Electrospun Nanofibrous Membranes Research Articles

Bioassay-guided fractionation of Verbascum thapsus extract and its combination with polyvinyl alcohol in the form electrospun nanofibrous membrane for efficient wound dressing application

Verbascum thapsus (V. thpsus), family Scrophulariaceae, has considerable importance in traditional medicine worldwide because of its antioxidant and anti-inflammatory activities. V. thpsus was used in traditional medicines as a useful drug for lung disease, sore throat, wound healing, and treatment of whooping cough. The aim of this study was to extract of V. thpsus bioactive fraction using antibacterial assay guided fractionation methodology and develop a system based on electrospun nanofibrous membrane (NFM) that can be effective by releasing the extract of V. thapsus for antibacterial and wound healing applications. For this purpose, the fractionation of total extract was done using Liquid-Liquid extraction method. The selected fraction based on its anti-bacterial activity was then subjected to the silica gel column chromatography for further purification. Since electrospinning is an economical and relatively simple method to produce continuous and uniform nanofibers, and due to its high specific surface area, adjustable pore size, and flexibility, special attention has been paid to loaded the most effective fraction on PVA nanofibers for applications such as wound dressings. The obtained result showed that, the purified V. Thapsus extract has a concentration-dependent antimicrobial activity against Escherichia coli and Staphylococcus aureus. The phytochemically analyses of bioactive fraction by High-performance liquid chromatography (HPLC) proved the presence of 6 phenolic acids, 4-hydroxybenzoic acid, chlorogenic acid, caffeic acid, p-coumaric acid, ferulic acid, and flavonoid, rutin, as the major compounds. Also, physicochemical characterization of PVA-selected extract loaded electrospun nanofibrous membranes (NFM) were analyzed by scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR). MTT and hemolysis assays were done to affirm the biocompatibility of fabricated scaffolds. Release profile of extract loaded- NFM showed continues release of extract from mat during 90h. Moreover, the capability of these NFM in wound healing application was evaluated in-vitro and in-vivo. The cell viability test (MTT), cell adhesion images, antioxidant, antibacterial, hemolysis assays and in-vitro and in-vivo wound healing assays confirmed that fabricated NFM containing 5 % butanolic extract were the most biocompatible scaffold for wound dressing applications and accelerates the rate of wound closure. The obtained outcomes confirmed that V. thpsus/PVA NFM can be considered as promising scaffold for potential wound dressings.

Polydopamine-mediated immobilization of BMP-2 onto electrospun nanofibers enhances bone regeneration

Dealing with bone defects is a significant challenge to global health. Electrospinning in bone tissue engineering has emerged as a solution to this problem. In this study, we designed a PVDF-b-PTFE block copolymer by incorporating TFE, which induced a phase shift in PVDF from α to β, thereby enhancing the piezoelectric effect. Utilizing the electrospinning process, we not only converted the material into a film with a significant surface area and high porosity but also intensified the piezoelectric effect. Then we used polydopamine to immobilize BMP-2 onto PVDF-b-PTFE electrospun nanofibrous membranes, achieving a controlled release of BMP-2. The scaffold’s characters were examined using SEM and XRD. To assess its osteogenic effects in vitro, we monitored the proliferation of MC3T3-E1 cells on the fibers, conducted ARS staining, and measured the expression of osteogenic genes. In vivo, bone regeneration effects were analyzed through micro-CT scanning and HE staining. ELISA assays confirmed that the sustained release of BMP-2 can be maintained for at least 28 d. SEM images and CCK-8 results demonstrated enhanced cell viability and improved adhesion in the experimental group. Furthermore, the experimental group exhibited more calcium nodules and higher expression levels of osteogenic genes, including COL-I, OCN, and RUNX2. HE staining and micro-CT scans revealed enhanced bone tissue regeneration in the defective area of the PDB group. Through extensive experimentation, we evaluated the scaffold’s effectiveness in augmenting osteoblast proliferation and differentiation. This study emphasized the potential of piezoelectric PVDF-b-PTFE nanofibrous membranes with controlled BMP-2 release as a promising approach for bone tissue engineering, providing a viable solution for addressing bone defects.

