Chitosan-based nanofibrous membranes for antibacterial filter applications

Formulation and optimization of surfactant-modified chitosan nanoparticles loaded with cefdinir for novel topical drug delivery: Elevating wound healing efficacy with enhanced antibacterial properties

Burn wounds remain a significant global health concern, frequently exacerbated by bacterial infections that hinder healing and raise morbidity rates. Cefdinir, a third-generation cephalosporin antibiotic, is used to treat various conditions, but it has limitations such as low water solubility, limited bioavailability, and a short biological half-life. This study aimed to fabricate and optimize novel surfactant-based Cefdinir-loaded chitosan nanoparticles (CFD-CSNPs) for enhancing topical CFD delivery and efficacy in burn healing. Box-Behnken Design (BBD) was employed to develop optimized CFD-CSNPs using Design Expert® software, where the independent factors were chitosan concentration, chitosan: sodium tripolyphosphate ratio, pH, and surfactant type. Particle size PS, zeta potential ZP, Polydispersity index PDI, and entrapment efficiency EE% were evaluated as dependent factors. CFD-CSNPs were produced using the ionic gelation method. The optimized formula was determined and then examined for further in vitro and in vivo assessments. The optimized CFD-CSNPs exhibited acceptable PS, PDI, and ZP values. The EE% of CFD from CSNPs reached 57.89 % ± 1.66. TEM analysis revealed spherical morphology. In vitro release studies demonstrated a biphasic release profile up to (75.5 % ± 3.8) over 48 hrs. The optimized CFD-CSNPs showed improved antimicrobial efficacy against the tested microorganisms, exhibiting superior performance for both biofilm prevention and eradication. Enhanced wound healing activity was achieved by the optimized CFD-CSNPs in both in vitro and in vivo studies as confirmed by scratch wound assay and skin burn mice model. The current study advocates the efficacy of the innovative topical application of CFD-CSNPs for wound healing purposes and treatment of wound infections.

Electrospun nanofibrous wound dressings with enhanced efficiency through carbon quantum dots and citrate incorporation

Nanofibers show promise for wound healing by facilitating active agent delivery, moisture retention, and tissue regeneration. However, selecting suitable dressings for diverse wound types and managing varying exudate levels remains challenging. This study synthesized carbon quantum dots (CQDs) from citrate salt and thiourea using a hydrothermal method. The CQDs displayed antibacterial activity against Staphylococcus aureus and Escherichia coli. A nanoscaffold comprising gelatin, chitosan, and polycaprolactone (GCP) was synthesized and enhanced with silver nanoparticle-coated CQDs (Ag-CQDs) to form GCP-Q, while citrate addition yielded GCP-QC. Multiple analytical techniques, including electron microscopy, FT-IR spectroscopy, dynamic light scattering, UV-Vis, photoluminescence, X-ray diffraction, porosity, degradability, contact angle, and histopathology assessments characterized the CQDs and nanofibers. Integration of CQDs and citrate into the GCP nanofibers increased porosity, hydrophilicity, and degradability-properties favorable for wound healing. Hematoxylin and eosin staining showed accelerated wound closure with GCP-Q and GCP-QC compared to GCP alone. Overall, GCP-Q and GCP-QC nanofibers exhibit significant potential for skin tissue engineering applications.

Biodegradable Electrospun Membranes for Sustainable Industrial Applications

The escalating demand for sustainable industrial practices has driven the exploration of innovative materials, prominently exemplified by biodegradable electrospun membranes (BEMs). This review elucidates the pivotal role of these membranes across diverse industrial applications, addressing the imperative for sustainability. Furthermore, a comprehensive overview of biodegradable materials underscores their significance in electrospinning and their role in minimizing the environmental impact through biodegradability. The application of BEMs in various industrial sectors, including water treatment, food packaging, and biomedical applications, are extensively discussed. The environmental impact and sustainability analysis traverse the lifecycle of BEMs, evaluating their production to disposal and emphasizing reduced waste and resource conservation. This review demonstrates the research about BEMs toward an eco-conscious industrial landscape for a sustainable future.

