Antibacterial Activity and Biodegradation of Cellulose Fiber Blends with Incorporated ZnO

Spectroscopic investigation, dielectric and antimicrobial properties of chitin-cellulose@ZnO/CuO conductive nanocomposites

In this research, we fabricated a functional conductive nanocomposite with valuable properties through a chitin (CH) and cellulose (CE) polymerization process, incorporating ZnO/(0.1, 0.2, 0.3 mol.%) CuO bioactive nanoparticles. These bioactive nanoparticles, synthesized through sol-gel and polymerization interactions, greatly enhanced the structural, dielectric, and antimicrobial characteristics of CH-CE@ZnO/CuO conductive nanocomposites. The morphological analysis revealed that these nanoparticles, with diameters ranging from 11-25 nm, formed covalent bonds with the membrane matrix, bolstering the conductive nanocomposites ' structural integrity and dielectric performance. The dielectric properties of the conductive nanocomposites were significantly enhanced by the even distribution of ZnO/CuO nanoparticles within the CH-CE composite. Additionally, antimicrobial assessments demonstrated that the CH-CE@ZnO/CuO conductive nanocomposites displayed significant antibacterial properties against the Escherichia coli and Staphylococcus aureus, showcasing their potential as active packaging materials for electronic, biosensors, and sustainable applications.

An evaluation of conventional and nature-based technologies for controlling antibiotic-resistant bacteria and antibiotic-resistant genes in wastewater treatment plants

Antibiotic resistance is a globally recognized health concern which leads to longer hospital stays, increased morbidity, increased mortality, and higher medical costs. Understanding how antibiotic resistance persists and exchanges in environmental systems like soil, water, and wastewater are critically important for understanding the emergence of pathogens with new resistance profiles and the subsequent exposure of people who indirectly/directly come in contact with these pathogens. There are concerns about the widespread application of prophylactic antibiotics in the clinical and agriculture sectors, as well as chemicals/detergents used in food and manufacturing industries, especially the quaternary ammonium compounds which have been found responsible for the generation of resistant genes in water and soil. The rates of horizontal gene transfer increase where there is a lack of proper water/wastewater infrastructure, high antibiotic manufacturing industries, or endpoint users - such as hospitals and intensive agriculture. Conventional wastewater treatment technologies are often inefficient in the reduction of ARB/ARGs and provide the perfect combination of conditions for the development of antibiotic resistance. The wastewater discharged from municipal facilities may therefore be enriched with bacterial communities/pathogens and provide a suitable environment (due to the presence of nutrients and other pollutants) to enhance the transfer of antibiotic resistance. However, facilities with tertiary treatment (either traditional/emerging technologies) provide higher rates of reduction. This review provides a synthesis of the current understanding of wastewater treatment and antibiotic resistance, examining the drivers that may accelerate their possible transmission to a different environment, and highlighting the need for tertiary technologies used in treatment plants for the reduction of resistant bacteria/genes.

Optimizing magnetic, dielectric, and antimicrobial performance in chitosan-PEG-Fe2O3@NiO nanomagnetic composites

There is a growing interest in eco-friendly and cost-effective organic-inorganic nanocomposites due to their alignment with the principles of "green" chemistry, as well as their biocompatibility and non-toxicity. This study focused on producing Chitosan-PEG-Fe2O3@NiO nanomagnetic composites to improve the stability, dielectric properties, and antimicrobial effectiveness of these nanocomposite materials. The process involved synthesizing Fe2O3@NiO via sol-gel and polymerizing chitosan-PEG. The nanocomposites were characterized by XRD, TEM, FTIR, optical, dielectric, and VSM. Incorporating Fe2O3@NiO significantly improved stability, and the interaction with Fe2O3 during the sol-gel process facilitated the formation of NiFe2O4 with an increase in the crystallinity within the chitosan-PEG matrix. The study examined optical and dielectric properties, highlighting that the 3 NiO-doped chitosan-PEG-Fe2O3 composites had high electrical conductivity (1.8 ∗ 10-3 S/cm) and a significant dielectric constant (106 at low frequencies). As the ratio of NiO NPs within the chitosan-PEG-Fe2O3 increases, the energy band gap of chitosan-PEG-Fe2O3 films decreases up to 3.7 eV. This decrease is owing to the quantum confinement effect. These composites also demonstrated improved antimicrobial activity against E. coli and S. aureus and higher activity in the presence of nanomagnetic particles. The minimum inhibitory concentrations of CS-PEG-Fe2O3/NiO NPs against (Bacillus cereus, M. luteus, S. aureus and (S. enterica, H. pylori, E. coli) were (22-35 mm) and (21-34 mm), respectively.

