ZnO Nanostructures in Active Antibacterial Food Packaging: Preparation Methods, Antimicrobial Mechanisms, Safety Issues, Future Prospects, and Challenges

Exploring the Potential of Halotolerant Actinomycetes from Rann of Kutch, India: A Study on the Synthesis, Characterization, and Biomedical Applications of Silver Nanoparticles

A tremendous increase in the green synthesis of metallic nanoparticles has been noticed in the last decades, which is due to their unique properties at the nano dimension. The present research work deals with synthesis mediated by the actinomycete Streptomyces tendae of silver nanoparticles (AgNPs), isolated from Little and Greater Rann of Kutch, India. The confirmation of the formation of AgNPs by the actinomycetes was carried out by using a UV-Vis spectrophotometer where an absorbance peak was obtained at 420 nm. The X-ray diffraction pattern demonstrated five characteristic diffraction peaks indexed at the lattice plane (111), (200), (231), (222), and (220). Fourier transform infrared showed typical bands at 531 to 1635, 2111, and 3328 cm-1. Scanning electron microscopy shows that the spherical-shaped AgNPs particles have diameters in the range of 40 to 90 nm. The particle size analysis displayed the mean particle size of AgNPs in aqueous medium, which was about 55 nm (±27 nm), bearing a negative charge on their surfaces. The potential of the S. tendae-mediated synthesized AgNPs was evaluated for their antimicrobial, anti-methicillin-resistant Staphylococcus aureus (MRSA), anti-biofilm, and anti-oxidant activity. The maximum inhibitory effect was observed against Pseudomonas aeruginosa at (8 µg/mL), followed by Escherichia coli and Aspergillus niger at (32 µg/mL), and against Candida albicans (64 µg/mL), whereas Bacillus subtilis (128 µg/mL) and Staphylococcus aureus (256 µg/mL) were much less sensitive to AgNPs. The biosynthesized AgNPs displayed activity against MRSA, and the free radical scavenging activity was observed with an increase in the dosage of AgNPs from 25 to 200 µg/mL. AgNPs in combination with ampicillin displayed inhibition of the development of biofilm in Pseudomonas aeruginosa and Streptococcus pneumoniae at 98% and 83%, respectively. AgNPs were also successfully coated on the surface of cotton to prepare antimicrobial surgical cotton, which demonstrated inhibitory action against Bacillus subtilis (15 mm) and Escherichia coli (12 mm). The present research integrates microbiology, nanotechnology, and biomedical science to formulate environmentally friendly antimicrobial materials using halotolerant actinomycetes, evolving green nanotechnology in the biomedical field. Moreover, this study broadens the understanding of halotolerant actinomycetes and their potential and opens possibilities for formulating new antimicrobial products and therapies.

Extraction of Nanocellulose from the Residue of Sugarcane Bagasse Fiber for Anti-Staphylococcus aureus (S. aureus) Application

Nanocellulose contains a large number of hydroxyl groups that can be used to modify its surface due to its structure. Owing to its appealing features, such as high strength, great stiffness, and high surface area, nanocellulose is currently gaining popularity in research and industry. The extraction of nanocellulose from the leftover bagasse fiber from sugarcane production by alkaline and acid treatment was successful in this study, with a production yield of 55.6%. The FTIR and XPS results demonstrated a difference in the functional and chemical composition of untreated sugarcane bagasse and extracted nanocellulose. SEM imaging was used to examined the size of the nanocellulose with ImageJ software v1.8.0. TGA, DTG, and XRD analyses were also performed to demonstrate the successful extraction of nanocellulose in terms of its morphology, thermal stability, and crystal structure before and after extraction. The anti-S. aureus activity of the extracted nanocellulose was discovered by using an OD600 test and a colony counting method, and an inhibitory rate of 53.12% was achieved. According to the results, nanocellulose produced from residual sugarcane bagasse could be employed as an antibacterial agent.

Driving Role of Zinc Oxide Nanoparticles with Different Sizes and Hydrophobicity in Metabolic Response and Eco-Corona Formation in Sprouts (Vigna radiata)

Zinc oxide nanoparticles (ZnO NPs) cause biotoxicity and pose a potential ecological threat; however, their effects on plant metabolism and eco-corona evolution between NPs and organisms remain unclear. This study clarified the molecular mechanisms underlying physiological and metabolic responses induced by three different ZnO NPs with different sizes and hydrophobicity in sprouts (Vigna radiata) and explored the critical regulation of eco-corona formation in root-nano systems. Results indicated that smaller-sized ZnO inhibited root elongation by up to 37.14% and triggered oxidative burst and apoptosis. Metabolomics confirmed that physiological maintenance after n-ZnO exposure was mainly attributed to the effective stabilization of nitrogen fixation and defense systems by biotransformation of the flavonoid pathway. Larger-sized or hydrophobic group-modified ZnO exhibited low toxicity in sprouts, with 0.89-fold upregulation of citrate in central carbon metabolism. This contributed to providing energy for resistance to NP stress through amino acid and carbon/nitrogen metabolism, accompanied by changes in membrane properties. Notably, smaller-sized and hydrophobic NPs intensely stimulated the release of root metabolites, forming corona complexes with exudates. The hydrogen-bonded wrapping mechanism in protein secondary structure and hydrophobic interactions of heterogeneous functional groups drove eco-corona formation, along with the corona evolution intensity of n-ZnO > s-ZnO > b-ZnO based on higher (α-helix + 3-turn helix)/β-sheet ratios. This study provides crucial insight into metabolic and eco-corona evolution in bionano fates.

Chitosan-Based Films Blended with Tannic Acid and Moringa Oleifera for Application in Food Packaging: The Preservation of Strawberries (Fragaria ananassa)

Biobased plastics provide a sustainable alternative to conventional food packaging materials, thereby reducing the environmental impact. The present study investigated the effectiveness of chitosan with varying levels of Moringa oleifera seed powder (MOSP) and tannic acid (TA). Chitosan (CS) biocomposite films with tannic acid acted as a cross-linker, and Moringa oleifera seed powder served as reinforcement. To enhance food packaging and film performance, Moringa oleifera seed powder was introduced at various loadings of 1.0, 3.0, 5.0, and 10.0 wt.%. Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy analyses were performed to study the structure and morphology of the CS/TA/MOSP films. The scanning electron microscopy results confirmed that chitosan/TA with 10.0 wt.% of MOSP produced a lightly miscible droplet/matrix structure. Furthermore, mechanical properties, swelling, water solubility, optical barrier, and water contact angle properties of the film were also calculated. With increasing Moringa oleifera seed powder contents, the biocomposite films' antimicrobial and antifungal activity increased at the 10.0 wt.% MOSP level; all of the observed bacteria [Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Aspergillus niger (A. niger), and Candida albicans (C. albicans)] had a notably increased percentage of growth. The film, with 10.0 wt.% MOSP content, effectively preserves strawberries' freshness, making it an ideal food packaging material.

