Characterization of electrospun lignin based carbon fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poursorkhabi, Vida; Mohanty, Amar; Misra, Manjusri

2015-05-22

The production of lignin fibers has been studied in order to replace the need for petroleum based precursors for carbon fiber production. In addition to its positive environmental effects, it also benefits the economics of the industries which cannot take advantage of carbon fiber properties because of their high price. A large amount of lignin is annually produced as the byproduct of paper and growing cellulosic ethanol industry. Therefore, finding high value applications for this low cost, highly available material is getting more attention. Lignin is a biopolymer making about 15 – 30 % of the plant cell walls andmore » has a high carbon yield upon carbonization. However, its processing is challenging due to its low molecular weight and also variations based on its origin and the method of separation from cellulose. In this study, alkali solutions of organosolv lignin with less than 1 wt/v% of poly (ethylene oxide) and two types of lignin (hardwood and softwood) were electrospun followed by carbonization. Different heating programs for carbonization were tested. The carbonized fibers had a smooth surface with an average diameter of less than 5 µm and the diameter could be controlled by the carbonization process and lignin type. Scanning electron microscopy (SEM) was used to study morphology of the fibers before and after carbonization. Thermal conductivity of a sample with amorphous carbon was 2.31 W/m.K. The electrospun lignin carbon fibers potentially have a large range of application such as in energy storage devices and water or gas purification systems.« less

Removal of aniline from air and water by polymers of intrinsic microporosity (PIM-1) electrospun ultrafine fibers.

PubMed

Satilmis, Bekir; Uyar, Tamer

2018-04-15

This research aims to investigate the possibility of electrospun fibers from Polymers of Intrinsic Microporosity (PIM-1) as an alternative adsorbent for aniline removal from both air and aqueous solution. Adsorption properties of electrospun PIM-1 fibers were compared with powder and film form of PIM-1. While electrospun PIM-1 nanofibrous mat can adsorb 871 mg g -1 aniline from air, it can also adsorb 78 ± 5.4 mg g -1 aniline from aqueous environment when 50 mg L -1 aniline solution is used. The experimental maximum adsorption capacity of electrospun PIM-1 fibers was found as (q e ) 138 mg g -1 . Langmuir and Freundlich isotherm models have been studied and Langmuir model found more appropriate for aniline adsorption on electrospun PIM-1 fibers. The study reveals that self-standing electrospun fibrous mat of PIM-1 has shown potential to be used as an efficient adsorbent material for the adsorption of VOCs from air and aqueous system thanks to its fast kinetic and high adsorption capacity. Copyright © 2018 Elsevier Inc. All rights reserved.

Polarized emission from CsPbBr3 nanowire embedded-electrospun PU fibers

NASA Astrophysics Data System (ADS)

Güner, Tuğrul; Topçu, Gökhan; Savacı, Umut; Genç, Aziz; Turan, Servet; Sari, Emre; Demir, Mustafa M.

2018-04-01

Interest in all-inorganic halide perovskites has been increasing dramatically due to their high quantum yield, band gap tunability, and ease of fabrication in compositional and geometric diversity. In this study, we synthesized several hundreds of nanometer long and ˜4 nm thick CsPbBr 3 nanowires (NWs). They were then integrated into electrospun polyurethane (PU) fibers to examine the polarization behavior of the composite fiber assembly. Aligned electrospun fibers containing CsPbBr 3 NWs showed a remarkable increase in the degree of polarization from 0.17-0.30. This combination of NWs and PU fibers provides a promising composite material for various applications such as optoelectronic devices and solar cells.

