Edita Voitechovič

Understanding biomolecular interactions is essential for disease diagnostics and therapeutic development, yet practical implementation is hampered by under-reported failure modes and technical constraints in the literature. Although commercial surface plasmon resonance (SPR) systems have advanced the field, real-world laboratories still face recurring pitfalls in data interpretation, surface chemistry, and microfluidic design that are often far from idealized reports. To address these practical obstacles, this study employs a null-ellipsometry phase-interrogation SPR imaging (SPRi) technique, which delivers high sensitivity and stability by extracting phase information rather than relying on intensity or simple angular-dip tracking. We show that conventional gold substrates limit both imaging and kinetic measurements, and that surface chemistry critically determines nonspecific binding. To overcome these limitations, we optimized surface functionalization via microcontact printing to produce protein-repellent and functionalized regions for immunoassays, revealing how nonspecific adsorption depends on coating chemistry. We also developed a custom microfluidic cell to accelerate solution exchange and reduce mass-transport artifacts that distort kinetic constants in commercial setups. Finally, we introduce a multilayer dielectric sensor chip that extends the detectable thickness range of protein complexes at a fixed angle of incidence around 60° and 658 nm illuminations, offering a scalable platform for analyzing complex multiprotein assemblies.

D‐Tagatose is a rare natural sugar, which is promising alternative for popular dietary sweeteners. To optimize and make D‐tagatose production more cost‐effective, a portable (bio)sensor would be beneficial for D‐tagatose quantification in bioreactor media during D‐tagatose (bio)synthesis. In this study, a pilot study of D‐tagatose quantification by a bioamperometric system is reported. A key feature of the system is usage of fructose dehydrogenase from Gluconobacter japonicus, widely known as a highly fructose‐specific enzyme, and 2‐arylamino‐1,4‐benzoquinone derivatives, as electron transfer mediators from the enzyme to carbon electrodes. The system has been validated as biosensor for D‐tagatose quantification in the fermentation medium.

The significant improvement of quality of life achieved over the last decades has stimulated the development of new approaches in medicine to take into account the personal needs of each patient. Precision medicine, providing healthcare customization, opens new horizons in the diagnosis, treatment and prevention of numerous diseases. As a consequence, there is a growing demand for novel analytical devices and methods capable of addressing the challenges of precision medicine. For example, various types of sensors or their arrays are highly suitable for simultaneous monitoring of multiple analytes in complex biological media in order to obtain more information about the health status of a patient or to follow the treatment process. Besides, the development of sustainable sensors based on natural chemicals allows reducing their environmental impact. This review is concerned with the application of such analytical platforms in various areas of medicine: analysis of body fluids, wearable sensors, drug manufacturing and screening. The importance and role of naturally-occurring compounds in the development of electrochemical multisensor systems and arrays are discussed.

D‐fructose amount in food and beverages should be carefully controlled in order to avoid its overconsumption by human, which can lead to various metabolic diseases. Thus, the development of a low‐cost and portable (bio)sensors, which realize the on‐site monitoring of D‐fructose, is still highly required. In this work, we proposed several reagentless bioelectrochemical systems (BioESs) based on fructose dehydrogenase EC1.1.99.11 from Gluconobacter japonicus (FDH) and on 2‐arylamine‐1,4‐benzoquinone (ABQ) derivatives as a platform for the development of D‐fructose electrochemical biosensor. To design a reliable and easily reproducible BioES, we used the simple physical sorption as the electrode modification strategy for ABQs and FDH immobilization that is suitable for low‐cost mass production of the biosensors by standard microfabrication techniques. To choose the most suitable ABQ compounds for BioESs design, we proposed a novel theoretical approach of potential ET mediator evaluation through its electrochemical properties. A set of newly synthesized and of previously applied ABQs was characterized both electrochemically and using the density functional theory (DFT). It was shown that results obtained by quantum chemical analysis were in a good agreement with the ABQ characteristics obtained in electrochemical measurements. We suggest that the calculated local ionization energy values and theoretical redox potential obtained by DFT are a powerful tool for prediction of ABQs electrochemical properties. The performance of the BioESs with FDH under study was determined by electrochemical and electronic properties of ABQ derivatives and FDH orientation and stabilization on the electrode surface. The most promising BioES was based on carbon paste electrodes and 2‐(3‐nitro(phenyl)amino)‐ cyclohexa‐2,5‐dien‐1,4‐dione as ET mediator, which accelerated FDH catalysis and improved its stability better, then other studied ABQs. The bioelectrocatalytic process was characterized by initial apparent maximum current density of 7.1 μA cm⁻² at the optimal conditions (+400 mV vs. Ag/AgCl, McIlvaine's buffer, pH 5.0 and 20 °C). The findings of this research open new possibilities for development of cost‐effective biosensors with FDH and, potentially, with other redox enzymes.

A series of new potential electron transfer mediators, 2-substituted 1,4-benzoquinone derivatives bearing an arylamino group with various substituents in o-, m- and p-positions of an aromatic ring were synthesised by adding a solution of aniline derivatives in aqueous acetic acid to an aqueous solution of 1,4-benzoquinone. The structure and properties of synthesised compounds were investigated by NMR spectroscopy methods in detail. The redox ability of 2-arylamino-1,4-benzoquinone derivatives has been estimated by calculations of quantum chemical structure– activity relationship (QSAR) descriptors within the framework of density functional theory.