Reduction In Fiber Diameter Research Articles

Effect of Fiber Chemical Treatments on Rice Straw Fiber Reinforced Composite Properties

ABSTRACT This work reports the effect of alkali, enzyme, and their sequential combination treatment on rice straw fiber properties (fiber diameter, aspect ratio, fiber length, bundle strength and elongation). The change in fiber properties and its association with rice straw fibers reinforced epoxy biocomposites has been studied. Biocomposites, prepared using the hand lay-up technique, were characterized using FTIR, TGA and SEM. The mechanical properties viz. tensile, flexural, impact and compression were measured according to the ASTM standards. Sound transmission loss and noise reduction coefficient of the composites was also determined. Results showed that the alkali and enzyme treatment to the rice straw significantly reduced fiber length and fiber diameter by 50%. Enzyme treatment caused the highest reduction in fiber diameter which increased the aspect ratio. The sequential combination of alkali and enzyme yielded significant improvements in the tensile (20%), flexural (22%), impact (98%), and compression (328%) strength of the composites. The noise reduction coefficient (0.95) of all rice straw composites was found excellent. Thus, alkali-enzyme pretreated rice straw fiber composite product is a good choice for agro-residue valorization and industrial product development.

Engineered polymer matrix novel biocompatible materials decorated with eucalyptus oil and zinc nitrate with superior mechanical and bone forming abilities

Electrospun scaffolds based on polymer-matrix composites have gained wide attention recently. A novel engineered biocompatible scaffold is manufactured using polyurethane (PU) loaded with eucalyptus oil (EL) and Zinc nitrate (ZnNO3) using the electrospinning technique. Morphological observations revealed the reduced fibre diameter for the PU/EL and PU/EL/ZnNO3 compared to PU. Contact angle studies indicated the increase in hydrophobic behaviour of the PU/EL whereas an increase in wettability for PU/EL/ZnNO3 compared to PU. EL and ZnNO3 presence in the PU matrix enhanced the mechanical strength. Surface topology analysis showed a decrease in the roughness for the PU/EL and PU/EL/ZnNO3 compared to the pristine PU. Both PU/EL and PU/EL/ZnNO3 showed prolonged clotting time and decreased haemolytic percentage compared to the polyurethane as indicated in their anticoagulation studies. In vitro bone mineralisation testing depicted the increase in calcium deposition for the modified PU samples compared to pure polyurethane sample. Hence, PU/EL and PU/EL/ZnNO3 scaffold with superior properties render full avenues for new bone generation.

Effects of stabilization on structures and properties of Electrospun Polyacrylonitrile based carbon nanofibers as a binder free electrode for supercapacitor application

Electrospun nanofibers were produced with Polyacrylonitrile (PAN) precursor using the Electrospinning technique. Stabilization is an important heat treatment process before carbonization. A total of 2 samples were considered for the carbonization process. Electrospun Pure PAN nanofiber mat was used with aluminium foil substrate for the heat treatment process in a tube furnace. The first sample was stabilized at 290 °C temperature at a 2 °C/min heating rate and constant heating for 3 h. The second sample was directly used for carbonization without stabilization. Fibers were carbonized at 500 °C under a nitrogen atmosphere with a dwell time of 1 h. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to study the influence on structures and properties of carbon fibers of both samples. To investigate elemental concentration in samples Energy-dispersive X-ray spectroscopy (EDX) was used. EDX results showed 45 % and 60 % carbon atom non stabilized and stabilized carbon nanofibers respectively. An SEM result reveals a drastic fiber diameter reduction in a sample that was not stabilized before carbonization as compared with the sample which was stabilized before the carbonization process. FTIR results showed the complete conversion of CN to CN at a stabilization temperature of 290 °C. Also, FTIR results reveal that 500 °C temperature is too low for complete carbonization as some peaks are still there after the carbonization. Low temperature carbonization is necessary to avoid the melting of aluminium foil substrate during the carbonization process. Further CNF mat will be peeled off from the substrate and will be used directly as electrode material for electrochemical characterization.

The Effect of Electrical Polarity on the Diameter of Biobased Polybutylene Succinate Fibers during Melt Electrospinning.

