Activity Of Mats Research Articles

Antibacterial Ag containing core‐shell polyvinyl alcohol‐poly (lactic acid) nanofibers for biomedical applications

AbstractCore‐shell‐structured polyvinyl alcohol (PVA)‐poly (lactic acid) (PLA) nanofibers combining the hydrophilic trait of PVA and the biocompatibility of PLA were produced using coaxial electrospinning. This allowed the incorporation of AgNO3 in the PVA core of the distinct fibers as shown through transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) showed relatively uniform and bead‐free fibers with smooth surfaces. Ag‐containing fibers show significantly decreased diameters compared with Ag‐free samples as a result of the increased conductivity of the spinning solutions with increasing amounts of AgNO3. In a postsynthetic treatment, the AgNO3 was reduced forming silver nanoparticles (Ag NPs). Ag NPs of 45 to 90 nm size were located in the PVA core but also on the surface of the core‐shell fibers and as individual, agglomerated, and polymer‐coated particles of 100‐200 nm. Powder X‐ray diffraction (PXRD), energy dispersive X‐ray spectroscopy (EDX), and UV‐vis absorption spectroscopy confirmed the increasing amounts of Ag in the core‐shell fibers when using increasing amounts of AgNO3 in the spinning solutions. The antibacterial activity of the nanofiber mats against two prokaryotes Escherichia coli (Gram‐negative) and Staphylococcus aureus (Gram‐positive) increased with increasing amounts of Ag, as expected and produces inhibition zones of 1 to 2 mm.

Electrospun wound dressing as a promising tool for the therapeutic delivery of ascorbic acid and caffeine.

Aim: The aim of this work is to formulate a wound dressing for the delivery of ascorbic acid and caffeine. Method: A wound dressing was developed from electrospun nanofiber containing ascorbic acid and caffeine. In vitro drug release was performed at 25°C and 32°C. Wound healing activity of the nanofiber mats wastested in vivo using rat model with skin excision. Antifungal activity of the dressing was tested on Candida albicans using the disc diffusion method. Results & conclusion: Zone of inhibition was 6.7mm for caffeine dressing; however, inhibition zone increased to 16.7mm for samples containing both caffeine and ascorbic acid. Animals treated with ascorbic acid showed collagen deposition and very few fibroblast cells. Blood vessels and fibroblasts were increased in caffeine-loaded dressings compared with the ascorbic acid group. The findings of the present work suggest the benefits of topical ascorbic acid and caffeine for its high wound healing effects.

Cerium oxide and peppermint oil loaded polyethylene oxide/graphene oxide electrospun nanofibrous mats as antibacterial wound dressings

Wound healing is a systematic response that can heal acute and chronic wounds by effectively regenerating new connective tissues with specific microstructures and function. Here, to improve the wound healing efficiency, encapsulation of cerium oxide (CeO2) and peppermint oil (PM oil) on polyethylene oxide/graphene oxide (PEO/GO) polymeric mats was done by electrospinning technique. The physico-chemical properties of the prepared nanofibrous mats were characterized by FTIR and UV–vis-NIR spectral analyses. The structural morphologies of the pristine and encapsulated mats were investigated using SEM and TEM analysis. The surface roughness and the thermal stability of the polymeric mats were evaluated by AFM and DSC studies. Further, the in vitro antibacterial activity of the nanofibrous mats were tested against gram positive bacteria (Staphylococcus aureus) and gram negative bacteria (Escherichia coli). The fabricated nanofibrous mats were then evaluated for in vitro cytotoxicity assay and the assessment indicated that the CeO2-PM oil-PEO/GO nanofibrous mat was less toxic to the L929 cell. The composite nanofibrous mat promotes wound healing as compared to plain CeO2 and PM oil loaded mats. The histological evaluations demonstrated that the incorporation of CeO2 and PM oil into PEO/GO nanofibrous mat accelerates the re-epithelialization and collagen deposition. Thus, the unique characteristics of CeO2-PM oil-PEO/GO nanofibrous mats make them a potential candidate to be applied as a wound dressing to prevent skin infections.

Monitoring of Antimicrobial Drug Chloramphenicol Release from Electrospun Nano- and Microfiber Mats Using UV Imaging and Bacterial Bioreporters.

