Search Results (53)

Mycotoxin contamination in agricultural products poses severe global health risks, with ochratoxins (particularly OTA and OTB) exhibiting marked nephrotoxicity and classified as Group 2B carcinogens by IARC. Conventional physical/chemical detoxification methods often impair food nutritional quality, highlighting the need for enzymatic alternatives. Herein, we systematically investigated the degradation mechanisms of ochratoxin A (OTA) and ochratoxin B (OTB) using Pleurotus ostreatus dye-decolorizing peroxidase (PoDyP4) coupled with redox mediators. Remarkably, hydroxybenzotriazole (HBT) enhanced degradation efficiency 26.7-fold for OTA and 10.6-fold for OTB compared to mediator-free systems, establishing it as the optimal catalytic enhancer. Through LC-MS/MS analysis, we identified five key degradation products, including 6-OH-OTA and OTB-quinone, elucidating a putative oxidative degradation pathway. In vitro cytotoxicological evaluation in HK-2 cells demonstrated that PoDyP4-treated ochratoxins significantly attenuated cytotoxicity, reducing malondialdehyde (MDA) levels by 48.7% (OTA) and 42.3% (OTB) (p < 0.01) and suppressing ROS generation. Molecular docking revealed strong binding affinities between PoDyP4 and ochratoxins, with calculated binding energies of −7.6 kcal/mol (OTA) and −8.6 kcal/mol (OTB), stabilized by hydrogen bond networks (1.9–3.4 Å). These findings position PoDyP4 as a promising biocatalyst for mycotoxin mitigation in food systems, offering a sustainable alternative to traditional detoxification methods. Full article

MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression and have emerged as critical biomarkers in various diseases, including cancer. Their stability in bodily fluids and role as oncogenes or tumor suppressors make them attractive targets for non-invasive diagnostics. However, conventional detection methods, such as Northern blotting, RT-PCR, and microarrays, are limited by low sensitivity, lengthy protocols, and limited specificity. Electrochemical biosensors offer a promising alternative, providing high sensitivity, rapid response times, portability, and cost-effectiveness. These biosensors translate miRNA hybridization events into quantifiable electrochemical signals, often leveraging redox-active labels, mediators, or intercalators. Recent advancements in nanomaterials and signal amplification strategies have further enhanced detection capabilities, enabling sensitive, label-free miRNA quantification. This review provides a comprehensive overview of the recent advances in electrochemical biosensing of miRNAs, emphasizing innovative redox-based detection strategies, probe immobilization techniques, and hybridization modalities. The critical challenges and future perspectives in advancing electrochemical miRNA biosensors toward clinical translation and point-of-care diagnostics are discussed. Full article

Plasma non-transferrin-bound iron (NTBI) comprises multiple subspecies, classified by their composition, chemical reactivity, and susceptibility to chelation. The redox-active and chelatable fraction of NTBI is referred to as labile plasma iron (LPI). The pathophysiological significance of NTBI and LPI lies in their ability to enter cells via alternative transport pathways that are not regulated by the transferrin receptor system or by cellular iron levels. Several mechanisms have been proposed for their cellular entry, including the hijacking of divalent metal transporters and passive diffusion. This unregulated uptake can lead to iron accumulation in vulnerable tissues such as the liver and the heart. NTBI and LPI bypassing normal cellular control mechanisms can rapidly exceed the cell’s capacity to safely store excess iron, leading to toxicity. Both NTBI and LPI contribute to oxidative stress by participating in free-radical-generating reactions. However, LPI concentration in the bloodstream may be differentially affected by the mode and extent of iron overload, the presence of residual serum iron-binding activity, and the antioxidant capacity of individual sera. In summary, both NTBI and LPI contribute to iron-mediated toxicity but differ in terms of reactivity, availability, and pathogenic potential depending on the pathophysiological conditions that influence the degree of toxicity. Full article