Melt electrospinning is a simple, versatile, and widely used technique for the production of microfibers and sub-microfibers. Polybutylene succinate (PBS) is a promising raw material for the preparation of melt-electrospun fibers at the laboratory scale. The inclusion of additives in the PBS melt can reduce the final fiber diameter, but economically feasible larger-scale processes remain challenging. The fiber diameter can also be reduced by machine optimization, although this is expensive due to the complexity of melt-electrospinning devices. Changes in electrical field polarity have provided a low-cost strategy to reduce the diameter of fibers produced by solution-electrospinning, but there is little information about the effect of this parameter on the final diameter of melt-electrospun fibers. We therefore determined the effect of field polarity on the diameter of melt-electrospun PBS fibers at the laboratory scale and investigated the transferability of these results to our 600-nozzle pilot-scale device. Changing the polarity achieved a significant reduction in fiber diameter of ~50% at the laboratory scale and ~30% at the pilot scale, resulting in a minimum average fiber diameter of 10.88 µm. Although the effect of field polarity on fiber diameter was similar at both scales, the fibers in the web stuck together at the laboratory scale but not at the pilot scale. We have developed an inexpensive method to reduce the diameter of melt-electrospun PBS fibers and our data provide insight into the transferability of melt electrospinning from the laboratory to a pilot-scale machine.

Cold atmospheric plasma modification and electrical conductivity induction in gelatin/polyvinylidene fluoride nanofibers for neural tissue engineering.

This research follows some investigations through neural tissue engineering, including fabrication, surface treatment, and evaluation of novel self-stimuli conductive biocompatible and degradable nanocomposite scaffolds. Gelatin as a biobased material and polyvinylidene fluoride (PVDF) as a mechanical, electrical, and piezoelectric improvement agent were co-electrospun. In addition, polyaniline/graphene (PAG) nanoparticles were synthesized and added to gelatin solutions in different percentages to induce electrical conductivity. After obtaining optimum PAG percentage, cold atmospheric plasma (CAP) treatment was applied over the best samples by different plasma variable parameters. Finally, the biocompatibility of the scaffolds was analyzed and approved by in vitro tests using two different PC12 and C6 cell lines. In the present study the morphology, FTIR, dynamic light scattering, mechanical properties, wettability, contact angle tests, differential scanning calorimetric, rate of degradation, conductivity, biocompatibility, gene expression, DAPI staining, and cell proliferation were investigated. The PAG percentage optimization results revealed fiber diameter reduction, conductivity enhancement, young's modulus improvement, hydrophilicity devaluation, water uptake decrement, and degradability reduction in electrospun nanofibers by increasing the PAG concentration. Furthermore, ATR-FTIR, FE-SEM, AFM, and contact angle tests revealed that helium CAP treatment improves scaffold characterizations for 90s in duration time. Furthermore, the results of the MTT assay, FE-SEM, DAPI staining, and RT-PCR revealed that samples containing 2.5% w/w of PAG are the most biocompatible, and CAP treatment increases cell proliferation and improves neural gene expression in the differentiation medium. According to the results, the samples with the 2.5% w/w of PAG could provide a suitable matrix for neural tissue engineering in terms of physicochemical and biological.

Two-dimensional numerical pore-scale investigation of oxygen evolution in proton exchange membrane electrolysis cells

Oxygen blocking the porous transport layer (PTL) increases the mass transport loss, and then limits the high current density condition of proton exchange membrane electrolysis cells (PEMEC). In this paper, a two-dimensional transient mathematical model of anode two-phase flow in PEMEC is established by the fluid volume method (VOF) method. The transport mechanism of oxygen in porous layer is analyzed in details. The effects of liquid water flow velocity, porosity, fiber diameter and contact angle on oxygen pressure and saturation are studied. The results show that the oxygen bubble transport in the porous layer is mainly affected by capillary pressure and follows the transport mechanism of ‘pressurization breakthrough depressurization’. The oxygen bubble goes through three stages of growth, migration and separation in the channel, and then be carried out of the electrolysis cell by liquid water. When oxygen breaks through the porous layer and enters the flow channel, there is a phenomenon that the branch flow is merged into the main stream, and the last limiting throat affects the maximum pressure and oxygen saturation during stable condition. In addition, increasing the liquid water velocity is helpful to bubble separation; changing the porosity and fiber diameter directly affects the width of pore throat and the correlative capillary pressure; increasing porosity, reducing fiber diameter and contact angle can promote oxygen breakthrough and reduce the stable saturation of oxygen.