Electrospun fibers for the prevention of human immunodeficiency virus

NASA Astrophysics Data System (ADS)

Ball, Cameron

HIV/AIDS education, testing, and treatment have thus far failed to cease the pandemic spread of the HIV virus. HIV prevention is hindered by a lack of protective options beyond the ABC approach of abstinence, being faithful, and using condoms. One approach to address this inadequacy is to develop antiviral products for vaginal or rectal application that provide receptive partner-initiated protection against viral infection during sex. Such products, termed anti-HIV microbicides, can especially empower young women to take control over their sexual health. This work explored a new approach to anti-HIV microbicides: electrospun fibers for the delivery of small-molecule antiretroviral drugs. Electrospun microbicides are nonwoven fabrics made from polymer-based nanofibers. The wide array of polymers available for electrospinning allowed for the incorporation and release of chemically diverse agents. Since electrospun fibers have an extremely high surface area to volume ratio, they serve as excellent delivery systems for rapid drug delivery of both hydrophilic and hydrophobic agents. The flexibility in the design of electrospun fibers afforded by coaxial electrospinning further enabled the formulation of sustained-release microbicides. To demonstrate the power of electrospinning to deliver drugs over multiple timescales, composite microbicide fabrics were created to provide both rapid and sustained drug release from a single device. This work has produced alternative microbicide formulations, while establishing methods for the thorough characterization of these systems and solutions for the needs of people at risk of HIV infection. By addressing problems in both HIV prevention and drug delivery, this work has expanded our capacity to engineer elegant solutions to complex and pressing global health challenges.

Properties of electrospun pollock gelatin/poly(vinyl alcohol) and pollock gelatin/poly(lactic acid) fibers

USDA-ARS?s Scientific Manuscript database

Pollock gelatin/poly(vinyl alcohol) (PVA) fibers were electrospun using deionized water as the solvent and pollock gelatin/poly(lactic acid) (PLA) fibers were electrospun using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the solvent. The chemical, thermal, and thermal stability properties were exami...

Engineered Polymer Composites Through Electrospun Nanofiber Coating of Fiber Tows

NASA Technical Reports Server (NTRS)

Kohlman, Lee W.

2013-01-01

Toughening and other property enhancements of composite materials are typically implemented by-modifying the bulk properties of the constituents, either the fiber or matrix materials. This often leads to difficulties in processing and higher material costs. Many composites consist of tows or yarns (thousands of individual fibers) that are either filament wound or processed into a fabric by weaving or braiding. The matrix material can be added to the tow or fabric before final processing, resulting in a prepreg material, or infused into the fiber material during final processing by a variety of methods. By using a direct electrospun deposition method to apply thermoplastic nanofiber to the surface of the tows, the tow-tow interface in the resulting composite can be modified while using otherwise conventional materials and handling processes. Other materials of interest could also be incorporated into the electrospun precursor.

Functional electrospun polystyrene nanofibers incorporating α-, β-, and γ-cyclodextrins: comparison of molecular filter performance.

PubMed

Uyar, Tamer; Havelund, Rasmus; Hacaloglu, Jale; Besenbacher, Flemming; Kingshott, Peter

2010-09-28

Electrospinning has been used to successfully create polystyrene (PS) nanofibers containing either of three different types of cyclodextrin (CD); α-CD, β-CD, and γ-CD. These three CDs are chosen because they have different sized cavities that potentially allow for selective inclusion complex (IC) formation with molecules of different size or differences in affinity of IC formation with one type of molecule. The CD containing electrospun PS nanofibers (PS/CD) were initially characterized by scanning electron microscopy (SEM) to determine the uniformity of the fibers and their fiber diameter distributions. X-ray photoelectron spectroscopy (XPS) was used to quantitatively determine the concentration of each CD on the different fiber surfaces. Static time-of-flight secondary ion mass spectrometry (static-ToF-SIMS) showed the presence of each type of CD on the PS nanofibers by the detection of both the CD sodium adduct molecular ions (M + Na+) and lower molecular weight oxygen containing fragment ions. The comparative efficiency of the PS/CD nanofibers/nanoweb for removing phenolphthalein, a model organic compound, from solution was determined by UV-vis spectrometry, and the kinetics of phenolphthalein capture was shown to follow the trend PS/α-CD > PS/β-CD > PS/γ-CD. Direct pyrolysis mass spectrometry (DP-MS) was also performed to ascertain the relative binding strengths of the phenolphthalein for the CD cavities, and the results showed the trend in the interaction strength was β-CD > γ-CD > α-CD. Our results demonstrate that nanofibers produced by electrospinning that incorporate cyclodextrins with different sized cavities can indeed filter organic molecules and can potentially be used for filtration, purification, and/or separation processes.