"One-Pot" Method Preparation of Dendritic Mesoporous Silica-Loaded Matrine Nanopesticide for Noninvasive Administration Control of Monochamus alternatus: The Vector Insect of Bursapherenchus xylophophilus

Monochamus alternatus is an important stem-boring pest in forestry. However, the complex living environment of Monochamus alternatus creates a natural barrier to chemical control, resulting in a very limited control effect by traditional insecticidal pesticides. In this study, a stable pesticide dendritic mesoporous silica-loaded matrine nanopesticide (MAT@DMSNs) was designed by encapsulating the plant-derived pesticide matrine (MAT) in dendritic mesoporous silica nanoparticles (DMSNs). The results showed that MAT@DMSNs, sustainable nanobiopesticides with high drug loading capacity (80%) were successfully constructed. The release efficiency of DMSNs at alkaline pH was slightly higher than that at acidic pH, and the cumulative release rate of MAT was about 60% within 25 days. In addition, the study on the toxicity mechanism of MAT@DMSNs showed MAT@DMSNs were more effective than MAT and MAT (0.3% aqueous solutions) in touch and stomach toxicity, which might be closely related to their good dispersibility and permeability. Furthermore, MAT@DMSNs are also involved in water transport in trees, which can further transport the plant-derived insecticides to the target site and improve its insecticidal effect. Meanwhile, in addition, the use of essential oil bark penetrants in combination with MAT@DMSNs effectively avoids the physical damage to pines caused by traditional trunk injections and the development of new pests and diseases induced by the traditional trunk injection method, which provides a new idea for the application of biopesticides in the control of stem-boring pests in forestry.

Electrospun PCL Filtration Membranes Enhanced with an Electrosprayed Lignin Coating to Control Wettability and Anti-Bacterial Properties

This study reports on the two-step manufacturing process of a filtration media obtained by first electrospinning a layer of polycaprolactone (PCL) non-woven fibers onto a paper filter backing and subsequently coating it by electrospraying with a second layer made of pure acidolysis lignin. The manufacturing of pure lignin coatings by solution electrospraying represents a novel development that requires fine control of the underlying electrodynamic processing. The effect of increasing deposition time on the lignin coating was investigated for electrospray time from 2.5 min to 120 min. Microstructural and physical characterization included SEM, surface roughness analysis, porosity tests, permeability tests by a Gurley densometer, ATR-FTIR analysis, and contact angle measurements vs. both water and oil. The results indicate that, from a functional viewpoint, such a natural coating endowed the membrane with an amphiphilic behavior that enabled modulating the nature of the bare PCL non-woven substrate. Accordingly, the intrinsic hydrophobic behavior of bare PCL electrospun fibers could be reduced, with a marked decrease already for a thin coating of less than 50 nm. Instead, the wettability of PCL vs. apolar liquids was altered in a less predictable manner, i.e., producing an initial increase of the oil contact angles (OCA) for thin lignin coating, followed by a steady decrease in OCA for higher densities of deposited lignin. To highlight the effect of the lignin type on the results, two grades of oak (AL-OA) of the Quercus cerris L. species and eucalyptus (AL-EU) of the Eucalyptus camaldulensis Dehnh species were compared throughout the investigation. All grades of lignin yielded coatings with measurable antibacterial properties, which were investigated against Staphylococcus aureus and Escherichia coli, yielding superior results for AL-EU. Remarkably, the lignin coatings did not change overall porosity but smoothed the surface roughness and allowed modulating air permeability, which is relevant for filtration applications. The findings are relevant for applications of this abundant biopolymer not only for filtration but also in biotechnology, health, packaging, and circular economy applications in general, where the reuse of such natural byproducts also brings a fundamental demanufacturing advantage.

Advances in electrospun materials for the adsorption and separation of environmental pollutants: A comprehensive review

Despite a broad range of new techniques developed, adsorption methods remain one of the technologies of choice for the removal of contaminants. However, significant progress has also been made in these, which finds reflection in a new spectrum of adsorbents that can be used. This comprehensive review discusses properties, advantages, and perspectives on the use of custom-made electrospun adsorbents in the processes of heavy metals, agrochemicals, and microplastic contaminants removal from the environment. It presents the versatility and adaptability of materials that can be used as electrospun fibers matrix, also considering the mechanism and parameters of the sorption process carried out with them. The presented review proves, that due to the use of new, custom-made sorbents, such as electrospun materials, the adsorption processes still possess great application potential and development opportunities to provide an attractive and effective alternative to other remediation techniques.

Multifunctional sodium alginate/chitosan-modified graphene oxide reinforced membrane for simultaneous removal of nanoplastics, emulsified oil, and dyes in water

Membrane technology is widely recognized as an efficient and advanced approach for wastewater treatment. However, the development of environmentally friendly and versatile membranes capable of effectively removing multiple contaminants remains a significant challenge. Inspired by natural magnets, we developed a heterostructured membrane using biomass materials to achieve the efficient removal of multiple contaminants from wastewater. Specifically, a bionic three-layer SA/GO/CS composite membrane was prepared by using sodium alginate (SA) and chitosan (CS) to modify graphene oxide (GO), respectively, and then assembled to both sides of the glass fiber (GF) membrane. The composite membranes achieved 99.87 % and 97.10 % removal of NPs with particle sizes of 500 nm and 50 nm. Moreover, the membrane demonstrated superior separation performance for mixed wastewater, enabling effective treatment of a broad spectrum of contaminants. Additionally, the membrane exhibited excellent stability when exposed to strong acid and alkali environments and demonstrated good recyclability throughout the multiple contaminants removal process. The bionic membrane, prepared using a straightforward method proposed in this study, provides an effective approach for enhanced removal of multiple contaminants in water. These findings contribute to the advancement of eco-friendly and versatile wastewater treatment membranes, opening new possibilities for sustainable water purification technologies.

