Activity Of Mats Research Articles

Foam-Mat Freeze Drying of Kiwiberry (Actinidia arguta) Pulp: Drying Kinetics, Main Properties and Microstructure

The kiwiberry is an interesting source of bioactive compounds (micronutrients, polyphenols vitamins and pectins) and enzyme actinidine but has limited durability. The aim of this study was to determine the impact of shelf temperature (10 °C, 25 °C and 40 °C) during freeze drying on the foam-mat kiwiberry pulp drying process and the quality of the obtained material based on analyses such as moisture content, water activity, hygroscopicity, solubility, microstructure and spectral measurement using the FTIR method. The use of higher shelf temperatures during freeze drying positively influenced the drying process, reducing its duration by up to 40.7%. The shelf temperature caused changes in the dry matter content (97.2–99.6%), water activity (0.159–0.221), structure and hygroscopic properties (1.41–4.41 g water/100 g d.m.) of the kiwiberry foam mats. Foam-mat drying at 40 °C exhibited a significantly lower water activity, total porosity and hygroscopicity, providing properties favorable for good microbiological and functional stability during storage. Furthermore, this temperature applied during freeze drying resulted in an increase in the solubility of the obtained material, which indicates its possible use in the matrix of other food products.

Electrospun Composites of Chitosan with Cerium Oxide Nanoparticles for Wound Healing Applications: Characterization and Biocompatibility Evaluation In Vitro and In Vivo.

Cerium oxide nanoparticles (CeONPs), as part of tissue regeneration matrices, can protect cells from reactive oxygen species and oxidative stress. In addition, they can influence the properties of the scaffold, including its electrospinnability and mechanical strength. In this work, we prepared electrospun fiber mats from a chitosan and polyethylene oxide blend (CS-PEO) with the addition of ceria nanoparticles (CS-PEO-CeONP). The addition of CeONPs resulted in a smaller fiber diameter and higher swelling compared to CS-PEO fiber mats. CeONP-modified fiber mats also had a higher Young's modulus due to the reinforcing effect of the nanoparticles. Both mats had comparable adhesion and cytocompatibility to mesenchymal stem cells, which had a more rounded morphology on CS-PEO-CeONP compared to elongated cells on the CS-PEO mats. Biocompatibility in an in vivo rat model showed no acute toxicity, no septic or allergic inflammation, and no rough scar tissue formation. The degradation of both mats passed the stage of matrix swelling. CS-PEO-CeONP showed significantly slower biodegradation, with most of the matrix remaining in the tissue after 90 days. The reactive inflammation was aseptic in nature with the involvement of multinucleated foreign-body type giant cells and was significantly reduced by day 90. CeONPs induced the formation of the implant's connective tissue capsule. Thus, the introduction of CeONPs influenced the physicochemical properties and biological activity of CS-PEO nanofiber mats.

Production and comprehensive characterization of PVA/chitosan transdermal composite mats loaded with bioactive curcumin; evaluation of its release kinetics, antioxidant, antimicrobial, and biocompatibility features

AbstractRecently, researchers have shown increasing interest in incorporating bioactive substances with therapeutic properties into fiber‐structured mat biomaterials, which are favored as tissue scaffolds for wound healing applications. In this study, curcumin (Cur)‐loaded polyvinyl alcohol (PVA)/chitosan (CS) composite mats were produced using the electrospinning method and followed by the freeze‐drying method. Scanning electron microscope images proved the homogeneous structure of the composite mats, and Fourier transform infrared spectroscopy analysis showed that the Cur‐loaded composite mats were successfully produced. The antibacterial activity of Cur‐loaded PVA/CS composite mats was evaluated against Escherichia coli and Staphylococcus aureus, and the results showed that the antibacterial activity of the composite mats increased with the addition of Cur. Furthermore, the antioxidant test, release kinetics tests, and in vitro biocompatibility studies such as cytotoxicity, staining, and scratch assay of Cur‐loaded PVA/CS composite mats were carried out. The results showed that adding Cur enhanced the bioactivity of PVA10/CS10 composite mats. Further, the biocompatibility findings indicated that 10Cur‐PVA10/CS10 exhibited the highest viability value throughout all incubation periods compared with the other samples. Moreover, the highest rate of scratch closure on the 10Cur‐PVA/10/CS10 composite mats was observed at the end of 24 h compared with the other composite mats. These findings indicate that the Cur‐loaded PVA10/CS10 composite mats significantly positively impact cell migration and wound healing, making them a promising candidate as transdermal composite mats for tissue engineering and wound care applications.