Low temperature synthesis of ZnO particles using a CO2-driven mechanism under high pressure

Low temperature synthesis of ZnO particles without using reactive materials, solvents and post-treatments is still a serious challenge for both fundamental research and industrial applications. In this research, we report the dry synthesis of ZnO particles only by using Zn(acac)2 and supercritical CO2 (scCO2) at the low temperature of 60 °C. The synthesis was performed using CO2 and N2 from 0.1 to 30.0 MPa for 18 h. As a result, ZnO yields increased with a rise in the CO2 pressure and reached 67% at 30.0 MPa while N2 medium gave low yields below 4.9% regardless of the pressure. Additionally, the detailed characterization results and the phase behavior observations evidentially showed the formation of zinc-CO/CO2-organic complexes in the solid phase of Zn(acac)2 powder under scCO2, resulting in the accelerated formation of ZnO particles. These findings suggest that scCO2 has potential value to drive the formation reaction of zinc-CO/CO2-organic complexes, which allows the low temperature synthesis of ZnO particles under dry conditions without using reactive materials, solvents and post-treatments.

A novel green preparation of zinc oxide nanoparticles with Hibiscus sabdariffa L.: photocatalytic performance, evaluation of antioxidant and antibacterial activity

This study investigates the eco-friendly synthesis of zinc oxide nanoparticles (ZnO NPs) utilizing an aqueous solution of Hibiscus sabdariffa L. flower extract, which is acts as reducing agent as well as capping agent. The Fourier transform infrared spectroscopy (FTIR) results revealed the presence of flavonoids and phenols in the plant extract, indicating that they were the major agents capable of reducing zinc nitrate salt. According to our x-ray diffraction (XRD) results, ZnO-NPs exhibit a particular phase wurtzite structure. The ZnO-NPs are spherical in shape and have an average size of 15 nm, according to the measurements of electron microscope (SEM) and transmission electron microscope (TEM) measurements. Energy dispersion (EDX) analysis demonstrates that the NPs are mainly composed of zinc and oxygen. The zeta potential of these nanoparticles shows that they are very stable. The antibacterial activity of ZnO-NPs was tested using agar dilutions with a variety of gram-positive and gram-negative microorganisms. According to the research results, ZnO-NPs can be established as an extremely specific antibacterial agent for a wide variety of organisms to prevent bacterial growth. Furthermore, the antioxidant properties of ZnO-NPs were determined using the 2,2 diphenyl-1-picrylhydrazyl hydrate (DPPH) radical scavenging approach, and the IC50 value of 38 μg/mL was measured for ZnO-NPs. Furthermore, the biosynthesized ZnO-NPs showed significant catalytic performance of methyl orange (MO) under UV irradiation. Overall, ZnO-NPs in their produced state have excellent potential in biomedical and wastewater treatment applications. Radical scavengers were used to evaluate the role of radicals in the reaction mechanism.

Sustainable polylactic acid spunlace nonwoven fabrics with lignin/zinc oxide/water-based polyurethane composite coatings

In this paper, polylactic acid spunlace nonwoven fabrics were coated with lignin/zinc oxide/water-based polyurethane composite formulations, including five different ratios of lignin and zinc oxide, via a film applicator and thermally cured. The coated and thermally cured nonwoven fabrics were tested in terms of color values, tensile strength, abrasion resistance, ultraviolet protection, hydrophobicity, antibacterial activity, air, and vapor permeability properties. Characterization studies were conducted by FTIR, DSC, TGA, XRD, and SEM. The ultraviolet protection factor of 215.47 and a water contact angle of 90.27° were obtained with the fabric coated with WPU-1:5 formulation. Nonwoven fabric coated with the WPU-1:5 formulation showed evident antibacterial activity against S. aureus and E. coli bacteria as 89 % and 100 %, respectively. With the addition of lignin/ZnO into water-based polyurethane coating paste, PLA nonwoven fabric exhibited improved antibacterial activity, tensile strength, abrasion resistance, and ultraviolet light protection performance. However, composite coatings decreased air and vapor permeability and hydrophobicity of fabrics, but acceptable results were obtained. The results indicate that polylactic acid nonwoven fabrics, when treated with lignin/ZnO/WPU composite coatings, exhibit enhanced mechanical and functional properties, rendering them promising for applications in protective medical textiles.

Advanced biopolymer-based edible coating technologies for food preservation and packaging

Along with the growth of the world's population that reduces the accessibility of arable land and water, demand for food, as the fundamental element of human beings, has been continuously increasing each day. This situation not only becomes a challenge for the modern food chain systems but also affects food availability throughout the world. Edible coating is expected to play a significant role in food preservation and packaging, where this technique can reduce the number of food loss and subsequently ensure more sustainable food and agriculture production through various mechanisms. This review provides comprehensive information related to the currently available advanced technologies of coating applications, which include advanced methods (i.e., nanoscale and multilayer coating methods) and advanced properties (i.e., active, self-healing, and super hydrophobic coating properties). Furthermore, the benefits and drawbacks of those technologies during their applications on foods are also discussed. For further research, opportunities are foreseen to develop robust edible coating methods by combining multiple advanced technologies for large-scale and more sustainable industrial production.

Antimicrobial activity of ZnO-Ag-MWCNTs nanocomposites prepared by a simple impregnation-calcination method

Zinc oxide (ZnO) nanorods and ZnO nanostructures composited with silver (Ag) and multi-walled carbon nanotubes (MWCNTs) have been synthesized by a simple impregnation-calcination method and have been shown to be suitable for use as antimicrobial agents. The preparation method used for composite materials is very simple, time-effective, and can be used for large-scale production. Several analytical techniques, including X-ray diffraction (XRD), scanning electron spectroscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and Fourier transmission infrared spectroscopy (FTIR), have been used to characterize the prepared ZnO-Ag-MWCNT composite materials. The effects on structural, morphological, and antimicrobial properties of (ZnO)100-x (Ag)x nanocomposites at various weight ratios (x = 0, 5, 10, 30, and 50 wt%) have been investigated. The antimicrobial properties of ZnO composited with Ag nanoparticles and MWCNTs towards both gram-positive and gram-negative bacteria species were studied. The effect of raw MWCNTs and MWCNTs composited with ZnO and Ag on the cell morphology and chemical composition of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) was studied by SEM and EDS, respectively. It was found that composite materials made of ZnO-Ag-MWCNTs exhibit greater antibacterial activities toward the microorganisms E. coli and S. aureus than ZnO-Ag, which could be beneficial for efficient antimicrobial agents in water and air treatment applications.

Innovations in Food Packaging for a Sustainable and Circular Economy

Packaging is fundamental to maintaining the quality of food, but its contribution with a negative footprint to the environment must be completely changed worldwide to reduce pollution and climate change. Innovative and sustainable packaging and new strategies of reutilization are necessary to reduce plastic waste accumulation, maintain food quality and safety, and reduce food losses and waste. The purpose of this chapter is to present innovations in food packaging for a sustainable and circular economy. First, to present the eco-design packaging approach as well as new strategies for recycled or recyclable materials in food packaging. Second, to show current trends in new packaging materials developed from the use of agro-industrial wastes as well as new methods of production, including 3D/4D printing, electrostatic spinning, and the use of nanomaterials.