New strategies are continuously sought for the treatment of skin and wound infections due to increased problems with non-healing wounds. Electrospun nanofiber mats with antibacterial agents as drug delivery systems provide opportunities for the eradication of bacterial infections as well as wound healing. Antibacterial activities of such mats are directly linked with their drug release behavior. Traditional pharmacopoeial drug release testing settings are not always suitable for analyzing the release behavior of fiber mats intended for the local drug delivery. We tested and compared different drug release model systems for the previously characterized electrospun chloramphenicol (CAM)-loaded nanofiber (polycaprolactone (PCL)) and microfiber (PCL in combination with polyethylene oxide) mats with different drug release profiles. Drug release into buffer solution and hydrogel was investigated and drug concentration was determined using either high-performance liquid chromatography, ultraviolet-visible spectrophotometry, or ultraviolet (UV) imaging. The CAM release and its antibacterial effects in disc diffusion assay were assessed by bacterial bioreporters. All tested model systems enabled to study the drug release from electrospun mats. It was found that the release into buffer solution showed larger differences in the drug release rate between differently designed mats compared to the hydrogel release tests. The UV imaging method provided an insight into the interactions with an agarose hydrogel mimicking wound tissue, thus giving us information about early drug release from the mat. Bacterial bioreporters showed clear correlations between the drug release into gel and antibacterial activity of the electrospun CAM-loaded mats.

Fabrication, characterization and fibroblast proliferative activity of electrospun Achillea lycaonica-loaded nanofibrous mats

The use of natural compounds such as biocompatible and non-toxic plant extracts, without undesired side effects, in tissue engineering applications, is highly preferred compared to chemical drugs. In this study, the characterization and performance of electrospun Achillea lycaonica-loaded (0.125, 0.250 and 0.500, wt%) poly(lactic acid) (PLA) (8%, w/v) nanofibrous mats for skin tissue engineering were investigated. SEM, FTIR, DSC, and tensile strength test of the electrospun nanofibers have been investigated. Drug releasing test and cell culture study were also carried out. Achillea lycaonica-loaded nanofibrous mats in 0.250 (wt%) and 0.500 (wt%) demonstrated excellent cell compatibility and increased the viability of NIH/3T3 (mouse embryo fibroblast) cells within 72 h. According to the results, Achillea lycaonica-loaded PLA nanofibers have proper tensile strength and controlled release. The working temperature range enlarged for the composites having higher plant extract content. Consequently, Achillea lycaonica-loaded nanofibrous mats have a great potential in skin tissue engineering applications.

Characterization of polyherbal-incorporated polycaprolactone nanofibrous mat for biomedical applications

The polyherbal-loaded polycaprolactone nanofibrous mat was prepared by electrospinning technique, and physical and chemical characteristics of nanofibrous mats were studied using scanning electron microscopy, x-ray diffraction, thermogravimetric analyzer, and Fourier transform infrared spectroscopy. The presence of various phytochemicals in the crude monoherbal and polyherbal extracts was analyzed. The antimicrobial activity and biocompatibility of the polyherbal-loaded nanofibrous mats were studied. The drug release pattern of the polyherbal-loaded nanofibrous mats was studied at different time intervals. The 5% drug-loaded nanofibrous mat shows higher sustainable drug release rate than 1% and 3% drug-loaded nanofibrous mats. The cell viability was found to be 98.91%, 98.77%, 98.5%, and 98.22% for polycaprolactone and 1%, 3%, and 5% for polyherbal-loaded nanofibrous mats, respectively.

