Electrospinning of sodium alginate with poly(ethylene oxide)

Multi-functional dual-layer nanofibrous membrane for prevention of postoperative pancreatic leakage

Postoperative pancreatic leakage due to pancreatitis in patients is a life-threatening surgical complication. The majority of commercial barriers are unable to meet the demands for pancreatic leakage due to poor adhesiveness, toxicity, and inability to degrade. In this study, we fabricated mitomycin-c and thrombin-loaded multifunctional dual-layer nanofibrous membrane with a combination of alginate, PCL, and gelatin to resolve the leakage due to suture line disruption, promote hemostasis, wound healing, and prevent postoperative tissue adhesion. Electrospinning was used to fabricate the dual-layer system. The study results demonstrated that high gelatin and alginate content in the inner layer decreased the fiber diameter and water contact angle, and crosslinking allowed the membrane to be more hydrophilic, making it highly biodegradable, and adhering firmly to the tissue surfaces. The results of in vitro biocompatibility and hemostatic assay revealed that the dual-layer had a higher cell proliferation and showed effective hemostatic properties. Moreover, the in vivo studies and in silico molecular simulation indicated that the dual layer was covered at the wound site, prevented suture disruption and leakage, inhibited hemorrhage, and reduced postoperative tissue adhesion. Finally, the study results proved that dual-layer multifunctional nanofibrous membrane has a promising therapeutic potential in preventing postoperative pancreatic leakage.

Sublingual Administration of Teucrium Polium-Loaded Nanofibers with Ultra-Fast Release in the Treatment of Diabetes Mellitus: In Vitro and In Vivo Evaluation

In this study, Teucrium polium (TP) methanolic extract, which has antidiabetic activity and protects the β-cells of the pancreas, was loaded in polyethylene oxide/sodium alginate nanofibers by electrospinning and administered sublingually to evaluate their effectiveness in type-2 diabetes mellitus (T2DM) by cell culture and in vivo studies. The gene expressions of insulin, glucokinase, GLUT-1, and GLUT-2 improved in TP-loaded nanofibers (TPF) on human beta cells 1.1B4 and rat beta cells BRIN-BD11. Fast-dissolving (<120 s) sublingual TPF exhibited better sustainable anti-diabetic activity than the suspension form, even in the twenty times lower dosage in streptozotocin/nicotinamide-induced T2DM rats. The levels of GLP-1, GLUT-2, SGLT-2, PPAR-γ, insulin, and tumor necrosis factor-alpha were improved. TP and TPF treatments ameliorated morphological changes in the liver, pancreas, and kidney. The fiber diameter increased, tensile strength decreased, and the working temperature range enlarged by loading TP in fibers. Thus, TPF has proven to be a novel supportive treatment approach for T2DM with the features of being non-toxic, easy to use, and effective.

Development of hybrid electrospun alginate-pulverized moringa composites

The consideration of biopolymers with natural products offers promising and effective materials with intrinsic and extrinsic properties that are utilized in several applications. Electrospinning is a method known for its unique and efficient performance in developing polymer-based nanofibers with tunable and diverse properties presented as good surface area, morphology, porosity, and fiber diameters during fabrication. In this work, we have developed an electrospun sodium alginate (SA) incorporated with pulverized Moringa oleifera seed powder (PMO) as a potential natural biosorbent material for water treatment applications. The developed fibers when observed using a scanning electron microscope (SEM), presented pure sodium alginate with smooth fiber (SAF) characteristics of an average diameter of about 515.09 nm (±114.33). Addition of pulverized Moringa oleifera at 0.5%, 2%, 4%, 6%, and 8% (w/w) reduces the fiber diameter to an average of about 240 nm with a few spindle-like pulverized Moringa oleifera particles beads of 300 nm (±77.97) 0.5% particle size and 110 nm (±32.19) with the clear observation of rougher spindle-like pulverized Moringa oleifera particle beads of 680 nm (±131.77) at 8% of alginate/Moringa oleifera fiber (AMF). The results from the rheology presented characteristic shear-thinning or pseudoplastic behaviour with a decline in viscosity, with characteristic behaviour as the shear rate increases, indicative of an ideal polymer solution suitable for the spinning process. Fourier transform infrared spectroscopy (FT-IR) shows the presence of amine and amide functional groups are prevalent on the alginate-impregnated moringa with water stability nanofibers and thermogravimetric analysis (TGA) with change in degradation properties in a clear indication and successful incorporation of the Moringa oleifera in the electrospun fiber. The key findings from this study position nanofibers as sustainable composites fiber for potential applications in water treatment, especifically heavy metal adsorption.

In vitro investigation of wound healing performance of PVA/chitosan/silk electrospun mat loaded with deferoxamine and ciprofloxacin

Electrospinning is an advanced method used for developing wound dressings. Biopolymer-based electrospun mats have been extensively studied in tissue engineering due to their similarity to the extracellular matrix. In this study, electrospun poly(vinyl alcohol)/chitosan/silk fibroin (PChS) mat demonstrated improved mechanical properties, including tensile strength, strain at break, and Young's modulus, compared to electrospun poly(vinyl alcohol) and poly(vinyl alcohol)/chitosan mats. Similarly, the swelling capability, thermal stability, and hydrophilicity were higher in the PChS mat compared to the other ones. Hence, the PChS mat was selected for further investigation. Ciprofloxacin (CIP) was added to the PChS electrospinning solution at 5 % and 10 % concentration, and deferoxamine (DFO) was immobilized on CIP-loaded mats at 1 and 2 g/L concentration using a polydopamine linker. Evaluating mats with the dimensions of 1 × 1 cm2 showed that those containing 5 % and 10 % CIP exhibited bactericidal activity against Escherichia coli and Staphylococcus aureus. Moreover, Human dermal fibroblast cells were compatible with the fabricated mats, as confirmed by the MTT assay. Finally, drug-loaded mats had a positive effect on wound healing in a scratch test, and mats with 10 % CIP and 2 g/L DFO showed the highest effect on promoting wound healing, indicating potential for use as a wound dressing.

