Packaging Covered with Antiviral and Antibacterial Coatings Based on ZnO Nanoparticles Supplemented with Geraniol and Carvacrol

The Influence of Zinc Oxide and Zinc Stearate on the Antimicrobial Activity of Coatings Containing Raspberry and Chokeberry Extracts

The goal of this research was to analyse the synergistic effect between selected plant extracts with zinc oxide particles, and zinc stearate. The influence of ZnO on the antimicrobial effectiveness of the selected extracts was confirmed in previous research carried out by the authors. However, the impact of zinc stearate on extract activity has yet to be analysed. The aim was to cover PLA films with active coatings based on hydroxy-propyl-methyl-cellulose (HPMC), or/and ethyl cellulose (EC) containing plant extracts and ZnO which has a synergistic effect. An additional aim was to use a CO2 extract of raspberry seed (RSE) with zinc stearate as active additives within the coatings. An examination of the antimicrobial properties (against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas syringae and Φ6 bacteriophage) of the covered films, as well as an investigation of layer presence with regards to PLA morphology (SEM, ATR-FTIR analysis) was carried out. The research work that was performed indicated that black chokeberry extract (ChE) and zinc oxide particles were effective against S. aureus, P. syringae and B. subtilis strains. In addition, the ChE with zinc stearate (ZnSt) was active against all analysed strains. The HPMC with ChE and ZnO as additives had antimicrobial properties against S. aureus, P. syringae and E. coli strains. The ChE was found to inhibit the growth of all of the analysed bacterial strains. When considering the coatings based on EC with the CO2 extract of raspberry seed (RSE) and ZnO, it was noted that they were only active against Gram-negative bacteria. The results of the experiments confirmed that AC1 (EC with RSE with ZnO) and AC2 (EC with RSE with ZnSt) coatings were not active against a phi6 bacteriophage. The HPMC coating containing the AC3 layer (ChE and ZnO) eliminated Φ6 particles, confirming its antiviral properties. In addition, the presence of the active (AC1, AC2 and AC3) coatings was confirmed by SEM and FTIR analysis.

Cast Extruded Films Based on Polyhydroxyalkanoate/Poly(lactic acid) Blend with Herbal Extracts Hybridized with Zinc Oxide

The aim of the presented work was to functionalize a blend based on polyhydroxyalkanoate (PHA): poly(hydroxybutyrate (PHB) with poly(lactic acid) (PLA) and a mixture of three selected herb extracts, namely, Hypericum L., Urtica L. and Chelidonium L., (E), zinc oxide (ZnO) and a combined system (EZnO), produced via extrusion. Before processing with bioresin, the natural modifiers were characterized using thermal analysis, FTIR and antimicrobial tests. The results revealed interactions between the extracts and the filler, leading to higher thermal stability in EZnO than when using E alone. Moreover, the mixture of extracts exhibited antimicrobial properties toward both Gram-negative (S. aureus) as well as Gram-positive bacteria (E. coli). Modified regranulates were transformed into films by cast extrusion. The influence of the additives on thermal (DSC, TGA and OIT), mechanical, barrier (WVTR and OTR), morphological (FTIR) and optical properties was investigated. The EZnO additive had the highest impact on the mechanical, barrier (OTR and WVTR) and optical properties of the bioresin. The microbial test results revealed that PHA-EZnO exhibited higher activity than PHA-ZnO and PHA-E and also reduced the number of S. aureus, E. coli and C. albicans cells. The findings confirmed the synergistic effect between the additive components. Modified polyester films did not eliminate the phi6 bacteriophage particles completely, but they did decrease their number, confirming moderate antiviral effectiveness.

The Influence of Functional Composite Coatings on the Properties of Polyester Films before and after Accelerated UV Aging

The aim of this study was to cover biopolymeric packaging films based on PLA/PHBV blend with a functional composite coating (to retain their ecological character) and to investigate their antimicrobial properties before and after UV irradiation. As an active coating, the carrier hydroxypropyl methyl cellulose (HPMC), as well as its modified form with Achillea millefolium L., Hippophae rhamnoides L., and Hypericum L. extract (E) and a combined system based on the extracts and nano-ZnO (EZ), was used to obtain active formulations. Additionally, film surface morphology (SEM, FTIR-ATR) and color (CIELab scale) analysis of the pre- and post-UV-treatment samples were performed. The results confirmed that the E and EZ-modified films exhibited antibacterial properties, but they were not effective against phage phi6. Q-SUN irradiation led to a decrease in the activity of E coating against Staphylococcus aureus, Pseudomonas syringae, and Candida albicans. In this case, the effectiveness of EZ against C. albicans at 24 h and 72 h UV irradiation decreased. However, the irradiation boosted the antiviral effectiveness of the EZ layer. SEM micrographs of the film surface showed that UV treatment did not significantly influence the native film morphology, but it had an impact on the coated film. FTIR analysis results showed that the coatings based on HPMC altered the IR absorption of the nonpolar groups of the biopolyester material. The applied coatings only marginally affected film color changes and increased their yellowness after UV irradiation, whereas a composite layer of nano-ZnO limited these changes.

