Food safety concerns in "COVID-19 era"

In March 2020, the World Health Organization (WHO) declared that the COVID-19 outbreak can be characterized as a pandemic. Human-to-human transmission of the SARS-CoV-2 virus may initially be blamed as the first cause of spread, but can an infection be contracted by ingestion of contaminated food or touching contaminated food surfaces? Recently cold-chain food contamination has been indicated as a possible source of many human cases in China. However, the risk of a food-related COVID-19 infection is still debated since the virus may reach people through a fresh product or packaging, which have been touched/sneezed on by infected people. This review summarizes the most recent evidence on the zoonotic origin of the pandemic, reports the main results regarding the transmission of SARS-CoV-2 through food or a food chain, as well as the persistence of the virus at different environmental conditions and surfaces. Emphasis is also posed on how to manage the risk of food-related COVID-19 spread and potential approaches that can reduce the risk of SARS-CoV-2 contamination.Copyright © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

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.

Surface Inactivation of a SARS-CoV-2 Surrogate with Hypochlorous Acid is Impacted by Surface Type, Contact Time, Inoculum Matrix, and Concentration.

Indirect contact with contaminated surfaces is a potential transmission route for COVID-19. Therefore, it is necessary to investigate convenient and inexpensive surface sanitization methods, such as HOCl, against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The SARS-CoV-2 surrogate, Phi6 (~ 7 log PFU/mL), was prepared in artificial saliva and tripartite matrices, spot inoculated on coupons of either stainless steel or vinyl, and allowed to dry. The coupons were sprayed with either 500 ppm or 1000 ppm HOCl, and remained on the surface for 0 s (control), 5 s, 30 s, or 60 s. Samples were enumerated via the double agar overlay assay. Statistical analysis was completed in R using a generalized linear model with Quasipoisson error approximations. Time, concentration, surface type, and inoculum matrix were all significant contributors to log reduction at P = 0.05. Significant three-way interactions were observed for 1000 ppm, vinyl, and 60 s (P = 0.03) and 1000 ppm, tripartite, and 60 s (P = 0.0121). A significant two-way interaction between vinyl and 60 s was also observed (P = 0.0168). Overall, increased HOCl concentration and exposure time led to increased Phi6 reduction. Notably, the highest estimated mean log reduction was 3.31 (95% CI 3.14, 3.49) for stainless steel at 60 s and 1000 ppm HOCl in artificial saliva, indicating that this method of sanitization may not adequately reduce enveloped viruses to below infective thresholds.

Poly(lactic acid)/Poly(vinyl alcohol) Biodegradable Blends Using Monobutyl Maleate as a Plasticizer and Compatibilizer

The Covid-19 pandemic situation has contributed to sparking discussions about an increase in packaging combined with the nonrecommendation of reuse. For this reason, many countries have encouraged the use of biodegradable polymers. In this study, blends of poly(lactic acid) (PLA) and poly(vinyl alcohol) (PVAL) were prepared at 80/20 (w/w) in the presence of specific amounts of monobutyl maleate (MBM) as a compatibilizer. All of these components are proven biodegradable. PLA/ PVAL/MBM blend films were obtained by thermopressing, and the thermal, mechanical, and morphological properties were evaluated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile tests, stress relaxation, and scanning electron microscopy (SEM). DSC results suggest that MBM can act as a plasticizer, at least for the PLA matrix, reducing the Tg from 60.2 degrees C (without MBM) to 23.5 degrees C in the case of the highest quantity of plasticizer (20%). Due to increase in macromolecular mobility, MBM also affects PLA crystallization. As a consequence of brittleness of the other samples, only those containing 15 and 20% of MBM (in PLA basis) did not fail the tensile and relaxation tests, showing more than 25% of elongation at break. Both the elastic and viscous parameters and the equilibrium modulus (Eeq) of the Maxwell-Wiechert mechanical system show lower values for the sample with higher MBM content. The SEM images show that the presence of the compatibilizer improves the adhesion between the PLA-rich phase and PVAL-rich phase.

