Fabrication and characterization of electrospun silk fibroin/TiO2 nanofibrous mats for wound dressings

Silk fibroin (SF) nanofibrous mats were fabricated via electrospinning process. These fibers were blended with TiO₂ nanoparticles (TiO₂ NPs). The influence of TiO₂ NPs on the nanofibrous matrices was investigated by scanning electron microscopy (SEM), transmission electron microscopy, energy‐dispersive X‐ray, and thermogravimetric analysis. The SEM images revealed that the average diameter of the SF/TiO₂ fibers was 385 ± 63 nm when the concentration of SF was up to 10% (w/v). Infrared spectra showed that the β‐sheet structure of the silk fibroin increased after acetone treatment. These SF/TiO₂ nanofibrous mats exhibited higher equilibrium water content and water vapor transmission rate than hydrocolloid dressing. The hemocompatibility and cytocompatibility of SF/TiO₂ nanofibrous mats were evaluated by complete blood count, cell attachment, and the spreading of L929 fibroblasts. These SF/TiO₂ nanofibrous mats exhibited antibacterial activity against Escherichia coli under UV irradiation. Thus, these novel nanocomposite mats may be used for biomedical applications such as wound dressing. Copyright © 2011 John Wiley & Sons, Ltd.     

Formation of functional nanofibrous electrospun polyurethane and murivenna oil with improved haemocompatibility for wound healing

Electrospinning is an emerging tool and promising method to fabricate polymer nanofibers. The aim of this work was to fabricate electrospun polyurethane mats reinforced with murivenna oil for wound dressings. The scanning electron microscopy (SEM) micrographs showed the fiber diameter of nanocomposites in the range of 740 ± 160 nm and found to be decreased compared to pure polyurethane. Surface of nanocomposites was analyzed by Fourier transform infrared spectroscopy (FTIR) insinuated the interactions between PU and murivenna oil by the formation of hydrogen bond and changes in the characteristics peaks. Contact angle of the PU incorporated murivenna oil showed a decrease in its value compared to pure PU indicating the increased wettability and hydrophilic nature. The thermal degradation and stability of fabricated composites was found be enhanced compared to pure PU. The surface morphology through atomic force microscopy (AFM) analysis showed a change in surface roughness due to presence of murivenna oil in the polymer matrix. In blood compatibility results, both activated partial thromboplastin time (APTT) and prothrombin time (PT) were delayed due to improved surface properties and the addition of murivenna oil in the PU matrix. Compared to pure PU, the hemolysis assay of the PU incorporated murivenna oil showed a significant decrease in the percentage of lysis of red blood cells indicating better blood compatibility. Following the results, it was confirmed that fabricated novel scaffolds having better physicochemical and enhanced blood compatibility properties may be utilized for wound dressing.     

Form-stable electrospun nanofibrous mats as a potential phase change material

A series of Poly vinyl butyral–Poly (acrylic acid) (PVB-PAA) based form-stable phase change materials (PCMs) have been prepared for the use of thermal energy storage applications. Six types of formulations containing five different fatty alcohols were prepared by adding PVB to PAA. Using electrospinning to fabricate nanofibrous mats, our aim was to investigate their properties as form-stable PCMs. Fatty alcohols, 1-Tetradecanol, 1-Hexadecanol, 1-Octadecanol, 1-Eicosanol and 1-Docosanol, were added separately to base formulation. The structural characterization tests were performed by ATR-FTIR spectroscopy. Morphological tests were conducted using Scanning Electron Microscope (SEM). Thermal performances and phase change behaviors were tested by thermogravimetric analysis system (TGA) and differential scanning calorimetry (DSC). The heating cycle phase change enthalpy is measured between 223 and 241?J/g, and the freezing cycle phase change enthalpy is found between 215 and 239?J/g. The main decomposition PVB-PAA based PCMs started at 220?°C. This study suggested that PVB-PAA based PCMs possess well phase change properties and they were found to have an applicable temperature range. With the presented results these materials promise a great potential in thermal energy storage applications.     

Recent advances on herb‐derived constituents‐incorporated wound‐dressing materials: A review

Since ancient times, wound dressings have evolved with persistent and substantial changes. Several efforts have been made toward the development of new dressing materials, which can meet the demanding conditions for the treatment of skin wounds. Currently, many studies have been focused on the production and designing of herb‐incorporated wound dressings. Herb‐derived constituents are more effective than conventional medicines because of their nontoxic nature and can be administered over long periods. Herbal medicines in wound healing provide a suitable environment for aiding the natural course of healing. This review mainly focuses on the diverse approaches that have been developed to produce a wound dressing material, which can deliver herb‐derived bioactive constituents in a controlled manner. This review also discusses the common wound‐dressing materials available, basic principles of wound healing, and wound‐healing agents from medicinal plants.     