Chitosan/poly (3-hydroxy butyric acid-co-3-hydroxy valeric acid) electrospun nanofibers with cephradine for superficial incisional skin wound infection management

The belated and compromised incisional skin wound healing caused by the invading of methicillin-resistance staphylococcus aureus is a serious problem in clinic. Designing a new therapeutic strategy to inhibit the growth of invading bacteria at post-surgical site might be helpful in fast healing of post-surgical wounds. In this study, we developed cephradine (Ceph) encapsulated chitosan and poly (3-hydroxy butyric acid-co-3-hydroxy valeric acid, (PHBV)) hybrid nanofibers (Ceph-CHP NFs) employing an electrospinning method to revamp the Ceph bioavailability at the post-surgical wound site to prevent the growth of invading bacteria and trigger the wound healing process. The fabricated nanofibers revealed smooth and uniform surface with a diameter range of 160 ± 25 to 190 ± 55 nm, depending on Ceph concentration. Further, the electrospun hybrid nanofibers exhibited a higher entrapment efficiency (EE) and drug loading capacity (DLC) nearly 72.8 ± 5.2 % and 16.5 ± 3.2 %, respectively. Moreover, the Ceph-CHP NFs showed high swelling rate and biodegradation in presence of lysozyme in contrast to blank CHP NFs. Ceph-CHP NFs exhibited fast drug release in initial few hours followed by slow and controlled drug release drug up to 48 h with a constant rate. In-vitro antimicrobial studies indicated the heightened efficacy of Ceph-CHP NFs against MRSA clinical isolates and exhibited no visible cytotoxicity against keratinocytes, HC11 and L929 cells. Lastly, Ceph-CHP NFs showed the enhanced wound healing and bacterial clearance from post-surgical wound compared to Ceph in C57BL/6 mice skin model. Overall, our results showed that Ceph-CHP NFs might be used as a promising wound dressing material for MRSA-infected post-surgical wounds.

Cell Electrospinning: A Mini-Review of the Critical Processing Parameters and Its Use in Biomedical Applications

Functional tissue engineering is a widely studied area of research with increasing importance in regenerative medicine, as well as in the development of in vitro models used for drug discovery and mimicking diseased tissues, among other applications. Electrospinning (ES) is one of the most widely used methods in these fields. It has attracted considerable interest because it can produce materials resembling the extracellular matrix of native tissues. The micro/nanofibers produced by this method provide a cell-friendly environment that promotes cellular activities. Cell electrospinning (C-ES) is based on the fundamental ES process and enables the encapsulation of viable cells in a micro/nanofibrous mesh. In this review, the process of C-ES and the materials used in this process are discussed. This work also discusses the applications of C-ES in tissue engineering, focusing on recent advances in this field.

Fabrication of ɛ-Polylysine-Loaded Electrospun Nanofiber Mats from Persian Gum-Poly (Ethylene Oxide) and Evaluation of Their Physicochemical and Antimicrobial Properties

In the present study, electrospun nanofiber mats were fabricated by mixing different ratios (96:4, 95:5, 94:6, 93:7, and 92:8) of Persian gum (PG) and poly (ethylene oxide) (PEO). The SEM micrographs revealed that the nanofibers obtained from 93% PG and 7% PEO were bead-free and uniform. Therefore, it was selected as the optimized ratio of PG:PEO for the development of antimicrobial nanofibers loaded with ɛ-Polylysine (ɛ-PL). All of the spinning solutions showed pseudoplastic behavior and the viscosity decreased by increasing the shear rate. Additionally, the apparent viscosity, G', and G″ of the spinning solutions increased as a function of PEO concentration, and the incorporation of ɛ-PL did not affect these parameters. The electrical conductivity of the solutions decreased when increasing the PEO ratio and with the incorporation of ɛ-PL. The X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectra showed the compatibility of polymers. The antimicrobial activity of nanofibers against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was investigated, and the samples loaded with ɛ-PL demonstrated stronger antimicrobial activity against S. aureus.