In vitro analysis of electrospun nanofibrous polycaprolactone loaded with Rhamnus prinoides leaf extract as potential wound dressing

AbstractRhamnus prinoides, an indigenous Ethiopian traditional medicinal plant, has been used for treating various ailments including skin conditions in traditional formulations. In this study, plant leaf extract has been incorporated into polycaprolactone (PCL) nanofibers through electrospinning at concentrations of 1%, 3%, 5%, 7% wt/vol for the first time. The presence of extract in the nanofiber was analyzed using Fourier transform infrared. The in vitro antibacterial activity, release, contact angle, thermal, and mechanical properties of the nano mats were characterized. The scanning electron microscopy (SEM) analysis revealed that the produced mats are continuous, smooth, bead‐less, and inter connected. The examination of SEM images using ImageJ revealed that the fiber diameter ranged from 219 ± 47 nm to 284 ± 114 nm. The mats showed excellent anti‐bactericidal activity against both Staphylococcus aureus and Escherichia coli. During the 72‐h in vitro release investigation, an initial burst release was observed within the first 12 h, followed by sustained release of the extract over long period of time. The contact angle analysis showed, addition of leaf extract to the PCL nanofiber increased hydrophilicity. Furthermore, the nanofiber membranes had favorable mechanical properties. Overall, these findings suggested that R. prinoides leaf extract‐functionalized PCL nanofibers could be effective wound dressings with broad‐spectrum antimicrobial activity.

Flexible, cuttable, origami-enabling ceramic nanofiber mat for visible light-driven catalysts

Despite possessing abundant potential, the brittleness of oxide ceramic nanofibers limits their use in self-standing flexible photocatalysts with easy separation/recycling and customized shaping. Here, we have reported a novel flexible ceramic constructed using electrospinning of metal oxide nanofiber mats of two different phases (CeO2–TiO2 [CTO]) with controllable composition. Although pure TiO2 and CeO2 nanofibers are too brittle to endure bending, CTO nanofibers show enhanced mechanical properties that make them flexible, bendable, cuttable, and origami-enabled. To study mechanical resilience and nanofiber structures, we have made a series of CTO nanofiber mats with different ratios of TiO2 and CeO2. The results reveal that the heterogeneous TiO2 and CeO2 interface creates stress transfer pathways, while the amorphous TiO2 phase absorbs stress. The CTO nanofiber mats can act as an efficient photocatalyst for the degradation of organic pollutants under visible light. The photocatalytic activity of the oxide ceramic mats is closely related to energy band positions and Ce3+ content. The decrease in the band gap of the CTO nanofiber mats enables the absorption of visible light, and the conduction band is positioned adequately to produce oxygen radicals via electron transfer. Consequently, the efficient degradation of organic pollutants can be achieved in the presence of the CTO nanofiber mat under visible light. Furthermore, the CTO nanofiber mats are coated with other metal oxides to form p–n junction band structures, which facilitate the separation of holes and electrons, resulting in even higher catalytic activity.

Bidirectional fabric evolution in Hamelin Pool microbialites, Shark Bay, Western Australia

AbstractHamelin Pool, Shark Bay, Western Australia hosts the world's largest and most extensive assemblages of living marine microbialites, comparable in size and shape to ancient structures found throughout the fossil record. Documented here are the internal fabrics of modern microbialites collected throughout Hamelin Pool. Mesoscale and microscale observations of microbialite polished slabs and thin section scans, optical microscopy and scanning electron microscopy coupled with energy‐dispersive X‐ray spectroscopy formed the basis for a fabric classification system that combines accretionary mat type with microfabric. Accretionary mat types included pustular, smooth, colloform, as well as ‘transitional’ mats that are a cross between pustular and smooth mats. Mapping of fabrics in 45 microbialite heads indicated bidirectional evolution. An upward progression of fabrics corresponded to changes in mat type as the head grew upward into shallower water. A downward evolution of microfabrics occurred as surface mats transitioned into the subsurface of the microbialite structure. Downward microfabric evolution occurred as a result of early taphonomic processes, and involved a progression from the original depositional architecture to subsequent stages of “Micritic Thickening”, and finally, “Cement Infilling”. The observed bidirectional evolution of microbialite microfabrics within Hamelin Pool offers a conceptual framework for the study of modern microbialites, not simply as the sole product of accretionary mat types but rather as the combined result of the activity of surface mats and their taphonomic evolution. Early taphonomic processes induce further lithification of the microbialites which may enhance preservation potential in the geological record.