Tutorial review on the processing and performance of fabrics with antipathogenic inorganic agents

Functionalized textiles have been increasingly used for enhancing antimicrobial or antiviral (antipathogenic) action. Those pathogens can cause recurring diseases by direct or indirect transmission. Particularly, airborne microorganisms may cause respiratory diseases or skin infections like allergies and acne and the use of inorganic agents such as metal and metal oxides has proven effective in antipathogen applications. This review is a tutorial on how to obtain functional fabric with processes easily applied for industrial scale. Also, this paper summarizes relevant textiles and respective incorporated inorganic agents, including their antipathogenic mechanism of action. In addition, the processing methods and functional finishing, on a laboratory and industrial scale, to obtain a functional textile are shown. Characterization techniques, including antipathogenic activity and durability, mechanical properties, safety, and environmental issues, are presented. Challenges and perspectives on the broader use of antipathogenic fabrics are discussed.

Importance of Protocol Design for Suitable Green In Situ Synthesis of ZnO on Cotton Using Aqueous Extract of Japanese Knotweed Leaves as Reducing Agent

This work presents two protocols for the green in situ synthesis of zinc oxide nanoparticles (ZnO-NP) on cotton with the aim to develop sustainable cotton fabric with an ultraviolet protection factor (UPF). The protocols differed in the order of immersing cotton fabric in reactive solutions of three batches, i.e., precursor (0.1 M zinc acetate dihydrate), reducing agent (aqueous extract of Japanese knotweed leaves) and alkali (wood ash waste). The scanning electron microscope (SEM) results showed that ZnO-NP were successfully synthesised on cotton using both protocols; however, only the protocol where cotton was first immersed in alkali, then in the precursor and, lastly, in the reducing agent enabled very high UPF and higher amount of Zn present on the sample. Due to the different order of cotton fabric immersion in the reactive solutions, dissimilar morphology of the ZnO particles was observed, which resulted in different UV blocking abilities of the samples. The antioxidant analysis (DPPH) showed that the natural reducing agent prepared from Japanese knotweed leaves has very high antioxidant activity, which is attributed to phenolic compounds present in the plant. The reflectance spectroscopy results confirmed that the colour yield and colour of the samples did not influence the UPF value. This protocol is an example of green circular economy where waste materials of invasive alien plant species and pellet heating was used as a natural source of phytochemicals, for the direct synthesis of ZnO-NP to develop cotton fabric with UV-protective properties.

Microencapsulation for Functional Textile Coatings with Emphasis on Biodegradability—A Systematic Review

The review provides an overview of research findings on microencapsulation for functional textile coatings. Methods for the preparation of microcapsules in textiles include in situ and interfacial polymerization, simple and complex coacervation, molecular inclusion and solvent evaporation from emulsions. Binders play a crucial role in coating formulations. Acrylic and polyurethane binders are commonly used in textile finishing, while organic acids and catalysts can be used for chemical grafting as crosslinkers between microcapsules and cotton fibres. Most of the conventional coating processes can be used for microcapsule-containing coatings, provided that the properties of the microcapsules are appropriate. There are standardised test methods available to evaluate the characteristics and washfastness of coated textiles. Among the functional textiles, the field of environmentally friendly biodegradable textiles with microcapsules is still at an early stage of development. So far, some physicochemical and physical microencapsulation methods using natural polymers or biodegradable synthetic polymers have been applied to produce environmentally friendly antimicrobial, anti-inflammatory or fragranced textiles. Standardised test methods for evaluating the biodegradability of textile materials are available. The stability of biodegradable microcapsules and the durability of coatings during the use and care of textiles still present several challenges that offer many opportunities for further research.