Going beyond Cellulose and Chitosan: Synthetic Biodegradable Membranes for Drinking Water, Wastewater, and Oil-Water Remediation

Membrane technology is an efficient way to purify water, but it generates non-biodegradable biohazardous waste. This waste ends up in landfills, incinerators, or microplastics, threatening the environment. To address this, research is being conducted to develop compostable alternatives that are sustainable and ecofriendly. Bioplastics, which are expected to capture 40% of the market share by 2030, represent one such alternative. This review examines the feasibility of using synthetic biodegradable materials beyond cellulose and chitosan for water treatment, considering cost, carbon footprint, and stability in mechanical, thermal, and chemical environments. Although biodegradable membranes have the potential to close the recycling loop, challenges such as brittleness and water stability limit their use in membrane applications. The review suggests approaches to tackle these issues and highlights recent advances in the field of biodegradable membranes for water purification. The end-of-life perspective of these materials is also discussed, as their recyclability and compostability are critical factors in reducing the environmental impact of membrane technology. This review underscores the need to develop sustainable alternatives to conventional membrane materials and suggests that biodegradable membranes have great potential to address this challenge.

Robustness of antiadhesion between nanofibers and surfaces covered with nanoripples of varying spatial period

Since nanofibers have a high surface-to-volume ratio, van der Waals forces render them attracted to virtually any surface. The high ratio provides significant advantages for applications in drug delivery, wound healing, tissue regeneration, and filtration. Cribellate spiders integrate thousands of nanofibers into their capture threads as an adhesive to immobilize their prey. These spiders have antiadhesive nanoripples on the calamistrum, a comb-like structure on their hindmost legs, and are thus an ideal model for investigating how nanofiber adhesion can be reduced. We found that these nanoripples had similar spacing in the cribellate species Uloborus plumipes, Amaurobius similis, and Menneus superciliosus, independent of phylogenetic relation and size. Ripple spacing on other body parts (i.e., cuticle, claws, and spinnerets), however, was less homogeneous. To investigate whether a specific distance between the ripples determines antiadhesion, we fabricated nanorippled foils by nanosecond UV laser processing. We varied the spatial periods of the nanoripples in the range ~203-613 nm. Using two different pulse numbers resulted in ripples of different heights. The antiadhesion was measured for all surfaces, showing that the effect is robust against alterations across the whole range of spatial periods tested. Motivated by these results, we fabricated irregular surface nanoripples with spacing in the range ~130-480 nm, which showed the same antiadhesive behavior. The tested surfaces may be useful in tools for handling nanofibers such as spoolers for single nanofibers, conveyor belts for producing endless nanofiber nonwoven, and cylindrical tools for fabricating tubular nanofiber nonwoven. Engineered fibers such as carbon nanotubes represent a further candidate application area.

Advanced Polymeric Nanocomposite Membranes for Water and Wastewater Treatment: A Comprehensive Review

Nanomaterials have been extensively used in polymer nanocomposite membranes due to the inclusion of unique features that enhance water and wastewater treatment performance. Compared to the pristine membranes, the incorporation of nanomodifiers not only improves membrane performance (water permeability, salt rejection, contaminant removal, selectivity), but also the intrinsic properties (hydrophilicity, porosity, antifouling properties, antimicrobial properties, mechanical, thermal, and chemical stability) of these membranes. This review focuses on applications of different types of nanomaterials: zero-dimensional (metal/metal oxide nanoparticles), one-dimensional (carbon nanotubes), two-dimensional (graphene and associated structures), and three-dimensional (zeolites and associated frameworks) nanomaterials combined with polymers towards novel polymeric nanocomposites for water and wastewater treatment applications. This review will show that combinations of nanomaterials and polymers impart enhanced features into the pristine membrane; however, the underlying issues associated with the modification processes and environmental impact of these membranes are less obvious. This review also highlights the utility of computational methods toward understanding the structural and functional properties of the membranes. Here, we highlight the fabrication methods, advantages, challenges, environmental impact, and future scope of these advanced polymeric nanocomposite membrane based systems for water and wastewater treatment applications.