“Clay-corn-caprolactone” a novel bioactive clay polymer nanofibrous scaffold for bone tissue engineering

Osteoconductive bone tissue scaffolds are of particular interest. Clay composed of aluminosilicate can play an essential role in bone repair and regeneration, enhancing osteoblastic differentiation and apatite deposition. Current research focuses on the fabrication of illite incorporated polycaprolactone/zein electrospun scaffolds. The prepared scaffolds by varying concentrations of Illite were characterized physiochemically and biologically. The composite scaffolds were analyzed for surface morphology, mechanical properties, thermal characteristic, crystal structure, surface wettability, and chemical modification. Biocompatibility of the composite scaffold was checked against the MC3T3-e1 cell line as a model. The biomineral apatite deposition was determined by incubating the scaffolds in simulated body fluid. The alkaline phosphatase staining evaluated osteoblastic differentiation. The results show that the clay composite scaffolds showed reduced fiber diameters and enhanced wettability. The addition of Illite improved the tensile strength and the Youngs Modulus of the composite scaffolds. The in vitro biomineralization of the composite scaffolds improved calcium deposition with the maximum Ca/P ratio of 1.55. The WST-1 assay and ALP staining show that the composite scaffolds have better cell viability and osteoblastic differentiation than the PCL/zein scaffolds. The overall results show that the clay-corn-caprolactone scaffold is a promising material for bone tissue engineering.

Optimization of high‐quality carbon fiber production from electrospun aligned lignin fibers

AbstractIn recent years, investigating lignin as an alternative carbon fiber precursor has received immense research attention as a way to reduce the cost and replace the unsustainable conventional petroleum‐based precursors for carbon fiber production. The predominant challenge for lignin‐based carbon fibers is its low mechanical performance compared to conventional ones. In this work, mechanical properties of electrospun lignin carbon fiber mats were shown to be considerably enhanced via alignment of the submicron fibers. Over 60% of the fibers were aligned via a rotating drum collector utilized during fiber production. The main electrospinning parameters, namely electric field, rotating speed, and flow rate were optimized with the Box–Behnken method to enhance mechanical properties with reduced fiber diameter and improved fiber alignment. The optimal electrospinning process parameter was achieved at 2000 rpm collection speed, 80 kV/m electric field, and 440 nl/s flow rate. The lignin carbon fibers produced under the optimized condition exhibited elastic modulus of 3145.47 ± 917.75 MPa, tensile strength of 18.78 ± 6.11 MPa, and average fiber diameter of 697.07 ± 96.41 nm. The analysis on the interactions between electrospinning parameters has laid a solid foundation for the production of high‐quality carbon fibers from lignin precursor.

Tailoring body surface infrared radiation behavior through colored nanofibers for efficient passive radiative heating textiles

• The IR emissivity is decreased by reducing fiber diameter to the nanoscale. • The light scattering adjustment improved the color depth of the nanofiber fabric. • The textile has 50% of high solar absorption and 15% of low IR emittance. • The textile keeps the human body temperature at 33–35 ℃ in cold outdoor ambient. Passive radiative heating textile offers an energy-saving pathway to increase body temperature in cold weather. However, the basic properties of clothing, such as color and comfort, are usually overlooked in the design of radiative heating materials, because conventional fiber materials cannot meet the needs of infrared thermal management. Herein, we achieved low infrared emissivity of the textile by reducing the fiber diameter to the submicron level through electrospinning. The electrospun polymer molecules can achieve uniform mixing with dye molecules during the preparation of the spinning solution. And the color depth of the prepared polyacrylonitrile nanofiber (NanoPAN) fabric can be turned by a scalable solvent impregnation method. Through compounding the Ag coating layer, the colored NanoPAN/Ag textile shows high solar energy utilization of 50% and low mid-infrared (IR) emittance of 15%, realizing superior IR heating performance. The resulted NanoPAN/Ag textile maintains human body temperature at 33–35 ℃ at a cold ambient temperature of 14 ℃, while, in the case of using dyed cotton fabrics, the body temperature will drop below 33 ℃. Moreover, due to the use of nanofiber, the colored NanoPAN/Ag textile has outstanding water vapor transmission rate, water evaporation rate, breathability and mechanical stability, exhibiting great potential for practical application in infrared thermal management textile.

