Electrospinning of chitosan–poly(ethylene oxide) blend nanofibers in the presence of micellar surfactant solutions

Current and Emerging Approaches to Engineer Antibacterial and Antifouling Electrospun Nanofibers

From ship hulls to bandages, biological fouling is a ubiquitous problem that impacts a wide range of industries and requires complex engineered solutions. Eliciting materials to have antibacterial or antifouling properties describes two main approaches to delay biofouling by killing or repelling bacteria, respectively. In this review article, we discuss how electrospun nanofiber mats are blank canvases that can be tailored to have controlled interactions with biologics, which would improve the design of intelligent conformal coatings or freestanding meshes that deliver targeted antimicrobials or cause bacteria to slip off surfaces. Firstly, we will briefly discuss the established and emerging technologies for addressing biofouling through antibacterial and antifouling surface engineering, and then highlight the recent advances in incorporating these strategies into electrospun nanofibers. These strategies highlight the potential for engineering electrospun nanofibers to solicit specific microbial responses for human health and environmental applications.

Electrospun Chitosan/Poly(ethylene oxide)/Lauric Arginate Nanofibrous Film with Enhanced Antimicrobial Activity

In this study, chitosan/poly(ethylene oxide) (PEO)/lauric arginate (LAE) composite nanofibrous films were fabricated via electrospinning. The addition of LAE did not change the physical properties of chitosan/PEO in acetic aqueous solutions, but increased the fluorescent intensity of chitosan by electrostatic interactions, resulting in uniform and bead-free nanofibers with an average diameter of 150 nm. The Fourier transform infrared spectra and thermal analysis indicated that the LAE molecules were homogeneously dispersed within the chitosan/PEO nanofibers. The formation of electrostatic and hydrogen bonding interactions induced by the LAE addition changed the inter- and intramolecular interactions between PEO and chitosan and further affected the mobility of the polymer molecules, leading to the increased crystallinity and decreased melting point. The hydrophilicity of the nanofibrous films was significantly increased by the incorporation of LAE, as indicated by the decreasing water contact angle from 39° to 10°. Meanwhile, the chitosan/PEO/LAE nanofibrous films showed LAE concentration dependent antimicrobial activity against Escherichia coli and Staphylococcus aureus, suggesting enhanced antimicrobial activity. The fluorescent staining experiments demonstrated that the antimicrobial mechanism of the nanofibrous films was cell membrane damage.

Electrospinning and wound healing activity of β-chitin extracted from cuttlefish bone

A nanofibrous β-chitin web was fabricated via electrospinning for use as a novel wound dressing material. β-chitin was extracted from cuttlefish bone using deproteinization and demineralization. First, cuttlefish bone was alkali-treated to remove the proteins and was then treated with the acid for demineralization. The extracted β-chitin was dissolved in formic acid as solvent to evaluate its electrospinnability, and the electrospinnability increased remarkably when β-chitin was blended with poly(ethylene oxide) (PEO) than without. The blended β-chitin/PEO nanofibers had a fiber diameter of about 400 nm, and the diameter decreased after soaking in water to remove the PEO. The structural and physical properties of the β-chitin material and its nanofibers were characterized using Attenuated total reflectance infrared spectroscopy (ATR-IR), Proton nuclear magnetic resonance (¹H NMR), Scanning electron microscopy/Energy dispersive spectroscopy (SEM/EDS), X-ray diffraction (XRD), texturometry, viscometry and contact angle measurements, and an animal test was conducted to investigate the wound healing effect. The β-chitin nanofibers were found to have great potential as nanomaterials for wound healing.

The Effect of Poly (Glycerol Sebacate) Incorporation within Hybrid Chitin-Lignin Sol-Gel Nanofibrous Scaffolds

Chitin and lignin primarily accumulate as bio-waste resulting from byproducts of crustacean crusts and plant biomass. Recently, their use has been proposed for diverse and unique bioengineering applications, amongst others. However, their weak mechanical properties need to be improved in order to facilitate their industrial utilization. In this paper, we fabricated hybrid fibers composed of a chitin–lignin (CL)-based sol–gel mixture and elastomeric poly (glycerol sebacate) (PGS) using a standard electrospinning approach. Obtained results showed that PGS could be coherently blended with the sol–gel mixture to form a nanofibrous scaffold exhibiting remarkable mechanical performance and improved antibacterial and antifungal activity. The developed hybrid fibers showed promising potential in advanced biomedical applications such as wound care products. Ultimately, recycling these sustainable biopolymers and other bio-wastes alike could propel a “greener” economy.