A biosensor for the determination of glucose, lactate, ethanol and starch in beverages has been developed using enzymes immobilized by a redox-active gel on a screen-printed electrode. A significant improvement proposed for multichannel biosensors, overcoming stability and sensitivity issues by covalently binding phenazine mediators to a biocompatible protein hydrogel, enhancing the packaging of the enzyme. Glucose oxidase (GOx), alcohol oxidase (AOx) and lactate oxidase (LOx) were used as biological materials, as well as a mixture of GOx with γ-amylase (Am). Redox gels were synthesized from bovine serum albumin (BSA) and phenazine derivatives. It was shown that a neutral red-based redox gel combined with single-walled carbon nanotubes is more promising than other substrates for enzyme immobilization. The lower limit of quantification for glucose, ethanol, lactate and starch using these systems is 0.035 mM, 2.3 mM, 15 mM and 2 mg/L, respectively. Biosensors were used to analyze the content of these substances in alcoholic, kvass and fermentation mass. Statistical analysis of the results showed that the values of glucose, ethanol, lactic acid and starch determined using biosensors and obtained by reference methods differ insignificantly. A set of biosensors developed on the basis of specifically selected enzymes is effective for controlling biotechnological processes and can be used as an alternative to classical analytical methods. Full article

Currently, the most promising alternative to the use of the phosgenation reaction, for large-scale production of isocyanates, ureas, and carbamates, appears to be the Pd-catalyzed oxidative carbonylation of arylamines. During the reaction, the Pd(II) catalytic species are reduced to Pd(0) and the addition of sacrificial oxidizing agents is usually necessary to restart the catalytic cycle. Among these oxidizing agents, molecular oxygen is undoubtedly the more appealing, from an economical and green point of view, but it is not so efficient, whereas several metal salts (named cocatalysts) can be used, able to form redox couples with Pd(0) or to act as electron transfer mediators with oxygen itself. Testing several Pd(II) complexes, metal cocatalysts, and promoters, we have found that the [PdCl₂(dppf)]/FeCl₃/LiBr = 1/1200/200 (mol/mol) system efficiently catalyzes the carbonylation of aniline to form 1,3–diphenylurea selectively (100%) with a TOF of ca. 1177 h⁻¹. On the other hand, the addition of oxygen to such a system strongly increases the aniline conversion (0.3 MPa of O₂ increases the TOF at ca. 3930 h⁻¹), but it moves the selectivity towards the phenyl isocyanate (65%, mol/mol). Full article

This study describes the development of catalytic surface immobilizing dopamine via cross-linking or tyrosinase through covalent bonds on an electrografted screen-printed carbon electrode with a 4-nitrobenzenediazonium ion. A simple electrochemical reduction approach was used to covalently graft aryldiazonium ions onto the surface of commercial electrodes. After functionalization with aminophenyl groups, dopamine, an important neurotransmitter, was immobilized by imine bond formation using glutaraldehyde as a bifunctional cross-linking molecule. The presence of immobilized dopamine was confirmed by cyclic voltammetry following the electrochemical response of the hydroquinone/quinone redox process from catechol functionalities on the surface, which are responsible for the catalytic activity. In addition, the surface was also characterized by cyclic voltammetry using the redox probe, [Fe(CN)₆]^3−/4−, obtaining a signal approximately 14 times higher than that of a bare electrode, achieving a dynamic concentration range spanning three orders of magnitude. Remarkable sensitivity was also obtained by combining the electrografting, in situ diazotation, to generate grafted aryl diazonium ions on the surface, and coupling reaction to anchor the tyrosinase enzyme to the electrode surface. The response of the TYR-biosensor towards catechol, using the redox probe as mediator, was 10 times higher than that obtained with the dopamine modified catalytic surface. These modified surfaces offer promising alternatives for the voltammetric quantification of catechol in environmental fields. Full article