Antifungal Activity of Chitosan/Poly(Ethylene Oxide) Blend Electrospun Polymeric Fiber Mat Doped with Metallic Silver Nanoparticles.

In this work, the implementation of advanced functional coatings based on the combination of two compatible nanofabrication techniques such as electrospinning and dip-coating technology have been successfully obtained for the design of antifungal surfaces. In a first step, uniform and beadless electrospun nanofibers of both polyethylene oxide (PEO) and polyethylene (PEO)/chitosan (CS) blend samples have been obtained. In a second step, the dip-coating process has been gradually performed in order to ensure an adequate distribution of silver nanoparticles (AgNPs) within the electrospun polymeric matrix (PEO/CS/AgNPs) by using a chemical reduction synthetic process, denoted as in situ synthesis (ISS). Scanning electron microscopy (SEM) has been used to evaluate the surface morphology of the samples, showing an evolution in average fiber diameter from 157 ± 43 nm (PEO), 124 ± 36 nm (PEO/CS) and 330 ± 106 nm (PEO/CS/AgNPs). Atomic force microscopy (AFM) has been used to evaluate the roughness profile of the samples, indicating that the ISS process induced a smooth roughness surface because a change in the average roughness Ra from 84.5 nm (PEO/CS) up to 38.9 nm (PEO/CS/AgNPs) was observed. The presence of AgNPs within the electrospun fiber mat has been corroborated by UV-Vis spectroscopy thanks to their characteristic optical properties (orange film coloration) associated to the Localized Surface Plasmon Resonance (LSPR) phenomenon by showing an intense absorption band in the visible region at 436 nm. Energy dispersive X-ray (EDX) profile also indicates the existence of a peak located at 3 keV associated to silver. In addition, after doping the electrospun nanofibers with AgNPs, an important change in the wettability with an intrinsic hydrophobic behavior was observed by showing an evolution in the water contact angle value from 23.4° ± 1.3 (PEO/CS) up to 97.7° ± 5.3 (PEO/CS/AgNPs). The evaluation of the antifungal activity of the nanofibrous mats against Pleurotus ostreatus clearly indicates that the presence of AgNPs in the outer surface of the nanofibers produced an important enhancement in the inhibition zone during mycelium growth as well as a better antifungal efficacy after a longer exposure time. Finally, these fabricated electrospun nanofibrous membranes can offer a wide range of potential uses in fields as diverse as biomedicine (antimicrobial against human or plant pathogen fungi) or even in the design of innovative packaging materials for food preservation.

Investigation through the antimicrobial activity of electrospun PCL nanofiber mats with green synthesized Ag–Fe nanoparticles