Effect of Pregelatinized Starch on the Properties of Poly (Vinyl Alcohol) Film for the Water-Soluble Laundry Bag

The goal of this study was to develop pregelatinized starch (P-St) and polyvinyl alcohol (PVOH) films as water-soluble laundry plastic bags to avoid having contact with COVID-19 infected clothes by extrusion method. The effects of pregelatinized starch (P-St) content on the properties of polyvinyl alcohol (PVOH) films were examined. PVOH and P-St blend were compounded by twin-screw extruder with various P-St content of 0, 10, 20, 30, and 40% by weight with fixed glycerol content of 20 phr. The blend films were produced by blown film extrusion. The chemical structure, thermal properties, water-solubility, mechanical properties, and the cross-sections morphological properties of PVOH/G/P-St were characterized. As a result, the formation of intermolecular interactions between PVOH, glycerol and P-St was confirmed by FTIR. Moreover, the addition of P-St on PVOH could reduce the thermal stability due to the content of P-St with amylose, a substance of amorphous structure, affecting the chains flexibility of PVOH/G/P-St. From the differential scanning calorimeter result, the glass transition temperature was increased with the increment of P-St content because the chains entanglement between PVOH and P-St had affected the reduction in crystallinity and led to the decrement of the melting temperature. Furthermore, the water solubility would strongly be dependent on the percentage of the gelatinized starch (%GS). The solubility decreased as the percentage of the GS increased. In addition, PVOH with 20% of P-St film possessed the highest value in tensile strength and modulus, and the particles of P-St have a good distribution in PVOH/G indicating to stronger interaction of P-St and PVOH/G. © 2022, Chiang Mai University. All rights reserved.

Biopolymeric sustainable materials and their emerging applications

Advancements in polymer science and engineering have helped the scientific community to shift its attention towards the use of environmentally benign materials for reducing the environmental impact of conventional synthetic plastics. Biopolymers are environmentally benign, chemically versatile, sustainable, biocompatible, biodegradable, inherently functional, and ecofriendly materials that exhibit tremendous potential for a wide range of applications including food, electronics, agriculture, textile, biomedical, and cosmetics. This review also inspires the researchers toward more consumption of biopolymer-based composite materials as an alternative to synthetic composite materials. Herein, an overview of the latest knowledge of different natural- and synthetic-based biodegradable polymers and their fiber-reinforced composites is presented. The review discusses different degradation mechanisms of biopolymer-based composites as well as their sustainability aspects. This review also elucidates current challenges, future opportunities, and emerging applications of biopolymeric sustainable composites in numerous engineering fields. Finally, this review proposes biopolymeric sustainable materials as a propitious solution to the contemporary environmental crisis. © 2022 Elsevier Ltd.

State-of-the-art review of advanced electrospun nanofiber yarn-based textiles for biomedical applications.

The pandemic of the coronavirus disease 2019 (COVID-19) has made biotextiles, including face masks and protective clothing, quite familiar in our daily lives. Biotextiles are one broad category of textile products that are beyond our imagination. Currently, biotextiles have been routinely utilized in various biomedical fields, like daily protection, wound healing, tissue regeneration, drug delivery, and sensing, to improve the health and medical conditions of individuals. However, these biotextiles are commonly manufactured with fibers with diameters on the micrometer scale (> 10 µm). Recently, nanofibrous materials have aroused extensive attention in the fields of fiber science and textile engineering because the fibers with nanoscale diameters exhibited obviously superior performances, such as size and surface/interface effects as well as optical, electrical, mechanical, and biological properties, compared to microfibers. A combination of innovative electrospinning techniques and traditional textile-forming strategies opens a new window for the generation of nanofibrous biotextiles to renew and update traditional microfibrous biotextiles. In the last two decades, the conventional electrospinning device has been widely modified to generate nanofiber yarns (NYs) with the fiber diameters less than 1000 nm. The electrospun NYs can be further employed as the primary processing unit for manufacturing a new generation of nano-textiles using various textile-forming strategies. In this review, starting from the basic information of conventional electrospinning techniques, we summarize the innovative electrospinning strategies for NY fabrication and critically discuss their advantages and limitations. This review further covers the progress in the construction of electrospun NY-based nanotextiles and their recent applications in biomedical fields, mainly including surgical sutures, various scaffolds and implants for tissue engineering, smart wearable bioelectronics, and their current and potential applications in the COVID-19 pandemic. At the end, this review highlights and identifies the future needs and opportunities of electrospun NYs and NY-based nanotextiles for clinical use.