Bioactive polymeric formulations for wound healing

Ricinoleic acid (RA) has potential to promote wound healing because of its analgesic and anti‐inflammatory properties. This study investigates the synthesis and characterization of RA liposomes infused in a hydrogel for topical application. Lecithin liposomes containing RA were prepared and incorporated into a chitosan solution and were subsequently cross‐linked with di‐aldehyde β‐cyclodextrin (Di‐β‐CD). Chitosan/Di‐β‐CD concentrations and reaction temperatures were varied to alter gelation time, water content, and mechanical properties of the hydrogel in an effort to obtain a wide range of RA release profiles. Hydrogel cross‐linking was confirmed by spectroscopy, and liposome and carrier hydrogel morphology via microscopy. Chitosan, Di‐β‐CD, and liposome concentrations within the formulation affected the extent of matrix swelling, mechanical strength, and pore and overall morphology. Higher cross‐linking density of the hydrogel led to lower water uptake and slower release rate of RA. Optimized formulations resulted in a burst release of RA followed by a steady release pattern accounting for 80% of the encapsulated RA over a period of 48 hours. However, RA concentrations above 0.1 mg/mL were found to be cytotoxic to fibroblast cultures in vitro because of the oily nature of RA. These formulations promoted wound healing when used to treat full thickness skin wounds (2 cm²) in Wister male rats. The wound contraction rates were significantly higher compared to a commercially available topical cream after a time period of 21 days. Histopathological analysis of the RA‐liposomal chitosan hydrogel group showed that the epidermis, dermis, and subcutaneous skin layers displayed an accelerated yet normal healing compared to control group.     

A review on electrospun polymeric nanofibers: Production parameters and potential applications

This review deals with electrospun nanofibers and their applications in several fields. Nanofibers have mainly been produced via electrospinning technique due to the simple, cost-effective, and versatile setup. Electrospinning is defined as a process, which produces fibers from its polymer solutions under exposure of high electric field voltage. The technique needs optimization of several parameters such solution, processing and ambient parameters to refine nanofiber morphology, diameter and porosity. The basic technique has been modified to produce composite fibers and to increase production capacity. Nanofiber characterization methods are summarized with examples. The relation between electrospinning and electrospraying is discussed. Nanofibers have the ability to form highly porous mesh with large surface to volume ratio enhancing its performance for various applications such as water filtration, tissue engineering scaffold, wounds, fiber composites, drug release and protective clothes. Single nanofibers could potentially be used as soft microrobots for drug delivery. Finally, results from modeling and simulations are illustrated.     

Electrospun poly(lactic acid) nanofibers loaded with silver sulfadiazine/[Mg–Al]‐layered double hydroxide as an antimicrobial wound dressing

Poly(lactic acid) (PLA) is a versatile, bioabsorbable, and biodegradable polymer with excellent biocompatibility and ability to incorporate a great variety of active agents. Silver sulfadiazine (SDZ) is an antibiotic used to control bacterial infection in external wounds. Aiming to combine the properties of PLA and SDZ, hydrotalcite ([Mg–Al]‐LDH) was used as a host matrix to obtain an antimicrobial system efficient in delivering SDZ from electrospun PLA scaffolds intended for wound skin healing. The structural reconstruction method was successfully applied to intercalate silver sulfadiazine in the [Mg–Al]‐LDH, as evidenced by X‐ray diffraction and thermogravimetric analyses. Observations by scanning electron microscopy revealed a good distribution of SDZ‐[Mg–Al]‐LDH within the PLA scaffold. Kinetics studies revealed a slow release of SDZ from the PLA scaffold due to the intercalation in the [Mg–Al]‐LDH. In vitro antimicrobial tests indicated a significant inhibitory effect of SDZ‐[Mg–Al]‐LDH against Escherichia coli and Staphylococcus aureus. This antibacterial activity was sustained in the 2.5‐wt% SDZ‐[Mg–Al]‐LDH–loaded PLA nanofibers, which also displayed excellent biocompatibility towards human cells. The multifunctionality of the PLA/SDZ‐[Mg–Al]‐LDH scaffold reported here is of great significance for various transdermal applications.     

