Heavy metals are encountered in nature, and are used in several human endeavors, including in dental fillings. It is well known that the safety of metals depends on their chemical form, as well as the dose and route through which biological systems are exposed to them. Here, we used the Nauphoeta cinerea model to examine the mechanism by which salts of the heavy metals used in dental fillings - silver and mercury - exert their neurotoxicity. Nymphs exposed to heavy metals presented with reduced motor and exploratory abilities as they spent more time immobile, especially in the periphery of a novel object, and covered less distance compared with control nymphs. Exposure to AgNO3 and HgCl2 also exacerbated levels of oxidative stress markers (MDA & ROS) and the neurotransmitter regulators - AChE and MAO, while reducing antioxidant activity markers, both in biochemical (thiol & GST) and RT-qPCR (TRX, GST, SOD, Catalase) examinations, in neural tissues of the cockroach. The observed disruptions in neurolocomotor control, synaptic transmission and redox balance explain how heavy metal salts may predispose organisms to neurological disorders.

Most organisms possess three biological oscillators, circadian clock, cell cycle, and redox rhythm, which are autonomous but interact each other. However, whether their interactions and autonomy are beneficial for organisms remains unclear. Here, we modeled a coupled oscillator system where each oscillator affected the phase of the other oscillators. We found that multiple types of coupling prevent a high H2O2 level in cells at M phase. Consequently, we hypothesized a high H2O2 sensitivity at the M phase and found that moderate coupling reduced cell damage due to oxidative stress by generating appropriate phase relationships between three rhythms, whereas strong coupling resulted in an elevated cell damage by increasing the average H2O2 level and disrupted the cell cycle. Furthermore, the multicellularity model revealed that phase variations among cells confer flexibility in synchronization with environments at the expense of adaptability to the optimal environment. Thus, both autonomy and synchrony among the oscillators are important for coordinating their phase relationships to minimize oxidative stress, and couplings balance them depending on environments.

Bacillus velezensis M3-1 strain isolated from the sediment of Myriophyllum aquatium constructed wetlands was found to efficiently convert NO3--N to NO2--N, and the requirements for carbon source addition were not very rigorous. This work demonstrates, for the first time, the feasibility of using the synergy of anammox and Bacillus velezensis M3-1 microorganisms for nitrogen removal. In this study, the possibility of M3-1 that converted NO3--N produced by anammox to NO2--N was verified in an anaerobic reactor. The NO3--N reduction ability of M3-1 and denitrifying bacteria in coupling system was investigated under different C/N conditions, and it was found that M3-1 used carbon sources preferentially over denitrifying bacteria. By adjusting the ratio of NH4+-N to NO2--N, it was found that the NO2--N converted from NO3--N by M3-1 participated in the original anammox.The nitrogen removal efficacy (NRE) of the coupled system was increased by 12.1%, compared to the control group anammox system at C/N = 2:1. Functional gene indicated that it might be a nitrate reducing bacterium.This study shows that the nitrate reduction rate achieved by the Bacillus velezensis M3-1 can be high enough for removing nitrate produced by anammox process, which would enable improve nitrogen removal from wastewater.

Heterogeneous iron-based catalysts have drawn increasing attention in the advanced oxidation of persulfates due to their abundance in nature, the lack of secondary pollution to the environment, and their low cost over the last a few years. In this paper, the latest progress in the research on the activation of persulfate by heterogeneous iron-based catalysts is reviewed from two aspects, in terms of synthesized catalysts (Fe0, Fe2O3, Fe3O4, FeOOH) and natural iron ore catalysts (pyrite, magnetite, hematite, siderite, goethite, ferrohydrite, ilmenite and lepidocrocite) focusing on efforts made to improve the performance of catalysts. The advantages and disadvantages of the synthesized catalysts and natural iron ore were summarized. Particular interests were paid to the activation mechanisms in the catalyst/PS/pollutant system for removal of organic pollutants. Future research challenges in the context of field application were also discussed.

The monitoring of biomarkers in wound exudate is of great importance for wound care and treatment, and electrochemical biosensors with high sensitivity are potentially useful for this purpose. However, conventional electrochemical biosensors always suffer from severe biofouling when performed in the complex wound exudate. Herein, an antifouling electrochemical biosensor for the detection of involucrin in wound exudate was developed based on a wound dressing, oxidized bacterial cellulose (OxBC) and quaternized chitosan (QCS) composite hydrogel. The OxBC/QCS hydrogel was prepared using an in-situ chemical oxidation and physical blending method, and the proportion of OxBC and QCS was optimized to achieve electrical neutrality and enhanced hydrophilicity, therefore endowing the hydrogel with exceptional antifouling and antimicrobial properties. The involucrin antibody SY5 was covalently bound to the OxBC/QCS hydrogel to construct the biosensor, and it demonstrated a low limit of detection down to 0.45 pg mL-1 and a linear detection range from 1.0 pg mL-1 to 1.0 μg mL-1, and it was capable of detecting targets in wound exudate. Crucially, the unique antifouling and antimicrobial capability of the OxBC/QCS hydrogel not only extends its effective lifespan but also guarantees the sensing performance of the biosensor. The successful application of this wound dressing, OxBC/QCS hydrogel for involucrin detection in wound exudate demonstrates its promising potential in wound healing monitoring.

