Edible alginate-based films with anti-SARS-CoV-2 activity

The viability of SARS-CoV-2 on food surfaces and its propagation through the food chain has been discussed by several stakeholders, as it may represent a serious public health problem, bringing new challenges to the food system. This work shows for the first time that edible films can be used against SARS-CoV-2. Sodium alginate-based films containing gallic acid, geraniol, and green tea extract were evaluated in terms of their antiviral activity against SARS-CoV-2. The results showed that all these films have strong in vitro antiviral activity against this virus. However, a higher concentration of the active compound (1.25%) is needed for the film containing gallic acid to achieve similar results to those obtained for lower concentrations of geraniol and green tea extract (0.313%). Furthermore, critical concentrations of the active compounds in the films were used to evaluate their stability during storage. Results showed that gallic acid-loaded films lose their activity from the second week of storage, while films with geraniol and green tea extract only show a drop in activity after four weeks. These results highlight the possibility of using edible films and coatings as antiviral materials on food surfaces or food contact materials, which may help to reduce the spreading of viruses through the food chain.

Edible alginate-based films with anti-SARS-CoV-2 activity.

The viability of SARS-CoV-2 on food surfaces and its propagation through the food chain has been discussed by several stakeholders, as it may represent a serious public health problem, bringing new challenges to the food system. This work shows for the first time that edible films can be used against SARS-CoV-2. Sodium alginate-based films containing gallic acid, geraniol, and green tea extract were evaluated in terms of their antiviral activity against SARS-CoV-2. The results showed that all these films have strong in vitro antiviral activity against this virus. However, a higher concentration of the active compound (1.25%) is needed for the film containing gallic acid to achieve similar results to those obtained for lower concentrations of geraniol and green tea extract (0.313%). Furthermore, critical concentrations of the active compounds in the films were used to evaluate their stability during storage. Results showed that gallic acid-loaded films lose their activity from the second week of storage, while films with geraniol and green tea extract only show a drop in activity after four weeks. These results highlight the possibility of using edible films and coatings as antiviral materials on food surfaces or food contact materials, which may help to reduce the spreading of viruses through the food chain.

SARS-CoV-2 air and surface contamination in residential settings.

SARS-CoV-2 transmission occurs mainly indoors, through virus-laden airborne particles. Although the presence and infectivity of SARS-CoV-2 in aerosol are now acknowledged, the underlying circumstances for its occurrence are still under investigation. The contamination of domiciliary environments during the isolation of SARS-CoV-2-infected patients in their respective rooms in individual houses and in a nursing home was investigated by collecting surface and air samples in these environments. Surface contamination was detected in different contexts, both on high and low-touch surfaces. To determine the presence of virus particles in the air, two sampling methodologies were used: air and deposition sampling. Positive deposition samples were found in sampling locations above the patient's height, and SARS-CoV-2 RNA was detected in impactation air samples within a size fraction below 2.5 µm. Surface samples rendered the highest positivity rate and persistence for a longer period. The presence of aerosolized SARS-CoV-2 RNA occurred mainly in deposition samples and closer to symptom onset. To evaluate the infectivity of selected positive samples, SARS-CoV-2 viability assays were performed, but our study was not able to validate the virus viability. The presented results confirm the presence of aerosolized SARS-CoV-2 RNA in indoor compartments occupied by COVID-19 patients with mild symptoms, in the absence of aerosol-generating clinical procedures.

UV-C irradiation-based inactivation of SARS-CoV-2 in contaminated porous and non-porous surfaces.

The SARS-CoV-2 pandemic emphasized effective cleaning and disinfection of common spaces as an essential tool to mitigate viral transmission. To address this problem, decontamination technologies based on UV-C light are being used. Our aim was to generate coherent and translational datasets of effective UV-C-based SARS-CoV-2 inactivation protocols for the application on surfaces with different compositions. Virus infectivity after UV-C exposure of several porous (bed linen, various types of upholstery, synthetic leather, clothing) and non-porous (types of plastic, stainless steel, glass, ceramics, wood, vinyl) materials was assessed through plaque assay using a SARS-CoV-2 clinical isolate. Studies were conducted under controlled environmental conditions with a 254-nm UV-C lamp and irradiance values quantified using a 254 nm-calibrated sensor. From each material type (porous/non-porous), a product was selected as a reference to assess the decrease of infectious virus particles as a function of UV-C dose, before testing the remaining surfaces with selected critical doses. Our data show that UV-C irradiation is effectively inactivating SARS-CoV-2 on both material types. However, an efficient reduction in the number of infectious viral particles was achieved much faster and at lower doses on non-porous surfaces. The treatment effectiveness on porous surfaces was demonstrated to be highly variable and composition-dependent. Our findings will support the optimization of UV-C-based technologies, enabling the adoption of effective customizable protocols that will help to ensure higher antiviral efficiencies.