Dependence of SARS-CoV-2 (COVID-19) inactivation ability on the crystallinity level of transparent Cu2O thin films

The inactivation ability of SARS-CoV-2 (COVID-19) was examined using two types of transparent Cu2O thin films with different crystallinities on a Na-free glass substrate. The low-crystallinity Cu2O thin film, which was fabricated by irradiating 254 nm ultraviolet (UV)-light with an intensity of 6.72 mW cm(-2) onto a spin-coated precursor film involving Cu2+ complexes at room temperature, exhibited an outstanding COVID-19 inactivation ability to reduce 99.999% of the virus after 1 h of incubation. The X-ray diffraction results of the UV-irradiated thin film indicated a cubic Cu2O lattice with a small crystallite size of 2 +/- 1 nm. Conversely, the high-crystallinity Cu2O thin film with a crystallite size of 16 +/- 3 nm, obtained by heating a spin-coated precursor film containing another Cu2+ complex, showed a negligibly low inactivation activity at the same level as the Na-free glass substrate. The eluted concentrations of Cu ions from both Cu2O thin films were analyzed after immersion in Dulbecco's modified Eagle's medium (DMEM) for 0.25-2 h. The eluted Cu-ion concentration of 1.16 ppm was observed for the UV-irradiated thin film by DMEM immersion after 1 h, but that of 0.04 ppm was observed for the heat-treated thin film. This indicated that an important factor of virus inactivation on Cu2O thin films is highly related to the elution of Cu ions that occurred from the surface in the medium.

Cuprous oxide nanoparticles incorporated into a polymeric matrix embedded in fabrics to prevent spread of SARS-CoV-2.

This paper describes the development of a coating for cotton and polypropylene (PP) fabrics based on a polymeric matrix embedded with cuprous oxide nanoparticles (Cu2O@SDS NPs) in order to inactivate SARS-CoV-2 and manufactured by a simple process using a dip-assisted layer-by-layer technology, at low curing temperature and without the need for expensive equipment, capable of achieving disinfection rates of up to 99%. The polymeric bilayer coating makes the surface of the fabrics hydrophilic, enabling the transportation of the virus-infected droplets to achieve the rapid inactivation of SARS-CoV-2 by contact with the Cu2O@SDS NPs incorporated in the coated fabrics.

Dependence of SARS-CoV-2 (COVID-19) inactivation ability on the crystallinity level of transparent Cu2O thin films

The inactivation ability of SARS-CoV-2 (COVID-19) was examined using two types of transparent Cu2O thin films with different crystallinities on a Na-free glass substrate. The low-crystallinity Cu2O thin film, which was fabricated by irradiating 254 nm ultraviolet (UV)-light with an intensity of 6.72 mW cm(-2) onto a spin-coated precursor film involving Cu2+ complexes at room temperature, exhibited an outstanding COVID-19 inactivation ability to reduce 99.999% of the virus after 1 h of incubation. The X-ray diffraction results of the UV-irradiated thin film indicated a cubic Cu2O lattice with a small crystallite size of 2 +/- 1 nm. Conversely, the high-crystallinity Cu2O thin film with a crystallite size of 16 +/- 3 nm, obtained by heating a spin-coated precursor film containing another Cu2+ complex, showed a negligibly low inactivation activity at the same level as the Na-free glass substrate. The eluted concentrations of Cu ions from both Cu2O thin films were analyzed after immersion in Dulbecco's modified Eagle's medium (DMEM) for 0.25-2 h. The eluted Cu-ion concentration of 1.16 ppm was observed for the UV-irradiated thin film by DMEM immersion after 1 h, but that of 0.04 ppm was observed for the heat-treated thin film. This indicated that an important factor of virus inactivation on Cu2O thin films is highly related to the elution of Cu ions that occurred from the surface in the medium.

Transparent Anti-SARS COV-2 Film from Copper(I) Oxide Incorporated in Zeolite Nanoparticles.

The high antibacterial and antiviral performance of synthesized copper(I) oxide (Cu2O) incorporated in zeolite nanoparticles (Cu-Z) was determined. Various Cu contents (1-9 wt %) in solutions were loaded in the zeolite matrix under neutral conditions at room temperature. All synthesized Cu-Z nanoparticles showed high selectivity of the cuprous oxide, as confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. An advantage of the prepared Cu-Z over the pristine Cu2O nanoparticles was its high thermal stability. The 7 and 9 wt % Cu contents (07Cu-Z and 09Cu-Z) exhibited the best activities to deactivate Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. The film coated with 07Cu-Z nanoparticles also had high antiviral activities against porcine coronavirus (porcine epidemic diarrhea virus, PEDV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Specifically, the 07Cu-Z-coated film could reduce 99.93% of PEDV and 99.94% of SARS-CoV-2 viruses in 5 min of contact time, which were higher efficacies and faster than those of any previously reported works. The anti-SARS-CoV-2 virus film was coated on a low-cost PET or PVC film. A very small amount of cuprous oxide in zeolite was used to fabricate the antivirus film; therefore, the film was more transparent (79.4% transparency) than the cuprous oxide film or other commercial products. The toxicity of 07Cu-Z nanoparticles was determined by a toxicity test on zebrafish embryo and a skin irritation test to reconstruct a human epidermis (RhE) model. It was found that the impact on the aquatic environment and human skin was lower than that of the pristine Cu2O.