Hemicelluloses-based sprayable and biodegradable pesticide mulch films for Chinese cabbage growth

In this study, one high-performance hemicelluloses (HC)-based sprayable and biodegradable pesticide mulch film was developed. Firstly, HC was transesterified with vinyl acetate (VA) to improve its solubility and film-forming ability. Then abamectin (ABA) was encapsulated by β-cyclodextrin (β-CD) to endow mulch film persistent anti-pesticide activity. After that, sodium alginate (SA) and gelatin were added to develop the mechanical performances of the mulch film. As a result, the obtained mulch film showed good characteristics, with optimum mechanical strength, elongation at break, water vapor permeability (WVP), swelling ratio (SR), and weight loss (biodegradability) of 7.9 ± 0.3 MPa, 43.6 ± 2.0 %, 2.1 ± 0.1 × 10^-11 g mm m^-2 s^-1 kPa^-1, 73.8 ± 2.0 %, and 69.3 %, respectively. After covering with mulch film, the soil moisture and temperature were developed to 90.8 % and 19.3 ± 0.2 °C, respectively, which could facilitate Chinese cabbage growth, with optimum germination rate of 98.6 ± 6.4 %.

Current status of microplastics and nanoplastics removal methods: Summary, comparison and prospect

In modern society, plastics also play an indispensable role in people's lives due to their various excellent properties. However, when these plastic products are discarded after being used, after being subjected to external influences, they will continue to be worn, damaged and degraded into micro- and nano-scale plastics, which are microplastics and nanoplastics (M/NPs). Although people's attention has been paid to M/NPs at present, the focus is still mainly on the detection and hazard of M/NPs, and how to remove M/NPs is relatively less popular. This review was written in order to draw the attention of more researchers to remove M/NPs. This review first briefly introduces the research background of M/NPs, and also shows the main analytical methods currently used for qualitative and quantitative M/NPs. Then, most of the current literature on the removal of M/NPs was collected, and they were classified, summarized, and introduced according to the classification of physical, physicochemical, and biological methods. The advantages and disadvantages of various methods are summarized, and they are also compared, which can help more researchers choose the appropriate method for research. In addition, the application scenarios of these methods are briefly introduced. Finally, some future research directions are proposed for the current research status of M/NPs removal. It is hoped that this will further promote the development on the method of removing M/NPs.

Electrospinning for the Modification of 3D Objects for the Potential Use in Tissue Engineering

Electrospinning is often investigated for biotechnological applications, such as tissue engineering and cell growth in general. In many cases, three-dimensional scaffolds would be advantageous to prepare tissues in a desired shape. Some studies thus investigated 3D-printed scaffolds decorated with electrospun nanofibers. Here, we report on the influence of 3D-printed substrates on fiber orientation and diameter of a nanofiber mat, directly electrospun on conductive and isolating 3D-printed objects, and show the effect of shadowing, taking 3D-printed ears with electrospun nanofiber mats as an example for potential and direct application in tissue engineering in general.

Turning food waste to antibacterial and biocompatible fungal chitin/chitosan monofilaments

Here, cell wall of a zygomycete fungus, Rhizopus delemar, grown on bread waste was wet spun into monofilaments. Using the whole cell wall material omits the common chitosan isolation and purification steps and leads to higher material utilization. The fungal cell wall contained 36.9% and 19.7% chitosan and chitin, respectively. Solid state NMR of the fungal cell wall material confirmed the presence of chitosan, chitin, and other carbohydrates. Hydrogels were prepared by ultrafine grinding of the cell wall, followed by addition of lactic acid to protonate the amino groups of chitosan, and subsequently wet spun into monofilaments. The monofilament inhibited the growth of Bacillus megaterium (Gram+ bacterium) and Escherichia coli (Gram- bacterium) significantly (92.2% and 99.7% respectively). Cytotoxicity was evaluated using an in vitro assay with human dermal fibroblasts, indicating no toxic inducement from exposure of the monofilaments. The antimicrobial and biocompatible fungal monofilaments, open new avenues for sustainable biomedical textiles from abundant food waste.

