Search Results (19)

Safe drinking water is essential, yet millions of people remain exposed to contaminated supplies. Conventional treatments such as chlorination and UV light can kill microbes, but they also create harmful byproducts, face resistance issues, and are not always sustainable. Green-synthesized nanomaterials (GSNMs) are emerging as an eco-friendly alternative. Produced with plants, microbes, algae, and natural polymers, these materials merge nanotechnology with green chemistry. Among them, silver, zinc oxide, copper oxide, titanium dioxide, and graphene-based nanomaterials show strong antimicrobial effects by disrupting membranes, generating reactive oxygen species (ROS), and damaging genetic material. Compared with chemically made nanoparticles, GSNMs are often safer, cheaper, and more environmentally compatible. Nevertheless, concerns about toxicity, environmental fate, and large-scale use remain. This review highlights recent progress in GSNM synthesis, antimicrobial mechanisms, and safety considerations, highlighting their potential to enable sustainable water disinfection while identifying critical areas for further research. Full article

This study comprehensively evaluated the antimicrobial performance of copper ions against three bacterial species relevant to water systems: E. coli (ATCC 25922), P. aeruginosa (ATCC 27853), and S. epidermidis (ATCC 12228). Disinfection kinetics were determined at three copper concentrations (0.5, 1.5, and 3.3 mg/L) using the Gard model. E. coli exhibited the highest susceptibility, with inactivation rate constants of 0.63, 3.27, and 9.83, achieving complete inactivation at 3.3 mg/L. P. aeruginosa was the most resistant, showing values below 1.0 across all concentrations, while S. epidermidis displayed intermediate responses. Selected experiments further examined the influence of growth phase, temperature, and water chemistry. Exponential-phase cells were more sensitive than stationary-phase cultures, and higher temperatures (37 °C vs. 5 °C) significantly enhanced inactivation. Moderate bicarbonate (50 mg/L) improved bacterial removal by stabilizing soluble Cu²⁺ ions (2.60 lg reduction), whereas elevated calcium and magnesium (Ca²⁺ 100 mg/L, Mg²⁺ 50 mg/L) reduced effectiveness (≤2.10 lg reduction) through competitive interactions. In addition to culture-based methods, adenosine triphosphate (ATP) bioluminescence assays and flow cytometry (FCM) provided complementary insights, confirming early metabolic disruption and membrane damage prior to culturability loss in selected experiments. Full article

Hypochlorous acid solutions are used as effective disinfectants in many settings, including operating rooms and other hospital environments. During and after the COVID-19 pandemic, their use increased significantly, and this work stems from that development. In fact, despite their undoubtedly excellent properties, these solutions can constitute a very aggressive system for a variety of different materials that are very common in those environments. Materials that can be subject to corrosion include steels, copper-based alloys, and components in electronic devices. This work aims to investigate the responses of these materials to long but intermittent exposures to HClO disinfectant solutions. It consists of a compatibility test, performed on several reference materials with HClO used as a surface disinfectant, connected with NaCl’s eventual presence/deposition over them. To perform the investigations in a manner consistent with the duration of compatible laboratory analyses, the samples were immersed in electrolytically prepared HClO solutions for 750 h, which is a duration considered equivalent to normal exposure to disinfectant aerosols over 3 years. Analyzing the large amount of experimental data gathered yielded interesting results. Where the exposure of non-metallic materials or steel did not lead to compatibility issues, bare metals showed degradation due to salt deposition. This article summarizes the morphological studies, i.e., a huge experimental work conducted at the ENEA IMPACT lab in Bologna and part of the PhD work of the corresponding author. Full article

Understanding cellular interaction with nanomaterials represents a subject of great interest for the validation of new diagnostic and therapeutic tools. A full characterization of a designed product includes the evaluation of its impact on specific biological systems, including the study of cell behavior as a response to that particular interaction. Copper and copper-based nanoparticles (CuO NPs) have emerged as valuable building blocks for various biomedical applications such as antibacterial and disinfecting agents for infectious diseases, and the evaluation of the metabolism of food, including the iron required for proteins and enzymes or as drug delivery systems in cancer therapy. In this study, the biological impact of manganese-doped crystalline copper oxide (CuO:Mn) nano-platelets on human normal BJ fibroblasts and human A375 skin melanoma was assessed. The particles were synthesized at room temperature via the hydrothermal method. A complete physicochemical characterization of the materials was performed by employing various techniques including X-ray diffraction, electron microscopy, X-Ray photoelectron spectroscopy, and dynamic light scattering. Morphological investigations revealed a flat structure with nearly straight edges, with sizes spanning in the nanometer range. XRD analysis confirmed the formation of the CuO phase with good crystallinity, while XPS provided insights into the Mn doping. The findings indicate that nano-platelets interact with cells actively by mediating essential molecular processes. The exogenous manganese triggers increased MnSOD production in mitochondria, compensating ROS produced by external stress factors (Cu²⁺ ions), and mimics the endogenous SODs production, which compensates internal ROS production as it normally results from cell biochemistry. The effect is differentiated in normal cells compared to malignant cells and deserves investigation. Full article