Electrospinning of Chitosan-Based Solutions for Tissue Engineering and Regenerative Medicine

Electrospinning has been used for decades to generate nano-fibres via an electrically charged jet of polymer solution. This process is established on a spinning technique, using electrostatic forces to produce fine fibres from polymer solutions. Amongst, the electrospinning of available biopolymers (silk, cellulose, collagen, gelatine and hyaluronic acid), chitosan (CH) has shown a favourable outcome for tissue regeneration applications. The aim of the current review is to assess the current literature about electrospinning chitosan and its composite formulations for creating fibres in combination with other natural polymers to be employed in tissue engineering. In addition, various polymers blended with chitosan for electrospinning have been discussed in terms of their potential biomedical applications. The review shows that evidence exists in support of the favourable properties and biocompatibility of chitosan electrospun composite biomaterials for a range of applications. However, further research and in vivo studies are required to translate these materials from the laboratory to clinical applications.

Application of response surface methodology to tailor the surface chemistry of electrospun chitosan-poly(ethylene oxide) fibers

Chitosan is a promising biocompatible polymer for regenerative engineering applications, but its processing remains challenging due to limited solubility and rigid crystalline structure. This work represents the development of electrospun chitosan/poly(ethylene oxide) blend nanofibrous membranes by means of a numerical analysis in order to identify and tailor the main influencing parameters with respect to accessible surface nitrogen functionalities which are of importance for the biological activity as well as for further functionalization. Depending on the solution composition, both gradient fibers and homogenous blended fiber structures could be obtained with surface nitrogen concentrations varying between 0 and 6.4%. Response surface methodology (RSM) revealed chitosan/poly(ethylene oxide) ratio and chitosan molecular weight as the main influencing factors with respect to accessible nitrogen surface atoms and respective concentrations. The model showed good adequacy hence providing a tool to tailor the surface properties of chitosan/poly(ethylene oxide) blends by addressing the amount of accessible chitosan.

Adsorption of hexavalent chromium by novel chitosan/poly(ethylene oxide)/permutit electrospun nanofibers

The Cr(vi) adsorption mechanism by CS/PEO/PT composite nanofibers includes electrostatic interaction, chelation, reduction and ion exchange.

Preparation and platelet adhesion of chitosan/PVA nanofibrous membrane

In this study, chitosan (CTS) dissolved in acetic acid was electrospun together with aqueous poly(vinyl alcohol) solution (PVA) to prepare membranes (CTS/PVA) with nanofibers. The morphology of the membranes varied with the electrospinning conditions. High polymer concentration, high distance or high voltage was facilitative in obtaining a membrane with nanofibers. A CTS/PVA membrane with evenly distributed nanofibers (50 nm dia.) was obtained under the following conditions: 4·5 g CTS in 55 ml 27% acetic acid, 0·4 g PVA in 5 ml water (H2O), 0·1 g sodium chloride (NaCl), electrospinning voltage of 40 kV and distance of 25 cm from the injector to the collector. The water contact angle of CTS/PVA membranes increased after cross-linking with glutaraldehyde steam. Platelet adhesion measurement expressed that CTS/PVA with only nanofibers had no platelet adhesion, indicating good blood compatibility. Cross-linked CTS/PVA mats were stable while in contact with phosphate-buffered saline solution.