Electrospun zein fibers using glyoxal as the cross-linking reagent

USDA-ARS?s Scientific Manuscript database

Glyoxal has been used to provide zein electrospun fibers that are resistant to dissolution by known zein solvents. Durable fibers with diameters between 0.2 and 0.7 micrometers could be produced. The reaction between zein and glyoxal was carried out in acetic acid at temperatures between 25 and 60...

Scaffold permeability as a means to determine fiber diameter and pore size of electrospun fibrinogen.

PubMed

Sell, Scott; Barnes, Catherine; Simpson, David; Bowlin, Gary

2008-04-01

The purpose of this study was to construct a flowmeter that could accurately measure the hydraulic permeability of electrospun fibrinogen scaffolds, providing insight into the transport properties of electrospun scaffolds while making the measurement of their topographical features (fiber diameter and pore size) more accurate. Three different concentrations of fibrinogen were used (100, 120, and 150 mg/mL) to create scaffolds with three different fiber diameters and pore sizes. The fiber diameters and pore sizes of the electrospun scaffolds were first analyzed with scanning electron microscopy and image analysis software. The permeability of each scaffold was measured with the flowmeter and used to calculate permeability-based fiber diameters and pore sizes, which were compared to values obtained through image analysis. Permeability measurement revealed scaffold permeability to increase with fibrinogen concentration, much like average fiber diameter and pore size. Comparison between the two measurement methods demonstrated the efficacy of the flowmeter as a way to measure scaffold features. Copyright 2007 Wiley Periodicals, Inc.

Investigation of drug release and matrix degradation of electrospun poly(DL-lactide) fibers with paracetanol inoculation.

PubMed

Cui, Wenguo; Li, Xiaohong; Zhu, Xinli; Yu, Guo; Zhou, Shaobing; Weng, Jie

2006-05-01

This study was aimed at assessing the potential use of electrospun fibers as drug delivery vehicles with focus on the different diameters and drug contents to control drug release and polymer fiber degradation. A drug-loaded solvent-casting polymer film was made with an average thickness of 100 microm for comparative purposes. DSC analysis indicated that electrospun fibers had a lower T(g) but higher transition enthalpy than solvent-casting polymer film due to the inner stress and high degree of alignment and orientation of polymer chains caused by the electrospinning process. Inoculation of paracetanol led to a further slight decrease in the T(g) and transition enthalpy. An in vitro drug release study showed that a pronounced burst release or steady release phase was initially observed followed by a plateau or gradual release during the rest time. Fibers with a larger diameter exhibited a longer period of nearly zero order release, and higher drug encapsulation led to a more significant burst release after incubation. In vitro degradation showed that the smaller diameter and higher drug entrapment led to more significant changes of morphologies. The electrospun fiber mat showed almost no molecular weight reduction, but mass loss was observed for fibers with small and medium size, which was characterized with surface erosion and inconsistent with the ordinarily polymer degrading form. Further wetting behavior analysis showed that the high water repellent property of electrospun fibers led to much slower water penetration into the fiber mat, which may contribute to the degradation profiles of surface erosion. The specific degradation profile and adjustable drug release behaviors by variation of fiber characteristics made the electrospun nonwoven mat a potential drug delivery system rather than polymer films and particles.