Engineered properties of polyurethane laden with beetroot and cerium oxide for cardiac patch application

The cardiac patch provides appropriate physicochemical properties and mechanical strength for the regeneration of damaged heart tissues. In this work, for the first-time, beetroot (BR) is blended with cerium oxide (CeO2) to produce nanofibrous polyurethane (PU) composite patch using electrospinning. The objective of this work is to fabricate the composite and examine its feasibility for cardiac patch applications. Morphological analysis revealed a dramatic reduction of fiber diameter of PU/BR (233 ± 175 nm) and PU/BR/CeO2 (331 ± 176 mm) compared to the pristine PU (994 ± 113 mm). Fourier transform infrared analysis (FTIR) analysis indicated functional peak intensities of the newly formed composite PU/BR and PU/BR/CeO2 were not similar to PU. The addition of beetroot rendered PU/BR hydrophilic (86° ± 2), whereas PU/BR/CeO2exhibited hydrophobic nature (99° ± 3). Atomic force microscopy (AFM) analysis depicted the reduced surface roughness of the PU/BR (312 ± 12 nm) and PU/BR/CeO2 (390 ± 125 nm) than the pristine PU (854 ± 32 nm). The incorporation of beetroot and CeO2 into PU enhanced the tensile strength compared with the pristine PU. The blood clotting time of PU/BR (APTT-204 ± 3 s and PT-103 ± 2 s) and PU/BR/CeO2 (APTT-205 ± 3 s and PT-105 ± 2s) were delayed significantly than the pristine PU(APTT-176 ± 2 s and PT-94 ± 2 s) as revealed in the coagulation study. Further, hemolysis assay showed the less toxic nature of the fabricated composites than the pristine PU. Hence, it can be inferred that the advanced physicochemical and blood compatible properties of electrospun PU/BR and PU/BR/CeO2 nanocomposite can be engineered successfully for cardiac patch applications.

Statistical optimization of polysilazane-derived ceramic: Electrospinning with and without organic polymer as a spinning aid for manufacturing thinner fibers

The manufacturing of electrospun mats from preceramic polymers is complex due to low and disperse molecular chain entanglements and a large number of operating parameters. Here, the electrospinning of polysilazane and polysilazane/polyacrylonitrile (PAN) solutions was evaluated and optimized. The reduction in Berry's number from 94 to 22 indicated the positive effect of adding organic polymer on the polysilazane chains to obtain homogeneous fibers. A fractional factorial design was first implemented to screen out the three most significant factors affecting the fiber diameter. Then, a response surface model was developed using the Box-Behnken design to obtain a quantitative relationship between operating parameters and fiber diameter. Finally, the models were used to find the optimal conditions that yield the thinnest fiber. For polysilazane, the feed rate showed a positive effect, while for polysilazane/PAN an interaction between the feed rate and the tip-to-collector-distance was the most significant factor, with a positive effect. The verification of the models was accomplished through model validation. The addition of PAN to polysilazane reduced fiber diameter from 1.79 ± 0.26 μm to 0.57 ± 0.04 μm. The polysilazane/PAN pyrolyzed at 1000 °C (SiCN_PAN) could shield more than 50% of electromagnetic energy from 100 MHz to 4.5 GHz. In addition to the presence of carbon-rich regions derived from PAN, thinner diameters caused an increase of interfaces between the voids and electrospun fibers, which intensified multi-reflection for dissipating electromagnetic energy. Owing to the optimized design, the SiCN_PAN fibers with satisfying electromagnetic shielding properties could meet advanced requirements of lightweight hybrid materials from aerospace to defense applications.