Since the COVID-19 pandemic, efforts in the field of surface decontamination have been redoubled. Finding innovative self-cleaning devices has become a challenge, and several solutions have been proposed in the market in recent years. In this work, an optimized powder/suspension plasma spray process at atmospheric pressure, using a Triplex Pro 210^TM torch, is implemented to produce Cu-TiO₂ surface coatings on stainless steel. The purpose is to investigate the potential improvement of antibacterial efficacy by the reactive surface species generated from TiO₂ photoactivity under irradiation. A water-based suspension, prepared with AnalaR NORMAPUR^TM TiO₂, is used as a precursor to incorporate the photocatalyst into an antibacterial copper matrix. Surface antibacterial tests according to ASTM 2180 standards were performed, and experiments were performed in treated contaminated water. Sub-stoichiometric blue TiO₂ coatings showed complete bacterial elimination after 90 min of visible light irradiation, and Cu-TiO₂ surface coatings were even able to disinfect the surfaces under white light, making the application interesting for bacterial destruction under natural illumination. These materials are also intended for application in water treatment, including both pathogens and chemical micropollutants, which is a pressing issue facing many countries today. Full article

Combinations of metal disinfectants (i.e., silver and copper) with chlorine in doses that meet the World Health Organization guidelines for drinking water operate synergistically to provide superior drinking water disinfection across a wide range of pathogens. Moreover, the combination of disinfectants allows for lower chlorine levels and a less objectionable taste and odor to the treated water (some people can taste or smell chlorine at concentrations as low as 300 μg/L). Towards chlorine-releasing materials for combination with silver- or copper-releasing materials in point-of-use water disinfection, N-chloramine containing polymer gels were developed and their potential for E. coli bacteria inactivation was assessed in deionized water that contained salts to simulate groundwater. Following the chlorination of gels containing chloramine precursors, these gels capably inactivated E. coli, achieving log₁₀ reductions—depending on the gel mass—ranging from 1.1 to 4.5. While chlorine released from the gels was not spectroscopically detected, free chlorine solutions inactivated E. coli in a concentration-dependent way, with 5 and 20 μg/L Cl₂ yielding log₁₀ reductions of 0.43 and 1.69, respectively, suggesting that low levels of chlorine, below both the limit of detection of spectroscopic assays (ca. 40 μg/L Cl₂) and levels known to create adverse taste and smell, are sufficient to inactivate bacteria. Unchlorinated gels or chlorinated control styrene gels (without chloramine precursor) did not inactivate bacteria, suggesting that disinfection did not come from the precursor or from chlorine trapped in the gels after chlorination. In addition, these gels were evaluated together with the MadiDrop (MD, a commercial silver-ceramic tablet) and a copper screen that release silver and copper disinfectants, respectively. Combinations of the gel and MD produced E. coli inactivation close to 2-log₁₀ reduction, with the combination, gels alone, and MD alone achieving 1.86-, 1.10-, and 0.69-log₁₀ reduction, respectively. When the gels were combined with the copper screen, however, neither an increase nor a decrease in bacterial reduction was observed compared to that achieved with the gels alone. The laboratory results in this study are promising and suggest the potential for chloramine-functionalized gels to serve as an alternative to existing commercial chlorine-based POU technologies and in combination with silver-based POU technologies. Full article

For decades, novel viral strains of respiratory tract infections have caused human pandemics and initiated widespread illnesses. The recent coronavirus disease 2019 (COVID-19) outbreak caused by the SARS-CoV-2 virus has raised an urgent need to develop novel antiviral coatings as one of the potential solutions to mitigate the transmission of viral pathogens. Titanium dioxide is considered an excellent candidate for viral disinfection under light irradiation, with the potential to be activated under visible light for indoor applications. This research assessed the antiviral performance of thermally sprayed TiO₂ coatings under UVA and ambient light. We also report the antiviral performance of TiO₂ composites with other oxides, such as Cu₂O and Al₂O₃, produced by suspension plasma spray, atmospheric plasma spray, and suspension high-velocity oxygen fuel techniques. To evaluate the antiviral performance of the above coatings in a containment level-2 laboratory, a human common cold coronavirus, HCoV-229E, was initially used as a relevant surrogate for SARS-CoV-2. Coatings were also analyzed using SEM and XRD and were classified based on their surface roughness, porosity, and phase composition. Collectively, the thermally sprayed coatings showed comparable or slightly better antiviral activity compared to copper. The most significant level of activity observed was approximately 20% to 50% higher than that of a pure copper plate. Full article