Electrospun Fibers as a Dressing Material for Drug and Biological Agent Delivery in Wound Healing Applications

PubMed Central

Gizaw, Mulugeta; Thompson, Jeffrey; Faglie, Addison; Lee, Shih-Yu; Neuenschwander, Pierre; Chou, Shih-Feng

2018-01-01

Wound healing is a complex tissue regeneration process that promotes the growth of new tissue to provide the body with the necessary barrier from the outside environment. In the class of non-healing wounds, diabetic wounds, and ulcers, dressing materials that are available clinically (e.g., gels and creams) have demonstrated only a slow improvement with current available technologies. Among all available current technologies, electrospun fibers exhibit several characteristics that may provide novel replacement dressing materials for the above-mentioned wounds. Therefore, in this review, we focus on recent achievements in electrospun drug-eluting fibers for wound healing applications. In particular, we review drug release, including small molecule drugs, proteins and peptides, and gene vectors from electrospun fibers with respect to wound healing. Furthermore, we provide an overview on multifunctional dressing materials based on electrospun fibers, including those that are capable of achieving wound debridement and wound healing simultaneously as well as multi-drugs loading/types suitable for various stages of the healing process. Our review provides important and sufficient information to inform the field in development of fiber-based dressing materials for clinical treatment of non-healing wounds. PMID:29382065

Zein/Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) electrospun blend fiber scaffolds: Preparation, characterization and cytocompatibility.

PubMed

Zhijiang, Cai; Qin, Zhang; Xianyou, Song; Yuanpei, Liu

2017-02-01

In the present work, a series of Zein/Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) blend fiber scaffolds have been prepared by electrospinning method. The electrospun fibers showed a circular and uniform morphology with random distribution. The blend fiber scaffolds possessed well interconnected porous fibrous network structure with high porosity and large aspect surface areas. The FTIR and XPS spectra of Zein/P(3HB-co-4HB) blend fibers demonstrated the same characteristics to that of pure Zein and P(3HB-co-4HB) electrospun fibers. However, Zein might hinder the crystallization of P(3HB-co-4HB) owing to the formation of weak intermolecular interactions, which can affect the preferential orientation of P(3HB-co-4HB) molecules. Only one glass transition temperature (Tg) can be detected for electrospun Zein/P(3HB-co-4HB) blend fiber scaffolds implying the miscibility of Zein and P(3HB-co-4HB) in the blend fibers. The Zein/P(3HB-co-4HB) blend fiber scaffolds showed about 50% of improvement in tensile strength and 400% of increase in elongation at break by increasing P(3HB-co-4HB) content from 20% to 80%. The cytocompatibility of the Zein/P(3HB-co-4HB) blend fiber scaffolds was preliminarily evaluated by cell culture in vitro. The as-prepared electrospun Zein/P(3HB-co-4HB) blend fiber scaffolds with the characteristics of good biocompatibility, excellent pore characteristic as well as sufficient mechanical properties should be more promising for applications as tissue engineering scaffold. Copyright © 2016 Elsevier B.V. All rights reserved.

High Areal Capacity Si/LiCoO 2 Batteries from Electrospun Composite Fiber Mats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Self, Ethan C.; Naguib, Michael; Ruther, Rose E.

Here, freestanding nanofiber mat Li-ion battery anodes containing Si nanoparticles, carbon black, and poly(acrylic acid) (Si/C/PAA) are prepared using electrospinning. The mats are compacted to a high fiber volume fraction (~0.85), and interfiber contacts are welded by exposing the mat to methanol vapor. A compacted+welded fiber mat anode containing 40 wt % Si exhibits high capacities of 1,484 mA h g -1 (3,500 mA h gmore » $$-1\\atop{Si}$$) at 0.1 C and 489 mAh g -1 at 1 C and good cycling stability (e.g., 73% capacity retention over 50 cycles). Post-mortem analysis of the fiber mats shows that the overall electrode structure is preserved during cycling. Whereas many nanostructured Si anodes are hindered by their low active material loadings and densities, thick, densely packed Si/C/PAA fiber mat anodes reported here have high areal and volumetric capacities (e.g., 4.5 mA h cm -2 and 750 mA h cm -3, respectively). A full cell containing an electrospun Si/C/PAA anode and electrospun LiCoO 2-based cathode has a high specific energy density of 270 Wh kg -1. The excellent performance of the electrospun Si/C/PAA fiber mat anodes is attributed to the: (i) PAA binder which interacts with the SiO x surface of Si nanoparticles and (ii) high material loading, high fiber volume fraction, and welded interfiber contacts of the electrospun mats« less

High Areal Capacity Si/LiCoO 2 Batteries from Electrospun Composite Fiber Mats

DOE PAGES

Self, Ethan C.; Naguib, Michael; Ruther, Rose E.; ...