Microstructure Manipulation of Polyurethane‐Based Macromolecular Scaffold for Tendon/Ligament Tissue Engineering

AbstractIn spite of improvements in tissue engineering approaches, tendon and ligament (T/L) regeneration is still a clinical challenge. The fabrication of functional scaffolds that possess the structural and biological properties of native T/L tissues is critical to a successful healing. Herein, the effect of scaffold microstructure on mesenchymal stem cells (MSCs) response is evaluated. Electrospun polyurethane (EPU) scaffolds with different alignment degrees of nanofibers are fabricated using five rotating speeds of the collector. Although the constructs display similarity in terms of porosity (85%), the increasing degree of alignment results in a notable reduction of fiber diameter. Accordingly, it also improves the tensile strength from 26.44 ± 0.50 to 35.76 ± 1.50 MPa and tensile modulus from 18.94 ± 1.02 to 31.10 ± 1.11 MPa. Furthermore, despite similarities of cell supporting behavior among all types of scaffolds in terms of cell attachment, spreading, proliferation, and infiltration, the aligned nanofibers noticeably direct cell orientation parallel to their alignment direction, resulting in significant upregulation of tendon‐related markers expression. Taken together, the results highlight that the aligned EPU scaffolds are a promising candidate for T/L regeneration, which deserves to be further investigated with long‐term studies.

Biocompatibility Computation of Muscle Cells on Polyhedral Oligomeric Silsesquioxane-Grafted Polyurethane Nanomatrix.

This study was performed to appraise the biocompatibility of polyhedral oligomeric silsesquioxane (POSS)-grafted polyurethane (PU) nanocomposites as potential materials for muscle tissue renewal. POSS nanoparticles demonstrate effectual nucleation and cause noteworthy enhancement in mechanical and thermal steadiness as well as biocompatibility of resultant composites. Electrospun, well-aligned, POSS-grafted PU nanofibers were prepared. Physicochemical investigation was conducted using several experimental techniques, including scanning electron microscopy, energy dispersive X-ray spectroscopy, electron probe microanalysis, Fourier transform infrared spectroscopy, and X-ray diffraction pattern. Adding POSS molecules to PU did not influence the processability and morphology of the nanocomposite; however, we observed an obvious mean reduction in fiber diameter, which amplified specific areas of the POSS-grafted PU. Prospective biomedical uses of nanocomposite were also appraised for myoblast cell differentiation in vitro. Little is known about C2C12 cellular responses to PU, and there is no information regarding their interaction with POSS-grafted PU. The antimicrobial potential, anchorage, proliferation, communication, and differentiation of C2C12 on PU and POSS-grafted PU were investigated in this study. In conclusion, preliminary nanocomposites depicted superior cell adhesion due to the elevated free energy of POSS molecules and anti-inflammatory potential. These nanofibers were non-hazardous, and, as such, biomimetic scaffolds show high potential for cellular studies and muscle regeneration.

Electrospun polyacrylonitrile nanofibrous membranes supported with montmorillonite for efficient PM2.5 filtration and adsorption of Cu (II) ions

AbstractIn this study, we have fabricated polyacrylonitrile/montmorillonite (PAN/Mt) nanofibrous nanocomposites with variation in concentration of Mt from 0.25% to 1.00%. The electrospinning process developed PAN/Mt nanofibrous nanocomposites having reduced fiber diameters and high surface roughness as observed in Field emission scanning electron microscopy. The nanocomposite nanofibers were characterized by X‐ray diffraction (XRD) and thermogravimetric analyzer for intercalation and thermal stability respectively. PAN/Mt nanofibrous nanocomposites were tested for their water vapor transmission rate, air permeability, burst strength, and tensile strength. The filtration efficiency of 0.75% PAN/Mt nanofibrous nanocomposite was found to be 98.7% for PM2.5 particles present in air with a pressure drop of 46.8 Pa. The adsorption of copper (II) (Cu (II)) ions using 0.75% PAN/Mt nanofibrous nanocomposites has also been studied. The effect of contact time and initial concentration of adsorbent on the adsorption of Cu (II) ions have been analyzed. It was found that the PAN/Mt nanofibrous membranes follows pseudo‐second‐order kinetic model and Langmuir adsorption isotherm for the adsorption of Cu (II) ions from aqueous solutions. This study suggests the potential implication of PAN/Mt nanofibrous nanocomposites for filtration of PM2.5 and adsorption of metal ions.