Poly-(lactic acid) composite films comprising carvacrol and cellulose nanocrystal-zinc oxide with synergistic antibacterial effects

Herein, carvacrol (CRV) and modified cellulose nanocrystal-zinc oxide (CNC-ZnO) were incorporated into a poly (lactic acid) (PLA) matrix to prepare a PLA-based composite film using a simple solution casting method to achieve antimicrobial effects for application in antimicrobial food packaging. Compared with films obtained from neat PLA, the PLA@CRV20%@CNC-ZnO3% composite film shows better performance in terms of mechanical properties, ultraviolet (UV) blocking, and antimicrobial effects. The PLA composites containing CRV and 3 wt% CNC-ZnO blends exhibit improved tensile strength (21.8 MPa) and elongation at break (403.1 %) as well as excellent UV resistance. In particular, CRV and the CNC-ZnO hybrid endow the obtained PLA composite films with a synergistic antibacterial effect, resulting in good antibacterial properties for microbes, such as Escherichia coli, Staphylococcus aureus and Aspergillus niger. The diameters of the inhibition zone of the PLA@CRV20%@CNC-ZnO3% composite films against E. coli, S. aureus, and A. niger were 4.9, 5.0, and 3.4 cm, respectively. Appling the PLA@CRV20%@CNC-ZnO3% composite film as an antibacterial food packaging material, the storage period for strawberries was considerably extended. This study provides a theoretical basis for developing new organic/inorganic composite antimicrobial film materials from PLA.

Optimizing Antimicrobial Efficacy: Investigating the Impact of Zinc Oxide Nanoparticle Shape and Size

Zinc oxide nanoparticles (ZnO NPs) have been investigated due to their distinct properties, variety of structures and sizes, and mainly for their antimicrobial activity. They have received a positive safety evaluation from the European Food Safety Authority (EFSA) for packaging applications as transparent ultraviolet (UV) light absorbers based on the absence of significant migration of zinc oxide in particulate form. ZnO NPs with different morphologies (spherical, flower, and sheet) have been synthesized via different sol-gel methods and extensively characterized by several solid-state techniques, namely vibrational spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), Fourier Transform Infrared Spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-VIS), electron paramagnetic resonance (EPR), and nitrogen adsorption-desorption isotherms. The ZnO NPs were assessed for their antibacterial activity against Escherichia coli (gram-negative bacteria) and Staphylococcus aureus (gram-positive bacteria) to study the influence of morphology and size on efficacy. ZnO NPs with different morphologies and sizes demonstrated antimicrobial activity against both bacteria. The highest microbial cell reduction rate (7-8 log CFU mL-1 for E. coli and 6-7 log CFU mL-1 for S. aureus) was obtained for the sheet- and spherical-shaped NPs as a result of the high specific surface area. In fact, the higher surface areas of the sheet- and spherical-shaped nanoparticles (18.5 and 13.4 m2 g-1, respectively), compared to the flower-shaped NPs (5.3 m2g-1), seem to promote more efficient bacterial cell reduction. The spherical-shaped particles were also smaller (31 nm) compared with the flower-shaped (233 × 249 nm) ones. The flower ZnO NP resulted in a 4-5 log CFU mL-1 reduction for E. coli and 3-4 log CFU mL-1 reduction for S. aureus. The lower apparent antibacterial activity of the flower-shaped could be associated with either the lack of defects on the particle core or the shape shielding effect. Compared to S. aureus, E. coli seems to be less resistant to ZnO NPs, which may be explained by the characteristics of its cell membrane. With simple synthesis techniques, which do not allow the size and shape of the nanoparticles to be controlled simultaneously, it is a challenge to elucidate the effect of each of these two parameters on antibacterial performance.

ZnO based 0-3D diverse nano-architectures, films and coatings for biomedical applications

Thin-film nano-architecting is a promising approach that controls the properties of nanoscale surfaces to increase their interdisciplinary applications in a variety of fields. In this context, zinc oxide (ZnO)-based various nano-architectures (0-3D) such as quantum dots, nanorods/nanotubes, nanothin films, tetrapods, nanoflowers, hollow structures, etc. have been extensively researched by the scientific community in the past decade. Owing to its unique surface charge transport properties, optoelectronic properties and reported biomedical applications, ZnO has been considered as one of the most important futuristic bio-nanomaterials. This review is focused on the design/synthesis and engineering of 0-3D nano-architecture ZnO-based thin films and coatings with tunable characteristics for multifunctional biomedical applications. Although ZnO has been extensively researched, ZnO thin films composed of 0-3D nanoarchitectures with promising thin film device bio-nanotechnology applications have rarely been reviewed. The current review focuses on important details about the technologies used to make ZnO-based thin films, as well as the customization of properties related to bioactivities, characterization, and device fabrication for modern biomedical uses that are relevant. It features biosensing, tissue engineering/wound healing, antibacterial, antiviral, and anticancer activity, as well as biomedical diagnosis and therapy with an emphasis on a better understanding of the mechanisms of action. Eventually, key issues, experimental parameters and factors, open challenges, etc. in thin film device fabrications and applications, and future prospects will be discussed, followed by a summary and conclusion.

