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

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.

Impact of different numerical approaches on the magnetocaloric effect modeling.

As an ecological alternative to the conventional refrigeration technology, magnetocaloric refrigeration is still facing scientific and technological challenges hindering their application. Magnetocaloric devices rely on the magnetocaloric effect, where temperature variations result from magnetic field changes. The correct implementation of the magnetocaloric effect in numerical models is crucial before prototyping the related solutions. Here, we present a comparison between the three most used numerical methods to simulate the magnetocaloric effect: continuous temperature change, discrete temperature change step and heat source obtained from adiabatic temperature. By varying the time and space steps, it was observed that the continuous temperature change method is the most appropriate for small time steps, but has the largest computational cost. The discrete method can only be applied to small time steps, but is the fastest method. Finally, the adiabatic temperature change power source method can be applied in the entire range and is the one that presents the best results for larger time steps.

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.

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.

PVC containing silver nanoparticles with antimicrobial properties effective against SARS-CoV-2.

Poly (vinyl chloride) (PVC) is commonly used to manufacture biomedical devices and hospital components, but it does not present antimicrobial activity enough to prevent biofouling. With the emergence of new microorganisms and viruses, such as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) that was responsible for the global pandemic caused by Coronavirus Disease 2019 (COVID-19), it is evident the importance of the development of self-disinfectant PVC for hospital environments and medical clinics where infected people remain for a long time. In this contribution, PVC nanocomposites with silver nanoparticles (AgNPs) were prepared in the molten state. AgNPs are well-known as antimicrobial agents suitable for designing antimicrobial polymer nanocomposites. Adding 0.1 to 0.5 wt% AgNPs significantly reduced Young's modulus and ultimate tensile strength of PVC due to the emergence of microstructural defects in the PVC/AgNP nanocomposites, but the impact strength did not change significantly. Furthermore, nanocomposites have a higher yellowness index (YI) and lower optical bandgap values than PVC. The PVC/AgNP nanocomposites present virucidal activity against SARS-CoV-2 (B.1.1.28 strain) within 48 h when the AgNP content is at least 0.3 wt%, suitable for manufacturing furniture and hospital equipment with self-disinfectant capacity to avoid secondary routes of COVID-19 contagion.

Multifunctional cotton fabrics with novel antibacterial coatings based on chitosan nanocapsules and polyacrylate.

Chitosan is a cationic polysaccharide with intrinsic antimicrobial properties that can be used as an ecological alternative to develop functional materials to inhibit the proliferation of microorganisms. This work evaluates chitosan nanocapsules (CNs) as a self-disinfecting agent to provide bactericidal activity on cotton fabrics (CF), using polyacrylate to bind the CNs on the CF surface. The fabrics were characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), contact angle (CA), moisture retention, and antimicrobial tests against Escherichia coli and Bacillus subtilis. The FTIR results showed new peaks related to chitosan structure, indicating the adequate fixation of the CNs on the cotton fibers. SEM images corroborated the polyacrylate binder's efficient adhesion, connecting the CNs and the cotton fiber surface. The CF surface properties were considerably modified, while CN/polyacrylate coating promoted antibacterial activity against the B. subtilis (gram-positive bacteria) for the developed wipe, but they do not display bactericidal effects against E. coli (gram-negative bacteria). Supplementary Information: The online version contains supplementary material available at 10.1007/s11998-023-00761-y.

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.

Cotton Fabrics Decorated with Antimicrobial Ag-Coated TiO2 Nanoparticles Are Unable to Fully and Rapidly Eradicate SARS-CoV-2.

The successful development of multifunctional cotton fabrics with antimicrobial and antiviral activities is essential to prevent the proliferation of microorganisms and transmission of coronavirus virions today, especially with the emergence of new variants of SARS-CoV-2. In this work, we developed antimicrobial cotton fabrics with Ag/TiO2 nanoparticles synthesized via sonochemistry. Here, we show that more than 50% of infectious SARS-CoV-2 remain active after prolonged direct contact self-disinfecting materials capable of inhibiting the proliferation of Escherichia coli and Staphylococcus aureus. The findings bring several epidemiologic worries about using silver and TiO2 as self-disinfecting nanostructured agents to prevent coronavirus transmission.

Effect of food restriction on energy expenditure of monosodium glutamate-induced obese rats.

The neonatal administration of monosodium glutamate (MSG) to rodents leads to obesity in the adult animal, characterized by increased fat storages. Chronic food restriction is known to induce reduction in body energy expenditure, as an adaptive mechanism to save energy. Our purpose was to examine whether obesity can alter the mechanism of energy conservation in food-restricted animals. Newborn female Wistar rats were injected either MSG (obese) or saline (control). At the age of 90 days, the animals were fed daily ad libitum (control and MSG) or restricted (50%) (control-restricted and MSG-restricted). After 30 days the animals were sacrificed and the energy balance was determined by calorimetric analysis. Some parameters of energy balance and body composition were affected by MSG treatment as well as food restriction. The percent reduction of the energy expenditure and fat content in MSG-restricted animals was lower than control-restricted animals, when compared with their respective ad libitum groups. These results indicate that all food-restricted animals were able to develop the mechanism of energy conservation, regardless of the obesity, but it was less efficient in MSG-obese animals.