Wound or device infections with drug resistant microorganisms are a major challenge in medicine that could increase morbidity and mortality rate, with a great financial burden on the health care system. Nanofibers with antimicrobial coating have been widely applied in wound dressing and tissue engineering to decrease the risk of infections. In the present study, Ag–Fe core-shell NPs were green synthesized by applying Ducrosia anethifolia plant extracted as a stabilizing and reducing agent. The novel nanocomposites by a combination of Ag–Fe and polymeric polycaprolactone (PCL) nanofibers were produced. Synthesized nanoparticles and nanocomposites were characterized using several physical and mechanical techniques, including scanning electron microscopy (SEM), dynamic light scattering method (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier transform infrared (FT-IR) spectroscopy, ultraviolet–visible absorption spectroscopy (UV–vis), and tensile test. The mean size of the synthesized Ag and Ag–Fe core-shell nanoparticles were 4.1 and 18.4 nm. Silver nanoparticles were successfully coated with Fe shell and nearly spherical core-shell shape. SEM images showed that PCL nanofibers have an average size of 265 nm. The results revealed that the increase in the Ag–Fe core-shell NPs' concentration leads to the smaller size of nanofibers. The antimicrobial properties of Ag–Fe core-shell and PCL/Ag–Fe nanocomposites were evaluated against some clinically important bacteria and fungi. Also, the cytotoxicity of PCL/Ag–Fe nanocomposites on fibroblast cells Natural man (NHDF) was assessed for 24, 48, and 72 h. The results of the study confirmed minimal cellular toxicity and considerable antimicrobial properties of green synthesized PCL/Ag–Fe nanocomposites, especially against some drug resistant pathogens, which could be promising new insight to improve the PCL-based composites applications in wound dressings or medical devices.

Ascorbyl palmitate–PCL fiber mats loaded with strontium polyphosphate nanoparticles for guided bone regeneration

Multifunctional fiber mats are explored as potential bioactive matrices for the development of the next generation of guided bone regeneration membranes with tunable microstructure, strength and therapeutic activity. In the present study, polycaprolactone (PCL) nanofibers with different concentrations of ascorbic acid derivatives (ascorbyl palmitate) and strontium polyphosphate nanoparticles (Sr-polyP NPs) were fabricated. The obtained PCL mats scaffolds were assessed not only for microstructure structure features, including morphological observation, hydrophilicity and tensile strength, but also in vitro water uptake, biodegradation (under enzymatic and hydrolytic conditions), bioactivity using SBF, as well as ascorbic acid release study. The observed results showed that the mean fiber diameter of the PCL fibers (388 ± 340 nm) increased with the increase in the concentration of the ASP and Sr-polyP NPs. The addition of ascorbyl palmitate caused an increase in viscosity from 40.6 ± 2.5 to 66.6 ± 2.0 cP in the case of 20% AsP/PCL; however, it caused a decrease in conductivity from 7.3 ± 0.4 to 6.38 µs, while there was an obvious increase in the viscosity and conductivity by Sr-polyP Nps addition from 40.6 ± 2.5 cP in the case of PCL only to 88.3 ± 2.5 cP in the case of PA1/SP15. The contact angle decreases from 125.9 ± 2.5° in the case of PCL only to 112 ± 4 and 102 ± 2.4° in the case of 20% loaded ascorbyl palmitate-PCL mats and 15% Sr/PCL, respectively. Moreover, the assessment of the antioxidant activity of PCL fiber mats containing 10% and 20% ascorbyl palmitate demonstrated that the 20% ascorbyl palmitate-PCL fiber mats have a higher antioxidant effectiveness compared to the 10% mats. This could be attributed to the controlled release of ascorbic acid from PCL, which occurs after 7 days. However, the highest tensile strength was observed for 5% Sr-polyP NPs-loaded PCL/AsP mats at 1.52 ± 0.51 MPa. Further increase of Sr-polyP NPs content resulted in a clear decrease of tensile strength to 1.13 ± 0.13and 0.93 ± 0.71 for 10% and 20% ascorbyl palmitate-PCL mats, respectively. Importantly, the fabricated AsP and Sr-polyP NPs-loaded PCL fiber mats showed induction of calcium phosphate deposition in SBF and the ability to sustain release of ascorbic acid over a time period of 28 d, in addition to the enhancement in cell proliferation compared to PCL only suggesting their application as a favorable synthetic matrix to amplify guided bone regeneration process.Graphical abstract

Essential Oils Infused Poly-ε-Caprolactone/Gelatin Electrospun Nanofibrous Mats: Biocompatibility and Antibacterial Study.