Novel Green In Situ Synthesis of ZnO Nanoparticles on Cotton Using Pomegranate Peel Extract

This work presents the novel and entirely green in situ synthesis of zinc oxide nanoparticles (ZnO-NP) on cotton fabric. Pomegranate peel extract was used as a reducing agent and wood ash extract was used as an alkali source for the formation of ZnO-NP from zinc acetate. Four different synthesis methods, which varied in drying between immersion of fabric in the active solutions for synthesis and the use of padding and ultrasonication, were investigated to evaluate the most suitable one to achieve excellent ultraviolet (UV) protective properties of the functionalized textile. For comparison, the cotton fabrics were also functionalized with each active solution separately or in a combination of two (i.e., Zn-acetate and plant extract). Scanning electron microscopy (SEM), inductively coupled plasma mass spectroscopy (ICP-MS), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) analysis, and atomic force microscopy (AFM) confirm the successful formation of ZnO-NP on cotton. Among the synthesis methods, the method that included continuous drying of the samples between immersion in the active solutions for synthesis (Method 4) was found to be the most suitable to deliver uniformly impregnated cotton fibers with numerous small ZnO wurtzite structured crystals and excellent UV protection, with a UV protection factor of 154.0. This research presents an example of a green circular economy where a bio-waste material can be used to produce ZnO-NP directly on cotton at low temperatures and short treatment times without the addition of chemicals and enables the production of cellulosic fabrics with excellent UV protection.

Medicinal Applications of Cannabinoids Extracted from Cannabis sativa (L.): A New Route in the Fight Against COVID-19?

Cannabis sativa is a well-known plant that has been recognized for its benefits since ancient times by several medicinal systems, including those of China, India, Greece, and Egypt. Although C. sativa is one of the most investigated medicinal plants in the world, it faces some of the greatest controversies surrounding its legalization and use as a medication. C. sativa contains several hundred phytoconstituents, including the infamous "cannabinoids". It is necessary to properly understand the medicinal importance of these phytochemicals and spread awareness among the countries where cannabis is still facing legal obstacles. The current review focuses on the most recent literature pertaining to various applications of cannabinoids, with a special focus on the medicinal aspect of these phytochemicals. Peer-reviewed articles focusing on the importance of cannabis and cannabinoids are the target of this review. Articles were selected based on the relevance to the general scope of the work, i.e., application of cannabinoids. Cannabinoids can truly be regarded as wonder drugs, considering their immense diversity of usage. Unfortunately, however, many of the mares have never been researched biologically or pharmacologically due to their low yield in the plant. However, the approval of some cannabinoids by the FDA (along with other recognized national medical health systems) has opened the horizon for the use of these natural drugs in medicines such as Epidiolex® (cannabidiol, used for the treatment of severe forms of epilepsy) and Sativex®(Δ⁹-tetrahydrocannabinol and cannabidiol, used for the treatment of spasticity caused by multiple sclerosis). Many pharmacological properties of C. sativa are attributed to cannabidiol (CBD), a non-psychoactive component, along with Δ9-tetrahydrocannabinol (Δ⁹-THC), a psychoactive component. This review addresses the most important applications or current utilization of cannabinoids in a variety of treatments such as chronic pain, cancer, emesis, anorexia, irritable bowel syndrome, communicable diseases, glaucoma, and central nervous system disorders. The biosynthetic pathway of cannabinoids is also discussed. In short, cannabis has a myriad of bioactive compounds that have the potential to increase the list of approved cannabinoids suitable for therapy.

Facile in situ fabrication of ZnO-embedded cellulose nanocomposite films with antibacterial properties and enhanced mechanical strength via hydrogen bonding interactions

Nano-ZnO were in situ prepared and permanently embedded in regenerated cellulose (RC) films by chemical precipitation to endow antibacterial of films and simultaneously strengthen tensile strength. ZnCl₂ was selected as a promoter of 1-allyl-3-methylimidazolium chloride for cellulose dissolution and as a precursor for nano-ZnO synthesis. Zn²⁺-absorbed cellulose solution was reacted with NaOH under ultrasonic to obtain nano-ZnO embedded RC films. The results indicated that RC films treated with the longest sonication time, highest regeneration solution basicity, and highest cellulose concentration were demonstrated to be the most effective against S. aureus, which agreed well with the dense and homogeneous distribution of high content of nano-ZnO on the film surface. The nanocomposite films achieved particularly high mechanical strength of 202.0 MPa with improved thermal stability. Strong H-bonding formed between nano-ZnO and cellulose, which contributed to high tensile strength and thermal stability of films. This work affords a simple approach to prepare cellulose nanocomposite with outstanding performance for potential application in packaging.