Ethanol-free Cross-Linking of Alginate Nanofibers Enables Controlled Release into a Simulated Gastrointestinal Tract Model

The use of alginate nanofibers in certain biomedical applications, including targeted delivery to the gut, is limited because an ethanol-free, biocompatible cross-linking method has not been demonstrated. Here, we developed water-stable, alginate-based nanofibers by systematically exploring post-electrospinning cross-linking approaches that used calcium ions dissolved in (1) a glycerol/water cosolvent system and (2) acidic, neutral, or basic aqueous solutions. Scanning electron microscopy proved that the fibers cross-linked in a glycerol cosolvent or pH-optimized solutions had maintained the same morphology as the ethanol-based literature control. Notably, cross-linked fibers were generally smaller in diameter than the as-spun fibers due to both chemical interactions and mass loss during cross-linking, which was supported by mass measurements, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. During stability tests wherein the cross-linked fibers were exposed to three aqueous solutions, the cross-linked fibers were stable in water and acid buffer yet swelled in phosphate buffer saline, making them useful scaffolds for pH-controlled release applications. Proof-of-concept release experiments were conducted using a simulated gastrointestinal tract model. As desired, the cargo remained encapsulated within the cross-linked nanofibers when exposed to an acidic solution that modeled the stomach. Upon exposure to a solution that mimicked the intestines, the cargo was released. We suggest that these cross-linked, alginate-based nanofiber mats hold the potential to be broadly used in biomedical and environmental applications.

Potential of Aligned Electrospun PLGA/SIS Blended Nanofibrous Membrane for Tendon Tissue Engineering

Tendons are responsible for transmitting mechanical forces from muscles to bones for body locomotion and joint stability. However, tendons are frequently damaged with high mechanical forces. Various methods have been utilized for repairing damaged tendons, including sutures, soft tissue anchors, and biological grafts. However, tendons experience a higher rate of retear post-surgery due to their low cellularity and vascularity. Surgically sutured tendons are vulnerable to reinjury due to their inferior functionality when compared with native tendons. Surgical treatment using biological grafts also has complications such as joint stiffness, re-rupture, and donor-site morbidity. Therefore, current research is focused on developing novel materials that can facilitate the regeneration of tendons with histological and mechanical characteristics similar to those of intact tendons. With respect to the complications in association with the surgical treatment of tendon injuries, electrospinning may be an alternative for tendon tissue engineering. Electrospinning is an effective method for fabrication of polymeric fibers with diameters ranging from nanometers to micrometers. Thus, this method produces nanofibrous membranes with an extremely high surface area-to-volume ratio, which is similar to the extracellular matrix structure, making them suitable candidates for application in tissue engineering. Moreover, it is possible to fabricate nanofibers with specific orientations that are similar to those of the native tendon tissue using an adequate collector. To increase the hydrophilicity of the electrospun nanofibers, natural polymers in addition to synthetic polymers are used concurrently. Therefore, in this study, aligned nanofibers composed of poly-d,l-lactide-co-glycolide (PLGA) and small intestine submucosa (SIS) were fabricated using electrospinning with rotating mandrel. The diameter of aligned PLGA/SIS nanofibers was 568.44 ± 135.594 nm, which closely resembles that of native collagen fibrils. Compared to the results of the control group, the mechanical strength exhibited by the aligned nanofibers was anisotropic in terms of break strain, ultimate tensile strength, and elastic modulus. Elongated cellular behavior was observed in the aligned PLGA/SIS nanofibers using confocal laser scanning microscopy, indicating that the aligned nanofibers were highly effective with regard to tendon tissue engineering. In conclusion, considering its mechanical properties and cellular behavior, aligned PLGA/SIS is a promising candidate for tendon tissue engineering.

Magnetic fields enable precise spatial control over electrospun fiber alignment for fabricating complex gradient materials

Musculoskeletal interfacial tissues consist of complex gradients in structure, cell phenotype, and biochemical signaling that are important for function. Designing tissue engineering strategies to mimic these types of gradients is an ongoing challenge. In particular, new fabrication techniques that enable precise spatial control over fiber alignment are needed to better mimic the structural gradients present in interfacial tissues, such as the tendon-bone interface. Here, we report a modular approach to spatially controlling fiber alignment using magnetically-assisted electrospinning. Electrospun fibers were highly aligned in the presence of a magnetic field and smoothly transitioned to randomly aligned fibers away from the magnetic field. Importantly, magnetically-assisted electrospinning allows for spatial control over fiber alignment at sub-millimeter resolution along the length of the fibrous scaffold similar to the native structural gradient present in many interfacial tissues. The versatility of this approach was further demonstrated using multiple electrospinning polymers and different magnet configurations to fabricate complex fiber alignment gradients. As expected, cells seeded onto gradient fibrous scaffolds were elongated and aligned on the aligned fibers and did not show a preferential alignment on the randomly aligned fibers. Overall, this fabrication approach represents an important step forward in creating gradient fibrous materials, where such materials are promising as tissue-engineered scaffolds for regenerating functional musculoskeletal interfacial tissues.

Thermally Treated Berberine-Loaded SA/PVA/PEO Electrospun Microfiber Membranes for Antibacterial Wound Dressings

This study aimed to develop a safe and advanced antibacterial material of electrospun microfiber membranes (MFMs) for wound dressings. Combinations of several materials were investigated; thermal treatment and electrospinning techniques were used to form the best quality of MFMs to suit its end applications. By comparing the fiber morphology, diameter changes, and fracture strength, the suitable ratio of raw materials and thermal treatment were obtained before and after adding Trition X-100 as a surfactant for MFMs of sodium alginate/polyvinyl alcohol/polyethylene oxide (SA/PVA/PEO). The electrospinning solution was mixed with berberine as an antibacterial substance; meanwhile, calcium chloride (CaCl₂) was used as the crosslinking agent. The antibacterial properties, water dissolution resistance, water content, and fracture strength were thoroughly investigated. The results showed that the antibacterial rates of MFMs with different mass fractions of berberine (0, 3, and 5 wt.%) to Escherichia coli (E. coli) were 14.7, 92.9, and 97.2%, respectively. The moisture content and fracture strength of MFMs containing 5 wt.% berberine were 72.0% and 7.8 MPa, respectively. In addition, the produced MFMs embodied great water dissolution resistance. Berberine-loaded SA/PVA/PEO MFMs could potentially serve as an antibacterial wound dressing substrate with low cost and small side effects.