2017-03-24

Here, freestanding nanofiber mat Li-ion battery anodes containing Si nanoparticles, carbon black, and poly(acrylic acid) (Si/C/PAA) are prepared using electrospinning. The mats are compacted to a high fiber volume fraction (~0.85), and interfiber contacts are welded by exposing the mat to methanol vapor. A compacted+welded fiber mat anode containing 40 wt % Si exhibits high capacities of 1,484 mA h g -1 (3,500 mA h gmore » $$-1\\atop{Si}$$) at 0.1 C and 489 mAh g -1 at 1 C and good cycling stability (e.g., 73% capacity retention over 50 cycles). Post-mortem analysis of the fiber mats shows that the overall electrode structure is preserved during cycling. Whereas many nanostructured Si anodes are hindered by their low active material loadings and densities, thick, densely packed Si/C/PAA fiber mat anodes reported here have high areal and volumetric capacities (e.g., 4.5 mA h cm -2 and 750 mA h cm -3, respectively). A full cell containing an electrospun Si/C/PAA anode and electrospun LiCoO 2-based cathode has a high specific energy density of 270 Wh kg -1. The excellent performance of the electrospun Si/C/PAA fiber mat anodes is attributed to the: (i) PAA binder which interacts with the SiO x surface of Si nanoparticles and (ii) high material loading, high fiber volume fraction, and welded interfiber contacts of the electrospun mats« less

Nitric Oxide-Releasing Silica Nanoparticle-Doped Polyurethane Electrospun Fibers

PubMed Central

Koh, Ahyeon; Carpenter, Alexis W.; Slomberg, Danielle L.; Schoenfisch, Mark H.

2013-01-01

Electrospun polyurethane fibers doped with nitric oxide (NO)-releasing silica particles are presented as novel macromolecular scaffolds with prolonged NO-release and high porosity. Fiber diameter (119–614 nm) and mechanical strength (1.7–34.5 MPa of modulus) were varied by altering polyurethane type and concentration, as well as the NO-releasing particle composition, size, and concentration. The resulting NO-releasing electrospun nanofibers exhibited ~83% porosity with flexible plastic or elastomeric behavior. The use of N-diazeniumdiolate- or S-nitrosothiol-modified particles yielded scaffolds exhibiting a wide range of NO release totals and durations (7.5 nmol mg−1–0.12 μmol mg−1 and 7 h to 2 weeks, respectively). The application of NO-releasing porous materials as coating for subcutaneous implants may improve tissue biocompatibility by mitigating the foreign body response and promoting cell integration. PMID:23915047

Rigid Amorphous Fraction in PLA Electrospun Fibers

NASA Astrophysics Data System (ADS)

Cebe, Peggy; Ma, Qian; Simona Cozza, Erika; Pyda, Marek; Mao, Bin; Zhu, Yazhe; Monticelli, Orietta

2013-03-01

Electrospun fibers of poly(lactic acid) (PLA) were formed by adopting a high-speed rotating wheel as the counter-electrode. The molecular orientation, crystallization mechanism, and phase structure and transitions of the aligned ES fibers were investigated. Using thermal analysis and wide angle X-ray scattering (WAXS), we evaluated the confinement that exists in as-spun amorphous, and heat-treated semicrystalline, fibers. Differential scanning calorimetry confirmed the existence of a constrained amorphous phase in as-spun aligned fibers, without the presence of crystals or fillers to serve as fixed physical constraints. Using WAXS, for the first time the mesophase fraction, consisting of oriented amorphous PLA chains, was quantitatively characterized in nanofibers. The authors acknowledge support from the National Science Foundation, Polymers Program under grant DMR-0602473. ESC acknowledges a Ph.D. grant supported by Italian Ministry of Education and Scientific Research.