Electrospinning of Quaternized Chitosan-Poly(vinyl alcohol) Composite Nanofiber Membrane: Processing Optimization and Antibacterial Efficacy

N-(2-hydroxy) propyl-3-trimethylammonium chitosan chloride (HTCC) is a type of quaternary ammonium chitosan derivative with an antibacterial activity superior to the pristine chitosan, but its electrospinnability is limited. In this study, polyvinyl alcohol (PVA) was blended with HTCC to improve the electrospinnability of nanofibers. The electrospinning of PVA–HTCC nanofiber membranes was optimized in terms of structural stability and antimicrobial performance. Based on scanning electron microscopic analysis, the morphology and diameter of the produced nanofibers were influenced by the applied voltage, flow rate of the feed solution, and weight ratio of the polymer blend. An increase in the HTCC content decreased the average nanofiber diameter. The maximum water solubility of the PVA–HTCC nanofibers reached the maximum value of 70.92% at 12 h and 25 °C. The antibacterial activity of PVA–HTCC nanofiber membranes against Escherichia coli was ~90%, which is significantly higher than that of PVA–chitosan nanofiber membrane. Moreover, the antibacterial efficiency of PVA–HTCC nanofiber membranes remained unaffected after 5 cycles of antibacterial treatment. The good antibacterial performance and biocompatibility of PVA–HTCC nanofiber membrane makes them attractive for biomedical and biochemical applications that necessitate sterile conditions.

Application of Electrospun Nonwoven Fibers in Air Filters

Air filtration has seen a sizable increase in the global market this past year due to the COVID-19 pandemic. Nanofiber nonwoven mats are able to reach certain efficiencies with a low-pressure drop, have a very high surface area to volume ratio, filter out submicron particulates, and can customize the fiber material to better suit its purpose. Although electrospinning nonwoven mats have been very well studied and documented there are not many papers that combine them. This review touches on the various ways to manufacture nonwoven mats for use as an air filter, with an emphasis on electrospinning, the mechanisms by which the fibrous nonwoven air filter stops particles passing through, and ways that the nonwoven mats can be altered by morphology, structure, and material parameters. Metallic, ceramic, and organic nanoparticle coatings, as well as electrospinning solutions with these same materials and their properties and effects of air filtration, are explored.

Stretchable unidirectional liquid-transporting membrane with antibacterial and biocompatible features based on chitosan derivative and composite nanofibers

Unidirectional liquid transport is critical in achieving high-performance moisture-management fabrics for medical care. However, realizing unidirectional liquid transport while simultaneously satisfying other requirements, such as antibacterial function, adhesiveness, low cytotoxicity, and adequate mechanical strength remains a challenge. In this study, Janus nanofibrous membranes exhibiting both unidirectional liquid transport and antibacterial activity were fabricated via electrospinning and a mild crosslinking procedure. This membrane provides continuous and spontaneous unidirectional water transport with a high one-way transport value (R) of 1483%. The membrane achieved antibacterial rates of 99.2% and 98.7% against E. coli and S. aureus, respectively, without leaching antibacterial agents. In addition, it has high elasticity and self-adhesive properties, which facilitates its use in a range of applications. The design of this versatile Janus nanofibrous membrane provides a new strategy for developing novel moisture-wicking systems, particularly in the field of medical dressings.

Electrospinning of Chitosan for Antibacterial Applications—Current Trends

Chitosan is a natural biopolymer that can be suitable for a wide range of applications due to its biocompatibility, rigid structure, and biodegradability. Moreover, it has been proven to have an antibacterial effect against several bacteria strains by incorporating the advantages of the electrospinning technique, with which tailored nanofibrous scaffolds can be produced. A literature search is conducted in this review regarding the antibacterial effectiveness of chitosan-based nanofibers in the filtration, biomedicine, and food protection industries. The results are promising in terms of research into sustainable materials. This review focuses on the electrospinning of chitosan for antibacterial applications and shows current trends in this field. In addition, various aspects such as the parameters affecting the antibacterial properties of chitosan are presented, and the application areas of electrospun chitosan nanofibers in the fields of air and water filtration, food storage, wound treatment, and tissue engineering are discussed in more detail.

Recent developments in polysaccharide-based electrospun nanofibers for environmental applications

Electrospinning has become an inevitable approach to produce nanofibrous structures for diverse environmental applications. Polysaccharides, due to their variety of types, biobased origins, and eco-friendly, and renewable nature are wonderful materials for the said purpose. The present review discusses the electrospinning process, the parameters involved in the formation of electrospun nanofibers in general, and the polysaccharides in specific. The selection of materials to be electrospun depends on the processing conditions and properties deemed desirable for specific applications. Thereby, the conditions to electrospun polysaccharides-based nanofibers have been focused on for possible environmental applications including air filtration, water treatment, antimicrobial treatment, environmental sensing, and so forth. The polysaccharide-based electrospun membranes, for instance, due to their active adsorption sites could find significant potential for contaminants removal from the aqueous systems. The study also gives some recommendations to overcome any shortcomings faced during the electrospinning and environmental applications of polysaccharide-based matrices.