Vinyl bag cover method to avoid droplet-containing aerosol escape from endoscopic forceps channel caps during COVID-19 pandemic (with Video 1 and Video 2).

Endoscopists are at high risk of allowing transmission of coronavirus disease 2019 (COVID-19) during gastrointestinal endoscopy (GIE) procedures under pandemic conditions. The main avenues of droplet-containing aerosol generated during GIE are the mouth, anus, and endoscopic forceps channel. Although the usefulness of personal protective equipment for preventing COVID-19 dissemination has been well reported, measures to address infected aerosol escaping during endoscopic forceps use have been neglected. Pathogen-contaminated aerosol from the endoscopic forceps channel, leading into the gastrointestinal lumen, has been confirmed and is a highly problematic source of infection. We developed a technique that entails covering the forceps entry/exit hole with a vinyl bag, thereby preventing contamination of the endoscopy room by the infected aerosol that escapes from this hole. The technique can be used in daily clinical endoscopic practice. Furthermore, this shielding technique is useful for all patients who undergo GIE, regardless of the purpose of the procedure such as for making a diagnosis, administering therapy, or in an urgent situation. In this letter, we introduce our novel, easily performed, inexpensive method of infection prevention by disallowing infected aerosol to escape from a COVID-19-infected patient into the air during a procedure that requires the use of endoscopic forceps.

SiO2-Ag Composite as a Highly Virucidal Material: A Roadmap that Rapidly Eliminates SARS-CoV-2.

COVID-19, as the cause of a global pandemic, has resulted in lockdowns all over the world since early 2020. Both theoretical and experimental efforts are being made to find an effective treatment to suppress the virus, constituting the forefront of current global safety concerns and a significant burden on global economies. The development of innovative materials able to prevent the transmission, spread, and entry of COVID-19 pathogens into the human body is currently in the spotlight. The synthesis of these materials is, therefore, gaining momentum, as methods providing nontoxic and environmentally friendly procedures are in high demand. Here, a highly virucidal material constructed from SiO2-Ag composite immobilized in a polymeric matrix (ethyl vinyl acetate) is presented. The experimental results indicated that the as-fabricated samples exhibited high antibacterial activity towards Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as well as towards SARS-CoV-2. Based on the present results and radical scavenger experiments, we propose a possible mechanism to explain the enhancement of the biocidal activity. In the presence of O2 and H2O, the plasmon-assisted surface mechanism is the major reaction channel generating reactive oxygen species (ROS). We believe that the present strategy based on the plasmonic effect would be a significant contribution to the design and preparation of efficient biocidal materials. This fundamental research is a precedent for the design and application of adequate technology to the next-generation of antiviral surfaces to combat SARS-CoV-2.

Nickel-Catalyzed Asymmetric Synthesis of α-Arylbenzamides.

A nickel-catalyzed asymmetric reductive hydroarylation of vinyl amides to produce enantioenriched α-arylbenzamides is reported. The use of a chiral bisimidazoline (BIm) ligand, in combination with diethoxymethylsilane and aryl halides, enables the regioselective introduction of aryl groups to the internal position of the olefin, forging a new stereogenic center α to the N atom. The use of neutral reagents and mild reaction conditions provides simple access to pharmacologically relevant motifs present in anticancer, SARS-CoV PLpro inhibitors, and KCNQ channel openers.