Electrospun fiber surface nanotopography influences astrocyte-mediated neurite outgrowth.

PubMed

Johnson, Christopher D; D'Amato, Anthony R; Puhl, Devan L; Wich, Douglas M; Vespermann, Amanda; Gilbert, Ryan J

2018-05-15

Aligned, electrospun fiber scaffolds provide topographical guidance for regenerating neurons and glia after central nervous system injury. To date, no study has explored how fiber surface nanotopography affects astrocyte response to fibrous scaffolds. Astrocytes play important roles in the glial scar, the blood brain barrier, and in maintaining homeostasis in the central nervous system. In this study, electrospun poly L-lactic acid fibers were engineered with smooth, pitted, or divoted surface nanotopography. Cortical or spinal cord primary rat astrocytes were cultured on the surfaces for either 1 or 3 days to examine the astrocyte response over time. The results showed that cortical astrocytes were significantly shorter and broader on the pitted and divoted fibers compared to those on smooth fibers. However, spinal cord astrocyte morphology was not significantly altered by the surface features. These findings indicate that astrocytes from unique anatomical locations respond differently to the presence of nanotopography. Western Blot results show that the differences in morphology were not associated with significant changes in GFAP or vinculin in either astrocyte population, suggesting that surface pits and divots do not induce a reactive phenotype in either cortical or spinal cord astrocytes. Finally, astrocytes were co-cultured with dorsal root ganglia to determine how the surfaces affected astrocyte-mediated neurite outgrowth. Astrocytes cultured on the fibers for shorter periods of time (1 day) generally supported longer neurite outgrowth. Pitted and divoted fibers restricted spinal cord astrocyte-mediated neurite outgrowth, while smooth fibers increased 3 day spinal cord astrocyte-mediated neurite outgrowth. In total, fiber surface nanotopography can influence astrocyte elongation and influence the capability of astrocytes to direct neurites. Therefore, fiber surface characteristics should be carefully controlled to optimize astrocyte-mediated axonal

Optical fiber ultrasound transmitter with electrospun carbon nanotube-polymer composite

NASA Astrophysics Data System (ADS)

Poduval, Radhika K.; Noimark, Sacha; Colchester, Richard J.; Macdonald, Thomas J.; Parkin, Ivan P.; Desjardins, Adrien E.; Papakonstantinou, Ioannis

2017-05-01

All-optical ultrasound transducers are promising for imaging applications in minimally invasive surgery. In these devices, ultrasound is transmitted and received through laser modulation, and they can be readily miniaturized using optical fibers for light delivery. Here, we report optical ultrasound transmitters fabricated by electrospinning an absorbing polymer composite directly onto the end-face of optical fibers. The composite coating consisting of an aqueous dispersion of multi-walled carbon nanotubes (MWCNTs) in polyvinyl alcohol was directly electrospun onto the cleaved surface of a multimode optical fiber and subsequently dip-coated with polydimethylsiloxane (PDMS). This formed a uniform nanofibrous absorbing mesh over the optical fiber end-face wherein the constituent MWCNTs were aligned preferentially along individual nanofibers. Infiltration of the PDMS through this nanofibrous mesh onto the underlying substrate was observed and the resulting composites exhibited high optical absorption (>97%). Thickness control from 2.3 μm to 41.4 μm was obtained by varying the electrospinning time. Under laser excitation with 11 μJ pulse energy, ultrasound pressures of 1.59 MPa were achieved at 1.5 mm from the coatings. On comparing the electrospun ultrasound transmitters with a dip-coated reference fabricated using the same constituent materials and possessing identical optical absorption, a five-fold increase in the generated pressure and wider bandwidth was observed. The electrospun transmitters exhibited high optical absorption, good elastomer infiltration, and ultrasound generation capability in the range of pressures used for clinical pulse-echo imaging. All-optical ultrasound probes with such transmitters fabricated by electrospinning could be well-suited for incorporation into catheters and needles for diagnostics and therapeutic applications.