Hybrid nanostructures exhibiting both photocatalytic and antibacterial activity-a review

The most vital issues of the modern world for a sustainable future are "health" and "the environment." Scientific endeavors to tackle these two major concerns for mankind need serious attention. The photocatalytic activity toward curbing environmental pollution and antibacterial performance toward a healthy society are two directions that have been emphasized for decades. Recently, materials engineering, in their nanodimension, has shown tremendous possibilities to integrate these functionalities within the same materials. In particular, hybrid nanostructures have shown magnificent prospects to combat both crucial challenges. Many researchers are separately engaged in this important field of research but the collective knowledge on this domain which can facilitate them to excel is badly missing. The present article integrates the development of different hybrid nanostructures which exhibit both photocatalytic degradations of environmental pollutants and antibacterial efficiency. Various synthesis techniques of those hybrid nanomaterials have been discussed. Hybrid nanosystems based on several successful materials have been categorically discussed for better insight into the research advancement in this direction. In particular, Ag-based, metal oxides-based, layered carbon material-based, and Mexene- and self-cleaning-based materials have been chosen for detailing their performance as anti-pollutant and antibacterial materials. Those hybrid systems along with some miscellaneous booming nanostructured materials have been discussed comprehensively with their success and limitations toward their bifunctionality as antipollutant and antibacterial agents.

Recent Advances in Sustainable Antimicrobial Food Packaging: Insights into Release Mechanisms, Design Strategies, and Applications in the Food Industry

In response to the issues of foodborne microbial contamination and carbon neutrality goals, sustainable antimicrobial food packaging (SAFP) composed of renewable or biodegradable biopolymer matrices with ecofriendly antimicrobial agents has emerged. SAFP offers longer effectiveness, wider coverage, more controllability, and better environmental performance. Analyzing SAFP information, including the release profile of each antimicrobial agent for each food, the interaction of each biomass matrix with each food, the material size, form, and preparation methods, and its service quality in real foods, is crucial. While encouraging reports exist, a comprehensive review summarizing these developments is lacking. Therefore, this review critically examines recent release-antimicrobial mechanisms, kinetics models, preparation methods, and key regulatory parameters for SAFPs based on slow- or controlled-release theory. Furthermore, it discusses fundamental physicochemical characteristics, effective concentrations, advantages, release approaches, and antimicrobial and preservative effects of various materials in food simulants or actual food. Lastly, inadequacies and future trends are explored, providing practical references to regulate the movement of active substances in different media, reduce the reliance on petrochemical-based materials, and advance food packaging and preservation technologies.

Chitosan-Based Antibacterial Films for Biomedical and Food Applications

Antibacterial chitosan films, versatile and eco-friendly materials, have garnered significant attention in both the food industry and medicine due to their unique properties, including biodegradability, biocompatibility, and antimicrobial activity. This review delves into the various types of chitosan films and their distinct applications. The categories of films discussed span from pure chitosan films to those enhanced with additives such as metal nanoparticles, metal oxide nanoparticles, graphene, fullerene and its derivatives, and plant extracts. Each type of film is examined in terms of its synthesis methods and unique properties, establishing a clear understanding of its potential utility. In the food industry, these films have shown promise in extending shelf life and maintaining food quality. In the medical field, they have been utilized for wound dressings, drug delivery systems, and as antibacterial coatings for medical devices. The review further suggests that the incorporation of different additives can significantly enhance the antibacterial properties of chitosan films. While the potential of antibacterial chitosan films is vast, the review underscores the need for future research focused on optimizing synthesis methods, understanding structure-property relationships, and rigorous evaluation of safety, biocompatibility, and long-term stability in real-world applications.

Various Applications of ZnO Thin Films Obtained by Chemical Routes in the Last Decade

This review addresses the importance of Zn for obtaining multifunctional materials with interesting properties by following certain preparation strategies: choosing the appropriate synthesis route, doping and co-doping of ZnO films to achieve conductive oxide materials with p- or n-type conductivity, and finally adding polymers in the oxide systems for piezoelectricity enhancement. We mainly followed the results of studies of the last ten years through chemical routes, especially by sol-gel and hydrothermal synthesis. Zinc is an essential element that has a special importance for developing multifunctional materials with various applications. ZnO can be used for the deposition of thin films or for obtaining mixed layers by combining ZnO with other oxides (ZnO-SnO₂, ZnO-CuO). Also, composite films can be achieved by mixing ZnO with polymers. It can be doped with metals (Li, Na, Mg, Al) or non-metals (B, N, P). Zn is easily incorporated in a matrix and therefore it can be used as a dopant for other oxidic materials, such as: ITO, CuO, BiFeO_3, and NiO. ZnO can be very useful as a seed layer, for good adherence of the main layer to the substrate, generating nucleation sites for nanowires growth. Thanks to its interesting properties, ZnO is a material with multiple applications in various fields: sensing technology, piezoelectric devices, transparent conductive oxides, solar cells, and photoluminescence applications. Its versatility is the main message of this review.

Updates on Biogenic Metallic and Metal Oxide Nanoparticles: Therapy, Drug Delivery and Cytotoxicity

The ambition to combat the issues affecting the environment and human health triggers the development of biosynthesis that incorporates the production of natural compounds by living organisms via eco-friendly nano assembly. Biosynthesized nanoparticles (NPs) have various pharmaceutical applications, such as tumoricidal, anti-inflammatory, antimicrobials, antiviral, etc. When combined, bio-nanotechnology and drug delivery give rise to the development of various pharmaceutics with site-specific biomedical applications. In this review, we have attempted to summarize in brief the types of renewable biological systems used for the biosynthesis of metallic and metal oxide NPs and the vital contribution of biogenic NPs as pharmaceutics and drug carriers simultaneously. The biosystem used for nano assembly further affects the morphology, size, shape, and structure of the produced nanomaterial. The toxicity of the biogenic NPs, because of their pharmacokinetic behavior in vitro and in vivo, is also discussed, together with some recent achievements towards enhanced biocompatibility, bioavailability, and reduced side effects. Because of the large biodiversity, the potential biomedical application of metal NPs produced via natural extracts in biogenic nanomedicine is yet to be explored.

Revolutionizing Food Safety with Quantum Dot-Polymer Nanocomposites: From Monitoring to Sensing Applications

The present review article investigates the prospective utilisation of quantum dot-polymer nanocomposites in the context of ensuring food safety. The text pertains to the advancement of nanocomposites, encompassing their distinctive optical and electrical characteristics, and their prospective to transform the detection and perception of food safety risks. The article explores diverse methodologies for producing nanocomposites and underscores their potential utility in identifying impurities, microorganisms, and harmful substances in food. The article provides an overview of the challenges and limitations associated with the utilisation of nanocomposites in food safety applications, encompassing concerns regarding toxicity and the necessity for standardised protocols. The review article presents a comprehensive examination of the present research status in this area and underscores the potential of quantum dots-polymer nanocomposites in transforming food safety monitoring and sensing.

Surface Photovoltage Response of ZnO to Phosphate-Buffered Saline Solution with and without Presence of Staphylococcus aureus

Nano- and microscale zinc oxide (ZnO) exhibits significant potential as a novel antibacterial agent in biomedical applications. However, the uncertainty regarding the underlying mechanisms of the observed antimicrobial action inhibits the realization of this potential. Particularly, the nature of interactions at the free crystalline surface and the influence of the local bacterial environment remains unclear. In this investigation, we utilize ZnO particles synthesized via tunable hydrothermal growth method as a platform to elucidate the effects of interactions with phosphate-rich environments and differentiate them from those with bacteria. This is achieved using the time- and energy-dependent surface photovoltage (SPV) to monitor modifications of the surface electronic structure and surface charge dynamics of the ZnO particles due to these interactions. It is found that there exists a dramatic change in the SPV transients after exposure to phosphate-rich environments. It also presents differences in the sub-bandgap surface electronic structure after these exposures. It can be suggested that these phenomena are a consequence of phosphate adsorption at surface traps corresponding to zinc deficiency defects. This effect is shown to be suppressed in the presence of Staphylococcus aureus bacteria. Our results support the previously proposed model of the competitive nature of interactions between S. aureus and aqueous phosphates with the free surface of ZnO and bring greater clarity to the effects of phosphate-rich environments on bacterial growth inhibition of ZnO.