Infections caused by antibiotic-resistant pathogens result in a delayed wound-healing process. As an approach to prevent infections, alternatives in the form of natural antimicrobial products have become public interest. Essential oils derived from plants are used as antimicrobials owing to their broad-spectrum activity against pathogenic organisms. In this study, essential oil from seeds of watermelon, jackfruit, and papaya was incorporated into poly-ε-caprolactone/gelatin nanofibers using an electrospinning technique. The synthesized nanofibers were smooth, continuous, and bead-free. The nanofibers were found to be mechanically competent as confirmed by the universal tensile tester. The antibacterial activity of the various essential oil-loaded nanofibrous mats was determined by disc diffusion assay. Furthermore, they were found to be non-toxic and biocompatible by MTT and CMFDA assays on fibroblast cells. The obtained results have demonstrated that essential oil-loaded nanofiber mats are promising alternatives to conventional antibacterial wound dressings.

Impact of meltwater flow intensity on the spatiotemporal heterogeneity of microbial mats in the McMurdo Dry Valleys, Antarctica

The meltwater streams of the McMurdo Dry Valleys are hot spots of biological diversity in the climate-sensitive polar desert landscape. Microbial mats, largely comprised of cyanobacteria, dominate the streams which flow for a brief window of time (~10 weeks) over the austral summer. These communities, critical to nutrient and carbon cycling, display previously uncharacterized patterns of rapid destabilization and recovery upon exposure to variable and physiologically detrimental conditions. Here, we characterize changes in biodiversity, transcriptional responses and activity of microbial mats in response to hydrological disturbance over spatiotemporal gradients. While diverse metabolic strategies persist between marginal mats and main channel mats, data collected from 4 time points during the austral summer revealed a homogenization of the mat communities during the mid-season peak meltwater flow, directly influencing the biogeochemical roles of this stream ecosystem. Gene expression pattern analyses identified strong functional sensitivities of nitrogen-fixing marginal mats to changes in hydrological activities. Stress response markers detailed the environmental challenges of each microhabitat and the molecular mechanisms underpinning survival in a polar desert ecosystem at the forefront of climate change. At mid and end points in the flow cycle, mobile genetic elements were upregulated across all mat types indicating high degrees of genome evolvability and transcriptional synchronies. Additionally, we identified novel antifreeze activity in the stream microbial mats indicating the presence of ice-binding proteins (IBPs). Cumulatively, these data provide a new view of active intra-stream diversity, biotic interactions and alterations in ecosystem function over a high-flow hydrological regime.

Designing nanofibrous poly(ε-caprolactone)/hydroxypropyl cellulose/zinc oxide/Melilotus Officinalis wound dressings using response surface methodology

Nanofibrous wound dressing is one of the most prominent stratagems for wound caring/management. This research is an approach for designing an electrospun wound dressing based on poly(ε-caprolactone)/hydroxypropyl cellulose/zinc oxide nanoparticles (PCL/HPC/n-ZnO), in which response surface methodology (RSM) was utilized to ascertain the optimum sample. It was observed that the addition of n-ZnO and Melilotus Officinalis (MO) extract could increase the fibers mean diameter, pore size, and crystallinity of mats. The mentioned quantities for a sample with the highest MO content (PHZM10) were equal to 469±105 nm, 544±370 nm, and 49.67%, respectively. Moreover, enhancing the amount of MO led to an increase in mechanical properties. In this respect, the PHZM10 sample had the modulus, strength, and toughness of 82.41±0.61, 20.45±0.30 MPa, and 4194.86 mJ, respectively. Also, according to the MTT assay, no cytotoxicity was reported from any of the manufactured samples. Besides, it was concluded that the antibacterial activity and nanofibrous structure of mats, and also their potential for release of MO extract could accelerate the wound healing. Hence, the wound closure index for the PHZM10 group was 99.3±1.1%. Based on all noted results, the PCL/HPC/n-ZnO/MO electrospun mats can be proposed as reassuring wound dressing candidates.

Enhanced In Vitro Wound Healing Using PVA/B-PEI Nanofiber Mats: A Promising Wound Therapeutic Agent against ESKAPE and Opportunistic Pathogens.