Inactivation of Bacteriophage ɸ6 and SARS-CoV-2 in Antimicrobial Surface Tests

Due to the COVID-19 pandemic, researchers have focused on new preventive measures to limit the spread of SARS-CoV-2. One promising application is the usage of antimicrobial materials on often-touched surfaces to reduce the load of infectious virus particles. Since tests with in vitro-propagated SARS-CoV-2 require biosafety level 3 (BSL-3) laboratories with limited capacities and high costs, experiments with an appropriate surrogate like the bacteriophage ɸ6 are preferred in most studies. The aim of this study was to compare ɸ6 and SARS-CoV-2 within antiviral surface tests. Different concentrations of copper coatings on polyethylene terephthalate (PET) were used to determine their neutralizing activity against ɸ6 and SARS-CoV-2. The incubation on the different specimens led to similar inactivation of both SARS-CoV-2 and ɸ6. After 24 h, no infectious virus particles were evident on any of the tested samples. Shorter incubation periods on specimens with high copper concentrations also showed a complete inactivation. In contrast, the uncoated PET foils resulted only in a negligible reduced inactivation during the one-hour incubation. The similar reduction rate for ɸ6 and SARS-CoV-2 in our experiments provide further evidence that the bacteriophage ɸ6 is an adequate model organism for SARS-CoV-2 for this type of testing.

Copper(II) and Cobalt(II) Complexes Based on Abietate Ligands from Pinus Resin: Synthesis, Characterization and Their Antibacterial and Antiviral Activity against SARS-CoV-2

Co-abietate and Cu-abietate complexes were obtained by a low-cost and eco-friendly route. The synthesis process used Pinus elliottii resin and an aqueous solution of CuSO₄/CoSO₄ at a mild temperature (80 °C) without organic solvents. The obtained complexes are functional pigments for commercial architectural paints with antipathogenic activity. The pigments were characterized by Fourier-transform infrared spectroscopy (FTIR), mass spectrometry (MS), thermogravimetry (TG), near-edge X-ray absorption fine structure (NEXAFS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and colorimetric analysis. In addition, the antibacterial efficiency was evaluated using the minimum inhibitory concentration (MIC) test, and the antiviral tests followed an adaptation of the ISO 21702:2019 guideline. Finally, virus inactivation was measured using the RT-PCR protocol using 10% (w/w) of abietate complex in commercial white paint. The Co-abietate and Cu-abietate showed inactivation of >4 log against SARS-CoV-2 and a MIC value of 4.50 µg·mL^-1 against both bacteria Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The results suggest that the obtained Co-abietate and Cu-abietate complexes could be applied as pigments in architectural paints for healthcare centers, homes, and public places.

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.

The COVID-19 pandemic redefining the mundane food packaging material industry?

COVID-19 pandemic has been the talk of the globe, as it swept across the world population, changing enumerable aspects. The pandemic affected all sectors directly or indirectly. The food sector took a direct hit. The food packaging sector rose to the occasion to serve and feed the pandemic affected, but there were interactions, reactions, and consequences that evolved through the course of the journey through the pandemic. The aim of this perspective is to address the importance of the food packaging industry (from the COVID-19 point of view) and to highlight the unpreparedness of the food packaging materials, for times as these. As the world has been asked to learn to live with Corona, improvisations are definitely necessary, the lapses in the system need to be rectified, and the entire packaging industry has to go through fortification to co-exist with Corona or confront something worse than Corona. This discussion is set out to understand the gravity of the actual situation, assimilating information available from the scattered shreds of reports. Food packaging materials were used, and plastic wastes were generated in bulks, single-use plastics for fear of contamination gained prominence, leading to an enormous turnover of wastes. Fear of Corona, sprayed overloads of sanitizers and disinfectants on food package material surfaces for surface sterilization. The food packages were tailored for food containment needs, never were they planned for sanitizer sprays. The consequences of these sanitization procedures are unprecedented, neglected and in the post-COVID-19 phase no action appears to have been taken. Corona took us by surprise this time, but next time atleast the food packaging industry needs to be fully equipped. Speculated consequences have been reviewed and plausible suggestions have been proposed. The need for extensive research focus in this direction in exploring the ground-reality has been highlighted.

Colloidal Solutions as Advanced Coatings for Active Packaging Development: Focus on PLA Systems

Due to rising consumer demand the food packaging industry is turning increasingly to packaging materials that offer active functions. This is achieved by incorporating active compounds into the basic packaging materials. However, it is currently believed that adding active compounds as a coating over the base packaging material is more beneficial than adding them in bulk or in pouches, as this helps to maintain the physicochemical properties of the base material along with higher efficiency at the interface with the food. Colloidal systems have the potential to be used as active coatings, while the application of coatings in the form of colloidal dispersions allows for prolonged and controlled release of the active ingredient and uniform distribution, due to their colloidal/nano size and large surface area ratio. The objective of this review is to analyse some of the different colloidal solutions previously used in the literature as coatings for active food packaging and their advantages. The focus is on natural bio-based substances and packaging materials such as PLA, due to consumer awareness and environmental and regulatory issues. The antiviral concept through the surface is also discussed briefly, as it is an important strategy in the context of the current pandemic crisis and cross-infection prevention.