A robust polypyrrole nanofibrous membrane for versatile applications: Oil-water separation and dye removal

Integrated approaches to oil-water separation and water remediation have significant implications for industrial applications and environmental sustainability. In this study, we focused on developing a versatile polypyrrole nanofibrous membrane (PPy NFM) based on electrospun nanofibrous membrane for the simultaneous and efficient separation of oil-in-water emulsions and removal of dyes from wastewater. PPy NFM with hydrophilicity and underwater oleophobicity exhibited good emulsion separation efficiency (96.7 %) after 20 cycles of gravity-driven filtration. It is also highly resistant to harsh environments, including strong acids, bases, and high-concentration salts. Additionally, PPy NFM demonstrates remarkable removal efficiency for anionic dyes (91.9 % ∼ 99.3 % at natural pH) and cationic dyes (41.3 % ∼ 58.0 % at pH=10) with a strong affinity towards anionic dyes, through multiple interactions, including electrostatic forces, π-π stacking, and hydrogen bonding, as supported by experimental evidence and computational simulations. These results highlight the tremendous application potential of PPy NFM in simultaneous oil-water separation and dye removal.

High Permeance Polyamide Nanofiltration Membranes Based on Poly(l-lactic acid) Electrospun Nanofibrous Membranes with Controlled Hydrophilicity

High Permeance Polyamide Nanofiltration Membranes Based on Poly(<scp>l</scp>-lactic acid) Electrospun Nanofibrous Membranes with Controlled Hydrophilicity

Cytocompatibility of electrospun poly-L-lactic acid membranes for Bruch's membrane regeneration using human embryonic stem cell-derived retinal pigment epithelial cells.

Cell replacement therapy is under development for dry age-related macular degeneration (AMD). A thin membrane resembling the Bruch's membrane is required to form a cell-on-membrane construct with retinal pigment epithelial (RPE) cells. These cells have been differentiated from human embryonic stem cells (hESCs) in vitro. A carrier membrane is required for cell implantation, which is biocompatible for cell growth and has dimensions and physical properties resembling the Bruch's membrane. Here a nanofiber electrospun poly-L-lactic acid (PLLA) membrane is tested for capacity to support cell growth and maturation. The requirements for laminin coating of the membrane are identified here. A porous electrospun nanofibrous PLLA membrane of ∼50 nm fiber diameter was developed as a prototype support for functional RPE cells grown as a monolayer. The need for laminin coating applied to the membrane following treatment with poly-L-ornithine (PLO), was identified in terms of cell growth and survival. Test membranes were compared in terms of hydrophilicity after laminin coating, mechanical properties of surface roughness and Young's modulus, porosity and ability to promote the attachment and proliferation of hESC-RPE cells in culture for up to 8 weeks. Over this time, RPE cell proliferation, morphology, and marker and gene expression, were monitored. The functional capacity of cell monolayers was identified in terms of transepithelial electrical resistance (TEER), phagocytosis of cells, as well as expression of the cytokines, vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF). PLLA polymer fibers are naturally hydrophobic, so their hydrophilicity was improved by pretreatment with PLO for subsequent coating with the bioactive protein laminin. They were then assessed for amount of laminin adsorbed, contact angle and uniformity of coating using scanning electron microscopy (SEM). Pretreatment with 100% PLO gave the best result over 10% PLO treatment or no treatment prior to laminin adsorption with significantly greater surface stiffness and modulus. By 6 weeks after cell plating, the coated membranes could support a mature RPE monolayer showing a dense apical microvillus structure and pigmented 3D polygonal cell morphology. After 8 weeks, PLO (100%)-Lam coated membranes exhibited the highest cell number, cell proliferation, and RPE barrier function measured as TEER. RPE cells showed the higher levels of specific surface marker and gene expression. Microphthalmia-associated transcription factor expression was highly upregulated indicating maturation of cells. Functionality of cells was indicated by expression of VEGF and PEDF genes as well as phagocytic capacity. In conclusion, electrospun PLLA membranes coated with PLO-Lam have the physical and biological properties to support the distribution and migration of hESC-RPE cells throughout the whole structure. They represent a good membrane candidate for preparation of hESC-RPE cells as a monolayer for implantation into the subretinal space of AMD patients.

Antimicrobial and Antiviral Nanofibers Halt Co-Infection Spread via Nuclease-Mimicry and Photocatalysis.