Recent Advances in ZnO Nanomaterial-Mediated Biological Applications and Action Mechanisms

In recent years, with the deepening research, metal zinc oxide (ZnO) nanomaterials have become a popular research object in the biological field, particularly in biomedicine and food safety, which is attributed to their unique physicochemical properties such as high surface area and volume ratio, luminescence effect, surface characteristics and biological activities. Herein, this review provides a detailed overview of the ZnO nanomaterial-mediated biological applications that involve anti-bacterial, anti-tumor, anti-inflammation, skin care, biological imaging and food packaging applications. Importantly, the corresponding action mechanisms of ZnO nanomaterials are pointed. Additionally, the structure and structure-dependent physicochemical properties, the common synthesis methods and the biosafety of ZnO nanoparticles are revealed in brief. Finally, the significance and future challenges of ZnO nanomaterial applications are concluded.

Green Synthesis of Zinc Oxide Nanoparticles Using an Aqueous Extract of Punica granatum for Antimicrobial and Catalytic Activity

The peel aqueous extract of Punica granatum was utilized to fabricate zinc oxide nanoparticles (ZnO-NPs) as a green approach. The synthesized NPs were characterized by UV-Vis spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy, which was attached to an energy dispersive X-ray (SEM-EDX). Spherical, well arranged, and crystallographic structures of ZnO-NPs were formed with sizes of 10-45 nm. The biological activities of ZnO-NPs, including antimicrobial and catalytic activity for methylene blue dye, were assessed. Data analysis showed that the antimicrobial activity against pathogenic Gram-positive and Gram-negative bacteria, as well as unicellular fungi, was observed to occur in a dose-dependent manner, displaying varied inhibition zones and low minimum inhibitory concentration (MIC) values in the ranges of 6.25-12.5 µg mL^-1. The degradation efficacy of methylene blue (MB) using ZnO-NPs is dependent on nano-catalyst concentration, contact time, and incubation condition (UV-light emission). The maximum MB degradation percentages of 93.4 ± 0.2% was attained at 20 µg mL^-1 after 210 min in presence of UV-light. Data analysis showed that there is no significant difference between the degradation percentages after 210, 1440, and 1800 min. Moreover, the nano-catalyst showed high stability and efficacy to degrade MB for five cycles with decreasing values of 4%. Overall, P. granatum-based ZnO-NPs are promising tools to inhibit the growth of pathogenic microbes and degradation of MB in the presence of UV-light emission.

Glycine betaine capped ZnO NPs eliminate oxidative stress to coriander plants grown under NaCl presence

Salinity is one of the major abiotic stresses for sustainable agriculture. The use of mineral nutrients in form of nanoparticles can be a novel strategy to fight against abiotic stresses. An in vitro study has been conducted to investigate the effect of zinc oxide nanoparticles (ZnO NPs) capped with glycine betaine (ZnOBt) on coriander plants exposed to saline (NaCl) stress. SEM and XRD analysis revealed 14.73 nm and 17.34 nm size of ZnO and ZnOBt NPs, respectively with spherical to hexagonal structures. Coriander plant length and biomass increased by the application of ZnO and ZnOBt NPs. ZnOBt NPs depicted promising results at 100 mg/L where, shoot and root length increased up to 14 cm and 13 cm, respectively as compared to plants grown under saline stress. ZnOBt NPs also increased fresh and dry weight of shoots and roots as compared to other treatments. The results depict that ZnOBt NPs mitigated stress condition. This is evident from concentration of phenolic and flavonoid contents that decreased in both roots and shoots. Free radical scavenging activity, total antioxidant capacity and total reducing power also decreased in plants by ZnOBt NPs when applied with stress. The concentration of superoxide and peroxide dismutase also decreased by application of ZnOBt NPs to salt stress plants. Glycine betaine with ZnO NPs, in conclusion, can be an effective remedy for salinity-exposed plants. These nanoparticles can be encouraged as a viable technique to overcome the detrimental effects of saline stress on plants.

Macrocyclic Compounds: Metal Oxide Particles Nanocomposite Thin Films Deposited by MAPLE

Nanocomposite films based on macrocyclic compounds (zinc phthalocyanine (ZnPc) and 5,10,15,20-tetra(4-pyridyl) 21H,23H-porphyrin (TPyP)) and metal oxide nanoparticles (ZnO or CuO) were deposited by matrix-assisted pulsed laser evaporation (MAPLE). 1,4-dioxane was used as a solvent in the preparation of MAPLE targets that favor the deposition of films with a low roughness, which is a key feature for their integration in structures for optoelectronic applications. The influence of the addition of ZnO nanoparticles (~20 nm in size) or CuO nanoparticles (~5 nm in size) in the ZnPc:TPyP mixture and the impact of the added metal oxide amount on the properties of the obtained composite films were evaluated in comparison to a reference layer based only on an organic blend. Thus, in the case of nanocomposite films, the vibrational fingerprints of both organic compounds were identified in the infrared spectra, their specific strong absorption bands were observed in the UV-Vis spectra, and a quenching of the TPyP emission band was visible in the photoluminescence spectra. The morphological analysis evidenced agglomerated particles on the composite film surface, but their presence has no significant impact on the roughness of the MAPLE deposited layers. The current density-voltage (J-V) characteristics of the structures based on the nanocomposite films deposited by MAPLE revealed the critical role played by the layer composition and component ratio, an improvement in the electrical parameters values being achieved only for the films with a certain type and optimum amount of metal oxide nanoparticles.

Effect of Sublethal Concentrations of Zinc Oxide Nanoparticles on Bacillus cereus

Zinc oxide nanoparticles (ZnONPs), which are produced on a large scale, pose a potential threat to various environments because they can interact with the microbial populations found in them. Bacteria that are widespread in soil, water, and plant material include the Bacillus cereus group, which plays an important role in biodegradation and the nutrient cycle and is a major factor determining ecological balance. This group includes, among others, the foodborne pathogen B. cereus sensu stricto (herein referred to as B. cereus). The aim of this study was a comprehensive assessment of the effects of commercially available ZnONPs on B. cereus. The MIC (minimum inhibitory concentration) for B. cereus was 1.6 mg/mL, and the MBC (minimum bactericidal concentration) was 1.8 mg/mL. Growth of B. cereus was inhibited by a concentration of ZnONPs lower than or equal to MIC50. Concentrations from 0.2 to 0.8 mg/mL inhibited the growth of these bacteria in liquid media, induced symptoms of oxidative stress, and stimulated an environmental stress response in the form of biofilm and endospore formation. In addition, ZnONPs negatively affected the ability of the bacteria to break down the azo dye Evans Blue but enhanced the antimicrobial properties of phenolic compounds. Sublethal concentrations of ZnONPs generally decreased the activity of B. cereus cells, especially in the presence of phenolics, which indicates their potential toxicological impact, but at the same time they induced universal defence responses in these cells, which in the case of potential pathogens can hinder their removal.