Electrospun alginate mats embedding silver nanoparticles with bioactive properties

Polysaccharide-based composites embedding silver nanoparticles (AgNPs) represent a promising alternative to common antimicrobial materials because of the effective, broad-spectrum biocidal properties of AgNPs combined with the biocompatibility and environmental safety of the naturally occurring polymeric component. In this work, AgNPs stabilized with alginate chains (Alg@AgNPs) were successfully synthesized in situ within the polysaccharide solution through a wet chemical approach carried out at different concentrations of the silver salt precursor. Once obtained, the aqueous suspensions were electrospun to prepare non-woven membranes, showing a homogeneous nanostructured texture (with fiber diameter between 100 and 150 nm), which was found to be influenced by the size (between 20 and 35 nm) of the embedded metal nanoparticles. The biocidal potential of the nanocomposite mats was preliminarily tested against Gram-negative E. coli. The results showed that the antimicrobial response of the investigated samples occurred within a day of incubation and can be observed for AgNPs content in the polysaccharide fibers far below the nanomolar regime.

Emulsion electrospinning of sodium alginate/poly(ε-caprolactone) core/shell nanofibers for biomedical applications

Electrospun nanofibers have shown great potential as drug vehicles and tissue engineering scaffolds. However, the successful encapsulation of multiple hydrophilic/hydrophobic therapeutic compounds is still challenging. Herein, sodium alginate/poly(ε-caprolactone) core/shell nanofibers were fabricated via water-in-oil emulsion electrospinning. The sodium alginate concentration, water-to-oil ratio, and surfactant concentration were optimized for the maximum stability of the emulsion. The results demonstrated that an increasing water-to-oil ratio results in more deviation from Newtonian fluid and leads to a broader distribution of the fibers' diameters. Moreover, increasing poly(ε-caprolactone) concentration increases loss and storage moduli and increases the diameter of the resulting fibers. The nanofibers' characteristics were investigated by scanning electron microscopy, transmission electron microscopy, confocal laser scanning microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and water contact angle measurements. It was observed that using an emulsion composition of 10% (w/v) PCL and a water-to-oil ratio of 0.1 results in smooth, cylindrical, and uniform core/shell nanofibers with PCL in the shell and ALG in the core. The in vitro cell culture study demonstrated the favorable biocompatibility of nanofibers. Overall, this study provides a promising and trustworthy material for biomedical applications.

Electrospun Smart Oxygen Indicating Tag for Modified Atmosphere Packaging Applications: Fabrication, Characterization and Storage Stability

Pack integrity is essential for the success of modified atmosphere packaging of food products. Colorimetric oxygen leak indicators or tags are simple and smart tools that can depict the presence or absence of oxygen within a package. However, not many bio-based electrospun materials were explored for this purpose. Ultraviolet light-activated kappa-carrageenan-based smart oxygen indicating tag was developed using the electrospinning technique in this study and its stability during storage was determined. Kappa-carrageenan was used with redox dye, sacrificial electron donor, photocatalyst, and solvent for preparing oxygen indicating electrospun tag. Parameters of electrospinning namely flow rate of the polymer solution, the distance between spinneret and collector, and voltage applied were optimized using Taguchi L9 orthogonal design. Rheological and microstructural studies revealed that the electrospinning solution was pseudoplastic and the mat fibers were compact and non-woven with an average fiber size of 1–2 microns. Oxygen sensitivity at different oxygen concentrations revealed that the tag was sensitive enough to detect as low as 0.4% oxygen. The developed tag was stable for at least 60 days when stored in dark at 25 °C and 65% RH. The developed mat could be highly useful in modified atmosphere packaging applications to check seal integrity in oxygen devoid packages.

Investigating pore-opening in hydrogel foams at the scale of free-standing thin films

Controlling the pore connectivity of polymer foams is key for most of their applications, ranging from liquid uptake, mechanics, and acoustic/thermal insulation to tissue engineering. Despite its importance, the scientific phenomena governing the pore-opening processes remain poorly understood, requiring tedious trial-and-error procedures for property optimisation. This lack of understanding is partly explained by the high complexity of the different interrelated, multi-scale processes which take place as the foam transforms from an initially fluid foam into a solid foam. To progress in this field, we take inspiration from long-standing research on liquid foams and thin films to develop model experiments in a microfluidic "Thin Film Pressure Balance". These experiments allow us to investigate isolated thin films under well-controlled environmental conditions reproducing those arising within a foam undergoing cross-linking and drying. Using the example of alginate hydrogel films, we correlate the evolution of isolated thin films undergoing gelation and drying with the evolution of the rheological properties of the same alginate solution in bulk. We introduce the overall approach and use a first set of results to propose a starting point for the phenomenological description of the different types of pore-opening processes and the classification of the resulting pore-opening types. This article is protected by copyright. All rights reserved.