The escalating spread of drug-resistant bacteria and viruses is a grave concern for global health. Nucleic acids dominate the drug-resistance and transmission of pathogenic microbes. Here, imidazolium-type poly(ionic liquid)/porphyrin (PIL-P) based electrospun nanofibrous membrane and its cerium (IV) ion complex (PIL-P-Ce) are developed. The obtained PIL-P-Ce membrane exhibits high and stable efficiency in eradicating various microorganisms (bacteria, fungi, and viruses) and decomposing microbial antibiotic resistance genes and viral nucleic acids under light. The nuclease-mimetic and photocatalytic mechanisms of the PIL-P-Ce are elucidated. Co-infection wound models in mice with methicillin-resistant S. aureus and hepatitis B virus demonstrate that PIL-P-Ce integrate the triple effects of cationic polymer, photocatalysis, and nuclease-mimetic activities. As revealed by proteomic analysis, PIL-P-Ce shows minimal phototoxicity to normal tissues. Hence, PIL-P-Ce has potential as a "green" wound dressing to curb the spread of drug-resistant bacteria and viruses in clinical settings.

Lactosporin loaded electrospun nanofibrous membrane: Novel antibacterial and wound dressing patch

IntroductionAny disruption in the cohesion of skin tissue is called a skin ulcer. If the skin lesion is a superficial lesion, it heals easily. But some wounds, such as diabetic wounds, bedsores, and burns, are difficult to heal and are often associated with infection. Therefore, one of the new methods used to treat such wounds is skin patch. MethodIn this study, partly purified lactosporin (LP), as novel postbiotic, was extracted from Bacillus coagulans, and its antibacterial properties against six bacterial species, namely Escherichia coli, Micrococcus Luteus, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermis, and Klebsiella pneumonia were investigated. An electrospun nanofibrous membrane (NFM) containing LP was electrospun based on the three polymers including hyaluronic acid (HA), chitosan, and polyvinyl alcohol (PVA) and its potential for biomedical applications was analized. The morphological characteristics, hydrophilic properties, cytotoxicity, and wound healing potential of LP-loaded NFMs were investigated. ResultsIt was revealed that extracted LP includes supperior antibacterial properties, which is beneficial for developing wound dressing patches. The results showed fabricated composite NFMs are bead-free and uniform. The average diameter of uncross-linked and cross-linked nanofibers are 281 ± 10 nm and 359 ± 51 nm, respectively. These NFMs are hydrophilic in both cross-linked and uncross-linked forms and the contact angles of them were 39 and 13°, respectively. These NFMs were also tested for cytotoxicity by the MTT assay and were found to be non-toxic. ConclusionThese results indicate that HA/CS/PVA/LP NFM could act as an efficient antibacterial and multifunctional wound dressing patch.

State-of-the-art of electrospun nanocomposite nanofibers and membranes with carbon nanoparticles—Prevailing progressions

This state-of-the-art overview emphasizes electrospinning technique and resulting electrospun nanofibers and nanofibrous membranes. Consequently, the electrospinning method as well as the formation and features of the electrospun nanofiber/membrane nanomaterials have been described. Properties of the electrospun nanofibers have found to be enhanced several folds through the incorporation of carbon nanoparticles in the nanofibers. Important properties and utilizations of carbon nanocomposite electrospun nanofibers were seemed to be affected by nanoparticle amount and dispersal. Importantly, diameter, microstructure, and physical features (thermal, mechanical, conductive, etc.) of the nanofibers and resulting membranes can be affected by the nanofiller behavior. The high performance electrospun nanofibers have been used to form efficient nanocomposite nanofibrous membranes. Sequentially, the electrospun nanocomposite nanofibrous membranes have been applied in technical membrane applications.

Introduction of an electrospun nanofibrous membrane incorporated by metal-organic framework-199 (MOF-199) with Lewis acid property for efficient extraction of sulfonamides in on-chip electromembrane extraction