3D printed multiplexed electrospinning sources for large-scale production of aligned nanofiber mats with small diameter spread

We report the design, fabrication, and characterization of novel, low-cost, and modular miniaturized nanofiber electrospinning sources for the scalable production of non-woven aligned nanofiber mats with low diameter variation. The devices are monolithic arrays of electrospinning emitters made via stereolithography; the emitters are arranged so each element has an independent line of sight to a rotating collector surface. Linear and zigzag emitter packing were evaluated using a PEO solution with the aim of maximizing the throughput of nanofibers with the smallest diameter and narrowest distribution. Current versus flowrate characterization of the devices showed that for a given flowrate a zigzag array produces more current per emitter than a linear array of the same emitter pitch and array size. In addition, the data demonstrate that larger and denser arrays have a net gain in flow rate per unit of active length. Visual inspection of the devices suggests uniform operation in devices with as many as 17 emitters with 300 μm inner diameter and 1.5 mm emitter gap. Well-aligned nanofiber mats were collected on a rotating drum and characterized; the 17-emitter device produced the same narrow nanofiber distribution (∼81 nm average diameter, ∼17 nm standard deviation) for all tested flow rates, which is strikingly different to the performance shown by 1-emitter sources where the average fiber diameter significantly increased and the statistics notably widened when the flowrate increases. Therefore, the data demonstrate that massively multiplexing the emitters is a viable approach to greatly increase the throughput of non-woven aligned nanofiber mats without sacrificing the statistics of the nanofibers generated. The production of dry nanofibers by the 17-emitter array is estimated at 33.0 mg min^-1 (1.38 mg min^-1 per mm of active length), which compares favorably with the reported multiplexed electrospinning arrays with emitters distributed along a line.

Recent advances on biomedical applications of scaffolds in wound healing and dermal tissue engineering

The tissue engineering field has developed in response to the shortcomings related to the replacement of the tissues lost to disease or trauma: donor tissue rejection, chronic inflammation and donor tissue shortages. The driving force behind the tissue engineering is to avoid the mentioned issues by creating the biological substitutes capable of replacing the damaged tissue. This is done by combining the scaffolds, cells and signals in order to create the living, physiological, three-dimensional tissues. A wide variety of skin substitutes are used in the treatment of full-thickness injuries. Substitutes made from skin can harbour the latent viruses, and artificial skin grafts can heal with the extensive scarring, failing to regenerate structures such as glands, nerves and hair follicles. New and practical skin scaffold materials remain to be developed. The current article describes the important information about wound healing scaffolds. The scaffold types which were used in these fields were classified according to the accepted guideline of the biological medicine. Moreover, the present article gave the brief overview on the fundamentals of the tissue engineering, biodegradable polymer properties and their application in skin wound healing. Also, the present review discusses the type of the tissue engineered skin substitutes and modern wound dressings which promote the wound healing.

Antibacterial electrospun chitosan-based nanofibers: A bacterial membrane perforator

This study investigates the antibacterial action of chitosan-based nanofibers (CNFs) obtained by the electrospinning process on the permeability of bacterial membranes. The bactericidal efficiency of CNFs was first determined against Gram-negative Escherichia coli and Salmonella Typhimurium, and Gram-positive Staphylococcus aureus and Listeria innocua bacteria as a baseline. The results strongly suggest that CNFs interact with the negatively charged bacterial cell wall causing membrane rupture and inducing leakage of intracellular components among which are proteins and DNA. Results clearly indicate that the release of such components after contact with CNFs is an indication of membrane permeabilization and perforation, as pore formation was observed in transmission electron microscopy (TEM). This work suggests a plausible antibacterial mechanism of action of CNFs and also provides clear evidence in favor of chitosan as a bacterial membrane disruptor and perforator. As a result, CNFs can find promising applications as bioactive food packaging materials capable to extend shelf life of food products while inhibiting the spread of alteration flora and foodborne pathogens.

Fabrication and characterization of two-layered nanofibrous membrane for guided bone and tissue regeneration application