Improved Bacteriostatic and Anticorrosion Effects of Polycaprolactone/Chitosan Coated Magnesium via Incorporation of Zinc Oxide

Magnesium has been recognized as a groundbreaking biodegradable biomaterial for implant applications, but its use is limited because it degrades too quickly in physiological solutions. This paper describes the research on the influence of polycaprolactone (PCL)/chitosan (CS)/zinc oxide (ZnO) composite coating (PCL/CS/ZnO) on the corrosion resistance and antibacterial activity of magnesium. The PCL/CS film presented a porous structure with thickness of about 40-50 μm, while after incorporation of ZnO into the PCL/CS, a homogenous film without pores and defects was attained. The ZnO embedded in PCL/CS enhanced corrosion resistance by preventing corrosive ions diffusion in the magnesium substrate. The corrosion, antibacterial, and cell interaction mechanism of the PCL/CS/ZnO composite coating is discussed in this study. In vitro cell culture revealed that the PCL/CS coating with low loaded ZnO significantly improved cytocompatibility, but coatings with high loaded ZnO were able to induce some cytotoxicity osteoblastic cells. It was also found that enhanced antibacterial activity of the PCL/CS/ZnO coating against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria, while less significant antibacterial activity was detected for uncoated Mg and PCL/CS coating. Based on the results, the PCL/CS coatings loaded with low ZnO content may be recommended as a candidate material for biodegradable Mg-based orthopedic implant applications.

New Insights into Antibacterial and Antifungal Properties, Cytotoxicity and Aquatic Ecotoxicity of Flame Retardant PA6/DOPO-Derivative Nanocomposite Textile Fibers

The aim of this study was to evaluate the antibacterial and antifungal activity, cytotoxicity, leaching, and ecotoxicity of novel flame retardant polyamide 6 (PA6) textile fibers developed by our research group. The textile fibers were produced by the incorporation of flame-retardant bridged 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivative (PHED) in the PA6 matrix during the in situ polymerization process at concentrations equal to 10 and 15 wt% (PA6/10PHED and PA6/15PHED, respectively). Whilst the nanodispersed PHED provided highly efficient flame retardancy, its biological activity led to excellent antibacterial activity against Escherichia coli and Staphylococcus aureus, as well as excellent antifungal activity against Aspergillus niger and Candida albicans. The results confirmed leaching of the PHED, but the tested leachates did not cause any measurable toxic effect to the duckweed Lemna minor. The in vitro cytotoxicity of the leached PHED from the PA6/15PHED sample was confirmed for human cells from adipose tissue in direct and prolonged contact. The targeted biological activity of the organophosphinate flame retardant could be beneficial for the development of PA6 textile materials with multifunctional properties and the low ecotoxicity profile, while the PHED's leaching and cytotoxicity limit their application involving the washing processes and direct contact with the skin.

Textile Materials Modified with Stimuli-Responsive Drug Carrier for Skin Topical and Transdermal Delivery

Textile materials, as a suitable matrix for different active substances facilitating their gradual release, can have an important role in skin topical or transdermal therapy. Characterized by compositional and structural variety, those materials readily meet the requirements for applications in specific therapies. Aromatherapy, antimicrobial substances and painkillers, hormone therapy, psoriasis treatment, atopic dermatitis, melanoma, etc., are some of the areas where textiles can be used as carriers. There are versatile optional methods for loading the biologically active substances onto textile materials. The oldest ones are by exhaustion, spraying, and a pad-dry-cure method. Another widespread method is the microencapsulation. The modification of textile materials with stimuli-responsive polymers is a perspective route to obtaining new textiles of improved multifunctional properties and intelligent response. In recent years, research has focused on new structures such as dendrimers, polymer micelles, liposomes, polymer nanoparticles, and hydrogels. Numerous functional groups and the ability to encapsulate different substances define dendrimer molecules as promising carriers for drug delivery. Hydrogels are also high molecular hydrophilic structures that can be used to modify textile material. They absorb a large amount of water or biological fluids and can support the delivery of medicines. These characteristics correspond to one of the current trends in the development of materials used in transdermal therapy, namely production of intelligent materials, i.e., such that allow controlled concentration and time delivery of the active substance and simultaneous visualization of the process, which can only be achieved with appropriate and purposeful modification of the textile material.

