This review provides an overview of the advancements in electrochemical sensors and biosensors, along with their applications. The review covers the methods and materials used for modifying the surface of electrodes, and also discusses the use of electrochemical sensors for quantitative analysis of biologically relevant compounds, such as hydrogen peroxide, dopamine, serotonin, glucose, and other markers of oxidative stress and neurotransmitters. Various electrochemical characterization methods have also been highlighted. Recently, there has been a growing interest in combining recognition elements with electronic elements to establish electrochemical sensors and biosensors. These devices have proven to be effective in detecting chemical and biological targets through changes in electrochemical activity at electrode interfaces. The use of nanomaterials has significantly improved the sensitivity and selectivity of electrochemical sensing platforms. Electrode materials are critical to the construction of high-performance sensors for detecting target molecules. The integration of functional nanomaterials can enhance catalytic activity, conductivity, and biocompatibility, leading to more accurate and sensitive biosensing. Overall, the development of functional electrode materials, along with various electrochemical methods, has greatly expanded the potential applications of electrochemical devices. Graphical Abstract

Engineering electrode surfaces through the electrodeposition of gold may provide a range of advantages in the context of biosensor development, such as greatly enhanced surface area, improved conductivity and versatile functionalization. In this work we report on the development of an electrochemical biosensor for the laccase-catalyzed assay of two catecholamines—dopamine and L-epinephrine. Variety of electrochemical techniques—cyclic voltammetry, differential pulse voltammetry, electrochemical impedance spectroscopy and constant potential amperometry have been used in its characterization. It has been demonstrated that the laccase electrode is capable of sensing dopamine using two distinct techniques—differential pulse voltammetry and constant potential amperometry, the latter being suitable for the assay of L-epinephrine as well. The biosensor response to both catecholamines, examined by constant potential chronoamperometry over the potential range from 0.2 to −0.1 V (vs. Ag|AgCl, sat KCl) showed the highest electrode sensitivity at 0 and −0.1 V. The dependencies of the current density on either catecholamine’s concentration was found to follow the Michaelis—Menten kinetics with apparent constants K_M^app = 0.116 ± 0.015 mM for dopamine and K_M^app = 0.245 ± 0.031 mM for L-epinephrine and linear dynamic ranges spanning up to 0.10 mM and 0.20 mM, respectively. Calculated limits of detection for both analytes were found to be within the sub-micromolar concentration range. The biosensor applicability to the assay of dopamine concentration in a pharmaceutical product was demonstrated (with recovery rates between 99% and 106%, n = 3).

The increasing global demand for natural bioactive compounds in the food, nutraceutical, and pharmaceutical sectors highlights the need for sustainable extraction technologies capable not only of efficiently valorizing crop biomass and agro-waste but also of producing reproducible and standardized botanical extracts. Subcritical water extraction (SWE), which utilizes pressurized hot water at temperatures between 100 °C and 374 °C to modify solvent properties, has emerged as a promising green alternative to conventional organic solvent-based extraction methods. Despite its advantages in terms of environmental compatibility, extraction efficiency and tunable selectivity, the industrial application of SWE remains limited, and strategies for obtaining standardized extracts using this technology are still insufficiently explored. This review provides a comprehensive overview of SWE in the context of natural product extraction and the development of standardized plant extracts. The fundamental principles of SWE are discussed, including temperature-dependent changes in water polarity, solvent–solute interactions, and the influence of key process parameters such as temperature, pressure, extraction time, and particle size. Particular emphasis is placed on how these factors affect extraction selectivity, phytochemical composition, and reproducibility, which are critical aspects for extract standardization. Mechanistic insights into plant cell disruption, compound stability, and hydrothermal transformations under SWE conditions are also examined. Recent applications of SWE for the extraction of phenolics, flavonoids, terpenoids, alkaloids, and other pharmacologically relevant compounds are reviewed, highlighting the relationship between extraction conditions and extract quality. Finally, current challenges and future perspectives for integrating SWE into the production of standardized botanical extracts suitable for food, nutraceutical, and pharmaceutical applications are discussed, paving the way for the wider industrial adoption of this environmentally friendly technology.

