blue Based (Bio)sensors through Power Generation. Analytical Chemistry, 2017. 89(12): p. 6290-6294. [2] Karyakin A.A., Prussian Blue and its analogues: Electrochemistry and analytical applications. Electroanalysis, 2001. 13(10): p. 813-819. [3] Sitnikova N.A., M.A. Komkova, I.V. Khomyakova, E.E. Karyakina and A.A. Karyakin, Transition Metal Hexacyanoferrates in Electrocatalysis of H2O2 Reduction: An Exclusive Property of Prussian Blue. Analytical Chemistry, 2014. 86(9): p. 4131-4134.