Modulation of anisotropy in electrospun tissue-engineering scaffolds: Analysis of fiber alignment by the fast Fourier transform

PubMed Central

Ayres, Chantal; Bowlin, Gary L.; Henderson, Scott C.; Taylor, Leander; Shultz, Jackie; Alexander, John; Telemeco, Todd A.; Simpson, David G.

2010-01-01

We describe the use of the fast Fourier transform (FFT) in the measurement of anisotropy in electrospun scaffolds of gelatin as a function of the starting conditions. In electrospinning, fiber alignment and overall scaffold anisotropy can be manipulated by controlling the motion of the collecting mandrel with respect to the source electrospinning solution. By using FFT to assign relative alignment values to an electrospun matrix it is possible to systematically evaluate how different processing variables impact the structure and material properties of a scaffold. Gelatin was suspended at varying concentrations (80, 100, 130, 150 mg/ml) and electrospun from 2,2,2 trifluoroethanol onto rotating mandrels (200–7000 RPM). At each starting concentration, fiber diameter remained constant over a wide range of mandrel RPM. Scaffold anisotropy developed as a function of fiber diameter and mandrel RPM. The induction of varying degrees of anisotropy imparted distinctive material properties to the electrospun scaffolds. The FFT is a rapid method for evaluating fiber alignment in tissue-engineering materials. PMID:16859744

Mechanical Characterization of Electrospun Nanocomposite Fibers

NASA Astrophysics Data System (ADS)

Alsmairat, Ohood

Electrospinning is considered one of the most efficient techniques used for producing fibers in the nanometer to micrometer ranges. The mechanical properties of the electrospun fibers depend on the solution used to produce them. The present study focuses on dissolving the PolyMethalylmethacrylate (PMMA) in acetone solvent. A concentration of 23% PMMA was found to be the best concentration for producing smooth fibers with almost no beads. We studied the effect of mixing the PMMA with two types of nanotubes on the mechanical properties of the fibers. A Carbon-Nano-Tubes (CNT) and Boron-Nitride-Nano-Tubes were mixed with PMMA solution at different ratios to produce a CNT/PMMA and BNNT/PMMA solutions with different concentrations of 0.1%, 0.25%, and 0.6%. Electrospinning technique was used to produce fibers from the PMMA, CNT/PMMA, and BNNT/PMMA solutions. All fibers were tested experimentally with a micro-tensile-tester to produce stress-strain curves that were used to extract the average modulus of elasticity, maximum strength, and fracture point for each fiber. Enhancements in the Youngs modulus and maximum tensile strength of the fibers were observed with the addition of CNTs. Further enhancements were observed with the addition of BNNTs. A random sample of 0.6% CNT/PMMA fibers was tested with Raman spectrometer and the results show a linear change in the frequency-strain curve.

Characterization and Modification of Electrospun Fiber Mats for Use in Composite Proton Exchange Membranes

NASA Astrophysics Data System (ADS)