This work studies two copper-based alloys as potential antimicrobial weapons for sectors where surface hygiene is essential. Effects of different alloying elements addition at the same Cu content (92.5% by weight) on the corrosion resistance and the antibacterial performance of two copper alloys were studied in an aerated disinfectant solution (0.25% v/v Aniosurf Premium (D)) by electrochemical corrosion, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS) and antibacterial tests. Results showed that the nature of the alloying elements had a clear influence on the corrosion resistance and antibacterial performance. Electrochemical impedance results and surface analyses demonstrate the presence of organic compounds bound on the substrate and that a film covers part of the total active surface and may act as a protective barrier by preventing the interaction between metal and solution, decreasing the antimicrobial performance of copper-based materials. Low zinc and silicon contents in copper alloys allows for better aging behavior in D solution while maintaining good antibacterial performance. The XPS and ToF-SIMS results indicated that artificial aging in disinfectant enhanced Cu enrichment in the organic film formed, which could effectively stimulate the release of Cu ions from the surface. Full article

In this study, a method for the bacterial disinfection of drinking water in the water storage systems based on the electric potential generated from a piezoelectric wind energy harvester is presented. First, an efficient galloping piezoelectric wind energy harvester is designed by adding curve- shaped attachments to the bluff body of the harvester. The simulated output voltage of the harvester is validated by performing different sets of experiments on an open environment. Later, the output voltage of the harvester is enhanced, using copper oxide nanowires (CuONWs) grown perpendicular to the surface of the center copper wire. The enhanced electric field is able to disinfect the bacterial water in a 25 min time period. The bacterial removal log efficiency of 2.33 is obtained with a supplied rms voltage of 0.1 V from the harvester. The findings of this study will help to provide alternate means to water treatment that are efficient, reliable, and also free from disinfection by-products. Full article

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019, which has been a global pandemic. Since SARS-CoV-2 is transmitted through contaminated surfaces and aerosols, environmental disinfection is important to block the spread of the virus. Photocatalysts are attractive tools for virus inactivation and are widely used as air purifiers and coating materials. However, photocatalysts are inactive in the dark, and some of them need to be excited with light of a specific wavelength. Therefore, photocatalysts that can effectively inactivate SARS-CoV-2 in indoor environments are needed. Here, we show that a WO₃ photocatalyst containing copper inactivated the SARS-CoV-2 WK-521 strain (Pango lineage A) upon irradiation with white light in a time- and concentration-dependent manner. Additionally, this photocatalyst also inactivated SARS-CoV-2 in dark conditions due to the antiviral effect of copper. Furthermore, this photocatalyst inactivated not only the WK-521 strain but also the Omicron variant BA.2. These results indicate that the WO₃ photocatalyst containing copper can inactivate indoor SARS-CoV-2 regardless of the variant, in visible light or darkness, making it an effective tool for controlling the spread of SARS-CoV-2. Full article

Novel composite self-disinfecting films of polylactic acid (PLA) filled with nanosized particles of double sodium–copper(II) paratungstate B Na₂Cu₃(CuOH)₂[W₁₂O₄₀(OH)₂]·32H₂O (POM) were developed. The solvent casting (POM/PLA film) and solvent-free melt extrusion methods (Extr. POM/PLA film) were applied for film preparation. The copper (II) ion release to water from both types of the films after 10 days at different temperatures demonstrated that the PLA matrix acts as a diffusion barrier, and the resulting concentration of released copper in water at room temperature remained low, at 0.79% for POM/PLA film and 0.51% for Extr. POM/PLA film. The POM-containing films reveals a significant inhibitory effect against E. coli ATCC 25922 in the agar diffusion test. The numbers of CFUs in washes of the films after incubation for 24 h were found to be 3.6 log CFU mL^–1 (POM/PLA film) and 4.1 log CFU mL^–1 (Extr. POM/PLA film). The films combine the antibacterial properties of POM and a bio-based polymer matrix, which makes them a prospective coating material for applications in hospital indoor environments. Excellent thermal stability of POM gives a technological advantage for industrial manufacturing to allow the processing of novel composite material in the solvent free (molten) state. Full article