Interdigitated electrodes (IDEs) enable electrochemical signal enhancement through repeated reduction and oxidation of the analyte molecule. Porosity on these electrodes is often used to lower the impedance background. However, their high capacitive current and signal interferences with oxygen reduction limit electrochemical detection ability. We present utilization of alkanethiol modification on nanoporous gold (NPG) electrodes to lower their background capacitance and chemically passivate them from interferences due to oxygen reduction, while maintaining their fast electron transfer rates, as validated by lower separation between anodic and cathodic peaks (ΔE) and lower charge transfer resistance (Rct) values in comparison to planar gold electrodes. Redox amplification based on this modification enables sensitive detection of various small molecules, including pyocyanin, p-aminophenol, and selective detection of dopamine in the presence of ascorbic acid. Alkanethiol NPG arrays are applied as a multiplexed sensor testbed within a well plate to screen binding of various peptide receptors to the SARS COV2 S-protein by using a sandwich assay for conversion of PAPP (4-aminophenyl phosphate) to PAP (p-aminophenol), by the action of AP (alkaline phosphatase), which is validated against optical ELISA screens of the peptides. Such arrays are especially of interest in small volume analytical settings with complex samples, wherein optical methods are unsuitable.

Iron is an essential element for life owing to its ability to participate in a diverse array of oxidation-reduction reactions. However, misregulation of iron-dependent redox cycling can also produce oxidative stress, contributing to cell growth, proliferation, and death pathways underlying aging, cancer, neurodegeneration, and metabolic diseases. Fluorescent probes that selectively monitor loosely bound Fe(II) ions, termed the labile iron pool, are potentially powerful tools for studies of this metal nutrient; however, the dynamic spatiotemporal nature and potent fluorescence quenching capacity of these bioavailable metal stores pose challenges for their detection. Here, we report a tandem activity-based sensing and labeling strategy that enables imaging of labile iron pools in live cells through enhancement in cellular retention. Iron green-1 fluoromethyl (IG1-FM) reacts selectively with Fe(II) using an endoperoxide trigger to release a quinone methide dye for subsequent attachment to proximal biological nucleophiles, providing a permanent fluorescent stain at sites of elevated labile iron. IG1-FM imaging reveals that degradation of the major iron storage protein ferritin through ferritinophagy expands the labile iron pool, while activation of nuclear factor-erythroid 2-related factor 2 (NRF2) antioxidant response elements (AREs) depletes it. We further show that lung cancer cells with heightened NRF2 activation, and thus lower basal labile iron, have reduced viability when treated with an iron chelator. By connecting labile iron pools and NRF2-ARE activity to a druggable metal-dependent vulnerability in cancer, this work provides a starting point for broader investigations into the roles of transition metal and antioxidant signaling pathways in health and disease.

Surface functionalization strategy is becoming a crucial bridge from magnetic nanoparticles (MNPs) to their broad bio-application. To realize the multiple functions of MNPs such as magnetic manipulation, target capture, and signal amplification in their use of electrochemical biosensing, co-crosslinking strategy was proposed here to construct dual-functionalized MNPs by combining ultra-sensitive redox moieties and specific biological probes. In this work, MNPs with a TEM size of 10 nm were synthesized by co-precipitation for amination and PEGylation to maintain colloid stability once dispersed in high-ionic-strength buffer (such as phosphate-buffered saline). Then, MNPs@IgG were prepared via the bis(sulfosuccinimidyl) suberate (BS3) cross-linker to conjugate these IgG onto the MNP surface, with a binding efficiency of 73%. To construct dual-functionalized MNPs, these redox probes of ferrocene-NHS (Fc) were co-crosslinked onto the MNP surface, together with IgG, by using BS3. The developed MNPs@Redox@IgG were characterized by SDS‒PAGE to identify IgG binding and by square wave voltammetry (SWV) to validate the redox signal. Additionally, the anti-CD63 antibodies were selected for the development of MNPs@anti-CD63 for use in the bio-testing of exosome sample capture. Therefore, co-crosslinking strategy paved a way to develop dual-functionalized MNPs that can be an aid of their potential utilization in diagnostic assay or electrochemical methods.

Oxidoreductases facilitating electron transfer between molecules are pivotal in metabolic pathways. Flavin-based electron bifurcation (FBEB), a recently discovered energy coupling mechanism in oxidoreductases, enables the reversible division of electron pairs into two acceptors, bridging exergonic and otherwise unfeasible endergonic reactions. This chapter explores the four distinct FBEB complex families and highlights a decade of structural insights into FBEB complexes. In this chapter, we discuss the architecture, electron transfer routes, and conformational changes across all FBEB families, revealing the structural foundation that facilitate these remarkable functions.

Antioxidants are widely used in medicine due to their ability to bind free radicals - active biomolecules that destroy the genetic apparatus of cells and the structure of their membranes, which makes it possible to reduce the intensity of oxidative processes in the body. In a living organism, free radicals are involved in various processes, but their activity is controlled by antioxidants. The purpose of this work was to conduct a series of studies to identify the antioxidant activity of new synthesized compounds of a series of oxalic acid diamides in the brain and liver tissue of white rats in vivo and in vitro experiments, as well as to determine their potential pharmacological properties. The studies were conducted on outbred white male rats, weighing 180-200 g, kept on a normal diet. After autopsy, the brain and liver were isolated, washed with saline, cleared of blood vessels, and homogenized in Tris-HCl buffer (pH-7.4) (in vitro). The research results showed significant antioxidant activity (AOA) of all compounds with varying effectiveness. The most pronounced activity was demonstrated by compound SV-425 in both brain and liver tissues. Compound SV-427 demonstrated the least activity, with levels in brain tissue and liver tissue. In addition, all physicochemical descriptors of the studied compounds comply with Lipinski\'s rule of five to identify new molecules for the treatment of oxidative stress. From the data obtained, it can be concluded that the studied compounds have antioxidant properties, helping to protect cells from oxidative stress. This is important for the prevention and treatment of diseases associated with increased levels of free radicals.