Nano-sized Metal Oxides and Their use as a Surface Disinfectant Against COVID-19: (Review and Perspective)

Contamination of surfaces has long been identified as a significant factor in viral transmission. Therefore, sustained efforts are required to address this issue. This work aims to build a scientific database on nano-sized metal oxides as intelligent materials for surface disinfection against corona viruses, synthesize and characterize nano-sized MgO, and discuss the possibility of using it in virus eradication. The MgO nanoparticle was prepared through the heating method. Meanwhile, XRD diffractometer, Scan electron microscope, and nitrogen adsorption were used to characterize the MgO nanoparticle. The synthesized MgO nanoparticle showed an average crystallite size of 18.55nm, lattice strain 0.0053, surface area 27.56 m(2)/g and d-spacing 2.1092. The outcomes of this review highlight the advantage and challenges of AgO, CuO, ZnO, TiO2 and MgO nanoparticles and their utilization for surface disinfection against coronaviruses.

Utilization of Medical Mask Wastes as Filter Material for Air Purification Units

The COVID-19 pandemic significantly increased the amount of infectious medical wastes produced, with medical mask wastes being one of the largest contributors. Present research focuses on trying to turn medical mask waste into a functioning air filter by modifying it with CuO/TiO2 to reduce the amount of infectious medical wastes laying around. Synthesis of CuO/TiO2 was confirmed with FESEM-EDX, UV-Vis DRS and XRD techniques. The optimum amount of Cu added (1%wt of TiO2) was determined by assessing the degradation performance of the modified medical mask wastes against an organic pollutant (methylene blue) and a biological pollutant (S. aureus). The filter was then integrated into a simple air purifying unit and complemented with a UV-C germicidal lamp and a plasma ion generator. The prototype of the simple air purifying unit was able to degrade 100% tobacco smoke in less than 15 min and 30.8% CO gas in 30 min. © 2022 Chemical Publishing Co.. All rights reserved.

Antimicrobial Properties of CuO Particles Deposited on a Medical Mask.

Medical face masks help to reduce the transmission of pathogens, however, the number of infections caused by antimicrobial-resistant pathogens continues to increase. The aim of this study was to investigate the antimicrobial effect of an experimental medical mask layer coated with copper oxide using an environmentally friendly non-thermal physical vapour deposition approach. Pure CuO nanoparticles were successfully deposited on the middle layer of a face mask. The particles were distributed in different size clusters (starting from less than 100 nm dots going up to about 1 µm cluster-like structures). The CuO clusters did not form uniform films, which could negatively influence airflow during use of the mask. We investigated the antimicrobial properties of the experimental mask layer coated with CuO NPs using 17 clinical and zoonotic strains of gram-negative, gram-positive, spore-forming bacteria and yeasts, during direct and indirect contact with the mask surface. The effectiveness of the coated mask layer depended on the deposition duration of CuO. The optimal time for deposition was 30 min, which ensured a bactericidal effect for both gram-positive and gram-negative bacteria, including antimicrobial-resistant strains, using 150 W power. The CuO NPs had little or no effect on Candida spp. yeasts.

Fast and Effective Deactivation of Human Coronavirus with Copper Oxide Suspensions.

The COVID-19 pandemic has demonstrated the need for versatile and robust countermeasures against viral threats. A wide range of viruses, including SARS-CoV-2, the virus that causes COVID-19, can be deactivated by metal and metal-oxide surface coatings. However, such coatings are expensive and cannot easily be retrofitted to existing infrastructure. Low-cost materials to halt the propagation of a variety of viruses must be produced with minimal quantities of expensive precursors. In this regard, we show that commercially available copper oxide nanoparticle suspensions can deactivate more than 99.55% of the human coronavirus 229E in 30 min, confirming the particles' efficiency as a fast antiviral material.

CuO–NPs, CuO–Ag nanocomposite and Cu(II)-curcumin complex coated cotton/starched cotton antimicrobial materials

Metal and metal oxide nanoparticles coated on textile fabrics have showed remarkable antibacterial characteristics, suggesting that they could be utilized to prevent the spread of the COVID-19 and reduce outbreaks. Textile materials, such as medical cloths and cleaning workers, could help to stop the spread of the COVID-19 Corona Virus in health institutions. Copper oxide nanoparticles (CuO-NPs) coated cotton/starched cotton, as well as their functionalized CuO–Ag nanocomposites and Cu(II)-curcumin complex, were synthesized in this study. CuO-NPs are less likely to leach when starched cotton materials are used instead of unstarched cotton. The none-toxic biocompatible starch material has improved the adhesion properties of the cotton fibers and enhanced its durability towards CuO-NPs. Deposition of CuO has improved by 39.5% after 3 wt% starch was used and its antimicrobial activity of CuO-coated cotton has increased by 50% for E. coli and by 23% for S. aureus. The functionalization of CuO-coated cotton with curcumin or Ag nanoparticles has enhanced the antimicrobial performance of the fabric because of the synergistic behavior of CuO, Ag, and curcumin. The results have showed excellent antimicrobial activity against E. coli and S. aureus.