ELECTROSPUN SODIUM ALGINATE/POLY(ETHYLENE OXIDE) NANOFIBERS FOR WOUND HEALING APPLICATIONS: CHALLENGES AND FUTURE DIRECTIONS

Alginate is an interesting natural biopolymer to be considered for biomedical applications due to its advantages and good biological properties. These biological properties make electrospun alginate nanofibers suitable for various uses in the biomedical field, such as wound healing dressings, drug delivery systems, or both. Unfortunately, the fabrication of alginate nanofibers by electrospinning is very challenging because of the high viscosity of the solution, high surface tension and rigidity in water due to hydrogen bonding, and also their diaxial linkages. This review presents an overview of the factors affecting the electrospinning process of sodium alginate/poly(ethylene oxide) (SA/PEO), the application of SA/PEO in drug delivery systems for wound healing applications, and the degradation and swelling properties of SA/PEO. The challenges and future directions of SA/PEO in the medical field are also discussed.

Core-sheath-like Poly(ethylene oxide)/Beeswax Composite Fibers Prepared by Single-spinneret Electrospinning. Antibacterial, Antifungal and Antitumor activities

Composite fibrous materials are prepared from poly(ethylene oxide) (PEO) and beeswax (BW) by single-spinneret electrospinning using chloroform as a common solvent. The obtained fibers have core-sheath-like structure, as evidenced by the water contact angle values and corroborated by the results on the elemental composition of the fibers surface determined by X-ray photoelectron spectroscopy (XPS) and by analyses with scanning electron microscopy (SEM) of fibers before and after selective extraction of PEO or of BW. Furthermore, the core-sheath-like structure is proven by transmission electron microcopy (TEM). This is attributed to self-assembly of BW molecules on the surface of the formed fibers driven by the incompatibility between PEO and BW. 5-Nitro-8-hydroxyquinoline (NQ) is embedded as a model drug with antibacterial, antifungal, and anticancer properties in the PEO/BW fibrous materials. XPS analyses reveal that NQ is present on the surface of the PEO/BW/NQ materials. Using a purposely designed cell for fixation of the fibrous materials the NQ release in phosphate buffer solution with рН 7.4 is followed. The new PEO/BW/NQ fibrous materials exhibit antibacterial activity against S. aureus and E. coli, antifungal effect against C. albicans, and selective anticancer activity against HeLa (human cervical adenocarcinoma cells) and SH-4 (human melanoma cells) cell lines. This article is protected by copyright. All rights reserved.

Fabrication and characterization of biaxially electrospun collagen/alginate nanofibers, improved with Rhodotorula mucilaginosa sp. GUMS16 produced exopolysaccharides for wound healing applications

Fabrication of scaffolds with enhanced mechanical properties and desirable cellular compatibility is critical for numerous tissue engineering applications. This study was aimed at fabrication and characterization of a nanofiber skin substitute composed of collagen (Col)/sodium alginate (SA)/ polyethylene oxide (PEO)/Rhodotorula mucilaginosa sp. GUMS16 produced exopolysaccharides (EPS) were prepared using the biaxial electrospinning technique. This study used collagen extracted from the bovine tendon as a natural scaffold, sodium alginate as an absorber of excess wound fluids, and GUMS16 produced exopolysaccharides as an antioxidant. Collagen was characterized using FTIR and EDS analyses. The cross-linked nanofibers were characterized by SEM, FTIR, tensile, contact-angle, swelling test, MTT, and cell attachment techniques. The average diameter of Col nanofiber was 910 ± 89 nm. The Col and Col-SA/PEO non-woven mats' water contact angle measurement was 41.6o and 56.4o, Col/EPS1%, Col/EPS2%, Col-SA/PEO + EPS1%, and Col-SA/PEO + EPS2% were 61.4o, 58.3o, 38.5o, and 50.6o, respectively. Cell viability of more than 100% was shown in Col-SA/PEO + EPS nanofibers. Also, SEM images of cells on nanofiber scaffolds demonstrated that all nanofibers incorporated with GUMS16-produced EPS have good cell growth and proliferation. The acquired results expressed that the GUMS16-produced EPS can be considered a novel biomacromolecule in electrospun fibers that increase cell viability and proliferation.

Electrospun Fibers Loaded with Natural Bioactive Compounds as a Biomedical System for Skin Burn Treatment. A Review

Burns are a major threat to public health and the economy due to their costly and laborious treatment and high susceptibility to infection. Efforts have been made recently to investigate natural bioactive compounds with potential use in wound healing. The importance lies in the capacities that these compounds could possess both in infection control by common and resistant microorganisms, as well as in the regeneration of the affected tissues, having in both cases low adverse effects. However, some bioactive molecules are chemically unstable, poorly soluble, and susceptible to oxidative degradation or have low bioavailability. Therefore, developing new technologies for an efficient treatment of wound healing poses a real challenge. In this context, electrospun nanofibers have gained increasing research interest because bioactive molecules can be easily loaded within the nanofiber, resulting in optimal burst control and enhanced drug stability. Additionally, the nanofibers can mimic the extracellular collagen matrix, providing a suitable highly porous structural support for growing cells that facilitate and accelerate skin burns healing. This review gives an overview of the current state of electrospun fibers loaded with natural bioactive compounds as a biomedical system for skin burn treatment.