In situ mineralization of hydroxyapatite on electrospun chitosan-based nanofibrous scaffolds

A biocomposite of hydroxyapatite (HAp) with electrospun nanofibrous scaffolds was prepared by using chitosan/polyvinyl alcohol (CS/PVA) and N-carboxyethyl chitosan/PVA (CECS/PVA) electrospun membranes as organic matrix, and HAp was formed in supersaturated CaCl2 and KH2PO4 solution. The influences of carboxylic acid groups in CECS/PVA fibrous scaffold and polyanionic additive poly(acrylic acid) (PAA) in the incubation solution on the crystal distribution of the HAp were investigated. Field-emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), wide-angle X-ray diffraction (WAXD), and Fourier transform infrared (FTIR) were used to characterize the morphology and structure of the deposited mineral phase on the scaffolds. It was found that addition of PAA to the mineral solution and use of matrix with carboxylic acid groups promoted mineral growth and distribution of HAp. MTT testing and SEM imaging from mouse fibroblast (L929) cell culture revealed the attachment and growth of mouse fibroblast on the surface of biocomposite scaffold, and that the cell morphology and viability were satisfactory for the composite to be used in bioapplications.     

A Cyanine Dye Encapsulated Porous Fibrous Mat for Naked‐Eye Ammonia Sensing

Electrospun ultrathin fiber‐based sensors are desirable because of their practicality and sensitivity. Ammonia‐detection systems are in high demand in different areas, including the industrial and agricultural fields. However, current technologies rely on large and complex instruments that restrict their actual utilization. Herein, we report a flexible naked‐eye ammonia sensor, the polylactic acid–cyanine (PLA‐Cy) fibrous mat, which was fabricated by blending a carboxyl‐functionalized cyanine dye ( D1 ) into electospun PLA porous fibers. The sensing mat was shown to undergo a naked‐eye‐detectable color change from white to blue upon exposure to ammonia vapor. The mat showed high selectivity to ammonia gas with a detection limit of 3.3 ppm. Aggregated D1 was first encapsulated by PLA and was then ionized by NH₃. These mechanisms were examined by photophysical studies and scanning electron microscopy. The aggregation–deaggregation process of D1 in the PLA‐Cy fibrous mat led to the color change. This work provides a facile method for the naked‐eye detection of ammonia and a novel strategy for the use of organic dyes in ammonia sensing.     

Injectable and self-healing hydrogels with tissue adhesiveness and antibacterial activity as wound dressings for infected wound healing

The design of wound dressings with excellent self-healing ability, adequate adhesion, good biocompatibility, and potential antibacterial ability is of great significance for the healing of infected wounds arising from human activities. Herein, a series of multi-functional hydrogel dressings, poly(ionized isocyanoethyl methacrylate-glutamine)/poly(hexamethylene guanidine) (iG_x/PHMG_y) hydrogels, were obtained through homopolymerization of fully ionized isocyanoethyl methacrylate-glutamine (iIEM-Gln) in the presence of poly(hexamethylene guanidine) (PHMG), in which strong hydrogen bonds were formed among urea groups in the P (iIEM-Gln) chain to form a stable hydrogel network. The prepared iG_x/PHMG_y hydrogels exhibited adequate self-healing ability and tissue adhesion, which could be firmly adhered to the wound surface and remained intact during application. In addition, the presence of PHMG imparted good antibacterial activity to the hydrogels for the effective promotion of the wound healing in S. aureus infected skin wound on mice. Overall, this multi-functional hydrogel provides a facile and effective strategy for the design of infected wound dressings, and may show great potential in clinical applications.     

A review on electrospun nanofibers for multiple biomedical applications

Electrospinning is a well-known technique since 1544 to fabricate nanofibers using different materials like polymers, metals oxides, proteins, and many more. In recent years, electrospinning has become the most popular technique for manufacturing nanofibers due to its ease of use and economic viability. Nanofibers have remarkable properties like high surface-to-volume ratio, variable pore size distribution (10–100 nm), high porosity, low density, and are suitable for surface functionalization. Therefore, electrospun nanofibers have been utilized for numerous applications in the pharmaceutical and biomedical field like tissue engineering, scaffolds, grafts, drug delivery, and so on. In this review article, we will be focusing on the versatility, current scenario, and future endeavors of electrospun nanofibers for various biomedical applications. This review discusses the properties of nanofibers, the background of the electrospinning technique, and its emergence in chronological order. It also covers the various types of electrospinning methods and their mechanism, further elaborating the factors affecting the properties of nanofibers, and applications in tissue engineering, drug delivery, nanofibers as biosensor, skin cancer treatment, and magnetic nanofibers.     