Background/Objectives: SARS-CoV-2 provokes acute oxidative stress in the lungs via cytokines, inflammatory mediators, and apoptotic factors, which might cause alveolar injury followed by severe respiratory syndrome during COVID-19 infection. The lack of particular antivirals for SARS-CoV-2 has opened novel avenues of complementary and alternative medicine as a potential remedy. The current study explored the mechanistic role of the ultradiluted formulation of Eupatorium (UDE) against SARS-CoV-2 recombinant S protein-mediated oxidative stress and mitochondriopathy. Methods: Cell line and BALB/c mice were used to report that SARS-CoV-2 S protein caused an inflammatory response and subsequent cytokine storm via the NF-κB pathway in the lung along with oxidative damage. Morphological examination was performed using DAPI staining and histology for treated cells and lung tissues of animals, respectively. The molecular mechanism of action of UDE was investigated through qRT-PCR for the genetic expressions of various cytokines, inflammatory, and apoptotic mediators; ELISA, immunofluorescence, immunohistochemistry, and Western blot for the translational expression of the same molecules assayed for genetic expressions; and biochemical assays for various enzymes and ROS. Results: UDE treatment suppressed the inflammatory cell infiltration and tissue-level oxidative stress and safeguarded mitochondrial integrity from free radical-mediated oxidative damage. Additionally, UDE played a direct role in restoring cellular redox homeostasis and reducing the inflammatory response by suppressing NF-κB, IL-1β, IL-18, caspase-1 expression, and ROS formation. Further, a plausible mechanism of action of UDE against S protein-induced damage was proposed. Conclusions: This study described a novel therapeutic approach against S protein-mediated hyperinflammation, apoptosis, and oxidative damage. Hence, UDE may be considered as a prospective alternative to combat life-threatening consequences of SARS-CoV-2 infection. Full article

Catalase (CAT) plays a crucial role in plant responses to environmental stresses and maintaining redox homeostasis. However, its putative heat lability might compromise its activity and function, thus restricting plant thermotolerance. Herein, we verified Arabidopsis CAT3 was of poor thermostability that was then engineered by fusion expression in Escherichia coli. We found that our selected fusion partners, three hyperacidic mini-peptides and the short rubredoxin from hyperthermophile Pyrococcus furiosus, were commonly effectual to enhance the solubility and thermostability of CAT3 and enlarge its improvement on heat tolerance in E. coli and yeast. Most importantly, this finding was also achievable in plants. Fusion expression could magnify CAT3-mediated thermotolerance in tobacco. Under heat stress, transgenic lines expressing CAT3 fusions generally outperformed native CAT3 which in turn surpassed wild-type tobacco, in terms of seed germination, seedling survival, plant recovery growth, protection of chlorophyll and membrane lipids, elimination of H₂O₂, as well as mitigation of cell damage in leaves and roots. Moreover, we revealed that the introduced CAT3 or its fusions seemed solely responsible for the enhanced thermotolerance in tobacco. Prospectively, this fusion expression strategy would be applicable to other crucial plant proteins of intrinsic heat instability and thus provide an alternative biotechnological route for ameliorating plant heat tolerance. Full article