In this study, a new supporting polymeric membrane having Lewis acid nature was introduced for immobilizing organic solvent in on-chip electromembrane extraction (on-chip EME). For this aim, a polymeric nanofibrous membrane incorporated by a copper based metal-organic framework (MOF-199), with coordinatively unsaturated metal sites and Lewis acid property, was prepared by electrospinning a mixture of polycaprolactone (PCL) and MOF-199. Based on the field emission scanning electron microscopy images, the obtained polymeric membrane consisted of intertwined nanofibers having empty space between the fibers which could provide a suitable place for immobilizing the organic solvent. To demonstrate remarkable extractability of the proposed membrane (PCL/MOF-199 nanofibers) via executing Lewis acid-base interactions, three sulfonamide drugs was selected as anionic polar analytes with Lewis base feature. The parameters affecting the extraction efficiency of the method were optimized through the experimental design method using the orthogonal and rotatable central composite design (CCD). Under optimum conditions, the extraction recoveries ranging from 35.5 to 71.2 %, the relative standard deviations (RSD%) less than 6.45 %, and the detection limits in the range of 0.2–0.5 μg L−1 were achieved. The comparison of the extraction efficiency of the on-chip EME method using the electrospun PCL/MOF-199 nanofibers and PCL nanofibers membranes indicated that the proposed membrane was more efficient for extraction of sulfonamides because of the significant Lewis acid-base interactions of sulfonamides with copper uncoordinated open sites in MOF-199. Finally, the performance of the proposed method for extraction and determination of sulfonamides in three real samples was assayed.

Gamma-irradiated janus electrospun nanofiber membranes for desalination and nuclear wastewater treatment

This study presents the fabrication of double-layer electrospun nanofibrous membranes (DL-ENMs) using polyvinylidene fluoride (PVDF) and polyether sulfone (PES) based polymers with different degrees of hydrophilicity (PES, sulfonated PES, and PES with hydroxyl terminals). A comparative analysis was carried out with single-layer electrospun nanofiber membranes (SL-ENM) with a total thickness of about 375 μm. Using feed solutions, including sodium chloride, sodium nitrate, and simulated nuclear wastewater (SNWW), the performance of DL-ENMs was evaluated for desalination and radionuclide decontamination by direct contact membrane distillation (DCMD) and air gap membrane distillation (AGMD) techniques. The results showed that DL-ENMs, especially those incorporating a sulfonated PES-based hydrophilic layer, exhibited superior permeate fluxes, reaching values of 72.72 kg/m2.h and 73.27 kg/m2.h in the DCMD using aqueous feed solutions of NaCl and NaNO3, respectively, and 70.80 kg/m2.h and 41.96 kg/m2.h using aqueous feed solutions of SNWW in DCMD and AGMD, respectively. Both SL-ENMs and DL-ENMs exhibited high rejection efficiencies and decontamination factors for the feed solutions (>99.9%). In addition, the prepared ENMs were exposed to gamma radiation to evaluate their applicability in real-life applications. The result of irradiation revealed the negative impact of gamma radiation on the fluorine content of PVDF which could be a critical point in using PVDF as a hydrophobic material for decontaminating nuclear wastewater by membrane distillation.

Coaxial electrospun PVA-SAP functional nanofibers embedded with betel leaf extract for enhanced germicidal activity and breathability

This study investigates the formation of coaxial electrospun nanofibrous membrane with enhanced germicidal activity and breathability using superabsorbent polymer and polyvinyl alcohol integrated with betel leaf extract and its utilization for developing performance textiles. The functional nanofibrous membrane was fabricated through the coaxial electrospinning technique and characterized for the intended applications. The morphological investigation of the developed nano-membrane using scanning electron microscopy revealed the formation of regular nanofibers with diameters ranging from 154 to 200 nm. The FTIR spectra suggested the existence of functional compounds in the nanofibers from their characteristic peaks. The presence of the bioactive compounds in the ethanolic extract of betel leaf was explored using phytochemical screening. The analysis of antibacterial activity against S. aureus and E.coli using the agar disc diffusion method showed an enhanced zone of inhibition with a maximum dimension of 27 mm and 24 mm against S. aureus and E.coli, respectively. The developed coaxial nanofibrous membranes also demonstrated acceptable particle barrier performance with greater than 95 % efficiency and a superior tensile strength of 99.5 N. Besides, the improved moisture management and air permeability of coaxial nano-membranes embedded with betel leaf extracts suggested an easy transfer of fluid and moisture vapor from the body to the environment via the membrane. Hence, the improved germicidal activity with acceptable particle filtration efficiency and enhanced breathability of the developed coaxial electrospun nano-membranes indicated their potentiality of utilizing them in designing performance textiles with simultaneous barrier performance and breathability for comfort.