Impact of Atmosphere on Recovered Carbon Fibers From Poly Ether Ether Ketone (PEEK) Based Composites During Thermoconversion

Carbon Fibers Reinforced Polymer composites (CFRP) are high added value materials used in many manufactured products. Especially in aeronautics, thermosetting resins tend to be replaced by heat-resistant thermoplastic polymers. The aim of the work is to evaluate suitable operating conditions of thermoconversion for the recovery of carbon fibers from Poly Ether Ether Ketone (PEEK)/carbon fibers composites. Micro and pilot scale tests have been performed in nitrogen, wet nitrogen, air, and wet air. Thermogravimetric analysis of PEEK/carbon fiber composites showed a moderate decomposition onset temperature of the composite at 515 °C and 510 °C in dry nitrogen and dry air respectively. The oxidative atmosphere did not significantly impact this temperature since the first mass loss was not atmosphere dependent. However, after the first PEEK degradation reaction, the nature of the atmosphere appeared as a great issue. Total mass loss was significantly improved with temperature (full oxidation of polymer and carbon fibers up to 800 °C) and with reaction time using air. Indeed, at pilot scale, the matrix was fully degraded in air atmosphere at 550 °C for 1 h while only 42% and 46% was reached in nitrogen and steam/nitrogen respectively. Comparison of thermogravimetric data between wet and dry atmospheres revealed that steam plays a thermal retardant role leading to some differences on the matrix degradation and on the surface morphology of the carbon fiber at pilot scale. Air treatments at pilot scale induced a reduction of fiber diameters (< − 3.7%) but the tensile strengths of recovered carbon fibers were preserved with an average retention of mechanical properties of 81%-85%. It has been concluded that recycling of PEEK/carbon composite required an oxidant to split up carbon fibers from the PEEK matrix.

Pre- and post-partum variation in wool cortisol and wool micron in Australian Merino ewe sheep (Ovis aries).

An individual merino sheep’s output of wool production is influenced by synergistic interactions of sheep genetics, climate, farm management, and nutrition available to the whole flock. The price paid to the producer for this wool commodity is determined via numerous tested parameters and /or subjective appraisal of the raw greasy wool. This research investigated the level of variation in wool cortisol (a physiological stress biomarker) and wool micron (MIC) in Merino ewes (Ovis aries), pre-partum and post-lambing (lactation/lambs at foot), using maiden ewe (n = 38) managed in an outdoor paddock in a commercial farm. The key findings of this study are; (1) wool quality indicators showed a significant variation between pre- and post- parturition including significant reduction in MIC and (2) there was a negative correlation between wool cortisol levels and wool micron pre-parturition (rs = − 0.179, p < 0.05). This relationship between wool cortisol and wool micron was positive (rs = + 0.29, p < 0.05) during post-parturition suggesting that ewes with lambs at foot ended up with finer wool (reduction in fibre diameter) but they also maintained high levels of wool cortisol. Furthermore, the comfort factor, curvature, standard deviation and spin fineness of the wool were also significantly reduced post-parturition. The results of this study show that metabolic resources partitioning in ewe associated with pregnancy and lambing can result in a reduction in wool quality indices. The activity of the HPA-axis is attenuated during late gestation and parturition as a maternal adaptation; however, the results of our study show that wool cortisol remained similar between pre- and post- lambing. This result indicates that environmental stressors that may have been operating on farm (e.g., cold winter period) could influence on maternal physiological stress response however the exact level of influence of environment conditions on ewe stress levels and productivity traits (e.g., lambing success and wool quality) warrants further investigation. In conclusion, the use of top-knot wool sampling in combination with wool cortisol analysis provides researchers with a convenient method to quantify wool quality and physiological stress simultaneously under commercial sheep production.

Role of PEGylated CdSe-ZnS quantum dots on structural and functional properties of electrospun polycaprolactone scaffolds for blood vessel tissue engineering

Conjugation of quantum dots (Q-dots) into tissue engineering scaffolds is extremely beneficial for designing composite scaffolds imparting multifunctional properties. In the present work, we report the efficacy of incorporating the PEGylated CdSe-ZnS (Q-dots) into electrospun poly(caprolactone)(PCL) scaffolds whose properties were evaluated for small diameter blood vessel applications. Incorporation of Q-dots was found to result in significant reduction in fiber diameter of electrospun scaffolds. Corresponding pore size ranges varied from 12 to 36 µm for composite scaffold compared with 12–60 µm in bare scaffold. Both PCL and composite scaffolds were found to possess better mechanical strength and elasticity than that of native arteries. Contact angle measurements revealed hydrophobic nature of scaffolds which significantly improved upon modification with fibrin. PCL/Q-dot composite scaffolds were found to possess optimum micro-structure for supporting uniform endothelial cell growth after 5 days of culture compared to the pristine PCL scaffold.