Green electrospinning of chitin propionate to manufacture nanofiber mats

Chitin is the second most abundant biopolymer after cellulose in nature, and it is currently under-utilized partially because of its insolubility in common solvents. Herein, chitin was propionylated to improve its dissolution in green solvents, i.e., ethanol and water, and manufactured nanofibers and nonwoven mats via electrospinning with poly(ethylene oxide) (PEO) as a co-spinning aid. Polymer solution viscosity, electrospun CP/PEO fiber morphology, mechanical, thermal, dynamic thermal, and surface contact angle of nanofiber mats were evaluated. Results showed that fibers with CP content up to 97% could be produced. The electrospun CP/PEO nanofiber mats exhibited good mechanical strength, thermal stability, and hydrophobicity with water contact angles up to 133°. Filtration test of separating carbon nanofibers and carbon nanotubes from water demonstrated the potential use of the CP/PEO nanofiber mats in fluid filtration of fibrous pollutants.

Preparation and characterization of sodium alginate-PVA polymeric scaffolds by electrospinning method for skin tissue engineering applications

Sodium alginate (SA) has proven its high potential in tissue engineering and regenerative medicine. One of the main weaknesses of this polysaccharide is its low spinnability. Nanofiber-based scaffolds are of interest to scientists for biomedical engineering. The main aim of this study was to improve the spinnability of SA in combination with polyvinyl alcohol (PVA). The main parameters in the electrospinning of the optimized SA:PVA ratio, including voltage, flow rate, and working space were also optimized. To achieve this, response surface methodology under central composite design was employed to design the experiments scientifically. The final nanofiber scaffolds were studied using scanning electron microscopy, Fourier transform infrared spectroscopy for degradability, swelling, tensile strength, porosity, nanofiber diameter, contact angle, and cytotoxicity. Based on the results, the best ratio for SA : PVA was 1 : 6.5 that was spinnable in various values for the process parameters. The fabricated scaffolds under these conditions revealed good physical, chemical, mechanical, and biological features. L929 cell lines revealed high viability during 48 h culture. The results revealed that uniform and homogeneous nanofibers with regular size distribution (166 nm) were obtained at 30 kV, 0.55 μL h^-1, and 12.50 cm. To sum up, the fabricated scaffolds with the optimized ratio under the reported conditions indicate at good biologically compatible candidates for skin tissue engineering.

Fabrication of Multilayered Composite Nanofibers Using Continuous Chaotic Printing and Electrospinning: Chaotic Electrospinning

Multi-material and multilayered micro- and nanostructures are prominently featured in nature and engineering and are recognized by their remarkable properties. Unfortunately, the fabrication of micro- and nanostructured materials through conventional processes is challenging and costly. Herein, we introduce a high-throughput, continuous, and versatile strategy for the fabrication of polymer fibers with complex multilayered nanostructures. Chaotic electrospinning (ChE) is based on the coupling of continuous chaotic printing (CCP) and electrospinning, which produces fibers with an internal multi-material microstructure. When a CCP printhead is used as an electrospinning nozzle, the diameter of the fibers is further scaled down by 3 orders of magnitude while preserving their internal structure. ChE enables the use of various polymer inks for the creation of nanofibers with a customizable number of internal nanolayers. Our results showcase the versatility and tunability of ChE to fabricate multilayered structures at the nanoscale at high throughput. We apply ChE to the synthesis of unique carbon textile electrodes composed of nanofibers with striations carved into their surface at regular intervals. These striated carbon electrodes with high surface areas exhibit 3- to 4-fold increases in specific capacitance compared to regular carbon nanofibers; ChE holds great promise for the cost-effective fabrication of electrodes for supercapacitors and other applications.

Green Nanotechnology in the Formulation of a Novel Solid Dispersed Multilayered Core-Sheath Raloxifene-Loaded Nanofibrous Buccal Film; In Vitro and In Vivo Characterization

Green nanotechnology utilizes the principles of green chemistry to formulate eco-friendly nanocarrier systems to mitigate patients and environment hazards. Raloxifene (RLX) demonstrates poor aqueous solubility (BCS class II) and low bioavailability, only 2% (extensive first-pass metabolism). The aim of this study is to enhance RLX solubility and bioavailability via development of novel solid dispersed multilayered core-sheath RLX-loaded nanofibers (RLX-NFs) without the involvement of organic solvents. A modified emulsion electrospinning technique was developed. Electrospinning of an RLX-nanoemulsion (RLX-NE) with polymer solution (poly vinyl alcohol (PVA), hydroxypropyl methylcellulose (HPMC), and chitosan (CS) in different volume ratios (1:9, 2:8, and 4:6) using D-optimal response surface methodology was adopted. In vitro characterization of RLX-loaded NFs was performed; scanning electron microscope (SEM), thermal analysis, drug content, release studies, and bioadhesion potential. The optimum NFs formula was evaluated for morphology using high-resolution transmission electron microscopy (HRTEM), and ex vivo drug permeation. The superiority of E2 (comprising RLX-NE and PVA (2:8)) over other NF formulae was statistically observed with respect to Q60 (56.048%), Q240 (94.612%), fiber size (594.678 nm), mucoadhesion time 24 h, flux (5.51 µg/cm2/h), and enhancement ratio (2.12). RLX pharmacokinetics parameters were evaluated in rabbits following buccal application of NF formula E2, relative to RLX oral dispersion. E2 showed significantly higher Cmax (53.18 ± 4.56 ng/mL), and relative bioavailability (≈2.29-fold).

