Novel Core-Sheath Cu/Cu2O-ZnO-Fe3O4 Nanocomposites with High-Efficiency Chlorine-Resistant Bacteria Sterilization and Trichloroacetic Acid Degradation Performance

High-Efficiency and Stable Cathode Disinfection in Real Water Systems via Convenient In Situ Prepared Copper-Cuprous Oxide Nanowires

As global pollution intensifies, water contamination─a critical issue for both human and ecological survival─has become increasingly severe. Consequently, there is an urgent need for a rapid and stable water disinfection method to ensure clean water. In this study, high-surface-area Cu composite films were first deposited on a conductive substrate through an in situ electrodeposition process. The derived copper nanowire (M-Cu/Cu2O NWs) electrodes were then synthesized by controlled in situ growth and electrochemical reduction-decomposition of the Cu composite films. The working electrode was then placed on the cathode for water disinfection. The results demonstrated excellent and stable antimicrobial performance against Escherichia coli, Staphylococcus aureus, and Citrobacter freundii. The in situ reduction method for preparing derived copper electrodes can help prevent reoxidation during synthesis, promote the formation of an excellent crystal structure, and reduce grain boundaries and defects, thereby enhancing the mechanical strength and chemical stability of the Cu/Cu2O nanowires. Furthermore, the cathodic environment of the working electrode significantly reduces metal corrosion caused by oxidation, further enhancing its durability. The sterilization mechanism is the membrane's electroporation caused by nanowires' tip effect. It has been demonstrated that the M-Cu/Cu2O NWs cathode electrode can continuously maintain a bacterial inactivation rate above 90% for 30 days at an 8 V working potential. Due to the simple electrode fabrication method, stable disinfection efficiency, and significant reduction in copper ion release, which minimizes secondary environmental contamination, this system holds great potential for safe and stable water treatment applications.

Exploration of Metal-Doped Iron Oxide Nanoparticles as an Antimicrobial Agent: A Comprehensive Review

Over the past two decades, nanotechnology has captured significant interest, especially in the medical field, where the unique characteristics of nanoscale particles offer substantial advantages. The family of nanosized materials, specifically iron oxide nanoparticles (IONPs), has emerged as promising due to their magnetic properties, biocompatibility, and substantial surface area for therapeutic molecule attachment. The review explores various strategies to enhance the antibacterial properties of IONPs, such as metal doping, which modifies their physicochemical, biological, electrical, and optical properties. Metal-doped IONPs, including those with nickel, copper, zinc, selenium, molybdenum, gold, and others, have shown that they effectively eradicate viruses and bacteria. The mechanisms behind their enhanced antibacterial activity involve generating reactive oxygen species (ROS), inhibiting antibiotic-resistant genes, disrupting cell walls and DNA, dysfunction of efflux pumps, and internalizing nanoparticles. The review also addresses the potential toxicity of IONPs, highlighting factors such as their dimension, form, and outermost layers, which change how they affect the overall condition of cellular structures. Surface coatings using polymers and essential oils are among the strategies being investigated as potential ways to reduce toxicity. This review additionally looks into IONPs' drug delivery potential for antibiotics and antifungals. The integration of IONPs with various pharmaceutical compounds and their controlled release mechanisms are also detailed. The review concludes by offering a positive outlook on the potential enhancements and prospects of IONPs. Challenges in synthesis technologies, size tuning, and surface alteration are acknowledged, emphasizing the need for continued research to fully harness the capabilities of IONPs in biomedical applications.

Biogenic synthesis of CuO/ZnO nanocomposite from Bauhinia variegate flower extract for highly sensitive electrochemical detection of vitamin B2