Lignocellulosic biomass is contemplated to be an inexpensive and copious feedstock that can be used for numerous industrial applications. However, lignin forms the lignin sheath and provides a physical barrier to enzymatic hydrolysis. In addition, lignin physically blocks cellulase, preventing it from being combined with the substrate in a process known as non-productive binding. Therefore, the depletion of lignin is a crucial method for obtaining fermentable sugars from the lignocellulosic biomass. Different white-rot fungi secrete different sets of lignin-mineralizing enzymes and each fungus secretes one or more of the three enzymes essential for lignin degradation. Among efficient redox enzymes, versatile peroxidase is extensively studied for its ability to degrade aromatics without the need for a mediator or polyvalent catalytic site. However, the presence of versatile peroxidase in F. spp. has not been studied. This study was planned with the objective of screening and comparing the production of versatile peroxidase enzymes from F. spp. and a standard culture of Pleurotus ostreatus MTCC-142. These fungal strains were first screened on solid media containing tannic acid, malachite green, or bromocresol green. The potency index for the tannic acid, malachite green, and bromocresol green on the 16th day of incubation was reported to be 1.28, 1.07, 1.09, and 1.10, respectively. Versatile peroxidase production patterns were investigated under solid state fermentation conditions for a period of 25 days at different temperatures ranging from 10 to 35 °C. The highest versatile peroxidase activity (592 UL⁻¹) in F. sp. was observed at 30 °C after the 7th day of incubation. The molecular confirmation showed the presence of the vp gene in F. sp. along with Pleurotus ostreatus MTCC-142. The results determined that F. sp. possesses a versatile peroxidase enzyme and is able to degrade lignin efficiently, and thus it could be utilized as an alternative to other ligninolytic enzyme-producing fungi. Full article

Layered double hydroxides (LDHs), also named hydrotalcite-like compounds, are anionic clays with a lamellar structure which have been extensively used in the last two decades as electrode modifiers for the design of electrochemical sensors. These materials can be classified into LDHs containing or not containing redox-active centers. In the former case, a transition metal cation undergoing a reversible redox reaction within a proper potential window is present in the layers, and, therefore, it can act as electron transfer mediator, and electrocatalyze the oxidation of an analyte for which the required overpotential is too high. In the latter case, a negatively charged species acting as a redox mediator can be introduced into the interlayer spaces after exchanging the anion coming from the synthesis, and, again, the material can display electrocatalytic properties. Alternatively, due to the large specific surface area of LDHs, molecules with electroactivity can be adsorbed on their surface. In this review, the most significant electroanalytical applications of LDHs as electrode modifiers for the development of voltammetric sensors are presented, grouping them based on the two types of materials. Full article

Phosphonates are a class of organic phosphorus (P) compounds that contribute ~25% of dissolved organic P. Recent studies reveal the important role of phosphonates mediated by prokaryotes in the marine P redox cycle. However, its bioavailability by eukaryotic phytoplankton is under debate. 2-Aminoethylphosphonic acid (2-AEP) and 2-amino-3-phosphonopropionic acid (2-AP3) are two biogenic phosphonates in the marine environment. Here, Thalassiosira pseudonana, a common diatom species in the ocean, is able to recover growth from P starvation when provided with 2-AEP and 2-AP3. Moreover, 2-AEP cultures exhibited a more similar growth rate at 12 °C than at 25 °C when compared with inorganic P cultures. The cellular stoichiometry of 2-AEP groups was further determined, the values of which are in-between the P-depleted and DIP-replete cultures. This study provides evidence that biogenic phosphonates could be adopted as alternative P sources to support diatom growth and may provide physiological adaptation. Full article

The human Vitamin K Epoxide Reductase Complex (hVKORC1), a key enzyme transforming vitamin K into the form necessary for blood clotting, requires for its activation the reducing equivalents delivered by its redox partner through thiol-disulfide exchange reactions. The luminal loop (L-loop) is the principal mediator of hVKORC1 activation, and it is a region frequently harbouring numerous missense mutations. Four L-loop hVKORC1 mutants, suggested in vitro as either resistant (A41S, H68Y) or completely inactive (S52W, W59R), were studied in the oxidised state by numerical approaches (in silico). The DYNASOME and POCKETOME of each mutant were characterised and compared to the native protein, recently described as a modular protein composed of the structurally stable transmembrane domain (TMD) and the intrinsically disordered L-loop, exhibiting quasi-independent dynamics. The DYNASOME of mutants revealed that L-loop missense point mutations impact not only its folding and dynamics, but also those of the TMD, highlighting a strong mutation-specific interdependence between these domains. Another consequence of the mutation-induced effects manifests in the global changes (geometric, topological, and probabilistic) of the newly detected cryptic pockets and the alternation of the recognition properties of the L-loop with its redox protein. Based on our results, we postulate that (i) intra-protein allosteric regulation and (ii) the inherent allosteric regulation and cryptic pockets of each mutant depend on its DYNASOME; and (iii) the recognition of the redox protein by hVKORC1 (INTERACTOME) depend on their DYNASOME. This multifaceted description of proteins produces “omics” data sets, crucial for understanding the physiological processes of proteins and the pathologies caused by alteration of the protein properties at various “omics” levels. Additionally, such characterisation opens novel perspectives for the development of “allo-network drugs” essential for the treatment of blood disorders. Full article