Breathing-Driven Self-Powered Pyroelectric ZnO Integrated Face Mask for Bioprotection

Rapid spread of infectious diseases is a global threat and has an adverse impact on human health, livelihood, and economic stability, as manifested in the ongoing coronavirus disease 2019 (COVID-19) pandemic. Even though people wear a face mask as protective equipment, direct disinfection of the pathogens is barely feasible, which thereby urges the development of biocidal agents. Meanwhile, repetitive respiration generates temperature variation wherein the heat is regrettably wasted. Herein, a biocidal ZnO nanorod-modified paper (ZNR-paper) composite that is 1) integrated on a face mask, 2) harvests waste breathing-driven thermal energy, 3) facilitates the pyrocatalytic production of reactive oxygen species (ROS), and ultimately 4) exhibits antibacterial and antiviral performance is proposed. Furthermore, in situ generated compressive/tensile strain of the composite by being attached to a curved mask is investigated for high pyroelectricity. The anisotropic ZNR distortion in the bent composite is verified with changes in ZnO bond lengths and OZnO bond angles in a ZnO₄ tetrahedron, resulting in an increased polarization state and possibly contributing to the following pyroelectricity. The enhanced pyroelectric behavior is demonstrated by efficient ROS production and notable bioprotection. This study exploring the pre-strain effect on the pyroelectricity of ZNR-paper might provide new insights into the piezo-/pyroelectric material-based applications.

Nano-antivirals: A comprehensive review

Nanoparticles can be used as inhibitory agents against various microorganisms, including bacteria, algae, archaea, fungi, and a huge class of viruses. The mechanism of action includes inhibiting the function of the cell membrane/stopping the synthesis of the cell membrane, disturbing the transduction of energy, producing toxic reactive oxygen species (ROS), and inhibiting or reducing RNA and DNA production. Various nanomaterials, including different metallic, silicon, and carbon-based nanomaterials and nanoarchitectures, have been successfully used against different viruses. Recent research strongly agrees that these nanoarchitecture-based virucidal materials (nano-antivirals) have shown activity in the solid state. Therefore, they are very useful in the development of several products, such as fabric and high-touch surfaces. This review thoroughly and critically identifies recently developed nano-antivirals and their products, nano-antiviral deposition methods on various substrates, and possible mechanisms of action. By considering the commercial viability of nano-antivirals, recommendations are made to develop scalable and sustainable nano-antiviral products with contact-killing properties.

Antiviral Properties against SARS-CoV-2 of Nanostructured ZnO Obtained by Green Combustion Synthesis and Coated in Waterborne Acrylic Coatings

The COVID-19 pandemic has increased the need for developing disinfectant surfaces as well as reducing the spread of infections on contaminated surfaces and the contamination risk from the fomite route. The present work reports on the antiviral activity of coatings containing ZnO particles obtained by two simple synthesis routes using Aloe vera (ZnO-aloe) or cassava starch (ZnO-starch) as reaction fuel. After detailed characterization using XRD and NEXAFS, the obtained ZnO particles were dispersed in a proportion of 10% with two different waterborne acrylic coatings (binder and commercial white paint) and brushed on the surface of polycarbonates (PC). The cured ZnO/coatings were characterized by scanning electron microscopes (SEM) and energy-dispersive X-ray spectroscopy (EDS). Wettability tests were performed. The virucidal activity of the ZnO particles dispersed in the waterborne acrylic coating was compared to a reference control sample (PC plates). According to RT-PCR results, the ZnO-aloe/coating displays the highest outcome for antiviral activity against SARS-CoV-2 using the acrylic binder, inactivating >99% of the virus after 24 h of contact relative to reference control.

Green-synthesized silver nanoparticle coating on paper for antibacterial and antiviral applications

The use of active packaging has attracted considerable attention over recent years to prevent and decrease the risk of bacterial and viral infection. Thus, this work aims to develop active packaging using a paper coated with green-synthesized silver nanoparticles (AgNPs). Effects of different silver nitrate (AgNO3) concentrations, viz. 50, 100, 150, and 200 mM (AgNPs-50, AgNPs-100, AgNPs-150, and AgNPs-200, respectively), on green synthesis of AgNPs and coated paper properties were investigated. A bio-reducing agent from mangosteen peel extract (ex-Garcinia mangostana (GM)) and citric acid as a crosslinking agent for a starch/polyvinyl alcohol matrix were also used in the synthetic process. The presence of AgNPs, ex-GM, and citric acid indicated the required synergistic antibacterial activities for gram-positive and gram-negative bacteria. The paper coated with AgNPs-150 showed complete inactivation of virus within 1 min. Water resistance and tensile strength of paper improved when being coated with AgNPs-150. The tensile strength of the coated paper was found to be in the same range as that of a common packaging paper. Result revealed that the obtained paper coated with AgNPs was proven to be effective in antibacterial and antiviral activities; hence, it could be used as an active packaging material for items that require manual handling by a number of people.