Seasonal development of a coastal microbial mat

Growth and activity of coastal microbial mats is strongly seasonal. The development of these mats starts in early spring and fully maturate during late summer, where after growth ceases and subsequently the mat deteriorates by erosion and decomposition in winter. Here, the composition of the microbial community of three different mats developing along the tidal gradient of the North Sea beach of the Dutch barrier island Schiermonnikoog was analysed. The 16S ribosomal RNA molecules and the associated gene were sequenced in order to obtain the active (RNA) and resident (DNA) community members, respectively. Proteobacteria, Cyanobacteria, and Bacteroidetes dominated the mats during the whole year but considerable differences among these groups were found along the tidal gradient and seasonally when observed at a finer taxonomic resolution. Richness and diversity increased during the year starting from a pioneering community that is gradually succeeded by a more diverse climax community. The initial pioneers consisted of the cold-adapted photoautotrophic cyanobacterium Nodularia sp. and potential cold adapted members of the alphaproteobacterial Loktanella genus. These pioneers were succeeded by, amongst others, cyanobacteria belonging to the genera Leptolyngbya, Lyngbya, and Phormidium. At the upper littoral (Dune site), which was characterized by an extensive salt marsh vegetation, the mats contained a distinct bacterial community that potentially contribute to or benefit from plant decay. This study reports in detail on the seasonal changes and succession of these coastal microbial mat communities and discusses the potential forces that drive these changes.

Chitosan-TiO2 microparticles LBL immobilized nanofibrous mats via electrospraying for antibacterial applications

The antibacterial materials with biodegradable and biocompatible nature have unveiled novel prospects to combat the bacterial infection, which has always been a troubling and challenging issue in the biomedical field. In this study, chitosan (CS) and Titanium dioxide (TiO2) microparticles were well immobilized on polylactic acid (PLA) mats by electrospinning–electrospraying hybrid technique. The surface morphology, chemical composition and characteristic group of the mats were characterized. The results indicated that CS/TiO2 microparticles were successfully immobilized on the surface of PLA mats. In addition, the antibacterial activity and cytotoxicity of the composite mats were investigated to confirm that the layer-by-layer immobilization of CS/TiO2 microparticles via electrospraying could enhance the antibacterial effect and biocompatibility of the mats. At the same time, the PLA-(CS/TiO2-1.5%)1.5 mats exhibited the best performance in antibacterial effect (up to about 95%) and cell viability (nearly 92% and 95% at 3 d and 5 d). The composite mats have great potential as an effective antibacterial material for the biomedical applications.

LBL deposition of chitosan and silk fibroin on nanofibers for improving physical and biological performance of patches.

Pelvic floor dysfunction diseases (PFD) become more prevalent with the increase of elderly population, and complications of pelvic floor reconstructive surgery (e.g. infection and exposure of mesh) have been troubling to patients and gynecologists. In this study, the nanofibrous mats were prepared by alternately depositing chitosan (CS) and silk fibroin (SF) on Nylon6 (N6) nanofibrous mats via layer-by-layer (LBL) technique. The as-prepared mats were characterized. The results showed that CS and SF molecules were successfully assembled on the nanofibers. Additionally, after LBL modification, the hydrophilicity of the nanofibrous mats was reduced and the mechanical properties were improved. Furthermore, the antibacterial activity of the LBL-structured mats reached >95% inhibiting Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The in vitro cell co-culture experiments indicated that LBL-structured mats had smaller toxic effects and more excellent biocompatibility to L929 fibroblasts, especially the mats with 15 bilayers coated films. Hence, the LBL-structured mats are promising materials for pelvic floor reconstruction to reduce postoperative pelvic complication rates.

Design and development of TiO2-Fe0 nanoparticle-immobilized nanofibrous mat for photocatalytic degradation of hazardous water pollutants

This study introduces, a titanium dioxide (TiO2) and zerovalent iron (Fe0) nanoparticles immobilized electrospun poly (acrylic acid)/poly (vinyl alcohol) (PAA/PVA) nanofibrous mat for photocatalytic degradation of hazardous water pollutant. For that, PAA/PVA nanofibrous mat was prepared by electrospinning followed by crosslinking and immobilization/incorporation of TiO2 and Fe0 nanoparticles through Layer-by-Layer (LbL) self-assembly method. The obtained PAA/PVA–TiO2 and PAA/PVA–TiO2–Fe0 was fully characterized by scanning electron microscopy (SEM), FTIR, TGA and porosity analysis. The results showed successful immobilization of both (TiO2 and Fe0) nanoparticles on the nanofibrous mat with uniform distribution. The latter exhibited catalytic activity towards the degradation of Methyl Blue (MB) and Brilliant Green (BG) dyes separately and mixed in the presence of UV light. UV–Vis spectroscopic analysis was used to monitor and quantitative analysis of the degradation. It has been found that high photocatalytic activity of the functional nanofibrous mats has been observed. The fastest conversion rate reached to 99.2% in 20 min at a rate constant of 0.0847/min providing adequate reusability of the nanofiber mats up to four consecutive cycles. A mechanism of the photocatalytic activities has been proposed by referring to the above results. The results opened a promising prospect for using nanofibrous based effective photocatalyst for environmental application.