Fabrication of well‐aligned electrospun nanofibrous membrane based on fluorinated polyimide

We have fabricated novel nanofibrous fluorinated polyimide membranes on a specially designed collector, which is composed of conductive aluminum plates and glass insulator materials and can be removed from the apparatus, using an electrospinning method. We describe the structure and water flux properties of the nanofibrous fluorinated polyimide membranes. The electrospun nanofibers were deposited across the plates and uniaxially aligned to the collector. In addition, the multi‐layer stacked nanofibrous membranes, consisting of three‐dimensionally ordered nanopores, were produced. The pure water fluxes for the stacked membranes were measured, using a stirred dead‐end filtration cell, and were linearly decreased with an increasing deposition time, indicating that the nanopores formed in the nanofibrous membrane were further narrowed due to the regularly accumulated nanofibers. Copyright © 2009 John Wiley & Sons, Ltd.     

Titanium Nanorods Loaded PCL Meshes with Enhanced Blood Vessel Formation and Cell Migration for Wound Dressing Applications

Proper management of nonhealing wounds is an imperative clinical challenge. For the effective healing of chronic wounds, suitable wound coverage materials with the capability to accelerate cell migration, cell proliferation, angiogenesis, and wound healing are required to protect the healing wound bed. Biodegradable polymeric meshes are utilized as effective wound coverage materials to protect the wounds from the external environment and prevent infections. Among them, electrospun biopolymeric meshes have got much attention due to their extracellular matrix mimicking morphology, ability to support cell adhesion, and cell proliferation. Herein, electrospun nanocomposite meshes based on polycaprolactone (PCL) and titanium dioxide nanorods (TNR) are developed. TNR incorporated PCL meshes are fabricated by electrospinning technique and characterized by scanning electron microscopy, energy dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy (FTIR) analysis, and X‐Ray diffraction (XRD) analysis. In vitro cell culture studies, in ovo angiogenesis assay, in vivo implantation study, and in vivo wound healing study are performed. Interestingly, obtained in vitro and in vivo results demonstrated that the presence of TNR in the PCL meshes greatly improved the cell migration, proliferation, angiogenesis, and wound healing. Owing to the above superior properties, they can be used as excellent biomaterials in wound healing and tissue regeneration applications.     

In vitro and in vivo evaluation of chitosan-alginate/gentamicin wound dressing nanofibrous with high antibacterial performance

Wound dressings based on nanofiber polymer scaffolds with good antimicrobial performance and skin reconstruction ability are promising options to thwart wound infection and accelerate wound healing. This paper reports on the synthesis via electrospinning of chitosan-alginate (CS-Alg) nanofiber dressings with various amounts of gentamicin (Gn; 0–10 wt%) as a drug delivery system. Smooth and continuous nanofibers with no obvious beads were created, with increases in the amount of Gn resulting in reduced fiber diameter. Antimicrobial tests showed the Gn-loaded nanofibers had good antibacterial performance as indicated by the inhibition of bacterial growth. CS-Alg nanofibers loaded with higher Gn concentrations exhibited greater antibacterial performance than those with lower Gn concentrations. In vitro cell culture studies demonstrated that CS-Alg wound dressings with 1–3% Gn improved L929 cell attachment and proliferation more than wound dressings with higher Gn concentrations. In vivo experiments revealed that Cs-Alg nanofibers loaded with 3% Gn significantly enhanced skin regeneration in a Balb/C mice model by stimulating the formation of a thicker dermis, increasing collagen deposition, and increasing the formation of new blood vessels and hair follicles. Collectively, Gn-loaded CS-Alg wound dressings can be considered a good candidate for drug delivery systems and skin regeneration applications.     

Electrospun non-woven nanofibrous hybrid mats based on chitosan and PLA for wound-dressing applications

Continuous defect-free nanofibers containing chitosan (Ch) or quaternized chitosan (QCh) were successfully prepared by one-step electrospinning of Ch or QCh solutions mixed with poly[(L-lactide)-co-(D,L-lactide)] in common solvent. XPS revealed the surface chemical composition of the bicomponent electrospun mats. Crosslinked Ch- and QCh-containing nanofibers exhibited higher kill rates against bacteria S. aureus and E. coli than the corresponding solvent-cast films. SEM observations showed that hybrid mats were very effective in suppressing the adhesion of pathogenic bacteria S. aureus. The hybrid nanofibers are promising for wound-healing applications.     