Novel simulation of the blood–brain barrier using the polyacrylonitrile electrospun nanofibrous membrane on 3D‐printed Transwell

AbstractThe blood–brain barrier (BBB) possesses an intricate structure and set of characteristics that effectively restricts the transportation of substances to the central nervous system. Consequently, the development of pharmaceuticals for brain disorders poses significant hurdles. Numerous attempts have been made to produce innovative simulates of BBB that exhibit a striking resemblance to BBB and are suitable for efficient drug screening, as well as being user‐friendly and easily reproducible. One of the models available is the commercial Transwell® system. In this system, chosen endothelial cells form a single layer on the rigid membrane of the upper chamber. In the present study, the two‐dimensional structure of this membrane was exchanged with a three‐dimensional membrane using the 3D printing method and developed a novel approach to fabricate the scaffold in one step on the fabricated Transwell. This novel method of horizontal electrospinning has reduced the mechanical damage associated with conventional vertical electrospinning, resulting in suitable mechanical properties for cell culture. The lower diameter of the nanofibers, the thickness of the mesh, bulk Young's modulus and hydrophobicity compared to conventional mesh‐based counterparts are characteristics which make it more similar to the natural basement membrane and improve cell culture necessities on the scaffold. The designed BBB model was characterized via cell morphology, trans‐endothelial electrical resistance, and permeability value. This human BBB model formed robust cell integrity and achieved the acceptable range of TEER and low permeability that confirm the polyacrylonitrile (PAN) scaffold as an in vitro cell culture platform with promising cell culture results of the brain microvascular endothelial cell line hCMEC/D3.

Polycaprolactone/chitosan electrospun nanofibrous membranes loaded Chinese yam polysaccharide for active food packaging

In this study, the electrospun nanofibrous membranes were prepared by blending electrospinning technology with Polycaprolactone/Chitosan (PCL/CS) as a spinning carrier and Chinese Yam Polysaccharide (CYP) as active material. The membranes were characterized and antimicrobial tested to determine whether they have potential value as food packaging. The results of SEM showed that the nanofiber membranes with different concentrations had good fiber morphology, the average fiber diameter was 313 ± 178 nm–426 ± 237 nm, and the PDI value indicated that the nanofiber was polydisperse. The addition of CYP enhanced the hydrophilicity and water solubility of the nanofiber membranes, but the mechanical strength of the membranes decreased. The spectra of FTIR and DSC indicated that the PCL/CS nanofiber membrane successfully loaded CYP, and the 4 % CYP nanofiber membrane had the best thermal stability. In vitro release tests also showed that most fibrous membranes still released CYP (56.4–81.7 %) after 240 h. In addition, the antibacterial zone diameter of PCL/CS/10 % CYP nanofiber membrane against Escherichia coli and Staphylococcus aureus was 22.01 ± 1.23 mm and 18.40 ± 0.84 mm, respectively, showing obvious antibacterial effect. In the tomato antibacterial experiment, PCL/CS/10 % CYP nanofiber membrane effectively delayed the water-loss rot of cherry tomato and kept the weight loss rate of fruit at 17.6 ± 0.14 %. The results showed that PCL/CS/10% CYP nanofiber membrane had the best effect as active food packaging.

In-situ polymerization of PANI nanocone array on PEN nanofibrous membranes for solar-driven interfacial evaporation

Solar-driven interfacial evaporation (SDIE) holds great potential for desalination, but it also poses challenges to application performance. Herein, a novel polyaniline (PANI) modified polyarylene ether nitrile (PEN) electrospun nanofibrous membranes (PANI@PEN) was developed by introducing PDA and CTAB, which increased the polymerization amount of PANI and controlled its morphology by sequential in-situ polymerization, aiming to enhance its SDIE comprehensive performance. This unique structure can generate multiple diffuse reflections under sunlight, resulting in the highest water evaporation rate of the nanofibrous membrane at 1.822 kg m−2 h−1, while evaporation rate at 1.527 kg m−2 h−1 for a 3.5 wt% sodium chloride solution. Due to the good flexibility of PEN polymer substrate, the obtained membranes can be easily arched, showcasing an interesting ability to collect salt through salt deposition. Meanwhile, PEN also provides a robust skeleton, endowed PANI@PENs with corrosion-resistant, capable of desalination in acidic media, purifying heavy metal ion solutions through evaporation, as well as good mechanical properties for reusability. The study potentially provides a strategy for utilizing dopamine and CTAB loaded on high-performance polymer nanofibrous membranes and the convenient in-situ polymerization to generate advanced photothermal PANI. This strategy paves a way to enable high-performance engineering polymer, PEN, with solar-thermal evaporation capabilities, further opening its potential applications in seawater desalination and industrial wastewater purification.