Electrochemical Immunosensor for the Determination of Antibodies against Prostate-Specific Antigen Based on ZnO Nanostructures

In this study, ZnO nanostructures with different types of morphologies and particle sizes were evaluated and applied for the development of an immunosensor. The first material was composed of spherical, polydisperse nanostructures with a particle size in the range of 10–160 nm. The second was made up of more compact rod-like spherical nanostructures with the diameter of these rods in the range of 50–400 nm, and approximately 98% of the particles were in the range of 20–70 nm. The last sample of ZnO was made up of rod-shaped particles with a diameter of 10–80 nm. These ZnO nanostructures were mixed with Nafion solution and drop-casted onto screen-printed carbon electrodes (SPCE), followed by a further immobilization of the prostate-specific antigen (PSA). The affinity interaction of PSA with monoclonal antibodies against PSA (anti-PSA) was evaluated using the differential pulse voltammetry technique. The limit of detection and limit of quantification of anti-PSA were determined as 1.35 nM and 4.08 nM for compact rod-shaped spherical ZnO nanostructures, and 2.36 nM and 7.15 nM for rod-shaped ZnO nanostructures, respectively.

Advances in two-dimensional engineered nanomaterials applications for the agro- and food-industries

Two-dimensional nanomaterials, such as graphene, transition metal dichalcogenides, MXenes, and other layered compounds, are the subject of intense theoretical and experimental research for applications in a wide range of advanced technological solutions, given their outstanding physical, chemical, and mechanical properties. In the context of food science and technology, their contributions are starting to appear, based on the advantages that two-dimensional nanostructures offer to agricultural- and food-related key topics, such as sustainable water use, nano-agrochemicals, novel nanosensing devices, and smart packaging technologies. These application categories facilitate the grasping of the current and potential uses of such advanced nanomaterials in the field, backed by their advantageous physical, chemical, and structural properties. Developments for water cleaning and reuse, efficient nanofertilizers and pesticides, ultrasensitive sensors for food contamination, and intelligent nanoelectronic disposable food packages are among the most promising application examples reviewed here and demonstrate the tremendous impact that further developments would have in the area as the fundamental and applied research of two-dimensional nanostructures continues. We expect this work will contribute to a better understanding of the promising characteristics of two-dimensional nanomaterials that could be used for the design of novel and feasible solutions in the agriculture and food areas. © 2023 Society of Chemical Industry.

Antimicrobial Nanomaterials as Advanced Coatings for Self-Sanitizing of Textile Clothing and Personal Protective Equipment

Controlling bioaerosols has become increasingly critical in affecting human health. Natural product treatment in the nano form is a potential method since it has lower toxicity than inorganic nanomaterials like silver nanoparticles. This research is important for the creation of a bioaerosol control system that is effective. Nanoparticles (NPs) are gradually being employed to use bacteria as a nonantibiotic substitute for treating bacterial infections. The present study looks at nanoparticles' antimicrobial properties, their method of action, their impact on drug-opposing bacteria, and the hazards connected with their operation as antimicrobial agents. The aspects that influence nanoparticle conduct in clinical settings, as well as their distinctive features and mode of action as antibacterial assistants, are thoroughly examined. Nanoparticles' action on bacterial cells is presently accepted by way of the introduction of oxidative stress induction, metal-ion release, and nonoxidative methods. Because many concurrent mechanisms of action against germs would necessitate multiple simultaneous gene modifications in the same bacterial cell for antibacterial protection to evolve, bacterial cells developing resistance to NPs is difficult. This review discusses the antimicrobial function of NPs against microbes and presents a comprehensive discussion of the bioaerosols: their origin, hazards, and their prevention. This state of the art method is dependent upon the use of personal protective gear against these bioaerosols. The benefit of the utmost significant categories of metal nanoparticles as antibacterial agents is given important consideration. The novelty of this review depends upon the antimicrobial properties of (a) silver (Ag), (b) zinc oxide (ZnO), and (c) copper oxide (CuO) nanoparticles. The value-added features of these nanoparticles are discussed, as well as their physicochemical characterization and pharmacokinetics, including the toxicological danger they pose to people. Lastly, the effective role of nanomaterials and their future in human wellness is discussed.

Assessing the effectiveness of green synthesized zinc oxide nanoparticles in controlling multidrug-resistant clinical bacteria

Multi-drug resistant pathogenic bacteria are life threaten agent associated with the misuse and overuse of antibiotics. The biological synthesis of metal oxide nanoparticles is a promising alternative treatment. The current study reported the synthesis of zinc oxide nanoparticles (ZnONPs) using different plants extracts of garlic (Allium sativum), ginger (Zingiber officinale), and lemon (Citrus lemon). The plant extracts not only acts as reducing agents but as stabilizing agents for the produced nanoparticles. Biosynthesized zinc oxide nanoparticles (ZnONPs) were confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM) with energy-dispersive X-ray studies (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and ultraviolet-visible (UV-vis) spectroscopy. XRD analysis confirmed the production of pure ZnONPs. UV-vis spectroscopy revealed the presence of ZnONPs and reported the characteristic absorption peak of ZnONPs at 370 nm. SEM and TEM confirmed the shape and size of nanoparticles, with an average mean size of 0.3-11.40 nm. This study reported the antibacterial activity and minimum inhibitory concentration of biosynthesized ZnONPs using the broth microdilution method against some clinical pathogenic bacteria. This study also reported the antimicrobial activity of ZnONPs prepared with garlic extract against Enterococcus sp. and Pseudomonas sp. While, those prepared with ginger extract were effective against Enterococcussp. and methicillin-resistant Staphylococcus aureus. ZnONPs synthesized by garlic extract were more powerful and effective than ZnONPs synthesized by ginger and lemon extracts.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-022-01048-3.

Recent Advances in the Investigation of Poly(lactic acid) (PLA) Nanocomposites: Incorporation of Various Nanofillers and their Properties and Applications

Poly(lactic acid) (PLA) is considered the most promising biobased substitute for fossil-derived polymers due to its compostability, biocompatibility, renewability, and good thermomechanical properties. However, PLA suffers from several shortcomings, such as low heat distortion temperature, thermal resistance, and rate of crystallization, whereas some other specific properties, i.e., flame retardancy, anti-UV, antibacterial or barrier properties, antistatic to conductive electrical characteristics, etc., are required by different end-use sectors. The addition of different nanofillers represents an attractive way to develop and enhance the properties of neat PLA. Numerous nanofillers with different architectures and properties have been investigated, with satisfactory achievements, in the design of PLA nanocomposites. This review paper overviews the current advances in the synthetic routes of PLA nanocomposites, the imparted properties of each nano-additive, as well as the numerous applications of PLA nanocomposites in various industrial fields.

Antimicrobial Clothing Based on Electrospun Fibers with ZnO Nanoparticles

There has been a surge in interest in developing protective textiles and clothes to protect wearers from risks such as chemical, biological, heat, UV, pollution, and other environmental factors. Traditional protective textiles have strong water resistance but lack breathability and have a limited capacity to remove water vapor and moisture. Electrospun fibers and membranes have shown enormous promise in developing protective materials and garments. Textiles made up of electrospun fibers and membranes can provide thermal comfort and protection against a wide range of environmental threats. Because of their multifunctional properties, such as semi-conductivity, ultraviolet absorption, optical transparency, and photoluminescence, their low toxicity, biodegradability, low cost, and versatility in achieving diverse shapes, ZnO-based nanomaterials are a subject of increasing interest in the current review. The growing uses of electrospinning in the development of breathable and protective textiles are highlighted in this review.