Electrospun poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) nanofibers for the controlled release of cilostazol

Drug delivery devices are attractive alternatives to drugs usually orally administrated. Therefore, this work aimed to produce PLA/PBAT-based nanofibers for the controlled release of cilostazol, evaluating the effect of different drug concentrations (20 and 30%) over the properties of the fibers. The fibers were characterized by scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), x-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric (TG/DTG), and mechanical analysis. SEM results indicated a high concentration of drug crystals on the surface of the fibers that contained 20% of cilostazol. These fibers were also thinner, more crystalline, less thermally stable, and less fragile in comparison to the fibers containing 30% of cilostazol, according to the XRD, DSC, TG/DTG, and mechanical results. The controlled release assays indicated that the fibers containing 20% of cilostazol would be attractive for short-term releases, reaching the equilibrium after approximately 6 h, while the ones containing 30% would ensure a slower release (~ 12 h). Despite the differences, both fibers would improve and enhance the efficiency of the treatment, and they would also prevent possible side effects caused by the drug to the gastric system.

Activated release of hexanal and salicylaldehyde from imidazolidine precursors encapsulated in electrospun ethylcellulose-poly(ethylene oxide) fibers

Hexanal and salicylaldehyde are naturally-occurring antimicrobial volatiles from edible plants known for their efficacy for post-harvest preservation of fruits and vegetables. Due to their volatility and susceptibility to oxidation, these volatiles must be encapsulated within a carrier to control their release, especially when applied in modified atmnosphere and active packaging applications. In this study, salicylaldehyde precursor (SP; 1,3-dibenzylethane-2-hydroxyphenyl imidazolidine) and hexanal precursor (HP) were synthetized through a Schiff base reaction between these aldehydes and N,N’-dibenzylethane-1,2-diamine. The structure of SP was confirmed using nuclear magnetic resonance and attenuated total reflection-Fourier transform infrared (FTIR) spectroscopies. SP and HP, separately and in combinations, were encapsulated within ethylcellulose–poly(ethylene oxide) (EC–PEO) nonwoven membranes, using a free-surface electrospinning technique. Scanning electron microscopy showed that the morphology of the fibers varied substantially with SP and HP ratio. Specific interactions between SP and HP with the polymers were not detected from the FTIR spectroscopy analysis, suggesting that the precursors were mainly physically entrapped within the EC–PEO fiber matrix. Headspace gas chromatography showed that the release of hexanal and salicylaldehyde could be activated by contacting the precursor-containing electrospun nonwoven with an acidified agarose gel containing 0.003–0.3 M of citric acid. The delivery system can be promising for controlled release of hexanal and salicylaldehyde to extend the shelf-life of fruits and vegetables.

Electrospun vancomycin-loaded nanofibers for management of methicillin-resistant Staphylococcus aureus-induced skin infections

Skin damage exposes the underlying layers to bacterial invasion, leading to skin and soft tissue infections. Several pathogens have developed resistance against conventional topical antimicrobial treatments and rendered them less effective. Recently, several nanomedical strategies have emerged as a potential approach to improve therapeutic outcomes of treating bacterial skin infections. In the current study, nanofibers were utilized for topical delivery of the antimicrobial drug vancomycin and evaluated as a promising tool for treatment of topical skin infections. Vancomycin-loaded nanofibers were prepared via electrospinning technique, and vancomycin-loaded nanofibers of the optimal composition exhibited nanosized uniform smooth fibers (ca. 200 nm diameter), high drug entrapment efficiency and sustained drug release patterns over 48 h. In vitro cytotoxicity assays, using several cell lines, revealed the biocompatibility of the drug-loaded nanofibers. In vitro antibacterial studies showed sustained antibacterial activity of the vancomycin-loaded nanofibers against methicillin-resistant Staphylococcus aureus (MRSA), in comparison to the free drug. The nanofibers were then tested in animal model of superficial MRSA skin infection and demonstrated a superior antibacterial efficiency, as compared to animals treated with the free vancomycin solution. Hence, nanofibers might provide an efficient nanodevice to overcome MRSA-induced skin infections and a promising topical delivery vehicle for antimicrobial drugs.

Dual spinneret electrospun nanofibrous/gel structure of chitosan-gelatin/chitosan-hyaluronic acid as a wound dressing: In-vitro and in-vivo studies

Structural and compositional similarity to the natural extracellular matrix (ECM) is a main characteristic of an ideal scaffold for tissue regeneration. In order to resemble the fibrous/gel structure of skin ECM, a multicomponent scaffold was fabricated using biopolymers with structural similarity to ECM and wound healing properties i.e., chitosan (CS), gelatin (Gel) and hyaluronic acid (HA). The CS-Gel and CS-HA nanofibers were simultaneously electrospun on the collector through dual-electrospinning technique. The presence of polymers, possible interactions, and formation of polyelectrolyte complex were proven by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and thermogravimetric analysis (TGA). The noncomplex component of CS-HA fibers formed a gel state when the scaffold was exposed to the aqueous media, while the CS-Gel fibers reserved their fibrous structure, resulting in formation of fibrous/gel structure. The CS-Gel/CS-HA scaffold showed significantly higher cell proliferation (109%) in the first 24 h comparing with CS (90%) and CS-Gel (96%) scaffolds. Additionally, the initial cell adhesion improved by incorporation of HA. The in-vivo wound healing results in rat elucidated more wound healing capability of the CS-Gel/CS-HA scaffold in which new tissue with most similarity to the normal skin was formed.