Simvastatin-loaded graphene oxide embedded in polycaprolactone-polyurethane nanofibers for bone tissue engineering applications

Abstract Here, the role of simvastatin-loaded graphene oxide embedded in polyurethane-polycaprolactone nanofibers for bone tissue engineering has been investigated. The scaffolds were physicochemically and mechanically characterized, and obtained polymeric composites were used as MG-63 cell culture scaffolds. The addition of graphene oxide-simvastatin to nanofibers generates a homogeneous and uniform microstructure as well as a reduction in fiber diameter. Results of water-scaffolds interaction indicated higher hydrophilicity and absorption capacity as a function of graphene oxide addition. Scaffolds’ mechanical properties and physical stability improved after the addition of graphene oxide. Inducing bioactivity after the addition of simvastatin-loaded graphene oxide terminated its capability for hard tissue engineering application, evidenced by microscopy images and phase characterization. Nanofibrous scaffolds could act as a sustained drug carrier. Using the optimal concentration of graphene oxide-simvastatin is necessary to avoid toxic effects on tissue. Results show that the scaffolds are biocompatible to the MG-63 cell and support alkaline phosphatase activity, illustrating their potential use in bone tissue engineering. Briefly, graphene-simvastatin-incorporated in polymeric nanofibers was developed to increase bioactive components’ synergistic effect to induce more bioactivity and improve physical and mechanical properties as well as in vitro interactions for better results in bone repair.

Regulatory Function of Sympathetic Innervation on the Endo/Lysosomal Trafficking of Acetylcholine Receptor.

Recent studies have demonstrated that neuromuscular junctions are co-innervated by sympathetic neurons. This co-innervation has been shown to be crucial for neuromuscular junction morphology and functional maintenance. To improve our understanding of how sympathetic innervation affects nerve–muscle synapse homeostasis, we here used in vivo imaging, proteomic, biochemical, and microscopic approaches to compare normal and sympathectomized mouse hindlimb muscles. Live confocal microscopy revealed reduced fiber diameters, enhanced acetylcholine receptor turnover, and increased amounts of endo/lysosomal acetylcholine-receptor-bearing vesicles. Proteomics analysis of sympathectomized skeletal muscles showed that besides massive changes in mitochondrial, sarcomeric, and ribosomal proteins, the relative abundance of vesicular trafficking markers was affected by sympathectomy. Immunofluorescence and Western blot approaches corroborated these findings and, in addition, suggested local upregulation and enrichment of endo/lysosomal progression and autophagy markers, Rab 7 and p62, at the sarcomeric regions of muscle fibers and neuromuscular junctions. In summary, these data give novel insights into the relevance of sympathetic innervation for the homeostasis of muscle and neuromuscular junctions. They are consistent with an upregulation of endocytic and autophagic trafficking at the whole muscle level and at the neuromuscular junction.

Effect of the spin‐line temperature profile on the mechanical properties of melt electrospun polyethylene fibers

AbstractThe covid‐19 pandemic has revealed the need for alternative production approaches with low startup costs like electrospinning for filter needs, the most imperative element of the personal protective equipment (PPE). Current attempts in advancing melt electrospinning deal with developing strategies for fiber diameter attenuation toward sub‐micron scale. Here, the attunement in the spinning‐zone temperature known as ''spin‐line temperature profile'' was utilized as a baseline for fiber diameter reduction. The mechanical performance of the melt‐electrospun linear low‐density polyethylene (LLDPE) fibers is reported to characterize their structural transformation with respect to various spin‐line temperature profiles. With an increase in the spin‐line temperature to above 100°C in the area of cone formation, an increased tensile and yield strength along with fiber diameter reduction by four‐folds was demonstrated. A significant increase in toughness, by almost three times, without compromising the stiffness and Young's modulus was observed. The dynamic mechanical analysis revealed that spinning in high temperatures produces changes in the alpha (α) relaxation, contributing to the significant increase in strain at break. These results are significant because polyolefin fibers are an imperative element of medical textiles and PPE. Therefore, developing a correlation for process‐structure‐properties for emerging production techniques like melt electrospinning becomes critical.