Biogenic sunflower oil-chitosan decorated fly ash nanocomposite film using white shrimp shell waste: Antibacterial and immunomodulatory potential

A new sunflower oil-chitosan decorated fly ash (sunflower oil/FA-CSNPs) bionanocomposite film was synthesized using the extract of Litopenaeus vannamei (White shrimp) and evaluated as an antibacterial and immunomodulatory agent. Fly ash-chitosan nanoparticles were produced by using chitosan (CS) isolated from white shrimp extract, glacial acetic acid and sodium tripolyphosphate solution as cross-linkage. The ultrafine polymeric sunflower oil-CS film was fabricated by treating fly ash-chitosan nanoparticles with sunflower oil in glacial acetic acid under continuous stirring for 24 h. The nanostructure of the fabricated polymeric film was confirmed and characterized by different microscopic and spectroscopic approaches. The surface morphology of pre-synthesized bionanocomposite film was found to be homogenous, even and without cracks and pores. The crystallinity of formed bionanocomposite film was noticed at angles (2θ) at 12.65°, 15.21°, 19.04°, 23.26°, 34.82°, and 37.23° in the XRD spectrum. The fabricated film displayed excellent stability up to 380 ⁰C. The formed sunflower oil/FA-CSNPs bionanocomposite film showed promising antibacterial towards Bacillus subtilis with highest zone of inhibition of 34 mm and Pseudomonas aeruginosa with zone of inhibition of 28 nm. The as-synthesized bionanocomposite film exhibited highest cell viability effect (98.95%), followed by FA-CSNPs (83.25%) at 200 μg mL-1 concentrations. The bionanocomposite film exerted notable immunomodulatory effect by promoting phagocytosis and enhancing the production of cytokines (NO, IL-6, IL-1β, and TNF-α) in macrophage-derived RAW264.7 cell line.

In vitro Evaluation of Antibacterial Activity of Synthetic Zeolite Supported AgZno Nanoparticle Against a Selected Group of Bacteria

Background

The development of novel and intriguing nanoparticle (NP)-based materials with antibacterial activity has recently received attention due to the problem of bacterial resistance to conventional antibiotics becoming more and more frequent. Thus, this study aimed to investigate the antibacterial effectiveness of a synthetic zeolite-supported AgZnO nanoparticle against selected bacteria in vitro.

Methods

Using the disc diffusion method, the antibacterial activity of synthetic zeolite-supported AgZnO nanoparticles was assessed against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Zinc oxide (ZnO) and Ag/ZnO nanoparticles were used to create the zeolite-supported Ag/ZnO composite. Chloramphenicol was used as a standard drug. The nanoparticles and composites were characterized using powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and atomic absorption spectroscopy (AAS).

Results

Synthetic zeolite-supported AgZnO nanoparticles showed promising antibacterial properties with the largest zone of inhibition against S. aureus bacteria in comparison to E. coli. The synthetic zeolite-supported AgZnO nanoparticle displayed a zone of inhibition against S. aureus and E. coli without a remarkable difference compared to the respective standard drug (Chloramphenicol). Zinc peaks were visible in the X-ray diffractograms, which supported the theory that the characteristic hexagonal wurtzite structure of zinc oxide was present.

Conclusion

All types of ZnO, AgZnO, and AgZnO-Zeolite showed wide-spectrum activity with better effect against gram-positive bacteria, while the Zeolite-Ag/ZnO composite showed even better antibacterial activity. The findings suggest a potential bactericide that needs further evaluation in future studies was observed in synthetic zeolite-supported Ag/ZnO nanoparticles.

Active Food Packaging Made of Biopolymer-Based Composites

Food packaging plays a vital role in protecting food products from environmental damage and preventing contamination from microorganisms. Conventional food packaging made of plastics produced from unrenewable fossil resources is hard to degrade and poses a negative impact on environmental sustainability. Natural biopolymers are attracting interest for reducing environmental problems to achieve a sustainable society, because of their abundance, biocompatibility, biodegradability, chemical stability, and non-toxicity. Active packaging systems composed of these biopolymers and biopolymer-based composites go beyond simply acting as a barrier to maintain food quality. This review provides a comprehensive overview of natural biopolymer materials used as matrices for food packaging. The antioxidant, water barrier, and oxygen barrier properties of these composites are compared and discussed. Furthermore, biopolymer-based composites integrated with antimicrobial agents-such as inorganic nanostructures and natural products-are reviewed, and the related mechanisms are discussed in terms of antimicrobial function. In summary, composites used for active food packaging systems can inhibit microbial growth and maintain food quality.

Polycaprolactone (PCL)-Polylactic Acid (PLA)-Glycerol (Gly) Composites Incorporated with Zinc Oxide Nanoparticles (ZnO-NPs) and Tea Tree Essential Oil (TTEO) for Tissue Engineering Applications

The search for new biocompatible materials that can replace invasive materials in biomedical applications has increased due to the great demand derived from accidents and diseases such as cancer in various tissues. In this sense, four formulations based on polycaprolactone (PCL) and polylactic acid (PLA) incorporated with zinc oxide nanoparticles (ZnO-NPs) and tea tree essential oil (TTEO) were prepared. The sol-gel method was used for zinc oxide nanoparticle synthesis with an average size of 11 ± 2 nm and spherical morphology. On the other hand, Fourier Transformed infrared spectroscopy (FTIR) showed characteristic functional groups for each composite component. The TTEO incorporation in the formulations was related to the increased intensity of the C-O-C band. The thermal properties of the materials show that the degradative properties of the ZnO-NPs decrease the thermal stability. The morphological study by scanning electron microscopy (SEM) showed that the presence of TTEO and ZnO-NPs act synergistically, obtaining smooth surfaces, whereas membranes with the presence of ZnO-NPs or TTEO only show porous morphologies. Histological implantation of the membranes showed biocompatibility and biodegradability after 60 days of implantation. This degradation occurs through the fragmentation of the larger particles with the presence of connective tissue constituted by type III collagen fibers, blood vessels, and inflammatory cells, where the process of resorption of the implanted material continues.

Ag-Decorated Iron Oxides-Silica Magnetic Nanocomposites with Antimicrobial and Photocatalytic Activity

Nanotechnology offers unlimited possibilities for creating effective hybrid materials, which combine functional performance in environment depollution and antimicrobial defense with a lack of toxicity, biocompatibility, biodegradability, and natural availability. This paper presents the silver effect on photocatalytic and antibacterial activities of double-coated iron oxide nanoparticles (NPs), Fe3O4@SiO2/ZnO-Ag. The structural, morphological, and textural information of the, core-shell iron oxides-based superparamagnetic nanoparticles (IOMNPs) decorated with 5% Ag by ultrasound-assisted synthesis were evaluated by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDX), X-ray diffraction, Raman spectroscopy, and Brunauer-Emmett-Teller physisorption measurements. Although two synthesis temperatures of 95 and 80 °C were used for the co-precipitated iron oxide cores, the XRD patterns revealed the formation of a single magnetite, Fe3O4, phase. The sorption-photocatalytic activities under dark and UV irradiation encountered a maximum removal efficiency of the MB (90.47%) for the Fe3O4@SiO2/ZnO-Ag sample with iron oxide core obtained at 80 °C. The rate constant for the second-order kinetics was 0.0711 min-1 for 2 h, and the correlation coefficient R2 closed to unity. Two samples with Ag-decorated hybrid SiO2/ZnO shell and hierarchically interconnected porous structure with large surface area (328.8 and 342.5 m2g-1) exhibited the best disk diffusion antimicrobial activity against four microorganisms, especially gram-positive Staphylococcus aureus.