Incorporation of Tannic Acid in Food-Grade Guar Gum Fibrous Mats by Electrospinning Technique.

The use of polysaccharides to produce functional micro- or nanoscale fibrous mats has attracted growing interest for their food-grade applications. In this study, the characterization and electro-spinnability of guar gum (GG) solutions loaded with tannic acid (TA) was demonstrated. Food-grade antioxidant materials were successfully produced by electrospinning while incorporating different loads of TA into GG fibers. Bead-free GG-TA fibers could be fabricated from GG solution (2 wt %) with 10 wt % TA. Increasing the amount of TA led to fibers with defects and larger diameter sizes. Fourier Transformed Infrared Spectroscopy and X-ray Diffraction of neat GG and TA loaded GG fibrous mats suggested that inclusion of TA interrupted the hydrogen bonding and that a higher density of the ordered junction zones formed with the increased TA. The high TA incorporation efficiency and retained antioxidant activity of the fibrous mats afford a potential application in active edible film or drug delivery system.

Wound dressing based on electrospun PVA/chitosan/starch nanofibrous mats: Fabrication, antibacterial and cytocompatibility evaluation and in vitro healing assay

Electrospun nanofibrous mats based on biopolymers have been widely investigated for tissue engineering in recent years, primarily due to remarkable morphological similarity to the natural extracellular matrix (ECM). In this research, electrospun PVA/Chitosan/Starch nanofibrous mats were fabricated using electrospinning method for wound dressing application. The prepared nanofibrous mats were then cross-linked to enhanced the water resistance and also optimize the biodegradation rate followed by characterization and evaluation of their properties as wound dressings. The morphological studies performed by SEM and AFM showed that uniform bead-free electrospun nanofibrous mats were formed. The structural properties of the fabricated mats were characterized by FTIR. The proper porosity and balanced water absorption and water vapor transmission rate (WVTR) of obtained dressings, demonstrate their ability in providing suitable moist environment for wound, result in the appropriate wound breathing and simultaneously efficient handling of wound exudates. Suitable mechanical properties of nanofibrous dressing in both dry and wet states confirm the capability of fabricated wound dressing to protect wound area against the external forces during the healing process. Antibacterial test revealed excellent antibacterial activity of nanofibrous mats against both gram negative and gram positive bacteria. Furthermore, the in vitro cytotoxicity evaluated by MTT assay, proved appropriate cytocompatibility and cell viability of the developed nanofibrous mats which were also verified with in vitro wound healing analysis performed by scratch assay, confirming the remarkable potential of the investigated nanofibrous mats for wound dressing application.

A novel approach for skin infections: Controlled release topical mats of poly(lactic acid)/poly(ethylene succinate) blends containing Voriconazole

The oral and injectable formulations of Voriconazole (VRZ), a known antifungal agent with low solubility, seem to cause severe side effects. Consequently, topical application of VRZ could be advantageous for skin fungal infections. In this study, VRZ embedded in a polymeric matrix composed of biocompatible poly(lactic acid) (PLA) and poly(ethylene succinate) (PESu). The mats were prepared via solvent evaporation and fully characterized by Fourier-Transformed Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), in vitro hydrolysis and release studies. The prepared blends defined as immiscible by DSC and SEM while FTIR spectroscopy did not disclose noticeable interactions between the polymers. It was found that hydrolysis was improved by increasing PESu content into the blend. VRZ loaded blends spectra exhibit slight differentiation compared to neat blends while the absence of VRZ melting peak, as DSC illustrated, indicated drug amorphization. Lastly, in vitro release studies depicted a controlled release pattern dependent on mats' hydrolysis degree. An improved antifungal activity of mats was detected by disc diffusion method against various microorganisms. Ex vivo studies of VRZ did not determine high permeation while histopathology results using mice were profitable. The irritation experiments displayed that the mats did not induce any skin irritation.