Membranes used in dentistry act as a barrier to prevent invasion of intruder cells to defected area and obtains spaces that are to be subsequently filled with new bone and provide required bone volume for implant therapy when there is insufficient volume of healthy bone at implant site. In this study a two-layered bioactive membrane were fabricated by electrospinning whereas one layer provides guided bone regeneration (GBR) and fabricated using poly glycerol sebacate (PGS)/polycaprolactone (PCL) and Beta tri-calcium phosphate (β-TCP) (5, 10 and 15%) and another one containing PCL/PGS and chitosan acts as guided tissue regeneration (GTR). The morphology, chemical, physical and mechanical characterizations of the membranes were studied using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), tensile testing, then biodegradability and bioactivity properties were evaluated. In vitro cell culture study was also carried out to investigate proliferation and mineralization of cells on different membranes. Transmission electron microscope (TEM) and SEM results indicated agglomeration of β-TCP nanoparticles in the structure of nanofibers containing 15% β-TCP. Moreover by addition of β-TCP from 5% to 15%, contact angle decreased due to hydrophilicity of nanoparticles and bioactivity was found to increase. Mechanical properties of the membrane increased by incorporation of 5% and 10% of β-TCP in the structure of nanofibers, while addition of 15% of β-TCP was found to deteriorate mechanical properties of nanofibers. Although the presence of 5% and 10% of nanoparticles in the nanofibers increased proliferation of cells on GBR layer, cell proliferation was observed to decrease by addition of 15% β-TCP in the structure of nanofibers which is likely due to agglomeration of nanoparticles in the nanofiber structure. Our overall results revealed PCL/PGS containing 10% β-TCP could be selected as the optimum GBR membrane in view point of physical and mechanical properties along with cell behavior. PCL/PGS nanofibers containing 10% β-TCP were electrospun on the GTR layer for fabrication of final membrane. Addition of chitosan in the structure of PCL/PGS nanofibers was found to decrease fiber diameter, contact angle and porosity which are favorable for GTR layer. Two-layered dental membrane fabricated in this study can serve as a suitable substrate for application in dentistry as it provides appropriate osteoconductivity and flexibility along with barrier properties.

Evaluation of nanofibrous scaffolds obtained from blends of chitosan, gelatin and polycaprolactone for skin tissue engineering

Polymer blending is a strategy commonly used to obtain hybrid materials possessing properties better than those of the individual constituents regarding their use in scaffolds for Tissue Engineering. In the present work, the scaffolds produced by electrospinning solutions of polymeric blends obtained using a polyester (polycaprolactone, PCL), a polysaccharide (chitosan, CS) and a protein (gelatin extracted from cold water fish skin, GEL), were investigated. Solutions conductivity, shear viscosity and surface tension were determined. GEL-containing scaffolds were crosslinked with vapour phase glutaraldehyde (GTA). The scaffolds were characterized physico-chemically regarding fibre morphology, porosity, water contact angle, mechanical properties, chemical bonds and fibre and dimensional stability upon immersion in water and cell culture medium. The scaffolds were further tested in vitro for cell adhesion, growth and morphology of human foetal fibroblasts (cell line HFFF2). Results show that the nanofibrous scaffolds are hydrophilic and display the typical porosity of non-woven fibre mats. The CS/PCL and CS/PCL/GEL scaffolds have the highest elastic modulus (48MPa). Dimensional stability is best for the CS/PCL/GEL scaffolds. FTIR spectra confirm the occurrence of cross-linking reactions of GTA with both GEL and CS. Cell adhesion ratio ranked from excellent (close to 100%) to satisfactory (around 50%) in the order PCL/GEL>CS/GEL>CS/PCL/GEL>CS/PCL. Cell populations show an extended lag phase in comparison with the controls but cell proliferation occurs on all scaffolds until confluence is reached. In conclusion, all scaffolds studied possess characteristics that enable them to be used in skin tissue engineering but the CS/PCL/GEL scaffolds have better physical properties whereas the PCL/GEL scaffolds support a higher cell adhesion.

Mechanism of Action of Electrospun Chitosan-Based Nanofibers against Meat Spoilage and Pathogenic Bacteria