Ultra-fast bacterial inactivation of Cu2O@Halloysite nanotubes hybrids with charge adsorption and physical piercing ability for medical protective fabrics

Metals have been used for wound treatment and toxicity testing since ancient times. With the development of nanotechnology, metal oxides have been proven to have excellent sterilization and disinfection functions. However, the rapid bacterial inactivation efficiency and trapping physicochemical killing ability remain simultaneously undemonstrated in antibacterial nanohybrids. Here, we demonstrate a method for in-situ reduction of small-sized Cu2O particles on one-dimensional inorganic halloysite nanotubes (HNTs). The resultant Cu2O@HNTs hybrids not only give Cu2O excellent dispersibility, but also exert the synergistic effect of the charge adsorption of metal oxides and the physical piercing effect of the small-sized nanotubes. Furthermore, the release of Cu2+ from hybrids damages cell membranes and denatures proteins and DNA. Through this sterilization mechanism, Cu2O@HNTs allow for the inactivation rate of Escherichia coli to reach 94.5% within 2 min and complete inactivation within 10 min. This excellent sterilization mode makes Cu2O@HNTs exhibit excellent broad-spectrum antibacterial activity and inactivation efficiency, while shows weak cytotoxicity. These hybrids were further applied in the processing of functional antibacterial fibers and fabrics. Thus, we believe that this excellent antibacterial hybrid is practically attractive in this critical time of the COVID-19 pandemic.

Nanostructured Copper Surface Kills ESKAPE Pathogens and Viruses in Minutes.

In the search for a fast contact-killing antimicrobial surface to break the transmission pathway of lethal pathogens, nanostructured copper surfaces were found to exhibit the desired antimicrobial properties. Compared with plain copper, these nanostructured copper surfaces with Cu(OH)2 nano-sword or CuO nano-foam were found to completely eliminate pathogens at a fast rate, including clinically isolated drug resistant species. Additionally these nanostructured copper surfaces demonstrated potential antiviral properties when assessed against bacteriophages, as a viral surrogate, and murine hepatitis virus, a surrogate for SARS-CoV-2. The multiple modes of killing, physical killing and copper ion mediated killing contribute to the superior and fast kinetics of antimicrobial action against common microbes, and ESKAPE pathogens. Prototypes for air and water cleaning with current nanostructured copper surface have also been demonstrated.

Biodegradable Nanofibrous Membranes for Medical and Personal Protection Applications: Manufacturing, Anti-COVID-19 and Anti-Multidrug Resistant Bacteria Evaluation.

Biodegradable nanofibrous hybrid membranes of polyvinyl alcohol (PVA) with ZnO and CuO nanoparticles were manufactured and characterized, and their anti-COVID-19 and anti-multidrug resistant bacteria activities were also evaluated. The morphological structures of the prepared PVA composites nanofibers were observed by scanning electron microscope (SEM), which revealed a homogenous pattern of the developed nanofibers, with an average fibrous diameter of 200-250 nm. Moreover, the results of the SEM showed that the fiber size changed with the type and the concentration of the metal oxide. Moreover, the antiviral and antibacterial potential capabilities of the developed nanofibrous membranes were tested in blocking the viral fusion of SARS-COV-2, as a representative activity for COVID-19 deactivation, as well as for their activity against a variety of bacterial strains, including multi-drug resistant bacteria (MDR). The results revealed that ZnO loaded nanofibers were more potent antiviral agents than their CuO analogues. This antiviral action was attributed to the fact that inorganic metallic compounds have the ability to extract hydrogen bonds with viral proteins, causing viral rupture or morphological changes. On the other hand, the anti-multi-drug resistant activity of the prepared nanofibers was also evaluated using two techniques; the standard test method for determining the antimicrobial activity of immobilized antimicrobial agents under dynamic contact conditions and the standard test method for determining the activity of incorporated antimicrobial agents in polymeric or hydrophobic materials. Both techniques proved the superiority of the ZnO loaded nanofibers over the CuO loaded fibers. The results of the antiviral and antibacterial tests showed the effectiveness of such nanofibrous formulas, not only for medical applications, but also for the production of personal protection equipment, such as gowns and textiles.

Cupric Oxide Coating That Rapidly Reduces Infection by SARS-CoV-2 via Solids.

The ongoing COVID-19 pandemic has created a need for coatings that reduce infection from SARS-CoV-2 via surfaces. Such a coating could be used on common touch surfaces (e.g., door handles and railings) to reduce both disease transmission and fear of touching objects. Herein, we describe the design, fabrication, and testing of a cupric oxide anti-SARS-CoV-2 coating. Rapid loss of infectivity is an important design criterion, so a porous hydrophilic coating was created to allow rapid infiltration of aqueous solutions into the coating where diffusion distances to the cupric oxide surface are short and the surface area is large. The coating was deposited onto glass from a dispersion of cuprous oxide in ethanol and then thermally treated at 700 °C for 2 h to produce a CuO coating that is ≈30 µm thick. The heat treatment oxidized the cuprous oxide to cupric oxide and sintered the particles into a robust film. The SARS-CoV-2 infectivity from the CuO film was reduced by 99.8% in 30 min and 99.9% in 1 h compared to that from glass. The coating remained hydrophilic for at least 5 months, and there was no significant change in the cross-hatch test of robustness after exposure to 70% ethanol or 3 wt % bleach.