Enhanced physical and biological properties of silk fibroin nanofibers by layer-by-layer deposition of chitosan and rectorite

The search for biodegradable and biocompatible materials applied to the antibacterial field has become a significant topic of interest worldwide. In this study, the electrospinning and electrostatic layer-by-layer self-assembly (LBL) techniques were applied to achieve composite mats with enhanced physical and biological properties. Electrospun silk fibroin (SF) was selected as the substrate, and chitosan (CS) and rectorite (REC) were assembled on the surface of the substrate as positively and negatively charged layers via electrostatic LBL. The morphology, composition and structure of the mats were examined, and the results suggested that LBL modification was successful. In addition, the variation of the bilayer numbers and the component of the outmost layer could affect the morphology and the physical and biological properties of LBL mats. Additionally, the morphology and the water contact angle investigation results of the as-prepared mats indicated that the surface features were changed through the LBL process, resulting in a rougher surface than in pure SF mats. Moreover, the mechanical properties of the SF mats were improved after the LBL process. Furthermore, the antibacterial activity of the LBL self-assembled SF mats against E. coli and S. aureus with a concentration of 106 CFU/mL were 84 and 92%, respectively. The cell-culture experiments demonstrated that the mats maintained superior biocompatibility after the introduction of CS and REC.

Catalytically active (Pd) nanoparticles supported by electrospun PIM-1: Influence of the sorption capacity of the polymer tested in the reduction of some aromatic nitro compounds

Microfibers of the first so-called polymer of intrinsic microporosity (PIM-1) were prepared by electrospinning 10 wt.% PIM-1 in tetrachloroethane and used as immobilized supports for catalytic reactions. Solutions with varied concentrations of palladium diacetate (PdAc2) were coated on electrospun PIM-1 to show that PIM-1 is a superior catalyst supporting material with a high surface per weight ratio. Palladium (Pd) nanoparticles (NPs) were produced via the reduction of the PdAc2 with ethanol followed by subsequent thermal treatment for durably fixing the NPs on the fibers. A comparison of the catalytic activity of PIM-1 supported PdNPs was made with that of similarly produced electrospun nanofibers of polyacrylonitrile (PAN) and polyimide (6FDA-6FpDA) with catalytic PdNPs.The morphology of the electrospun fibers and the distribution of the Pd nanoparticles on the outer surface of the fibers were determined by scanning electron microscopy (SEM). Transmission electron microscopy (TEM) analysis of the cross section of the fibers showed the distribution of PdNPs across the fiber with a slight excess on the outer surface of the fibers. The nanoparticles (NPs) supported by the electrospun polymers catalyzed the reduction of different aromatic nitro compounds to their corresponding amino derivatives. The kinetics of the reduction reactions were monitored by ultraviolet-visible (UV-Vis) spectroscopy. Results showed that the PdNPs supported by electrospun PIM-1 fiber possessed high activity in the reduction reaction with an only slight dependence on the fiber diameter in the case of p-nitrophenol, while in the case of the dinitro compounds the dependence of the kinetics on the fiber diameter was more pronounced. The catalytic tests on two dinitro compounds proved the higher sorption of PIM-1 for p-nitrophenol is responsible for the higher catalytic activity of PIM-1 based catalytic nanofiber mats. These results clearly show that the catalytic activity of the PIM-1 fiber mats is higher compared to the fiber mats from PAN or 6FDA-6FpDA in the case of small reactants, which is mainly due to the fact that the PdNPs are also formed within the microporous PIM-1 fibers, while this is not the case for the other more dense fibers, where the catalytic particles are located only on the outer surface.