Opportunistic skin pathogens and their resistance to pre-existing therapeutics are a challenge to normal physiological wound healing processes. Consistent development of antimicrobial agents is required to overcome the complications raised by antimicrobial resistance. An effective alternative proposed in recent research includes the use of antimicrobial nanoparticles or nanobiopolymers. Unfortunately, metallic nanoparticles that have been proven as antimicrobial agents also possess a certain level of toxicity. In this work, we demonstrate the use of a cationic polymer, branched polyethyleneimine (B-PEI), that has been electrospun to obtain a scaffold/fiber (B-PEI NF) mat resulting in a large surface area-to-volume ratio. SEM analysis revealed that the average diameter of the obtained fibers is 240 nm. The formation of nanoscaffold modulates the controlled release of the polymer from the matrix resulting in long-term effects. The antimicrobial and antibiofilm activity of the B-PEI nanofiber (B-PEI NF) was evaluated against ESKAPE pathogens (Pseudomonas aeruginosa and Staphylococcus aureus) and also against Candida albicans. Dose-dependent inhibition was observed for microbial growth and biofilm for all three test organisms, the minimum inhibitory concentration required for inhibiting P. aeruginosa, S. aureus, and C. albicans is 33.125, 26.5, and 19.875 μM, respectively, in 2 mL of bacterial/fungal broth. Crystal violet and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays showed significant reduction in biomass and cell viability of sessile cells, respectively, within the biofilm after treatment using B-PEI NFs. A B-PEI NF matrix promotes cell migration and wound healing processes by mimicking the extracellular matrix. In vitro wound healing studies showed a fivefold increase in cell migration and wound healing by B-PEI NFs (97% wound coverage in 17 h) when compared to B-PEI (15% wound coverage in 17 h). The in vitro wound healing assays confirmed the biocompatibility and better wound healing activity of B-PEI NF mats.

The effect of cobalt on morphology, structure, and ORR activity of electrospun carbon fibre mats in aqueous alkaline environments.

An innovative approach for the design of air electrodes for metal–air batteries are free-standing scaffolds made of electrospun polyacrylonitrile fibres. In this study, cobalt-decorated fibres are prepared, and the influence of carbonisation temperature on the resulting particle decoration, as well as on fibre structure and morphology is discussed. Scanning electron microscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, elemental analysis, and inductively coupled plasma optical emission spectrometry are used for characterisation. The modified fibre system is compared to a benchmark system without cobalt additives. Cobalt is known to catalyse the formation of graphite in carbonaceous materials at elevated temperatures. As a result of cobalt migration in the material the resulting overall morphology is that of turbostratic carbon. Nitrogen removal and nitrogen-type distribution are enhanced by the cobalt additives. At lower carbonisation temperatures cobalt is distributed over the surface of the fibres, whereas at high carbonisation temperatures it forms particles with diameters up to 300 nm. Free-standing, current-collector-free electrodes assembled from carbonised cobalt-decorated fibre mats display promising performance for the oxygen reduction reaction in aqueous alkaline media. High current densities at an overpotential of 100 mV and low overpotentials at current densities of 333 μA·cm−2 were found for all electrodes made from cobalt-decorated fibre mats carbonised at temperatures between 800 and 1000 °C.

Silver nanoparticle embedded polymethacrylic acid/ polyvinylpyrrolidone nanofibers for catalytic application

A facile way to fabricate the highly uniform and mono-disperse silver nanoparticles (AgNPs) immobilized in polymer nanofibers has been successfully developed by combining electrospinning technique and photo-reduction method, applicable as efficient catalysts. Herein, poly-vinyl pyrrolidone (PVP) forbids the silver grain growth due to its steric effect and polymethacrylic acid (PMAA) contributes abundant carboxylic groups, which enhances the absorption of silver ions in nanofibers ensuring the growth of high density of AgNPs. UV exposure of nanofibers for 24 h leads to the maximum density of growth of AgNPs in PMAA/PVP nanofibers. The present investigation indicates that the size and spatial distribution of AgNPs can be tailored by changing the concentration of AgNO3 solution consequently, controlling the catalytic activity of AgNPs-immobilized nanofibrous mats. Interestingly, the prepared nanofibers exhibit good catalytic activity towards the reduction of methylene blue an environmental organic pollutant, due to the high density of AgNPs formation in nanofibers.