Calix[4]arene-based fluorescent probe and the adsorption capacity of its electrospun nanofibrous film for the cesium cation as an adsorbent

Calix[4]arene-based cation receptor 1 has been synthesised by following a multi-step synthetic procedure. The fluorescence properties of 1 upon the addition of various metal ions were investigated by fluorescence spectroscopy. As a result, it was revealed that 1 displayed dramatic quenching effect upon the exposure to Cs⁺. In contrast, no significant quenching effects were observed upon the addition of other metal ions such as Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ag⁺, Zn²⁺ and Ni²⁺. Compound 1 was also found by Job plot to form a 1:1 complex with Cs⁺. In addition, we also prepared 1-embedded electrospun nanofibrous film (NF-1) as an adsorbent for Cs⁺. NF-1 is proved to adsorb Cs⁺ effectively from an aqueous solution, indicating that it would be usefully utilised as an adsorbent to remove Cs⁺.     

Fabrication and characterization of a novel wound scaffold based on polyurethane added with Channa striatus for wound dressing applications

Abstract

Wound healing is a complex process and it involves restoration of damaged skin tissues. Several wound dressings comprising naturally made substances are constantly investigated to assist wound healing. In this research, a new wound dressing based on polyurethane (PU) supplemented with essence of Channa striatus (CS) fish oil was made by electrospinning. Morphological study depicted the reduction in fiber diameter than PU with the addition of fish oil (0.552?±?0.109?μm for 8:1 v/v% and 0.519?±?0.196?μm 7:2 v/v%) than the pristine PU (0.971?±?0.205?µm). Fourier transform infrared spectroscopy (FTIR) analysis revealed the presence of fish oil in the composite as identified through increasing peak intensity. Fish oil resulted in the hydrophilic behavior (88?±?3 (8:1 v/v) and 70?±?6 (7:2 v/v)) as revealed in the contact angle analysis. Thermal gravimetric analysis (TGA) showed the superior thermal behavior of the wound dressing patch compared to the PU. Atomic force microscopy (AFM) analysis insinuated a decrease in the surface roughness of the pristine polyurethane with the added fish oil. Coagulation assays signified the delay in the blood clotting time portraying its anti-thrombogenic behavior. Hemolytic assay revealed the less toxic nature of the developed nanocomposites with the red blood cells (RBC’s) depicting its safety with blood. Hence, polyurethane nanofibers supplemented with fish oil made them as deserving candidates for wound dressing application.     

Preparation and evaluation of poly glycerol sebacate/poly hydroxy butyrate core‐shell electrospun nanofibers with sequentially release of ciprofloxacin and simvastatin in wound dressings

Biodegradable wound dressing of poly glycerol sebacate/poly hydroxy butyrate was fabricated via the coaxial electrospinning process. Simvastatin and ciprofloxacin were loaded in the core and shell of the fibers, respectively. Scanning electron microscopy and transmission electron microscopy images showed a uniform core/shell structure. Introducing drugs into the polymers would cause the dressing samples to become more hydrophilic and degradation to occur faster. Drugs release would face no interventions, in which, approximately 60% of ciprofloxacin was released during the first 24 hours. Simvastatin exhibited a slower and controlled release behavior, with its release peak recorded after 2 days. The drug‐containing samples showed a proper bactericidal activity against both Gram‐positive and Gram‐negative bacteria. It may be concluded that the drug‐laden wound dressing fabricated in this study is capable of releasing the 2 drugs sequentially and that it is the ideal conditions for controlling infections and reducing wound healing duration.     

Fabrication and invitro evaluation of electrospun gum ghatti-polyvinyl alcohol polymeric blend green nanofibre mat (GG-PVA NFM) as a novel material for polymeric scaffolds in wound healing

The present research is mainly based on the fabrication of biodegradable nanofiber mats (NFM) through the process of electrospinning using a novel combination of Gum Ghatti (GG) and Poly vinyl alcohol (PVA). The prepared NFM was crosslinked (CL-1) using Glutaraldeyde-HCl vapours and was characterized for its tensile strength along other analytical characterizations using FTIR, TGA, DSC and XRD. The mechanical strength of the NFM was found to be sufficiently high than in comparison to noncrosslinked sample and PVA NFM. The internal architecture of the CL-1 by use of atomic force microscopy (AFM) revealed that there was very well formed crosslinks suitable for drug loading as well as cell proliferation. The wound healing properties of the CL-1 in mice animal model indicated the healing within 5 days as compared to the control wound. Moreover, the sample was also analysed for its ability as polymeric scaffold and no toxicity was found onto the locally applied tissue on histological investigations.