Recently, metal oxide nanoparticles (NPs) have attracted attention as promising components for the protection and stimulation of plant microclones in tissue culture in vitro. However, the effect of NPs on the genetic mechanisms underlying plant adaptive responses remains poorly understood. We studied the effect of column-shaped CuO NPs 50 nm in diameter and 70–100 nm in length at a concentration of 0.1–10 mg/L on the development of phytopathogenic fungi Alternaria alternata, Fusarium oxysporum, and Fusarium avenaceum in culture, as well as on the infection of downy birch micro-clones with phytopathogens and the level of genes expression associated with the formation of plant responses to stress induced by microorganisms. CuO NPs effectively suppressed the development of colonies of phytopathogenic fungi A. alternata and F. avenaceum (up to 68.42% inhibition at 10 mg/L CuO NPs) but not the development of a colony of F. oxysporum. Exposure to the NPs caused multidirectional responses at the level of plant genes transcription: 5 mg/L CuO NPs significantly increased the expression level of the LEA8 and MYB46 genes and decreased the expression of DREB2 and PAL. Infection with A. alternata significantly increased the level of MYB46, LEA8, PAL, PR-1, and PR-10 transcripts in birch micro-clones; however, upon exposure to a medium with NPs and simultaneous exposure to a phytopathogen, the expression of the MYB46, PR-1, and PR-10 genes decreased by 5.4 times, which is associated with a decrease in the pathogenic load caused by the effect of NPs and the simultaneous stimulation of clones in vitro. The results obtained can be used in the development of preparations based on copper oxide NPs for disinfection and stimulation of plant phytoimmunity during clonal micropropagation of tree crops. Full article

Consumption of contaminated water may lead to dangerous and even fatal water-borne diseases. Disinfection of drinking water is the most effective solution for this problem. The most common water treatment methods are based on the use of toxic disinfectants. Composites of polymers with nanosized metals and their oxides may become a good alternative to the existing methods. Expanding the scope of our previous publication, copper, cuprous, and copper oxide nanoparticles were immobilized onto linear low-density polyethylene by a simple thermal adhesion method. The antibacterial efficiency of the immobilized nanoparticles was tested against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus in batch experiments and for the first time the efficiency of these composites is reported for continuous flow regime. Immobilized copper and cuprous oxide nanoparticles demonstrated a high ability to eradicate bacteria after 30 min. These composites showed no or very limited leaching of copper ions into the aqueous phase both in the presence and in the absence of a bacterial suspension. Immobilized copper and cuprous oxide nanoparticles can be used for batch or continuous disinfection of water. Full article

The aim of this systematic review was to investigate the effectiveness of various disinfection methods available for stethoscopes. In March 2019, we performed a search in PubMed and Scopus using the search terms: “reducing stethoscopes contamination” and “disinfection stethoscopes”; the Mesh terms used in PubMed were “Decontamination/methods” or “Disinfection/methods” and “Stethoscopes/microbiology”. Selection criteria were: English language; at least one disinfection method tested. A total of 253 publications were screened. After title, abstract, and full-text analysis, 17 papers were included in the systematic review. Ethanol at 90%, Ethanol-Based Hands Sanitizer (EBHS), triclosan, chlorhexidine, isopropyl alcohol, 66% ethyl alcohol, sodium hypochlorite, and benzalkonium chloride have been proven to lower the presence of bacteria on stethoscopes’ surfaces. In addition, alcohol wipes show effective results. A wearable device emitting ultraviolet C by Light-Emitting Diode (LED) resulted efficacious against common microorganisms involved in Healthcare Associated Infections. The cover impregnated with silver ions seemed to be associated with significantly higher colony counts. Instead, copper stethoscopes surface reduced bacterial load. The disinfection of stethoscopes appears to be essential. There are many valid methods available; the choice depends on various factors, such as the cost, availability, and practicality. Full article

The rapid spreading of resistance among common bacterial pathogens towards the misused antibiotics/disinfectant agents has drawn much attention worldwide to bacterial infections. In light of this, the present work aimed at the realization of core–shell nanoparticles possessing remarkable antimicrobial properties thanks to the synergistic action of the metal core and the disinfectant shell. Copper nanoparticles stabilized by benzalkonium chloride were prepared, characterized, and implemented in poly-vinyl-methyl ketone to obtain nanoantimicrobial composite coatings. Bioactivity tests are reported, proving the excellent disinfectant properties of the proposed nanomaterials, as compared to one of the well-known and strongest silver-based nanoantimicrobials. Applications are also briefly described. Full article