Passive antifouling and active self-disinfecting antiviral surfaces

Viruses pose a serious threat to human health and society in general, as virus infections are one of the main causes of morbidity and mortality. Till May 2022, over 513 million people around the world have been confirmed to be infected and more than 6.2 million have died due to SARS-CoV-2. Although the COVID-19 pandemic will be defeated in the near future, we are likely to face new viral threats in the coming years. One of the important instruments to protect from viruses are antiviral surfaces, which are essentially capable of limiting their spread. The formulation of the concept of antiviral surfaces is relatively new. In general, five types of mechanism directed against virus spread can be proposed for antiviral surfaces; involving: direct and indirect actions, receptor inactivation, photothermal effect, and antifouling behavior. All antiviral surfaces can be classified into two main types - passive and active. Passive antiviral surfaces are based on superhydrophobic coatings that are able to repel virus contaminated droplets. In turn, viruses can become biologically inert (e.g., blocked or destroyed) upon contact with active antiviral surfaces, as they contain antiviral agents: metal atoms, synthetic or natural polymers, and small molecules. The functionality of antiviral surfaces can be significantly improved with additional properties, such as temperature- or pH-responsivity, multifunctionality, non-specific action on different virus types, long-term application, high antiviral efficiency and self-cleaning.

Biogenic Synthesis of ZnO Nanoparticles and Their Application as Bioactive Agents: A Critical Overview

Zinc oxide is a safe material for humans, with high biocompatibility and negligible cytotoxicity. Interestingly, it shows exceptional antimicrobial activity against bacteria, viruses, fungi, etc., especially when reduced to the nanometer size. As it is easily understandable, thanks to its properties, it is at the forefront of safe antimicrobials in this pandemic era. Besides, in the view of the 2022 European Green Deal announced by the European Commission, even science and nanotechnology are moving towards “greener” approaches to the synthesis of nanoparticles. Among them, biogenic ZnO nanoparticles have been extensively studied for their biological applications and environmental remediation. Plants, algae, fungi, yeast, etc., (which are composed of naturally occurring biomolecules) play, in biogenic processes, an active role in the formation of nanoparticles with distinct shapes and sizes. The present review targets the biogenic synthesis of ZnO nanoparticles, with a specific focus on their bioactive properties and antimicrobial application.

Antiviral and Antibacterial Effect of Honey Enriched with Rubus spp. as a Functional Food with Enhanced Antioxidant Properties

The aim of this study was to investigate the effect of blackberry and raspberry fruits (1 and 4%) and leaves (0.5 and 1%) on the biological activities of rape honey. Honey and plant material extracts were analyzed regarding total phenolic, flavonoid, anthocyanin contents, HPTLC and HPLC polyphenol profiles, as well as antioxidant activity. The antiviral potential was analyzed against bacteriophage phi 6-a coronavirus surrogate-whereas antimicrobial was tested against S. aureus and E. coli. Blackberry extracts were more abundant in antioxidants than raspberry extracts, with better properties found for leaves than fruits and for cultivated rather than commercial plants. The addition of both Rubus plant additives significantly increased the antioxidant potential of honey by four-fold (for 4% fruits additive) to five-fold (for 1% of leaves). Honey with the addition of fruits possessed higher antiviral potential compared with raw rape honey (the highest for 4% of raspberry fruit and 1% of blackberry leaf additive). Honey enriched with Rubus materials showed higher antibacterial potential against S. aureus than rape honey and effectively inhibited S. aureus biofilm formation. To summarize, honey enriched with Rubus fruit or leaves are characterized by increased pro-health value and can be recommended as a novel functional food.

Metal and metal oxide-based antiviral nanoparticles: Properties, mechanisms of action, and applications

Certain types of metal-based nanoparticles are effective antiviral agents when used in their original form ("bare") or after their surfaces have been functionalized ("modified"), including those comprised of metals (e.g., silver) and metal oxides (e.g., zinc oxide, titanium dioxide, or iron dioxide). These nanoparticles can be prepared with different sizes, morphologies, surface chemistries, and charges, which leads to different antiviral activities. They can be used as aqueous dispersions or incorporated into composite materials, such as coatings or packaging materials. In this review, we provide an overview of the design, preparation, and characterization of metal-based nanoparticles. We then discuss their potential mechanisms of action against various kinds of viruses. Finally, the applications of some of the most common metal and metal oxide nanoparticles are discussed, including those fabricated from silver, zinc oxide, iron oxide, and titanium dioxide. In general, the major antiviral mechanisms of metal and metal oxide nanoparticles have been observed to be 1) attachment of nanoparticles to surface moieties of viral particles like spike glycoproteins, that disrupt viral attachment and uncoating in host cells; 2) generation of reactive oxygen species (ROS) that denature viral macromolecules such as nucleic acids, capsid proteins, and/or lipid envelopes; and 3) inactivation of viral glycoproteins by the disruption of the disulfide bonds of viral proteins. Several physicochemical properties of metal and metal oxide nanoparticles including size, shape, zeta potential, stability in physiological conditions, surface modification, and porosity can all impact the antiviral efficacy of the nanoparticles.