The Potential of Electrospun Membranes in the Treatment of Textile Wastewater: A Review.

Water security and industrial wastewater treatment are significant global concerns. One of the main issues with environmental contamination has been the discharge of dye wastewater from the textile and dye industries, contributing to an ever-growing problem with water pollution, poisoning water supplies, and harming the ecosystem. The traditional approach to wastewater treatment has been found to be inefficient, and biosorption techniques and mechanisms have been proven to be a successful replacement for conventional methods. Recent developments have led to the recognition of fibrous materials as an environmentally friendly option with broad application in several industries, including wastewater treatment. This review explores the potential of fibrous materials produced by the electrospinning technique as adsorbents for wastewater treatment, while at the same time, for the removal of adsorbates such as oil, dyes, heavy metals, and other substances, as reported in the literature. Textile wastewater filtering structures, produced by electrospinning, are summarized and the use of synthetic and natural polymers for this purpose is discussed. The limitations of electrospun textile wastewater filtering structures are also mentioned. Electrospun nanofibrous membranes appear to be a very promising route to filter textile wastewater and therefore contribute to water reuse and to reducing the contamination of water courses.

High-efficient and intelligent antibacterial face mask integrated with airflow-temperature dual-function sensors for respiratory monitoring and disease prevention

Intelligent face masks play crucial roles in health monitoring and disease prevention, having attracted huge attention in recent years. However, most of the current intelligent face masks focus on monitoring single physical signal, which were unable to provide comprehensive information. Herein, an intelligent face mask with airflow and temperature sensing abilities, high-efficiency filtration and excellent antibacterial activity was proposed. The real-time airflow monitoring was realized by a triboelectric nanogenerator (TENG), which was composed of electrospun nanofibrous membrane and polydimethylsiloxane (PDMS) composite film. The fabricated electrospun nanofibrous membrane simultaneously played roles as tribo-positive material, filter and antibacterial membrane. The PDMS composite film prepared by co-blending and surface modification was applied as tribo-negative material. It was found that the combination of co-blending and surface modification enhanced the tribo-negative property of the PDMS film, resulting in an increment of output performance of TENG. The TENG integrated into a face mask could monitor respiratory rate and respiration intensity in real time. Additionally, the temperature sensing was achieved by a serpentine PDMS/laser-induced graphene temperature sensor. The temperature sensor exhibited a temperature coefficient of resistance of 0.316% °C−1, which could detect subtle temperature variations. Furthermore, the electrospun nanofibrous membrane exhibited excellent filtration performance and antibacterial activity. Therefore, the prepared intelligent face mask showed promising potential for healthcare applications.

Polyamide Electrospun Nanofibers Functionalized with Silica and Titanium Dioxide Nanoparticles for Efficient Dye Removal

In this work, novel multifunctional electrospun nanofibrous membranes made of polyamide (PA6) and loaded with silica (SiO2) and/or titanium dioxide (TiO2) nanoparticles were fabricated. SiO2 NPs were first prepared and then characterized by TEM, FE-SEM, and FTIR, and by using XRD techniques, confirming the formation of cristobalite tetragonal crystals with high purity. Different nanofibrous mats, loaded with SiO2 NPs, TiO2 NPs, or both SiO2 and TiO2 NPs, were investigated. Morphological studies indicated that SiO2 and TiO2 nanoparticles tend to be arranged along the fiber surface, also promoting the formation of anatase nanorods when they are mixed into the nanofibers. In this last scenario, mechanical tests have demonstrated that the presence of SiO2 contributed to balancing the mechanical response of fibers that are negatively affected by the presence of TiO2 NPs—as confirmed by tensile tests. More interestingly, the presence of SiO2 did not negatively affect the antibacterial response against different bacteria populations (i.e., Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, Bacillus subtilis, and Candida albicans), which is mainly ascribable to the presence of TiO2 particles. Accordingly, the TiO2- and TiO2/SiO2-loaded fibers showed higher methylene blue (MB) absorption values—i.e., 26 mg/g and 27 mg/g—respectively, compared to the SiO2-loaded fibers (23 mg/g), with kinetics in good agreement with the second-order kinetic model. The obtained findings pave the way for the formation of novel antibacterial membranes with a promising use in water purification.