Since Mallouk’s earliest contribution, dye-sensitized photoelectrochemical cells (DSPECs) have emerged as a promising class of photoelectrochemical devices capable of storing solar light into chemical bonds. This review primarily focuses on metal complexes outlining stabilization strategies and applications. The ubiquity and safety of water have made its splitting an extensively studied reaction; here, we present some examples from the outset to recent advancements. Additionally, alternative oxidative pathways like HX splitting and organic reactions mediated by a redox shuttle are discussed. Full article

Three decades ago, dye-sensitized solar cells (DSSCs) emerged as a route for harnessing the sun’s energy and converting it into electricity. Since then, an impressive amount of work has been devoted to improving the global photovoltaic efficiency of DSSCs, trying to optimize all components of the device. Up to now, the best efficiencies have usually been reached with ruthenium(II) photosensitizers, even if in the last few years many classes of organic compounds have shown record efficiencies. However, the future of DSSCs is stringently connected to the research and development of cheaper materials; in particular, the replacement of rare metals with abundant ones is an important topic in view of the long-term sustainability of DSSCs intended to replace the consolidated fossil-based technology. In this context, copper is a valid candidate, being both an alternative to ruthenium in the fabrication of photosensitizers and a material able to replace the common triiodide/iodide redox couple. Thus, recently, some research papers have confirmed the great potential of copper(I) coordination complexes as a cheap and convenient alternative to ruthenium dyes. Similarly, the use of copper compounds as electron transfer mediators for DSSCs can be an excellent way to solve the problems related to the more common I₃⁻/I⁻ redox couple. The goal of this mini-review is to report on the latest research devoted to the use of versatile copper complexes as photosensitizers and electron shuttles in DSSCs. The coverage, from 2022 up to now, illustrates the most recent studies on dye-sensitized solar cells based on copper complexes as molecular materials. Full article

The chromium (Cr) limit values are currently tightened to 25 μg L⁻¹ (EU), 5 μg L⁻¹ (Germany), and possibly 10 μg L⁻¹ Cr(VI) (California). The combined process of chemical reduction, coagulation, and biotic filtration (RCbF) efficiently removes Cr(VI) in drinking water. In this study, redox-active substances (O₂, NO₃⁻, Fe²⁺, MnO₂) were investigated concerning their effect on the RCbF process. The experiments were performed at two-stage pilot waterworks for biological iron and manganese removal. O₂ or NO₃⁻ as oxidants affected the RCbF process, neither by consumption of the reductant Fe(II) nor by re-oxidation of already formed Cr(III) in the supernatant of the filter bed. However, the oxidation of Cr(III) by O₂ to Cr(VI) with MnO₂ as a mediator was identified as potential risk for Cr breakthrough. Up to one third of the initial Cr(III) concentration was oxidized to Cr(VI) in the second filter bed within a contact time of only 5 min. The kinetically relevant mechanism seemed to be the formation of Cr(III)Fe(III)-hydroxides and not the reduction of Cr(VI) by Fe(II). Further, the mixing of Cr(VI) containing raw water with Fe(II) containing groundwater was determined as a chemical-free alternative for the RCbF process, depending on the resulting Fe(II) concentration after mixing. Full article