Transcriptomic analysis of stress response to novel antimicrobial coatings in a clinical MRSA strain

Multi-drug resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) cause nosocomial infections that can have deleterious effects on human health. Thus, it is imperative to find solutions to treat these detrimental infections as well as to control their spread. We tested the effect of two different antimicrobial materials, functionalised graphene oxide (GOX), and AGXX® coated on cellulose fibres, on the growth and transcriptome of the clinical MRSA strain S. aureus 04-02981. In addition, we investigated the effect of a third material as a combination of GOX and AGXX® fibres on S. aureus 04-02981. Standard plate count assay revealed that the combination of fibres, GOX-AGXX® inhibited the growth of S. aureus 04-02981 by 99.98%. To assess the effect of these antimicrobials on the transcriptome of our strain, cultures of S. aureus 04-02981 were incubated with GOX, AGXX®, or GOX-AGXX® fibres for different time periods and then subjected to RNA-sequencing. Uncoated cellulose fibres were used as a negative control. The antimicrobial fibres had a huge impact on the transcriptome of S. aureus 04-02981 affecting the expression of 2650 genes. Primarily genes related to biofilm formation and virulence (such as agr, sarA, and those of the two-component system SaeRS), and genes crucial for survival in biofilms (like arginine metabolism arc genes) were repressed. In contrast, the expression of siderophore biosynthesis genes (sbn) was induced, a probable response to stress imposed by the antimicrobials and the conditions of iron-deficiency. Genes associated with potassium transport, intracellular survival and pathogenesis (kdp) were also differentially expressed. Our data suggest that the combination of GOX and AGXX® acts as an efficient antimicrobial against S. aureus 04-02981. Thus, these materials are potential candidates for applications in antimicrobial surface coatings.

Optimization of ZnO Nanorods Growth on Polyetheresulfone Electrospun Mats to Promote Antibacterial Properties

Zinc oxide (ZnO) nanorods grown by chemical bath deposition (CBD) on the surface of polyetheresulfone (PES) electrospun fibers confer antimicrobial properties to the obtained hybrid inorganic–polymeric PES/ZnO mats. In particular, a decrement of bacteria colony forming units (CFU) is observed for both negative (Escherichia coli) and positive (Staphylococcus aureus and Staphylococcus epidermidis) Grams. Since antimicrobial action is strictly related to the quantity of ZnO present on surface, a CBD process optimization is performed to achieve the best results in terms of coverage uniformity and reproducibility. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) provide morphological and compositional analysis of PES/ZnO mats while thermogravimetric analysis (TGA) is useful to assess the best process conditions to guarantee the higher amount of ZnO with respect to PES scaffold. Biocidal action is associated to Zn²⁺ ion leaching in solution, easily indicated by UV–Vis measurement of metallation of free porphyrin layers deposited on glass.

Preparation and Performance of Ultra-Fine Polypropylene Antibacterial Fibers via Melt Electrospinning

Polypropylene (PP) fibers are employed commonly as the raw material of technical textiles (nonwovens), and the research focuses on fine-denier fibers and their functionalities. In this work, antibacterial PP masterbatches with different dosage (1–5 wt.%) of nano-ZnO particles as the antibacterial agent were prepared via a twin-screw extruder. The as-prepared PP masterbatches were electrospun on a home-made electrospinning device to afford ultra-fine PP fibers. The morphologies of as-spun ultrathin PP fibers with 16 μm of average diameter were observed by SEM. The structure and element distribution were characterized by means of energy-dispersive spectroscopy (EDS) and Fourier-transfer infrared spectroscopy (FTIR), respectively. There was some zinc obviously distributed on the surface when a dosage of ZnO more than 1 wt.% was used, which contributed to the antibacterial activity. The crystallinity of PP fibers was not affected strongly by the dosage of ZnO based on the differential scanning calorimetry (DSC) heating curves, while thermal decomposition improved with the increase in ZnO content, and the mechanical strength decreased predictably with the increase in inorganic ZnO content.