ZnO@Polyvinyl Alcohol/Poly(lactic acid) Nanocomposite Films for the Extended Shelf Life of Pork by Efficient Antibacterial Adhesion

The proliferation of microorganisms is an important reason for meat spoilage and deterioration. Freezing and packaging by polymer films and preservatives are commonly used to preserve meat. While the energy consumption of freezing is very big, the polymer films made by petroleum bring up heavy environmental pressure. In the present study, biodegradable antibacterial ZnO@PLA (ZP) and ZnO@PVA/PLA (ZPP) nanocomposite films used as food packaging have been synthesized by the solvent evaporation method and coating method, respectively. Compared with films without ZnO NPs, ZP and ZPP both had long-term bacteriostasis for 24 and 120 h at temperatures of 25 and 4 °C, respectively. Moreover, the antibacterial effect showed positive relevance with the increase of the ZnO NP concentration. In addition, the antibacterial effect of ZPP was better than that of ZP in the same condition. Scanning electron microscopy showed that the numbers of methicillin-resistant staphylococcus aureus (MRSA) on ZP and ZPP were significantly reduced compared to that in the blank film, and ZPP caused the morphology of MRSA to change, which means that the antibacterial mechanism of ZP and ZPP composite films might be related to antibacterial adhesion. In conclusion, ZPP films have great potential to be regarded as the candidate of food packing to extend the shelf life of pork.

Novel pectin-based nanocomposite film for active food packaging applications

Novel pectin-based films reinforced with crystalline nanocellulose (CNC) and activated with zinc oxide nanoparticles (ZnO NPs) were prepared by solvent-casting method. Film ingredients enhanced UV-blocking, thermal, and antibacterial properties of active films against well-known foodborne pathogens. Optimal active films exhibited higher mechanical, water vapor barrier properties compared to pristine pectin films. SEM confirmed the even distribution of CNC and ZnO NPs in pectin matrix and their interactions were proven using FTIR. Wrapping hard cheese samples artificially contaminated with Staphylococcus aureus and Salmonella enterica with the ternary nanocomposite film at 7 °C for 5 days significantly reduced the total population counts by at least 1.02 log CFU/g. Zn²⁺ migrating to wrapped cheese samples was below the specific limit (5 mg/kg), confirming their safety for food contact. Overall, ZnO/CNC/pectin nanocomposite films represent promising candidates for active food packaging as safe, eco-friendly alternatives for synthetic packaging materials.

The plastic pandemic: COVID-19 has accelerated plastic pollution, but there is a cure

Plastic pollution is now present in all areas of our planet, including its last wilderness, Antarctica, and the plastic crisis has further escalated because of COVID-19. The pandemic has caused a significant increase in the global consumption of single-use protective items such as masks and gloves. These and other plastic items add to the suite of plastic pollution issues, from entanglement of wildlife to microplastic bioaccumulation. Given plastics are a major threat facing humans and wildlife, swift action to reduce plastic pollution is urgently needed. Solutions to plastic pollution are within reach. With collective, impactful action we will ensure a better future for our planet and ourselves. Here, we propose several measures for decision-makers to implement to achieve a solution and tackle plastic pollution as a united, global community.

Green synthesis of multifunctional ZnO/chitosan nanocomposite film using wild Mentha pulegium extract for packaging applications

Following the global corona virus pandemic and environmental contamination caused by chemical plastic packaging, awareness of the need for environmentally friendly biofilms and antibacterial coatings is increasing. In this study, a biodegradable hybrid film, comprising of green-synthesized zinc oxide nanoparticles (ZnO NPs) with a chitosan (CS) matrix, was fabricated using a simple casting procedure. The ZnO NPs were synthesized using wild Mentha pulegium extract, and the synthesized NPs and films were characterized using different approaches. The structural, morphological, mechanical, antibacterial, and optical properties, as well as the hydrophilicity, of the prepared samples were investigated using various techniques. Gas chromatography-mass spectrometry measurements revealed the presence of phenolic compounds in the M. pulegium extract. In addition, a strong coordination connection between Zn²⁺ and the chitosan matrix was confirmed, which resulted in a good dispersion of ZnO in the chitosan film. The surface of the composite films was transparent, smooth, and uniform, and the flexible bio-based hybrid films exhibited significant antibacterial and antioxidant characteristics, strong visible emission in the 480 nm region, and UV-blocking properties. The ZnO/CS films displayed a potential to extend the shelf life of fruits by up to eight days when stored at 23°C, and also acted as an acceptable barrier against oxygen and water. The biodegradable ZnO/CS film is expected to keep fruit fresher than general chemical plastic films and be used for the packaging of active ingredients.

Model Study for Interaction of Sublethal Doses of Zinc Oxide Nanoparticles with Environmentally Beneficial Bacteria Bacillus thuringiensis and Bacillus megaterium

Zinc oxide nanoparticles (ZnO NPs), due to their antibacterial effects, are commonly used in various branches of the economy and can affect rhizobacteria that promote plant growth. We describe the effect of ZnO NPs on two model bacteria strains, B. thuringiensis and B. megaterium, that play an important role in the environment. The MIC (minimum inhibitory concentration) value determined after 48 h of incubation with ZnO NPs was more than 1.6 mg/mL for both strains tested, while the MBC (minimum bactericidal concentration) was above 1.8 mg/mL. We tested the effect of ZnO NPs at concentrations below the MIC (0.8 mg/mL, 0.4 mg/mL and 0.2 mg/mL (equal to 50%, 25% and 12,5% MIC, respectively) in order to identify the mechanisms activated by Bacillus species in the presence of these nanoparticles. ZnO NPs in sublethal concentrations inhibited planktonic cell growth, stimulated endospore formation and reduced decolorization of Evans blue. The addition of ZnO NPs caused oxidative stress, measured using nitroblue tetrazolium (NBT), and reduced the activity of catalase. It was confirmed that zinc oxide nanoparticles in sublethal concentrations change metabolic processes in Bacillus bacteria that are important for their effects on the environment. B. thuringiensis after treatment with ZnO NPs decreased indole acetic acid (IAA) production and increased biofilm formation, whereas B. megaterium decreased IAA production but, inversely, increased biofilm formation. Comparison of different Bacillus species in a single experiment made it possible to better understand the mechanisms of toxicity of zinc oxide nanoparticles and the individual reactions of closely related bacterial species.