Preparation of polymyxin B-loaded gellan-polylysine polyion complex fibers with high affinity to endotoxin

Endotoxemia, a life-threatening disease affecting people worldwide, can be treated by hemoperfusion alone. New hemoperfusion materials with high biocompatibility and endotoxin-combination ability are always in demand. Herein, polymyxin B (PMB), a specific endotoxin binding molecule, was loaded onto gellan-polylysine polyion complex, and the obtained material was used in preparing wet-spun fibers. The tensile strength of the as-spun yarns (100 fibers) ranged from 1.49 N to -1.58 N and that of the dried and rewetted yarns ranged from 1.45 N to 1.56 N. The adsorption ability of the fibers with lipopolysaccharides from E. coli was 2.784 ± 0.036 EU/mg in simulated human body fluid and 2.452 ± 0.107 EU/mg in mouse plasma. The fibers showed no cytotoxicity toward U2OS cells and no hemolysis toward mouse blood. The influence of the fibers on the clotting time of mouse blood was negligible, and the blood cells were not adhesive to the fibers. Thus, the PMB-loaded gellan-polylysine complex fiber and its derivate fabrics can be used in hemoperfusion.

Surface modification of small intestine submucosa in tissue engineering

With the development of tissue engineering, the required biomaterials need to have the ability to promote cell adhesion and proliferation in vitro and in vivo. Especially, surface modification of the scaffold material has a great influence on biocompatibility and functionality of materials. The small intestine submucosa (SIS) is an extracellular matrix isolated from the submucosal layer of porcine jejunum, which has good tissue mechanical properties and regenerative activity, and is suitable for cell adhesion, proliferation and differentiation. In recent years, SIS is widely used in different areas of tissue reconstruction, such as blood vessels, bone, cartilage, bladder and ureter, etc. This paper discusses the main methods for surface modification of SIS to improve and optimize the performance of SIS bioscaffolds, including functional group bonding, protein adsorption, mineral coating, topography and formatting modification and drug combination. In addition, the reasonable combination of these methods also offers great improvement on SIS surface modification. This article makes a shallow review of the surface modification of SIS and its application in tissue engineering.

Ameliorative and protective effects of fucoidan and sodium alginate against lead-induced oxidative stress in Sprague Dawley rats

The current study was performed to evaluate the possible protective effects of fucoidan (F) and sodium alginate (SA) against lead-induced oxidative damage in vivo, and to identify relevant underlying mechanisms. Health Sprague Dawley (SD) rats were divided into nine groups of ten rats each and treated orally with lead acetate (5 mg/kg, Pb2+) for 4 weeks, then gavaged with DMSA (Meso-2, 3-dimercaptosuccinic acid, 25 mg/kg), F (50, 100, 200 mg/kg) and SA (50, 100, 200 mg/kg) individually after successful modelling. We found that the administration of both F or SA resulted in a beneficial effect by significantly decreasing lead levels (p < 0.05) in the kidneys from 2.85 mg/kg to 0.79 mg/kg and improving antioxidant status (SOD, GSH, and CAT) thereby alleviating lead-induced damage and injury of the liver and kidneys (AST, BUN, and Cr). Both natural extracts exerted dose-dependent effects. Protective effects were further demonstrated by histopathology. Our results demonstrate that the F and SA are effective natural extracts for lead-eliminating, and that they can ameliorate oxidative damage induced by lead toxicity.

Electrospinning Highly Concentrated Sodium Alginate Nanofibres without Surfactants by Adding Fluorescent Carbon Dots

In this study, sodium alginate (SA) nanofibres were obtained by electrospinning via the assistance of traditional poly(ethyl oxide) (PEO) and dimethyl sulfoxide (DMSO) with a high SA/PEO ratio of up to 94:6. However, surfactants with more or less toxicities were replaced by nontoxic and fluorescent carbon dots (CDs) to improve spinnability. Experimental details were conducted by fixing the ratio of SA/PEO to 90:10. Then, the electrospinning products of solutions with different compositions were observed with scanning electron microscopy. Properties such as conductivity, surface tension and rheology of the solutions were investigated to determine the key influencing factors. Moreover, since CDs have excellent fluorescence properties, the fluorescent properties of the nanofibre membrane that was blended with CDs were then collected. In addition, in vitro cytotoxicity assessment of the nanofibres were conducted to evaluate the toxicities and biocompatibility.

Cell-Electrospinning and Its Application for Tissue Engineering

Electrospinning has gained great interest in the field of regenerative medicine, due to its fabrication of a native extracellular matrix-mimicking environment. The micro/nanofibers generated through this process provide cell-friendly surroundings which promote cellular activities. Despite these benefits of electrospinning, a process was introduced to overcome the limitations of electrospinning. Cell-electrospinning is based on the basic process of electrospinning for producing viable cells encapsulated in the micro/nanofibers. In this review, the process of cell-electrospinning and the materials used in this process will be discussed. This review will also discuss the applications of cell-electrospun structures in tissue engineering. Finally, the advantages, limitations, and future perspectives will be discussed.