When Scent Becomes a Weapon—Plant Essential Oils as Potent Bioinsecticides

Crop protection still mostly relies on synthetic pesticides for crop pest control. However, the rationale for their continued use is shaded by the revealed adverse effects, such as relatively long environmental persistence that leads to water and soil contamination and retention of residues in food that brings high risks to human and animal health. As part of integrated pest management, biopesticides may provide crop protection, being eco-friendly and safe for humans and non-target organisms. Essential oils, complex mixtures of low-molecular-weight, highly volatile compounds, have been highlighted as major candidates for plant-derived bioinsecticides that are up to the sustainable biological standard. In this review, we screened the insecticidal activity of essential oils or their purified compounds, with focus given to their modes of action, along with the analyzed advantages and problems associated with their wider usage as plant-derived insecticides in agriculture.

Antiviral Characterization of Advanced Materials: Use of Bacteriophage Phi 6 as Surrogate of Enveloped Viruses Such as SARS-CoV-2

The bacteriophage phi 6 is a virus that belongs to a different Baltimore group than SARS-CoV-2 (group III instead of IV). However, it has a round-like shape and a lipid envelope like SARS-CoV-2, which render it very useful to be used as a surrogate of this infectious pathogen for biosafety reasons. Thus, recent antiviral studies have demonstrated that antiviral materials such as calcium alginate hydrogels, polyester-based fabrics coated with benzalkonium chloride (BAK), polyethylene terephthalate (PET) coated with BAK and polyester-based fabrics coated with cranberry extracts or solidified hand soap produce similar log reductions in viral titers of both types of enveloped viruses after similar viral contact times. Therefore, researchers with no access to biosafety level 3 facilities can perform antiviral tests of a broad range of biomaterials, composites, nanomaterials, nanocomposites, coatings and compounds against the bacteriophage phi 6 as a biosafe viral model of SARS-CoV-2. In fact, this bacteriophage has been used as a surrogate of SARS-CoV-2 to test a broad range of antiviral materials and compounds of different chemical natures (polymers, metals, alloys, ceramics, composites, etc.) and forms (films, coatings, nanomaterials, extracts, porous supports produced by additive manufacturing, etc.) during the current pandemic. Furthermore, this biosafe viral model has also been used as a surrogate of SARS-CoV-2 and other highly pathogenic enveloped viruses such as Ebola and influenza in a wide range of biotechnological applications.

Antiviral Biodegradable Food Packaging and Edible Coating Materials in the COVID-19 Era: A Mini-Review

With the onset of the COVID-19 pandemic in late 2019, and the catastrophe faced by the world in 2020, the food industry was one of the most affected industries. On the one hand, the pandemic-induced fear and lockdown in several countries increased the online delivery of food products, resulting in a drastic increase in single-use plastic packaging waste. On the other hand, several reports revealed the spread of the viral infection through food products and packaging. This significantly affected consumer behavior, which directly influenced the market dynamics of the food industry. Still, a complete recovery from this situation seems a while away, and there is a need to focus on a potential solution that can address both of these issues. Several biomaterials that possess antiviral activities, in addition to being natural and biodegradable, are being studied for food packaging applications. However, the research community has been ignorant of this aspect, as the focus has mainly been on antibacterial and antifungal activities for the enhancement of food shelf life. This review aims to cover the different perspectives of antiviral food packaging materials using established technology. It focuses on the basic principles of antiviral activity and its mechanisms. Furthermore, the antiviral activities of several nanomaterials, biopolymers, natural oils and extracts, polyphenolic compounds, etc., are discussed.

Zinc associated nanomaterials and their intervention in emerging respiratory viruses: Journey to the field of biomedicine and biomaterials

Respiratory viruses represent a severe public health risk worldwide, and the research contribution to tackle the current pandemic caused by the SARS-CoV-2 is one of the main targets among the scientific community. In this regard, experts from different fields have gathered to confront this catastrophic pandemic. This review illustrates how nanotechnology intervention could be valuable in solving this difficult situation, and the state of the art of Zn-based nanostructures are discussed in detail. For virus detection, learning from the experience of other respiratory viruses such as influenza, the potential use of Zn nanomaterials as suitable sensing platforms to recognize the S1 spike protein in SARS-CoV-2 are shown. Furthermore, a discussion about the antiviral mechanisms reported for ZnO nanostructures is included, which can help develop surface disinfectants and protective coatings. At the same time, the properties of Zn-based materials as supplements for reducing viral activity and the recovery of infected patients are illustrated. Within the scope of noble adjuvants to improve the immune response, the ZnO NPs properties as immunomodulators are explained, and potential prototypes of nanoengineered particles with metallic cations (like Zn2+) are suggested. Therefore, using Zn-associated nanomaterials from detection to disinfection, supplementation, and immunomodulation opens a wide area of opportunities to combat these emerging respiratory viruses. Finally, the attractive properties of these nanomaterials can be extrapolated to new clinical challenges.