Electrospun Nanofibrous Membranes for Tissue Engineering and Cell Growth

In biotechnology, the field of cell cultivation is highly relevant. Cultivated cells can be used, for example, for the development of biopharmaceuticals and in tissue engineering. Commonly, mammalian cells are grown in bioreactors, T-flasks, well plates, etc., without a specific substrate. Nanofibrous mats, however, have been reported to promote cell growth, adhesion, and proliferation. Here, we give an overview of the different attempts at cultivating mammalian cells on electrospun nanofiber mats for biotechnological and biomedical purposes. Starting with a brief overview of the different electrospinning methods, resulting in random or defined fiber orientations in the nanofiber mats, we describe the typical materials used in cell growth applications in biotechnology and tissue engineering. The influence of using different surface morphologies and polymers or polymer blends on the possible application of such nanofiber mats for tissue engineering and other biotechnological applications is discussed. Polymer blends, in particular, can often be used to reach the required combination of mechanical and biological properties, making such nanofiber mats highly suitable for tissue engineering and other biotechnological or biomedical cell growth applications.

Chitin and chitosan on the nanoscale

In a matter of decades, nanomaterials from biomass, exemplified by nanocellulose, have rapidly transitioned from once being a subject of curiosity to an area of fervent research and development, now reaching the stages of commercialization and industrial relevance. Nanoscale chitin and chitosan, on the other hand, have only recently begun to raise interest. Attractive features such as excellent biocompatibility, antibacterial activity, immunogenicity, as well as the tuneable handles of their acetylamide (chitin) or primary amino (chitosan) functionalities indeed display promise in areas such as biomedical devices, catalysis, therapeutics, and more. Herein, we review recent progress in the fabrication and development of these bio-nanomaterials, describe in detail their properties, and discuss the initial successes in their applications. Comparisons are made to the dominant nanocelluose to highlight some of the inherent advantages that nanochitin and nanochitosan may possess in similar application.

Cost-Effective Face Mask Filter Based on Hybrid Composite Nanofibrous Layers with High Filtration Efficiency

One of the main protective measures against COVID-19's spread is the use of face masks. It is therefore of the utmost importance for face masks to be high functioning in terms of their filtration ability and comfort. Notwithstanding the prevalence of the commercial polypropylene face masks, its effectiveness is under contention, leaving vast room for improvement. During the pandemic, the use of at least one mask per day for each individual results in a massive number of masks that need to be safely disposed of. Fabricating biodegradable filters of high efficiency not only can protect individuals and save the environment but also can be sewed on reusable/washable cloth masks to reduce expenses. Wearing surgical masks for long periods of time, especially in hot regions, causes discomfort by irritating sensitive facial skin and warmed inhaled air. Herein, we demonstrate the fabrication of novel electrospun composites layers as face mask filters for protection against pathogens and tiny particulates. The combinatorial filter layers are made by integrating TiO₂ nanotubes as fillers into chitosan/poly(vinyl alcohol) polymeric electrospun nanofibers as the outer layer. The other two filler-free layers, chitosan/poly(vinyl alcohol) and silk/poly(vinyl alcohol) as the middle and inner composite layers, respectively, were used for controlled protection, contamination prevention, and comfort for prolonged usage. The ASTM standards evaluation tests were adopted to evaluate the efficacy of the assembled filter, revealing high filtration efficiency compared to that of commercial surgical masks. The TiO₂/Cs/PVA outer layer significantly reduced Staphylococcus aureus bacteria by 44.8% compared to the control, revealing the dual effect of TiO₂ and chitosan toward the infectious bacterial colonies. Additionally, molecular dynamics calculations were used to assess the mechanical properties of the filter layers.

Chitosan-Based Nanocomposite Polymeric Membranes for Water Purification-A Review

During the past few years, researchers have focused their attention on developing innovative nanocomposite polymeric membranes with applications in water purification. Natural and synthetic polymers were considered, and it was proven that chitosan-based materials presented important features. This review presents an overview regarding diverse materials used in developing innovative chitosan-based nanocomposite polymeric membranes for water purification. The first part of the review presents a detailed introduction about chitosan, highlighting the fact that is a biocompatible, biodegradable, low-cost, nontoxic biopolymer, having unique structure and interesting properties, and also antibacterial and antioxidant activities, reasons for using it in water treatment applications. To use chitosan-based materials for developing nanocomposite polymeric membranes for wastewater purification applications must enhance their performance by using different materials. In the second part of the review, the performance's features will be presented as a consequence of adding different nanoparticles, also showing the effect that those nanoparticles could bring on other polymeric membranes. Among these features, pollutant's retention and enhancing thermo-mechanical properties will be mentioned. The focus of the third section of the review will illustrate chitosan-based nanocomposite as polymeric membranes for water purification. Over the last few years, researchers have demonstrated that adsorbent nanocomposite polymeric membranes are powerful, important, and potential instruments in separation or removal of pollutants, such as heavy metals, dyes, and other toxic compounds presented in water systems. Lastly, we conclude this review with a summary of the most important applications of chitosan-based nanocomposite polymeric membranes and their perspectives in water purification.