Evaluation of Nigella sativa oil loaded electrospun polyurethane nanofibrous mat as wound dressing

Electrospun nanofibers have a natural wound healing effect due to their similarity to the extracellular matrix (ECM). Nigella sativa oil, which has therapeutic properties, is used for a wide variety of applications in traditional medicine. The aim of this study was to investigate the release characteristic and wound healing performance of Nigella sativa oil (NSO) loaded polyurethane (PU) electrospun nanofibrous mats in wound dressing applications. In addition, the antibacterial activity and cytotoxicity of the electrospun mats were studied. Analyses using a scanning electron microscope (SEM) showed that PU/NSO nanofibrous mat with an average fiber diameter of 416 ± 66 nm were successfully fabricated. NSO was released at a maximum ratio of 30% from the electrospun mat, and the Korsmeyer-Peppas model was identified as best for determining the release mechanism. Significant antibacterial activity was observed against Staphylococcus aureus (90.26%) and Escherichia coli (95.75%). The developed PU/NSO nanofibrous mat increased the cell viability more than 100% in human umbilical vein endothelial cell line (HUVEC) cell line. The NSO loaded PU nanofibrous mat significantly promoted the wound healing process on a rat wound model, and its wound closure reached approximately 85% compared to the control groups on the 9th day (p < 0.01). The results indicated PU/NSO nanofibrous mat is a suitable candidate for a wound dressing.

Influence of chitosan and hydroxyapatite incorporation on properties of electrospun PVA/HA nanofibrous mats for bone tissue regeneration: Nanofibers optimization and in-vitro assessment

3D-scaffolds composed of polyvinyl alcohol-hyaluronan (PVA/HA) nanofiber mats were fabricated by electrospinner. Spinning conditions of PVA/HA were optimized for obtaining uniform and smooth nanofibers (NFs). Resultant NFs were investigated by SEM, FT-IR and mechanical tensile. Chitosan was incorporated into NFs mats during spinning for reducing bleeding, microbial growth of wound bed, and enhancing viability/proliferation of cells in damaged tissues. Hydroxyapatite (HAP) after silanization using (3-aminopropyl)triethoxysilane (APTES) was also incorporated into scaffolds due to its similar chemical composition with mineral composition of bone, which stimulates interactions between bone tissue and biomaterial resulting in a prominent interface after implantation. NFs with different compositions were bio-evaluated in vitro using antimicrobial activity, hemolysis(%), cytotoxicity, and cell adhesion tests. Results revealed that, addition of HAP into PVA/HA mats improved significantly their mechanical/thermal stability and relatively hindered swelling index, compared to mats without HAP. However, addition of chitosan enhanced swelling index and antimicrobial activity of mats. All tested mats with different compositions showed high cell-viability, regardless incubation time or concentration of tested nanofibers. In-vitro cell adhesion results indicated that, WI38 cells adhered and proliferated adequately with nanofibers containing HAP. Such findings support the ability for using PVA/HA/CH/HAP NFs as biomaterials for bone tissue regeneration soon.

The in situ catalytic oxidation of sulfamethoxazole via peroxydisufate activation operated in a NG/rGO/CNTs composite membrane filtration.

Metal-free carbonaceous composite membranes have been proven to effectively drive novel in situ catalytic oxidation for the degradation of organic pollutants via persulfates activation. In this study, nitrogen-doped graphene (NG) was employed as a modifier to enhance the catalytic activity of the carbon mats by assembly with reduced graphene oxide (rGO) and carbon nanotubes (CNTs) on the top of a nylon supporter. The morphology and performance of the NG/rGO/CNTs composite membrane were compared to those obtained without the addition of NG (rGO/CNTs). Owing to the larger nanochannels for water delivery and stronger hydrophobicity on the surface, the NG/rGO/CNTs composite membrane shows a superior low-pressure filtration performance in favor of energy-saving operation. For the in situ catalytic oxidation of the NG/rGO/CNTs composite membrane through the activation of peroxydisufate (PDS), the average removal rate of sulfamethoxazole (SMX), one of frequently detected sulfonamide antibiotics in water, can reach 21.7 mg·m-2·h-1 under continuous filtration mode, which was 17% more rapid than that of the rGO/CNTs, resulting in significant detoxifying of the oxidation intermediates. Owing to the addition of NG into the carbon mats, the reactive nitrogen-doped sites identified by X-Ray photoelectron spectroscopy (XPS), such as pyridinic and graphitic N, played important roles in PDS activation, while both the radical and non-radical pathways were involved in in situ catalytic oxidation. According to the experimental evidence of the effects that solution environment has on the SMX removal and transmembrane pressure, the NG/rGO/CNTs composite membrane shows a relatively high resistance to changes in the solution pH, chloride ion inhibition, and background organics fouling. These results suggest a new approach to the application of activated persulfate oxidation in water treatment, such that improvements to the reaction stability warrant further investigation.