Interactions between ZnO Nanoparticles and Polyphenols Affect Biological Responses

Zinc oxide (ZnO) nanoparticles (NPs) are used as a food additive Zn supplement due to the role of Zn in biological functions. They are directly added to complex processed foods or Zn-fortified functional foods. Hence, the interactions between ZnO NPs and nutritional or functional components can occur. In this study, the effects of ZnO NP interactions with two polyphenols (quercetin and rutin) on cytotoxicity, antioxidant activity, ex vivo intestinal absorption, and solubility were evaluated. Moreover, the characterization on the interactions was carried out by analyzing crystallinity, surface chemical bonding, chemical composition, and surface chemistry. The results demonstrate that the interactions caused higher cytotoxicity, ex vivo intestinal transport, and solubility of ZnO NPs than pristine ZnO NPs but did not affect antioxidant activity nor intestinal absorption of the polyphenols. The interaction effects were more evident by ZnO NPs interacted with quercetin than with rutin. The crystallinity of ZnO NPs was not influenced, but the degree of exposure of the chemical bondings, elemental compositions, and chemical group intensities on the surface of ZnO NPs, quercetin, or rutin were quenched or decreased to some extent by the interactions, especially by ZnO NPs interacted with quercetin. It is, therefore, concluded that the interactions affect chemical characteristics and surface chemical sates of ZnO NPs, quercetin, or rutin, which can cause high cytotoxicity, intestinal absorption, and solubility of ZnO NPs. Further study is required to elucidate the mechanism of action of the interactions.

ZnO-based antimicrobial coatings for biomedical applications

Rapid transmission of infectious microorganisms such as viruses and bacteria through person-to-person contact has contributed significantly to global health issues. The high survivability of these microorganisms on the material surface enumerates their transmissibility to the susceptible patient. The antimicrobial coating has emerged as one of the most interesting technologies to prevent growth and subsequently kill disease-causing microorganisms. It offers an effective solution a non-invasive, low-cost, easy-in-use, side-effect-free, and environmentally friendly method to prevent nosocomial infection. Among antimicrobial coating, zinc oxide (ZnO) stands as one of the excellent materials owing to zero toxicity, high biocompatibility to human organs, good stability, high abundancy, affordability, and high photocatalytic performance to kill various infectious pathogens. Therefore, this review provides the latest research progress on advanced applications of ZnO nanostructure-based antibacterial coatings for medical devices, biomedical applications, and health care facilities. Finally, future challenges and clinical practices of ZnO-based antibacterial coating are addressed.

Gelatin/Cellulose Nanofiber-Based Functional Nanocomposite Film Incorporated with Zinc Oxide Nanoparticles

A novel bio-based nanocomposite film was developed using the combination of gelatine and cellulose nanofiber (CNF) as a polymer matrix and zinc oxide nanoparticles (ZnONP) as nanofillers. The nanocomposite film solution was developed using simple solution mixing and film prepared by the following casting methods. The fabricated nanocomposite film containing 2 wt% of ZnONP shows excellent UV-light barrier properties (>95%) and high transparency (>75%). The presence of ZnONP also improves the mechanical strength of the film by ~30% compared to pristine gelatin/CNF-based film, while the flexibility and rigidity of the nanocomposite film were also slightly improved. The addition of ZnONP slightly increased (~10%) the hydrophobicity while the water vapor barrier properties remain unaltered. The hydrodynamic properties of the bio-based film were also changed in the presence of ZnONP, moisture content and the swelling ratio slightly enhanced, whereas water solubility was decreased. Moreover, the integration of ZnONP introduced antibacterial activity toward foodborne pathogens. The fabricated bio-based nanocomposite film could be useful in active packaging applications.

Recent Developments and Applications of Nanosystems in the Preservation of Meat and Meat Products

Due to their high water, lipid, and protein content, meat and meat products are highly perishable. The principal spoilage mechanisms involved are protein and lipid oxidation and deterioration caused by microbial growth. Therefore, efforts are ongoing to ensure food safety and increase shelf life. The development of low-cost, innovative, eco-friendly approaches, such as nanotechnology, using non-toxic, inexpensive, FDA-approved ingredients is reducing the incorporation of chemical additives while enhancing effectiveness and functionality. This review focuses on advances in the incorporation of natural additives that increase the shelf life of meat and meat products through the application of nanosystems. The main solvent-free preparation methods are reviewed, including those that involve mixing organic–inorganic or organic–organic compounds with such natural substances as essential oils and plant extracts. The performance of these additives is analyzed in terms of their antioxidant effect when applied directly to meat as edible coatings or marinades, and during manufacturing processes. The review concludes that nanotechnology represents an excellent option for the efficient design of new meat products with enhanced characteristics.

Electrospinning of PLA Nanofibers: Recent Advances and Its Potential Application for Food Packaging

Poly(lactic acid), also abbreviated as PLA, is a promising biopolymer for food packaging owing to its environmental-friendly characteristic and desirable physical properties. Electrospinning technology makes the production of PLA-based nanomaterials available with expected structures and enhanced barrier, mechanical, and thermal properties; especially, the facile process produces a high encapsulation efficiency and controlled release of bioactive agents for the purpose of extending the shelf life and promoting the quality of foodstuffs. In this study, different types of electrospinning techniques used for the preparation of PLA-based nanofibers are summarized, and the enhanced properties of which are also described. Moreover, its application in active and intelligent packaging materials by introducing different components into nanofibers is highlighted. In all, the review establishes the promising prospects of PLA-based nanocomposites for food packaging application.

Nanocomposite Film Development Based on Chitosan/Polyvinyl Alcohol Using ZnO@montmorillonite and ZnO@Halloysite Hybrid Nanostructures for Active Food Packaging Applications

The global turn from the linear to the circular economy imposes changes in common activities such as food packaging. The use of biodegradable materials such as polyvinyl alcohol, natural raw materials such as clays, and food byproducts such as chitosan to develop novel food packaging films attracts the interest of industrial and institutional research centers. In this study, novel hybrid nanostructures were synthesized via the growth of zinc oxide nanorods on the surface of two nanoclays. The obtained nanostructures were incorporated with chitosan/polyvinyl alcohol composite either as nanoreinforcement or as an active agent to develop packaging films. The developed films were characterized via XRD, FTIR, mechanical, water-vapor diffusion, water sorption, and oxygen permeability measurements. Antimicrobial activity measurements were carried out against four different pathogen microorganisms. XRD indicated the formation of an intercalated nanocomposite structure for both types of nanoclays. Furthermore, improved tensile, water/oxygen barrier, and antimicrobial properties were recorded for all films compared to the pure chitosan/polyvinyl alcohol film. Overall, the results indicated that the use of the bio-based developed films led to an extension of food shelf life and could be used as novel active food packaging materials. Among them, the most promising film was the 6% wt. ZnO@halloysite.

Plant protein-based nanocomposite films: A review on the used nanomaterials, characteristics, and food packaging applications

Consumer demands to utilize environmentally friendly packaging have led researchers to develop packaging materials from naturally derived resources. In recent years, plant protein-based films as a replacement for synthetic plastics have attracted the attention of the global food packaging industry due to their biodegradability and unique properties. Biopolymer-based films need a filler to show improved packaging properties. One of the latest strategies introduced to food packaging technology is the production of nanocomposite films which are multiphase materials containing a filler with at least one dimension less than 100 nm. This review provides the recent findings on plant-based protein films as biodegradable materials that can be combined with nanoparticles that are applicable to food packaging. Moreover, it investigates the characterization of nanocomposite plant-based protein films/edible coatings. It also briefly describes the application of plant-based protein nanocomposite films/coating on fruits/vegetables, meat and seafood products, and some other foods. The results indicate that the functional performance, barrier, mechanical, optical, thermal and antimicrobial properties of plant protein-based materials can be extended by incorporating nanomaterials. Recent reports provide a better understanding of how incorporating nanomaterials into plant protein-based biopolymers leads to an increase in the shelf life of food products during storage time.