In this study, we report the preparation of bio-inspired binary CuO/ZnO nanocomposite (bb-CuO/ZnO nanocomposite) via the biological route using Bauhinia variegata flower extract following hydrothermal treatment. The prepared bb-CuO/ZnO nanocomposite was electrophoretically deposited (EPD) on indium tin oxide (ITO) substrate to develop bb-CuO/ZnO/ITO biosensing electrode which is employed for the determination of vitamin B2 (Riboflavin) through electrochemical techniques. Physicochemical assets of the prepared bb-CuO/ZnO nanocomposite have been extensively evaluated and make use of different characterization techniques including powder XRD, FT-IR, AFM, SEM, TEM, EDX, XPS, Raman, and TGA. Electrochemical characteristics of the bb-CuO/ZnO/ITO biosensing electrode have been studied towards vitamin B2 determination. Furthermore, different biosensing parameters such as response time, reusability, stability, interference, and real sample analysis were also estimated. From the linear plot of scan rate, charge transfer rate constant (Ks), surface concentration of electrode (γ), and diffusion coefficient (D) have been calculated, and these are found to be 6.56 × 10-1 s-1, 1.21 × 10-7 mol cm-2, and 6.99 × 10-3 cm2 s-1, respectively. This biosensor exhibits the linear range of vitamin B2 detection from 1 to 40 μM, including sensitivity and limit of detection (LOD) of 1.37 × 10-3 mA/μM cm2 and 0.254 μM, respectively. For higher concentration range detection linearity is 50-100 μM, with sensitivity and the LOD of 1.26 × 10-3 mA/μM cm2 and 0.145 μM, respectively. The results indicate that the bio-inspired nanomaterials are promising sustainable biosensing platforms for various food and health-based biosensing devices.

The Promise of Metal-Doped Iron Oxide Nanoparticles as Antimicrobial Agent

Antibiotic resistance (AMR) is one of the pressing global public health concerns and projections indicate a potential 10 million fatalities by the year 2050. The decreasing effectiveness of commercially available antibiotics due to the drug resistance phenomenon has spurred research efforts to develop potent and safe antimicrobial agents. Iron oxide nanoparticles (IONPs), especially when doped with metals, have emerged as a promising avenue for combating microbial infections. Like IONPs, the antimicrobial activities of doped-IONPs are also linked to their surface charge, size, and shape. Doping metals on nanoparticles can alter the size and magnetic properties by reducing the energy band gap and combining electronic charges with spins. Furthermore, smaller metal-doped nanoparticles tend to exhibit enhanced antimicrobial activity due to their higher surface-to-volume ratio, facilitating greater interaction with bacterial cells. Moreover, metal doping can also lead to increased charge density in magnetic nanoparticles and thereby elevate reactive oxygen species (ROS) generation. These ROS play a vital role to disrupt bacterial cell membrane, proteins, or nucleic acids. In this review, we compared the antimicrobial activities of different doped-IONPs, elucidated their mechanism(s), and put forth opinions for improved biocompatibility.

The chloroperoxidase immobilized on porous carbon nanobowls for the detection of trichloroacetic acid by electroenzymatic synergistic catalysis

Trichloroacetic acid (TCA), as a by-product of chlorination disinfection, is a highly carcinogenic chemical. Due to the widespread use of chlorination disinfection, it is critical to detect TCA in drinking water to decrease the incidence of disease. In this work, we developed an efficient TCA biosensor via electroenzymatic synergistic catalysis. The porous carbon nanobowls (PCNB) are prepared and wrapped by an amyloid like proteins formed by phase-transitioned lysozyme (PTL-PCNB), then, chloroperoxidase (CPO) is abounding to PTL-PCNB owing to its strong adhesion. The ionic liquid of 1-ethyl-3-methylimidazolium bromide (ILEMB) is co-immobilized on PTL-PCNB to from CPO-ILEMB@PTL-PCNB nanocomposite to assist the direct electron transfer (DET) of CPO. The PCNB plays two roles here. In addition, to increasing the conductivity, it serves as an ideal support for holding CPO; The CPO-ILEMB@PTL-PCNB nanocomposite modified electrode presents high efficiency for sensing TCA. Through electroenzymatic synergistic catalysis, a wide detection range of 33 μmol L-1 to 98 mmol L-1 can be achieved with a low detection limit of 5.9 μmol L-1, and high stability, selectivity as well as reproducibility, which ensures its potential practical applicability. This work provides a new platform for the electro-enzyme synergistic catalysis in one pot.