Intrafibrillar Dispersion of Cuprous Oxide (Cu2O) Nanoflowers within Cotton Cellulose Fabrics for Permanent Antibacterial, Antifungal and Antiviral Activity.

With increasingly frequent highly infectious global pandemics, the textile industry has responded by developing commercial fabric products by incorporating antibacterial metal oxide nanoparticles, particularly copper oxide in cleaning products and personal care items including antimicrobial wipes, hospital gowns and masks. Current methods use a surface adsorption method to functionalize nanomaterials to fibers. However, this results in poor durability and decreased antimicrobial activity after consecutive launderings. In this study, cuprous oxide nanoparticles with nanoflower morphology (Cu2O nanoflowers) are synthesized in situ within the cotton fiber under mild conditions and without added chemical reducing agents from a copper (II) precursor with an average maximal Feret diameter of 72.0 ± 51.8 nm and concentration of 17,489 ± 15 mg/kg. Analysis of the Cu2O NF-infused cotton fiber cross-section by transmission electron microscopy (TEM) confirmed the internal formation, and X-ray photoelectron spectroscopy (XPS) confirmed the copper (I) reduced oxidation state. An exponential correlation (R2 = 0.9979) between the UV-vis surface plasmon resonance (SPR) intensity at 320 nm of the Cu2O NFs and the concentration of copper in cotton was determined. The laundering durability of the Cu2O NF-cotton fabric was investigated, and the superior nanoparticle-leach resistance was observed, with the fabrics releasing only 19% of copper after 50 home laundering cycles. The internally immobilized Cu2O NFs within the cotton fiber exhibited continuing antibacterial activity (≥99.995%) against K. pneumoniae, E. coli and S. aureus), complete antifungal activity (100%) against A. niger and antiviral activity (≥90%) against Human coronavirus, strain 229E, even after 50 laundering cycles.

Drastic Reduction of Bacterial, Fungal and Viral Pathogen Titers by Cuprous Oxide Impregnated Medical Textiles.

Hospital patients and personnel are at risk of nosocomial viral infections, as clearly manifested during the COVID-19 pandemic. Transmission of respiratory viral pathogens can occur through contaminated surfaces, including from medical textiles. Copper has potent biocidal properties, and cuprous oxide impregnated medical textiles (CMT) reduce hospital-acquired bacterial infections. In the current study we confirm the antimicrobial properties of CMT and determine their capacity to reduce infectious titres of human coronavirus (HCoV-229E) in an independent laboratory. The antibacterial and antiviral activities of the CMT were determined according to AATCC TM100-2019 and ISO 18184:2019 standards, respectively. The CMT reduced by 4 logs the viable titers of MRSA, Klebsiella pneumoniae, Enterococcus faecalis, and Candida auris after 2 h of incubation. Viable titers of Clostridium difficile were reduced by 2.3, 3, and 4 logs after 2, 6, and 18 h, respectively. Infectious titers of HCoV-229E exposed to CMT for 2 h were reduced by 2.8 and 4 logs (99.85% and 99.99% reductions) as compared to Time-0 control and initial inoculum, respectively. The CMT retain their antibacterial efficacy even after 100 industrial washings. Use of cuprous oxide impregnated textiles in clinical settings may reduce not only hospital acquired infections caused by bacterial and fungal pathogens, but also, and equally important, those caused by coronavirus and other viruses.

A Surface Coating that Rapidly Inactivates SARS-CoV-2.

SARS-CoV-2, the virus that causes the disease COVID-19, remains viable on solids for periods of up to 1 week, so one potential route for human infection is via exposure to an infectious dose from a solid. We have fabricated and tested a coating that is designed to reduce the longevity of SARS-CoV-2 on solids. The coating consists of cuprous oxide (Cu2O) particles bound with polyurethane. After 1 h on coated glass or stainless steel, the viral titer was reduced by about 99.9% on average compared to the uncoated sample. An advantage of a polyurethane-based coating is that polyurethane is already used to coat a large number of everyday objects. Our coating adheres well to glass and stainless steel as well as everyday items that people may fear to touch during a pandemic, such as a doorknob, a pen, and a credit card keypad button. The coating performs well in the cross-hatch durability test and remains intact and active after 13 days of being immersed in water or after exposure to multiple cycles of exposure to the virus and disinfection.