Antibacterial efficacy of quaternized chitosan/poly (vinyl alcohol) nanofiber membrane crosslinked with blocked diisocyanate

N-[(2-hydroxyl-3-trimethylammonium) propyl] chitosan chloride (HTCC), which is a type of chitosan derivative with quaternary ammonium groups, possesses a higher antibacterial activity as compared to the pristine chitosan. The nanofiber membranes made of HTCC are attractive for applications demanding for antibacterial function. However, the hydrophilic nature of HTCC makes it unsuitable for electrospinning of nanofibers. Hence, biodegradable polyvinyl alcohol (PVA) was proposed as an additive to improve the electrospinnability of HTCC. In this work, PVA/HTCC nanofiber membrane was crosslinked with the blocked diisocyanate (BI) to enhance the stability of nanofiber membrane in water. Microbiological assessments showed that the PVA/HTCC/BI nanofiber membranes possessed a good antibacterial efficacy (∼100 %) against E. coli. Moreover, the biocompatibility of PVA/HTCC/BI nanofiber membrane was proven by the cytotoxicity test on mouse fibroblasts. These promising results indicated that the PVA/HTCC/BI nanofiber membrane can be a promising material for food packaging and as a potential wound dressing for skin regeneration.

Efficient removal of water bacteria and viruses using electrospun nanofibers

Pathogenic contamination has been considered as a significant worldwide water quality concern. Due to providing promising opportunities for the production of nanocomposite membranes with tailored porosity, adjustable pore size, and scaled-up ability of biomolecules incorporation, electrospinning has become the center of attention. This review intends to provide a detailed summary of the recent advances in the fabrication of antibacterial and antiviral electrospun nanofibers and discuss their application efficiency as a water filtration membrane. The current review attempts to give a functionalist perspective of the fundamental progress in construction strategies of antibacterial and antiviral electrospun nanofibers. The review provides a list of antibacterial and antiviral agents commonly used as water membrane filters and discusses the challenges in the incorporation process. We have thoroughly studied the recent application of functionalized electrospun nanofibers in the water disinfection process, with an emphasis on their efficiency. Moreover, different antibacterial and antiviral assay techniques for membranes are discussed, the gaps and limitations are highlighted and promising strategies to overcome barriers are studies.

Functionalization of 3D Chitinous Skeletal Scaffolds of Sponge Origin Using Silver Nanoparticles and Their Antibacterial Properties

Chitin, as one of nature's most abundant structural polysaccharides, possesses worldwide, high industrial potential and a functionality that is topically pertinent. Nowadays, the metallization of naturally predesigned, 3D chitinous scaffolds originating from marine sponges is drawing focused attention. These invertebrates represent a unique, renewable source of specialized chitin due to their ability to grow under marine farming conditions. In this study, the development of composite material in the form of 3D chitin-based skeletal scaffolds covered with silver nanoparticles (AgNPs) and Ag-bromide is described for the first time. Additionally, the antibacterial properties of the obtained materials and their possible applications as a water filtration system are also investigated.

A comparison of antibacterial inhibitory effect on Streptococcus mutans and tensile strength between chitosan-based bonding adhesives and commercial products

Background

Adhesive bonding is the material used to attach a bracket to the enamel surface of the tooth. Streptococcus mutans contributes to enamel demineralization during orthodontic treatment.

Objectives

To analyze the antimicrobial inhibitory effect of Streptococcus mutans bacteria and tensile strength of chitosan and CaCO₃-based adhesive bonding material.

Materials and Methods

The investigation constituted laboratory experimental research featuring analytical observation and a random sampling method. The antibacterial inhibitory effect of chitosan and CaCO₃-based adhesive bonding against Streptococcus mutans involved six groups: two control groups using commercial light cure and self-cure adhesive bonding products and four groups using adhesive bonding consisting of 75% CaCO₃ + 17.6% Bis-GMA + 22.4% MMA with various percentages of chitosan composition (A1: 25%, A2: 50%, A3: 75%, and A4: 100%) each group consisting of two samples (n = 12). A diametric test was conducted consisting of three samples (n = 15) to measure the tensile strength of each group. Data were analyzed by a combination of one-way analysis of variance and least significant difference tests.