This study investigates the antibacterial mechanism of action of electrospun chitosan-based nanofibers (CNFs), against Escherichia coli, Salmonella enterica serovar Typhimurium, Staphylococcus aureus and Listeria innocua, bacteria frequently involved in food contamination and spoilage. CNFs were prepared by electrospinning of chitosan and poly(ethylene oxide) (PEO) blends. The in vitro antibacterial activity of CNFs was evaluated and the susceptibility/resistance of the selected bacteria toward CNFs was examined. Strain susceptibility was evaluated in terms of bacterial type, cell surface hydrophobicity, and charge density, as well as pathogenicity. The efficiency of CNFs on the preservation and shelf life extension of fresh red meat was also assessed. Our results demonstrate that the antibacterial action of CNFs depends on the protonation of their amino groups, regardless of bacterial type and their mechanism of action was bactericidal rather than bacteriostatic. Results also indicate that bacterial susceptibility was not Gram-dependent but strain-dependent, with non-virulent bacteria showing higher susceptibility at a reduction rate of 99.9%. The susceptibility order was: E. coli > L. innocua > S. aureus > S. Typhimurium. Finally, an extension of one week of the shelf life of fresh meat was successfully achieved. These results are promising and of great utility for the potential use of CNFs as bioactive food packaging materials in the food industry, and more specifically in meat quality preservation.

Fabrication and characterization of electrospun feather keratin/poly(vinyl alcohol) composite nanofibers

We have fabricated random and aligned feather keratin (FK)/PVA composite nanofibers through an electrospinning process. The morphology, molecular interactions, crystallization behavior, and tensile properties of the nanofibers were investigated.

Potential of electrospun chitosan fibers as a surface layer in functionally graded GTR membrane for periodontal regeneration

OBJECTIVE

The regeneration of periodontal tissues lost as a consequence of destructive periodontal disease remains a challenge for clinicians. Guided tissue regeneration (GTR) has emerged as the most widely practiced regenerative procedure. Aim of this study was to electrospin chitosan (CH) membranes with a low or high degree of fiber orientation and examines their suitability for use as a surface layer in GTR membranes, which can ease integration with the periodontal tissue by controlling the direction of cell growth.

METHODS

A solution of CH-doped with polyethylene oxide (PEO) (ratio 95:5) was prepared for electrospinning. Characterization was performed for biophysiochemical and mechanical properties by means of scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, swelling ratio, tensile testing and monitoring degradation using pH analysis, weight profile, ultraviolet-visible (UV-vis) spectroscopy and FTIR analysis. Obtained fibers were also assessed for viability and matrix deposition using human osteosarcoma (MG63) and human embryonic stem cell-derived mesenchymal progenitor (hES-MP) cells.

RESULTS

Random and aligned CH fibers were obtained. FTIR analysis showed neat CH spectral profile before and after electrospinning. Electropsun mats were conducive to cellular attachment and viability increased with time. The fibers supported matrix deposition by hES-MPs. Histological sections showed cellular infiltration as well.

SIGNIFICANCE

The surface layer would act as seal to prevent junctional epithelium from falling into the defect site and hence maintain space for bone regeneration.

Functionalized chitosan electrospun nanofiber for effective removal of trace arsenate from water

An environment-friendly iron functionalized chitosan elctrospun nanofiber (ICS-ENF) was synthesized for trace arsenate removal from water. The ICS-ENF was fabricated by electrospinning a mixture of chitosan, PEO and Fe(3+) followed by crosslinking with ammonia vapor. The physicochemical properties of ICS-ENF were characterized by FESEM, TEM-EDX and XRD. The ICS-ENF was found to be highly effective for As(V) adsorption at neutral pH. The As(V) adsorption occurred rapidly and achieved equilibrium within 100 min, which was well fitted by pseudo-second-order kinetics model. The As(V) adsorption decreased with increased ionic strength, suggesting an outer-sphere complexation of As(V) on ICS-ENF. Freundlich model well described the adsorption isotherm, and the maximum adsorption capacity was up to 11.2 mg/g at pH 7.2. Coexisting anions of chloride and sulfate showed negligible influence on As(V) removal, but phosphate and silicate significantly reduced As(V) adsorption by competing for adsorption sites. FTIR and XPS analysis demonstrated -NH, -OH and C-O were responsible for As(V) uptake. ICS-ENF was easily regenerated using 0.003 M NaOH, and the removal rate remained above 98% after ten successively adsorption-desorption recycles. This study extends the potential applicability of electrospun nanofibers for water purification and provides a promising approach for As(V) removal from water.