Nanoparticles—Attractive Carriers of Antimicrobial Essential Oils

Microbial pathogens are the most prevalent cause of chronic infections and fatalities around the world. Antimicrobial agents including antibiotics have been frequently utilized in the treatment of infections due to their exceptional outcomes. However, their widespread use has resulted in the emergence of multidrug-resistant strains of bacteria, fungi, viruses, and parasites. Furthermore, due to inherent resistance to antimicrobial drugs and the host defence system, the advent of new infectious diseases, chronic infections, and the occurrence of biofilms pose a tougher challenge to the current treatment line. Essential oils (EOs) and their biologically and structurally diverse constituents provide a distinctive, inexhaustible, and novel source of antibacterial, antiviral, antifungal, and antiparasitic agents. However, due to their volatile nature, chemical susceptibility, and poor solubility, their development as antimicrobials is limited. Nanoparticles composed of biodegradable polymeric and inorganic materials have been studied extensively to overcome these limitations. Nanoparticles are being investigated as nanocarriers for antimicrobial delivery, antimicrobial coatings for food products, implantable devices, and medicinal materials in dressings and packaging materials due to their intrinsic capacity to overcome microbial resistance. Essential oil-loaded nanoparticles may offer the potential benefits of synergism in antimicrobial activity, high loading capacity, increased solubility, decreased volatility, chemical stability, and enhancement of the bioavailability and shelf life of EOs and their constituents. This review focuses on the potentiation of the antimicrobial activity of essential oils and their constituents in nanoparticulate delivery systems for a wide range of applications, such as food preservation, packaging, and alternative treatments for infectious diseases.

Polyethylene Films Containing Plant Extracts in the Polymer Matrix as Antibacterial and Antiviral Materials

Low density polyethylene (LDPE) films covered with active coatings containing mixtures of rosemary, raspberry, and pomegranate CO₂ extracts were found to be active against selected bacterial strains that may extend the shelf life of food products. The coatings also offer antiviral activity, due to their influence on the activity of Φ6 bacteriophage, selected as a surrogate for SARS-CoV-2 particles. The mixture of these extracts could be incorporated into a polymer matrix to obtain a foil with antibacterial and antiviral properties. The initial goal of this work was to obtain active LDPE films containing a mixture of CO₂ extracts of the aforementioned plants, incorporated into an LDPE matrix via an extrusion process. The second aim of this study was to demonstrate the antibacterial properties of the active films against Gram-positive and Gram-negative bacteria, and to determine the antiviral effect of the modified material on Φ6 bacteriophage. In addition, an analysis was made on the influence of the active mixture on the polymer physicochemical features, e.g., mechanical and thermal properties, as well as its color and transparency. The results of this research indicated that the LDPE film containing a mixture of raspberry, rosemary, and pomegranate CO₂ extracts incorporated into an LDPE matrix inhibited the growth of Staphylococcus aureus. This film was also found to be active against Bacillus subtilis. This modified film did not inhibit the growth of Escherichia coli and Pseudomonas syringae cells; however, their number decreased significantly. The LDPE active film was also found to be active against Φ6 particles, meaning that the film had antiviral properties. The incorporation of the mixture of CO₂ extracts into the polymer matrix affected its mechanical properties. It was observed that parameters describing mechanical properties decreased, although did not affect the transition of LDPE significantly. Additionally, the modified film exhibited barrier properties towards UV radiation. Modified PE/CO₂ extracts films could be applied as a functional food packaging material with antibacterial and antiviral properties.

Past and Current Progress in the Development of Antiviral/Antimicrobial Polymer Coating towards COVID-19 Prevention: A Review

The astonishing outbreak of SARS-CoV-2 coronavirus, known as COVID-19, has attracted numerous research interests, particularly regarding fabricating antimicrobial surface coatings. This initiative is aimed at overcoming and minimizing viral and bacterial transmission to the human. When contaminated droplets from an infected individual land onto common surfaces, SARS-CoV-2 coronavirus is able to survive on various surfaces for up to 9 days. Thus, the possibility of virus transmission increases after touching or being in contact with contaminated surfaces. Herein, we aim to provide overviews of various types of antiviral and antimicrobial coating agents, such as antimicrobial polymer-based coating, metal-based coating, functional nanomaterial, and nanocomposite-based coating. The action mode for each type of antimicrobial agent against pathogens is elaborated. In addition, surface properties of the designed antiviral and antimicrobial polymer coating with their influencing factors are discussed in this review. This paper also exhibits several techniques on surface modification to improve surface properties. Various developed research on the development of antiviral/antimicrobial polymer coating to curb the COVID-19 pandemic are also presented in this review.