Fabrication of curcumin-loaded electrospun nanofiberous polyurethanes with anti-bacterial activity

Two series of polyurethane (PU), based on polycaprolactone (PCL) as soft segments with two different molecular weights (2000 and 530 Da), and hexamethylene diisocyanate (HDI) and 1,4-butandiol (BDO) as hard segments were synthesized to fabricate curcumin-loaded electrospun nanofibrous PCL-based PU substrate. Chemical structures of the synthesized PUs were characterized by FTIR and NMR spectroscopy techniques. The thermal properties were analyzed by differential scanning calorimetry (DSC) and surface hydrophilicity was studied by static contact angle and bulk hydrophilicity was evaluated by water uptake test. Thereafter, bead-free PU nanofiberous substrate containing curcumin was fabricated by electrospinning and morphology of the mats was observed by scanning electron microscopy (SEM). Mechanical properties of the electrospun mats in comparison with polymeric films were assessed by a universal test machine. The in vitro release of curcumin was studied by UV–Vis spectroscopy. The optical density of the bacterial solutions was used to evaluate the antibacterial activity of the curcumin-loaded nanofibrous mats against Escherichia coli (E-coli ATCC: 25922). The results showed that curcumin-loaded PU synthesized by PCL with molecular weight of 2000 Da displayed better mechanical properties as well as better antibacterial properties in wound dressing application.Graphical abstract

Developing a potential antibacterial long-term degradable electrospun gelatin-based composites mats for wound dressing applications

Antibacterial electrospun fibrous membranes are widely applied as dressings for treatment the wounds and burns. However, developing long-term gelatin-based fibrous membrane is still the main challenge inhibiting their uses for long-term treatments. Novel antibacterial electrospun gelatin-based mats were introduced by combining gelatin, glycerol, glucose and silver nanoparticles (Ag NPs), which together could exhibit optimal physicochemical characteristics as long-term electrospun fibrous mats. Therefore, Ag NPs were synthesized in-situ within the acidic electrospun solutions during preparing electrospun gelatin-glycerol-Ag NPs (GEL-GLY-Ag) and gelatin-glycerol-glucose-Ag NPs (GEL-GLY-GLU-Ag) mats. Conventional spectroscopic techniques based on XRD, FTIR, SEM, DTA, and water uptake-degradation tests and antibacterial studies were used to characterize the preparations. The results showed that the electrospun gelatin-based composites mats revealed free beads dense fibrous textures, and exhibited a high water uptake and long-term degradation behavior. The Ag NPs could be successfully synthesized in-situ within electrospinning solutions and the results confirmed that the in-situ prepared Ag NPs enhanced the antibacterial activity of electrospun mats against positive and negative bacteria.

Development and characterization of multifunctional electrospun ferric oxide-gelatin-glycerol nanofibrous mat for wound dressing applications

In this study, we developed optimal multifunctional electrospun wound dressings possessing an antibacterial activity and rich in iron, a vital trace element for cell growth. Therefore, synthetic ferric oxide nanoparticles (α-Fe2O3 NPs) were ultrasonically dispersed into preheated gelatin-glycerol solution. A variety of techniques (X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential thermal analysis (DTA), in-vitro swelling-degradation studies and antibacterial tests) were used to characterize the electrospun mats. The results highlight that α-Fe2O3 NPs could be successfully dispersed into the electrospun gelatin nanofibers. The electrospun ferric oxide-gelatin-glycerol nanofibrous mats revealed free beads nanofibers with appropriated swelling-degradation behavior. It was observed that addition of α-Fe2O3 NPs enhanced the antibacterial activity of electrospun mats against positive and negative bacteria.

The impact of long-term hydrocarbon exposure on the structure, activity, and biogeochemical functioning of microbial mats

Photosynthetic microbial mats are metabolically structured systems driven by solar light. They are ubiquitous and can grow in hydrocarbon-polluted sites. Our aim is to determine the impact of chronic hydrocarbon contamination on the structure, activity, and functioning of a microbial mat. We compared it to an uncontaminated mat harboring similar geochemical characteristics. The mats were sampled in spring and fall for 2years. Seasonal variations were observed for the reference mat: sulfur cycle-related bacteria dominated spring samples, while Cyanobacteria dominated in autumn. The contaminated mat showed minor seasonal variation; a progressive increase of Cyanobacteria was noticed, indicating a perturbation of the classical seasonal behavior. Hydrocarbon content was the main factor explaining the differences in the microbial community structure; however, hydrocarbonoclastic bacteria were among rare or transient Operational Taxonomic Units (OTUs) in the contaminated mat. We suggest that in long-term contaminated systems, hydrocarbonoclastic bacteria cannot be considered a sentinel of contamination.

Silver nanoparticles supported on electrospun polyacrylonitrile nanofibrous mats for catalytic applications

Abstract