Herbal Plant Leaf Extracts Immobilized PCL Nanofibrous Mats as Skin-Inspired Anti-infection Wound Healing Material

In this study, an attempt has been made using PCL nanofibrous mats as support material for immobilizing a couple of medicinal plants Achyranthes aspera (AS) and Datura metel (DM) leaf extract and screen the in vitro antimicrobial and in vivo wound healing properties with the aim to develop these nanofibrous mats as a biocompatible antimicrobial wound dressing material. The Achyranthes aspera leaf extract immobilized electrospun PCL nanofibrous mat (PCL-AS) and Datura metel leaf extract immobilized electrospun PCL nanofibrous mat (PCL-DM) were characterized by SEM, XRD, and EDAX. The morphology, porosity, swelling, and weight loss percentage of the electrospun PCL, PCL-AS, and PCL-DM nanofibrous mats have been investigated. The antibacterial activity of both PCL-AS and PCL-DM nanofibrous mats show better inhibition against some bacterial strains. The cytotoxicity of the prepared PCL-AS and PCL-DM mats show very low toxicity to the vero cells. The in vivo wound healing activity was performed in rats by the treatment of wounds with PCL-AS and PCL-DM nanofibrous mats and showed that the PCL-AS and PCL-DM nanofibrous mats heal the wounds completely. The histopathological results of the skin recovered from wounds treated by PCL-AS and PCL-DM nanofibrous mats confirm the formation of skin tissues within 9 days. The results of the work show that the nanofibrous mats act as an enhancer of wound healing by treating the surfaces that contain pathogenic microorganisms especially in hospital environment. Traditional medicinal plants are considered to be an influential source of new and wide range of natural substances to treat chronic and some infectious diseases with their potential therapeutic effects. Though the medicinal plants are beneficial to treat wounds and infections caused by some bacteria, they may have poor contact with wounds if it is used as bare extract. Therefore the medicinal plant extracts have to be facilitated via a support material. Electrospun PCL nanofibrous mats used as a support material for immobilizing two medicinal plant leaf extract and monitor the in vitro antimicrobial and in vivo wound healing properties. Therefore, the results of this study shows that the developed nanofibrous mats have ability as a biocompatible antimicrobial wound dressing material.

Detection and community-level identification of microbial mats in the McMurdo Dry Valleys using drone-based hyperspectral reflectance imaging

AbstractThe reflectance spectroscopic characteristics of cyanobacteria-dominated microbial mats in the McMurdo Dry Valleys (MDVs) were measured using a hyperspectral point spectrometer aboard an unmanned aerial system (remotely piloted aircraft system, unmanned aerial vehicle or drone) to determine whether mat presence, type and activity could be mapped at a spatial scale sufficient to characterize inter-annual change. Mats near Howard Glacier and Canada Glacier (ASPA 131) were mapped and mat samples were collected for DNA-based microbiome analysis. Although a broadband spectral parameter (a partial normalized difference vegetation index) identified mats, it missed mats in comparatively deep (&gt; 10 cm) water or on bouldery surfaces where mats occupied fringing moats. A hyperspectral parameter (B6) did not have these shortcomings and recorded a larger dynamic range at both sites. When linked with colour orthomosaic data, B6 band strength is shown to be capable of characterizing the presence, type and activity of cyanobacteria-dominated mats in and around MDV streams. 16S rRNA gene polymerase chain reaction amplicon sequencing analysis of the mat samples revealed that dominant cyanobacterial taxa differed between spectrally distinguishable mats, indicating that spectral differences reflect underlying biological distinctiveness. Combined rapid-repeat hyperspectral measurements can be applied in order to monitor the distribution and activity of sentinel microbial ecosystems across the terrestrial Antarctic.