Antimicrobial Nanomaterials Derived from Natural Products-A Review

Modern medicine has relied heavily on the availability of effective antibiotics to manage infections and enable invasive surgery. With the emergence of antibiotic-resistant bacteria, novel approaches are necessary to prevent the formation of biofilms on sensitive surfaces such as medical implants. Advances in nanotechnology have resulted in novel materials and the ability to create novel surface topographies. This review article provides an overview of advances in the fabrication of antimicrobial nanomaterials that are derived from biological polymers or that rely on the incorporation of natural compounds with antimicrobial activity in nanofibers made from synthetic materials. The availability of these novel materials will contribute to ensuring that the current level of medical care can be maintained as more bacteria are expected to develop resistance against existing antibiotics.

Electrospinning of PEGylated polyamidoamine dendrimer fibers

Polyamidoamine (PAMAM) dendrimers have emerged as an important class of nanostructured materials and have found a broad range of applications. There is also an ongoing effort to synthesize higher-complexity structures using PAMAM dendrimers as enabling building blocks. Herein, we report for the first time the fabrication of electrospun nanocomposite fibers composed of dendrimer derivatives, namely PEGylated PAMAM dendrimers, blended with a small amount of high-molecular-weight polyethylene oxide (PEO). Morphological features and mechanical properties of the resulting dendrimer fiber mats were assessed.

The Influence of Non-Ionic Surfactant on the Physical Characteristics of Curcumin-Loaded Nanofiber Manufactured by Electrospinning Method

Electrospinning is one of techniques used for nanofiber fabrication as drug delivery systems. Curcumin possesses challenging properties as it has low solubility and poor absorption. Incorporation of curcumin into nanofiber is expected to enhance solubility and absorption. In this study, curcumin loaded nanofiber for oral delivery has been developed. Nanofibers were synthesized from curcumin and Polyvinylpyrrolidone (PVP) with mass ratio of 1:10 using electrospinning method. Various PVP concentration from 5 to 10 % (w/v) were used. To further assess the variation in the physical characteristics of fiber, the influence of Polysorbate 20, a nonionic surfactant, was studied. Electrospinning of curcumin-PVP nanofiber with the addition of Polysorbate 20 yielded fiber with overall diameter of 350-400 nm. In the absence of Polysorbate 20, the diameter was higher i.e 540-660 nm. The highest diameter was observed in highest PVP concentration at 10% (w/v). Drug release study showed that more than 50% of curcumin has been released within 45 minutes in all formulas. Initial rapid release occurred in the formula containing Polysorbate 20. As a summary, the presence of Polysorbate 20 reduced the diameter of curcumin-loaded PVP nanofiber and enhanced the release of curcumin from the fiber.

Random-cavity lasing from electrospun polymer fiber networks

Lasing emission from random cavities formed in networks of electrospun Rhodamine-doped polymer fibers is presented. Spatially resolved spectroscopy and spectral analysis prove that the observed laser emission stems from individual ring resonators randomly distributed throughout the network. These electrospun fiber lasers represent a facile and straightforward configuration for developing novel photonic devices that may advantageously utilize the network morphology.

Antibacterial wound dressing from chitosan/polyethylene oxide nanofibers mats embedded with silver nanoparticles

Novel antibacterial nanomaterials have been developed for biomedical applications. The present study involves the preparation and properties of antibacterial nanofibers from chitosan/polyethylene oxide electrospun nanofibers incorporated with silver nanoparticles. Silver nanoparticles were efficiently synthesized in situ after ultra violet (UV) with AgNO3 as precursor and chitosan/polyethylene oxide as reducing agent and protecting agent, respectively. Then the resultant solutions were electrospun into nanofibers. The formation of silver nanoparticles was confirmed with ultraviolet visible (UV-vis) and transmission electron microscopy (TEM), and the electrospun nanofibers were characterized by scanning electron microscopy and energy dispersive X-ray. The resultant fibers exhibited uniform morphology with silver nanoparticles distributed throughout the fiber. Also, the fibers showed certain tensile strength and excellent antibacterial activity against Gram-positive ( Staphylococcus aureus) and Gram-negative ( Escherichia coli) bacteria. Sustained release of silver nanoparticles from fibers could last for over 72 h. The silver-containing chitosan/polyethylene oxide nanofibers showed excellent cytocompatibility.