Result

The antibacterial inhibitory effect showed significant differences between groups (A1: 2.9467 ± 0.4163, A2: 3.6500 ± 0.6245, A3: 5.1267 ± 0.2517, A4: 4.7267 ± 0.9238; P = 0.0000; P < 0.05). A diametric tensile strength test confirmed significant differences between groups (A1: 7.2733 ± 5.0046, A2: 6.7667 ± 4.4346, A3: 6.4533 ± 2.9994, A4: 1.0058 ± 1.0058, K1: 15.6167 ± 3.1250; P = 0.009; P < 0.05).

Conclusion

Chitosan-based adhesive bonding with good tensile strength has an antibacterial inhibitory effect against Streptococcus mutans.

New Materials Based on Cationic Porphyrins Conjugated to Chitosan or Titanium Dioxide: Synthesis, Characterization and Antimicrobial Efficacy

The post-functionalization of 5,10,15-tris(1-methylpyridinium-4-yl)-20-(pentafluorophenyl)porphyrin tri-iodide, known as a highly efficient photosensitizer (PS) for antimicrobial photodynamic therapy (aPDT), in the presence of 3- or 4-mercaptobenzoic acid, afforded two new tricationic porphyrins with adequate carboxylic pending groups to be immobilized on chitosan or titanium oxide. The structural characterization of the newly obtained materials confirmed the success of the porphyrin immobilization on the solid supports. The photophysical properties and the antimicrobial photodynamic efficacy of the non-immobilized porphyrins and of the new conjugates were evaluated. The results showed that the position of the carboxyl group in the mercapto units or the absence of these substituents in the porphyrin core could modulate the action of the photosensitizer towards the bioluminescent Gram-negative Escherichia coli bacterium. The antimicrobial activity was also influenced by the interaction between the photosensitizer and the type of support (chitosan or titanium dioxide). The new cationic porphyrins and some of the materials were shown to be very stable in PBS and effective in the photoinactivation of E. coli bacterium. The physicochemical properties of TiO2 allowed the interaction of the PS with its surface, increasing the absorption profile of TiO2, which enables the use of visible light, inactivating the bacteria more efficiently than the corresponding PS immobilized on chitosan.

Wet Relaxation of Electrospun Nanofiber Mats

Electrospinning can be used to produce nanofiber mats. One of the often used polymers for electrospinning is polyacrylonitrile (PAN), especially for the production of carbon nanofibers, but also for a diverse number of other applications. For some of these applications—e.g., creation of nano-filters—the dimensional stability of the nanofiber mats is crucial. While relaxation processes—especially dry, wet and washing relaxation—are well-known and often investigated for knitted fabrics, the dimensional stability of nanofiber mats has not yet been investigated. Here we report on the wet relaxation of PAN nanofiber mats, which are dependent on spinning and solution parameters such as: voltage, electrode distance, nanofiber mat thickness, and solid content in the solution. Our results show that wet relaxation has a significant effect on the samples, resulting in a dimensional change that has to be taken into account for nanofiber mats in wet applications. While the first and second soaking in pure water resulted in an increase of the nanofiber mat area up to approximately 5%, the dried sample, after the second soaking, conversely showed an area reduced by a maximum of 5%. For soaking in soap water, small areal decreases between approximately 1–4% were measured.

Characterization and Microstructure of Linear Electrode-Electrospun Graphene-Filled Polyvinyl Alcohol Nanofiber Films

With the aim of achieving controllable mass production of electrospun nanofiber films, this study proposes and investigates the feasibility of using a custom-made linear electrode- electrospun device to produce conductive graphene (GR)-filled polyvinyl alcohol (PVA) nanofibers. The film morphology and diameter of nanofibers are observed and measured to examine the effects of viscosity and conductivity of the PVA/GR mixtures. Likewise, the influence of the content of graphene on the hydrophilicity, electrical conductivity, electromagnetic interference shielding effectiveness (EMSE), and thermal stability of the PVA/GR nanofiber films is investigated. The test results show that the PVA/GR mixture has greater viscosity and electric conductivity than pure PVA solution and can be electrospun into PVA/GR nanofiber films that have good morphology and diameter distribution. The diameter of the nanofibers is 100 nm and the yield is 2.24 g/h, suggesting that the process qualifies for use in large-scale production. Increasing the content of graphene yields finer nanofibers, a smaller surface contact angle, and higher hydrophilicity of the nanofiber films. The presence of graphene is proven to improve the thermal stability and strengthens the EMSE by 20 dB at 150–1500 MHz. Mass production is proven to be feasible by the test results showing that PVA/GR nanofiber films can be used in the medical hygiene field.