Eco-friendly and effective antimicrobial Melaleuca alternifolia essential oil Pickering emulsions stabilized with cellulose nanofibrils against bacteria and SARS-CoV-2.

Melaleuca alternifolia essential oil (MaEO) is a green antimicrobial agent suitable for confection eco-friendly disinfectants to substitute conventional chemical disinfectants commonly formulated with toxic substances that cause dangerous environmental impacts. In this contribution, MaEO-in-water Pickering emulsions were successfully stabilized with cellulose nanofibrils (CNFs) by a simple mixing procedure. MaEO and the emulsions presented antimicrobial activities against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Moreover, MaEO deactivated the SARS-CoV-2 virions immediately. FT-Raman and FTIR spectroscopies indicate that the CNF stabilizes the MaEO droplets in water by the dipole-induced-dipole interactions and hydrogen bonds. The factorial design of experiments (DoE) indicates that CNF content and mixing time have significant effects on preventing the MaEO droplets' coalescence during 30-day shelf life. The bacteria inhibition zone assays show that the most stable emulsions showed antimicrobial activity comparable to commercial disinfectant agents such as hypochlorite. The MaEO/water stabilized-CNF emulsion is a promissory natural disinfectant with antibacterial activity against these bacteria strains, including the capability to damage the spike proteins at the SARS-CoV-2 particle surface after 15 min of direct contact when the MaEO concentration is 30 % v/v.

Omicron SARS-CoV-2 antiviral on poly(lactic acid) with nanostructured copper coating: Wear effects

Graphical Surface modification corresponds to a set of viable technological approaches to introduce antimicrobial properties in materials that do not have such characteristics. Antimicrobial materials are important to prevent the proliferation of microorganisms and minimize the transmission of diseases caused by pathogens. Herein, poly(lactic acid) (PLA) was decorated with nanocones through copper sputtering followed by a plasma etching. Antiviral assays by Quantitative Reverse Transcription-Polymerase Chain Reaction (RT-qPCR) show that nanostructured Cu-coated PLA has high antiviral activity against Omicron SARS-CoV-2, showing a relative reduction in the amplified RNA (78.8 ± 3.9 %). Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS), and wear-resistance tests show that 20 wear cycles disrupt the surface nanocone patterns and significantly reduce the Cu content at the surface of the nanostructured Cu-coated PLA, leading to total loss of the antiviral properties of nanostructured PLA against Omicron SARS-CoV-2.

Bioinspired Antimicrobial PLA with Nanocones on the Surface for Rapid Deactivation of Omicron SARS-CoV-2.

Bioinspired bactericidal surfaces are artificial surfaces that mimic the nanotopography of insect wings and are capable of inhibiting microbial growth by a physicomechanical mechanism. The scientific community has considered them an alternative method to design polymers with surfaces that inhibit bacterial biofilm formation, suitable for self-disinfectant medical devices. In this contribution, poly(lactic acid) (PLA) with nanocone patterns was successfully produced by a novel two-step procedure involving copper plasma deposition followed by argon plasma etching. According to reverse transcription-quantitative polymerase chain reaction tests, the bioinspired PLA nanostructures display antiviral performance to inactivate infectious Omicron severe acute respiratory syndrome coronavirus 2 particles, reducing the amount of the viral genome to less than 4% in just 15 min due to a possible combined effect of mechanical and oxidative stress. The bioinspired antiviral PLA can be suitable for designing personal protection equipment to prevent the transmission of contagious viral diseases, such as Coronavirus Disease 2019.

Copper coatings on poly(lactic acid) via rapid magnetron sputtering: Morphology, chemistry, and antimicrobial performance against bacteria and SARS-CoV-2

Materials with antimicrobial properties are highly desirable for making food packaging and personal protective equipment due to their intrinsic ability to prevent the proliferation of pathogenic microorganisms and food contamination. Poly(lactic acid) (PLA) is a biodegradable, compostable, and recyclable polymer that presents interesting mechanical properties for such applications. However, this polymer does not show intrinsic antimicrobial activity. Herein, we applied Radio Frequency Magnetron Sputtering (RF-MS) to produce antimicrobial copper coatings on the PLA surface. The results indicate that the prolongation in the copper deposition time causes an increase in surface roughness. The PLA coating with copper using a short deposition time (5–20 s) was sufficient to guarantee a bactericidal effect against Escherichia coli and Bacillus subtilis, in addition to conferring antiviral activity against Omicron Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Nuclear magnetic resonance (NMR) and high-resolution x-ray photoelectron (XPS) spectroscopic studies indicate that occurs only localized degradation on the PLA surface via polymer chain scission. The RF-MS technique was suitable for rapidly manufacturing antimicrobial Cu-coated PLA and providing low copper consumption in the antimicrobial coating process.

Delta SARS-CoV-2 inactivation and bactericidal performance of cotton wipes decorated with TiO2/Ag nanoparticles like Brazilian heavy-fruited Myrciaria cauliflora.

The current pandemic of Coronavirus Disease 2019 (COVID-19) raised several concerns about using conventional textiles for manufacturing personal protective equipment without self-disinfecting properties since the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is transmitted mainly by aerosols that can transpose cotton masks. Therefore, developing new cotton fibers with high self-disinfecting ability is essential to avoid a new pandemic due to new SARS-CoV-2 variants. Herein, we developed cotton wipes (CFs) with fibers coated by Ag, TiO2, and Ag/TiO2 hybrid nanoparticles like Brazilian heavy-fruited Myrciaria cauliflora by a sonochemical approach. Moreover, the coated CFs present high antimicrobial performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), being able to inactivate infectious SARS-CoV-2 (Delta variant) by the destruction of the spike, membrane, and nucleocapsid proteins while the viral RNA is not significantly affected, according to the molecular biological findings.

Questioning ZnO, Ag, and Ag/ZnO nanoparticles as antimicrobial agents for textiles: Do they guarantee total protection against bacteria and SARS-CoV-2?

Coronavirus Disease 2019 (COVID-19) occasioned global economic and health systems collapse. Also, it raised several concerns about using conventional cotton fabrics for manufacturing personal protective equipment without the antimicrobial capacity to inactivate viruses, such as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and its variants. Therefore, developing antimicrobial cotton fibers is crucial to avoid new global pandemics or the transmission of dangerous pathogens that remain on surfaces for long periods, especially in hospitals and medical clinics. Herein, we developed antimicrobial cotton fabrics with Ag, ZnO, and Ag/ZnO nanoparticles and evaluated their bactericidal activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), photocatalytic activity, and antiviral activity against Delta SARS-CoV-2. Although the antimicrobial fabrics are effective against these bacteria, they only reduce part of the SARS-CoV-2 virions during the first 15 min of direct contact via damage only to biological structures on the viral surface particle while the viral RNA remains intact.