Identification of Dynamic Active Sites Among Cu Species Derived from MOFs@CuPc for Electrocatalytic Nitrate Reduction Reaction to Ammonia

Direct electrochemical nitrate reduction reaction (NITRR) is a promising strategy to alleviate the unbalanced nitrogen cycle while achieving the electrosynthesis of ammonia. However, the restructuration of the high-activity Cu-based electrocatalysts in the NITRR process has hindered the identification of dynamical active sites and in-depth investigation of the catalytic mechanism. Herein, Cu species (single-atom, clusters, and nanoparticles) with tunable loading supported on N-doped TiO2/C are successfully manufactured with MOFs@CuPc precursors via the pre-anchor and post-pyrolysis strategy. Restructuration behavior among Cu species is co-dependent on the Cu loading and reaction potential, as evidenced by the advanced operando X-ray absorption spectroscopy, and there exists an incompletely reversible transformation of the restructured structure to the initial state. Notably, restructured CuN4&Cu4 deliver the high NH3 yield of 88.2 mmol h-1 gcata-1 and FE (~ 94.3%) at - 0.75 V, resulting from the optimal adsorption of NO3- as well as the rapid conversion of *NH2OH to *NH2 intermediates originated from the modulation of charge distribution and d-band center for Cu site. This work not only uncovers CuN4&Cu4 have the promising NITRR but also identifies the dynamic Cu species active sites that play a critical role in the efficient electrocatalytic reduction in nitrate to ammonia.

Multicomponent hydroxides supported Cu/Cu2O nanoparticles for high efficient photocatalytic ammonia synthesis

Environmentally friendly photocatalytic N₂ fixation process has attracted considerable attention. Developing efficient photocatalysts with high electron-hole separation rates and gas adsorption capacities remains quite challenging. Herein, a facile fabrication strategy of Cu-Cu₂O and multicomponent hydroxide S-scheme heterojunctions with carbon dot charge mediators is reported. The rational heterostructurebrings excellent N₂ absorption ability and high photoinduced electron/hole separation efficiency, and the ammonia produced yield reach above 210 µmol·g_cal^-1·h^-1 during the nitrogen photofixation process. More superoxide and hydroxyl radicals are generated simultaneously in the as-prepared samples under light illumination. This work offers a reasonable construction method to further develop suitable photocatalysts for ammonia synthesis.

ZnO/Cu2O/g-C3N4 heterojunctions with enhanced photocatalytic activity for removal of hazardous antibiotics

In view of the environmental pollution caused by antibiotics, the creation of an efficient photocatalytic material is an effectual way to carry out water remediation. Herein, we developed a smart strategy to synthesize ZnO/Cu₂O/g-C₃N₄ heterojunction photocatalysts for the photodegradation of hazardous antibiotics by one-pot synthesis method. In this system, the Cu₂O nanoparticles with electrons reducing capacity were coupled with g-C₃N₄ composites. The photocarriers were generated from the electric field of type Ⅰ heterojunction between ZnO and g-C₃N₄ and type Ⅱ heterojunction between Cu₂O and g-C₃N₄. ZnO as a co-catalyst was doped to Cu₂O/g-C₃N₄ catalyst system for removal of broad-spectrum antibiotics with the condition of visible light to protect Cu₂O from photocorrosion, which thereby accelerated photocatalytic reactivity. Benefiting by new p-n-n heterojunction, the resulting ZnO/Cu₂O/g-C₃N₄ composites had an excellent degradation performance of broad-spectrum antibiotics such as tetracycline (TC), chlortetracycline (CTC), oxytetracycline (OTC) and ciprofloxacin (CIP), the degradation of which were 98.79%, 99.5%, 95.35% and 73.53%. In particular, ZnO/Cu₂O/g-C₃N₄ photocatalysts showed a very high degradation rate of 98.79% for TC in first 30 min under visible light, which was 1.35 and 10.62 times higher than that of Cu₂O/g-C₃N₄ and g-C₃N₄, respectively. This work gives a fresh visual aspect for simultaneously solving the instability deficiencies of traditional photocatalysts and improving photocatalytic performance.

Microbial diversity in full-scale water supply systems through sequencing technology: a review

The prevalence of microorganisms in full-scale water supply systems raises concerns about their pathogenicity and threats to public health. Clean tap water is essential for public health safety. The conditions of the water treatment process from the source water to tap water, including source water quality, water treatment processes, the drinking water distribution system (DWDS), and building water supply systems (BWSSs) in buildings, greatly influence the bacterial community in tap water. Given the importance of drinking water biosafety, the study of microbial diversity from source water to tap water is essential. With the development of molecular biology methods and bioinformatics in recent years, sequencing technology has been applied to study bacterial communities in full-scale water supply systems. In this paper, changes in the bacterial community and the influence of each treatment stage on microbial diversity in full-scale water supply systems are classified and analyzed. Microbial traceability analysis and control are discussed, and suggestions for future drinking water biosafety research and its prospects are proposed.