Chitosan-Stabilized CuO Nanostructure-Functionalized UV-Crosslinked PVA/Chitosan Electrospun Membrane as Enhanced Wound Dressing.

Electrospun nanofibrous membranes are of great interest for tissue engineering, active material delivery, and wound dressing. These nanofibers possess unique three-dimensional (3D) interconnected porous structures that result in a higher surface-area-to-volume ratio and porosity. This study was carried out to prepare nanofibrous membranes by electrospinning a blend of PVA/chitosan polymeric solution functionalized with different ratios of copper oxide. Chitosan-stabilized CuO nanoparticles (CH-CuO NPs) were biosynthesized successfully utilizing chitosan as the capping and reducing agent. XRD analysis confirmed the monoclinic structure of CH-CuO NPs. In addition, the electrospun nanofibrous membranes were UV-crosslinked for a definite time. The membranes containing CH-CuO NPs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-vis) spectrophotometry, and dynamic light scattering (DLS). SEM results showed the nanosize of the fiber diameter in the range of 147-207 nm. The FTIR spectroscopy results indicated the successful incorporation of CH-CuO NPs into the PVA/chitosan nanofibrous membranes. DSC analysis proved the enhanced thermal stability of the nanofibrous membranes due to UV-crosslinking. Swelling and degradation tests were carried out to ensure membrane stability. Greater antimicrobial activity was observed in the nanoparticle-loaded membrane. An in vitro release study of Cu2+ ions from the membrane was carried out for 24 h. The cytotoxicity of CH-CuO NP-incorporated membranes was investigated to estimate the safe dose of nanoparticles. An in vivo test using the CH-CuO NP-loaded PVA/chitosan membrane was conducted on a mice model, in which wound healing occurred in approximately 12 days. These results confirmed that the biocompatible, nontoxic nanofibrous membranes are ideal for wound-dressing applications.

Tuning and optimization of structure and surface properties of thin and fine hydrophilic nanofibrous substrates through low‐pressure heat‐press treatment

AbstractThe properties of electrospun nanofibrous membranes (ENMs), including pore size, surface roughness, and hydrophilicity, significantly affect crosslinking, thickness, and morphology of the polyamide selective layer formed on top of ENM substrate in thin film composite membranes, and, ultimately the performance of membranes. We produced polyamide 66 nanofiber layers with a thickness of 10 μm and a fiber diameter of 55 nm, considerably thinner and finer than usual ENM substrates. We then subjected this thin layer to post‐production treatment using the efficient low‐pressure heat‐press (LPHP) method at a pressure of 3 kPa at three different temperatures and two different time intervals. It was found that the morphology of the nanofiber layer was preserved, and its structural characteristics, including pore structure, surface roughness, wettability, crystallinity, and specific surface area, were favorable with LPHP treatment. The optimal conditions were obtained with treatment at 190°C for 3600 s, in which the roughness of the nanofiber substrate decreased from 64 to 25 nm. Using these substrates offers new, less‐explored opportunities for optimizing the LPHP treatment of the substrate. These substrates are proposed for a new generation of TFC membranes in a continuous production line, with the possibility of scaling up for pressure‐ and osmosis‐driven membranes.

Graphene and its derivatives for air purification: A mini review

Acceleration of industrialization causes an increase in concentration of greenhouse gases (GHGs), particularly CO2, as well as particulate matter in the air. Therefore, it is necessary to develop strategies for the elimination of GHGs. Graphene and its derivatives were reported to be excellent candidates for CO2 adsorption and also for the removal of particulate matter by air filtration. For the fabrication of air filtration membranes, by using graphene/graphene derivatives, they were incorporated with certain polymers such as polyacrylonitrile and made into nanofibrous membranes. Electrospun nanofibrous membranes are characterised by high porosity, small pore size and excellent connectivity, have been found to be a promising candidate for air filtration. The review article focuses on two aspects of air purification, first part discuss the use of graphene/graphene derivatives for CO2 adsorption and the second part discuss the use of graphene based electrospun nanofibrous membranes for particulate matter removal. The factors influencing the efficiency of filtration has been discussed in detail.