Mixtures of Scutellaria baicalensis and Glycyrrhiza L. Extracts as Antibacterial and Antiviral Agents in Active Coatings

The aim of this study was to develop active packaging materials covered in active coatings (offering antibacterial and antiviral properties) that contain selected plant extracts. In addition, the synergistic effect of the active substances in these extracts was also analysed. The results of the study demonstrated that Scutellaria baicalensis and Glycyrrhiza L. extracts (two of six analysed plant extracts) were the most active agents against selected Gram-positive and Gram-negative bacterial strains. Additionally, the synergistic effect of S. baicalensis and Glycyrrhiza L. extracts was noted, meaning that the effect of these two plant extract mixtures on Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas syringae growth was higher than the activity of individual pure extracts. Mixtures of the extracts were introduced into the coating carrier. A polyethylene (PE) foil was then coated with active layers containing mixtures of S. baicalensis and Glycyrrhiza L. extracts as antimicrobial agents. The results of this research showed that all of the active coatings had a bacteriolytic effect on B. subtilis and a bacteriostatic effect on S. aureus cells. The coatings were found to be inactive against E. coli and P. syringae cells. This means that the coatings could be used as internal coatings to preserve food products against Gram-positive bacteria that may be responsible for food spoilage. The results of this study also demonstrated that the coatings were highly active against phage phi 6 phage particles, used as SARS-CoV-2 surrogate. This means that the coatings could be used as external coatings to limit the spread of SARS-CoV-2 and pathogenic Gram-positive bacteria via human hands.

Polyethylene Films Coated with Antibacterial and Antiviral Layers Based on CO2 Extracts of Raspberry Seeds, of Pomegranate Seeds and of Rosemary

The main goal of the work was to create an internal coating based on super critical CO2 extracts of raspberry seeds, pomegranate seeds and rosemary that could be active against chosen bacterial strains. Additionally, the synergistic effect of these substances in the coating were then analysed. The next goal of the work was to demonstrate the antiviral activity of the coatings against phi6 bacteriophage particles (airborne viruses surrogate). The results of the study indicated that three coatings containing a mixture of extracts showed bacteriolytic activity against S. aureus cells and bacteriostatic activity against E. coli and B. subtilis strains. Two coatings showed bacteriolytic activity against a P. syringae strain. As a result of the experiments, a synergistic effect was noted in the active additives/compounds in the coatings. These coatings may be used as internal coatings for packaging films to extend the shelf life of selected food products. All seven coatings may also be used as external coatings with antiviral activity, as these coatings demonstrated significant effects on the phi6 phage, selected as a surrogate for airborne viruses, e.g., coronaviruses. It could be concluded that coatings I–VII will also show antiviral effects on SARS-CoV-2 particles.

Zn-based physiometacomposite nanoparticles: distribution, tolerance, imaging, and antiviral and anticancer activity

The aim of this study was to investigate the distribution, tolerance, and anticancer and antiviral activity of Zn-based physiometacomposites (PMCs). Manganese, iron, nickel and cobalt-doped ZnO, ZnS or ZnSe were synthesized. Cell uptake, distribution into 3D culture and mice, and biochemical and chemotherapeutic activity were studied by fluorescence/bioluminescence, confocal microscopy, flow cytometry, viability, antitumor and virus titer assays. Luminescence and inductively coupled plasma mass spectrometry analysis showed that nanoparticle distribution was liver >spleen >kidney >lung >brain, without tissue or blood pathology. Photophysical characterization as ex vivo tissue probes and LL37 peptide, antisense oligomer or aptamer delivery targeting RAS/Ras binding domain (RBD) was investigated. Treatment at 25 μg/ml for 48 h showed ≥98-99% cell viability, 3D organoid uptake, 3-log inhibition of β-Galactosidase and porcine reproductive respiratory virus infection. Data support the preclinical development of PMCs for imaging and delivery targeting cancer and infectious disease.

Gallic Acid Based Black Tea Extract as a Stabilizing Agent in ZnO Particles Green Synthesis

In this work, zinc oxide particles (ZnO NPs) green synthesis with the application of black tea extract (BT) is presented. A thorough investigation of the properties of the extract and the obtained materials was conducted by using Fourier transform infrared spectroscopy (FTIR), liquid chromatography-mass spectrometry (LC-MS), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and quadrupole mass spectroscopy (QMS). The obtained results indicated that the amount of used BT strongly influenced the morphology, chemical, and crystalline structure of the obtained particles. The investigation demonstrated that the substance present in black tea (BT) extract, which was adsorbed on the ZnO surface, was in fact gallic acid. It was found that gallic acid controls the crystallization process of ZnO by temporarily blocking the zinc cations. Additionally, these organic molecules interact with the hydroxide group of the precipitant. This blocks the dehydration process stabilizing the zinc hydroxide forms and hinders its transformation into zinc oxide. Performed measurements indicated that obtained ZnO particles have great antioxidant and antimicrobial properties, which are significantly correlated with ZnO-gallic acid interactions.

Metal Nano/Microparticles for Bioapplications

Nano/micro particles are considered to be the most valuable and important functional materials in the field of materials science and engineering [...].