Lipid peroxidation is a major process that determines the quality of various oil samples during their use and storage, in which the primary products are hydroperoxides (HP’_S). HP’_S are very stable compounds at ambient conditions and are harmful to human health. Therefore, the evaluation of the degree of oil oxidation is an excellent tool for ensuring food safety. The peroxide value (PV) is the main parameter used for quality control in oils. Herein, we propose an alternative electrochemical method to the classical iodometric titration method most widely used for determining the PV. Our approach is based on the electrochemical quantification of hydroperoxides/peroxides in an organic solvent medium (acetonitrile and organic ammonium salt) using a composite electrocatalyst–glassy carbon electrode modified with 2D-nanomaterial graphitic carbon nitride doped with Co₃O₄. Calibration was made by the method of standard addition using benzoyl peroxide (BPO) as a model peroxide compound, dissolved in chloroform and added to fresh Rivana-branded anti-cellulite oil, used as a model oil sample. Calibration plots showed a linear response and the very good reproducibility of the analytical result (R² ˃ 0.99). Further, in terms of accuracy, the method showed good results, since the BPO quantitative analysis was close to the theoretical response. In addition, the accuracy of the electrochemical method was compared with that of the standard iodometric titration method for determining the PV of vegetable fats (according to a standard method). Finally, using the electrochemical method, the concentration of peroxides was determined in a real sample—an anti-cellulite oil of the trademark Rivana with an expired shelf life.

Hydroperoxides generated on lipid peroxidation are highly reactive compounds, tend to form free radicals, and their elevated levels indicate the deterioration of lipid samples. A good alternative to the classical methods for hydroperoxide monitoring are the electroanalytical methods (e.g., a catalytic electrode for their redox-transformation). For this purpose, a series of metal oxides—doped graphitic carbon nitride 2D nanomaterials—have been examined under mild conditions (pH = 7, room temperature) as catalysts for the electrochemical reduction of two water-soluble hydroperoxides: hydrogen peroxide and tert-butyl hydroperoxide. Composition of the electrode modifying phase has been optimized with respect to the catalyst load and binding polymer concentration. The resulting catalytic electrode has been characterized by impedance studies, cyclic voltammetry and chronoamperometry. Electrocatalytic effect of the Co-g-C₃N₄/Nafion modified electrode on the electrochemical reduction of both hydroperoxides has been proved by comparative studies. An optimal range of operating potentials from −0.215 V to −0.415 V (vs. RHE) was selected with the highest sensitivity achieved at −0.415 V (vs. RHE). At this operating potential, a linear dynamic range from 0.4 to 14 mM has been established by means of constant-potential chronoamperometry with a sensitivity, which is two orders of magnitude higher than that obtained with polymer-covered electrode.

This study investigated the effects of germination on gamma-aminobutyric acid (GABA), free sugars, organic acids, polyphenols, protein content, and antioxidant activity in six legumes (mung beans, Dobrudzha beans, white beans, brown lentils, red lentils and chickpeas). Seeds were germinated for 5 days at room temperature, with or without an initial freezing pretreatment at −18 °C for 20 h. Daily analysis revealed significant increases in GABA across all legumes, especially chickpeas, which showed an 18-fold rise to 210.5 mg/100 g dry weight (DW), alongside elevated glutamate decarboxylase activity. Total polyphenols increased 3.4-fold in white beans and chickpeas by day five. Antioxidant activity (ORAC) rose in parallel, reaching 123.8 and 83.3 µmol TE/g DW in germinated white beans and chickpeas, compared to 68.4 and 45.4 µmol TE/g DW in non-germinated controls. While protein content remained stable, levels of free sugars (notably maltose) increased during germination. Organic acids rose across all samples as well, with quinic acid being the most abundant and showing the sharpest increase. Initial freezing had a clear effect on enhancing GABA accumulation compared to non-treated seeds, but generally exerted neutral effects on other bioactive components. Overall, germination triggered biochemical transformations in seeds, enriching them with bioactive compounds and enhancing their nutritional and functional properties, with chickpeas emerging as a particularly rich source of GABA, polyphenols, and organic acids, supporting their potential in functional food development.