Mannarino, Matthew Marchand

Electrostatic fiber formation, or electrospinning, offers a particularly simple and robust method to create polymeric nanofibers of various sizes and morphologies. In electrospinning, a viscoelastic fluid is charged so that a liquid jet is ejected from the surface of the fluid (typically in the form of a drop supplied by a needle or spinneret) and collected on a grounded plate, creating a nonwoven fiber mat. Modification of the diameter of the fibers as well as the porosity, specific surface area, and mechanical properties of the mat allows one to tailor electrospun mats for specific applications. Despite the widespread and rapidly growing use of electrospinning in the fabrication of novel nanomaterials, there are no simple, universal methods of predicting, a priori, the properties of electrospun fibers from knowledge of the polymer solution properties and electrospinning operating conditions alone. Changing a single fluid or processing parameter can affect the jet and fiber formation through several mechanisms. For example, using a different solvent can change several properties of the electrospinning fluid, such as the dielectric constant, conductivity, surface tension, and solute-solvent interaction. The work in this thesis seeks to develop a simple relation for predicting terminal jet diameter during electrospinning, which accounts for solution viscoelasticity as well as solution conductivity and operating parameters that can be easily measured and controlled. The mechanical and tribological properties of electrospun fiber mats are of paramount importance to their utility as components in a variety of applications. Although some mechanical properties of these mats have been investigated previously, reports of their tribological properties are essentially nonexistent. In this thesis, electrospun nanofiber mats of poly(trimethyl hexamethylene terephthalamide) (PA 6(3)T) and poly(hexamethylene adipamide) (PA 6,6) are characterized mechanically and tribologically

Computational predictions of the tensile properties of electrospun fiber meshes: effect of fiber diameter and fiber orientation

PubMed Central

Stylianopoulos, Triantafyllos; Bashur, Chris A.; Goldstein, Aaron S.; Guelcher, Scott A.; Barocas, Victor H.

2008-01-01

The mechanical properties of biomaterial scaffolds are crucial for their efficacy in tissue engineering and regenerative medicine. At the microscopic scale, the scaffold must be sufficiently rigid to support cell adhesion, spreading, and normal extracellular matrix deposition. Concurrently, at the macroscopic scale the scaffold must have mechanical properties that closely match those of the target tissue. The achievement of both goals may be possible by careful control of the scaffold architecture. Recently, electrospinning has emerged as an attractive means to form fused fiber scaffolds for tissue engineering. The diameter and relative orientation of fibers affect cell behavior, but their impact on the tensile properties of the scaffolds has not been rigorously characterized. To examine the structure-property relationship, electrospun meshes were made from a polyurethane elastomer with different fiber diameters and orientations and mechanically tested to determine the dependence of the elastic modulus on the mesh architecture. Concurrently, a multiscale modeling strategy developed for type I collagen networks was employed to predict the mechanical behavior of the polyurethane meshes. Experimentally, the measured elastic modulus of the meshes varied from 0.56 to 3.0 MPa depending on fiber diameter and the degree of fiber alignment. Model predictions for tensile loading parallel to fiber orientation agreed well with experimental measurements for a wide range of conditions when a fitted fiber modulus of 18 MPa was used. Although the model predictions were less accurate in transverse loading of anisotropic samples, these results indicate that computational modeling can assist in design of electrospun artificial tissue scaffolds. PMID:19627797

Polydopamine Inter-Fiber Networks: New Strategy for Producing Rigid, Sticky, 3D Fluffy Electrospun Fibrous Polycaprolactone Sponges.

PubMed

Choi, Wuyong; Lee, Slgirim; Kim, Seung-Hyun; Jang, Jae-Hyung

2016-06-01

Designing versatile 3D interfaces that can precisely represent a biological environment is a prerequisite for the creation of artificial tissue structures. To this end, electrospun fibrous sponges, precisely mimicking an extracellular matrix and providing highly porous interfaces, have capabilities that can function as versatile physical cues to regenerate various tissues. However, their intrinsic features, such as sheet-like, thin, and weak structures, limit the design of a number of uses in tissue engineering applications. Herein, a highly facile methodology capable of fabricating rigid, sticky, spatially expanded fluffy electrospun fibrous sponges is proposed. A bio-inspired adhesive material, poly(dopamine) (pDA), is employed as a key mediator to provide rigidity and stickiness to the 3D poly(ε-caprolactone) (PCL) fibrous sponges, which are fabricated using a coaxial electrospinning with polystyrene followed by a selective leaching process. The iron ion induced oxidation of dopamine into pDA networks interwoven with PCL fibers results in significant increases in the rigidity of 3D fibrous sponges. Furthermore, the exposure of catecholamine groups on the fiber surfaces promotes the stable attachment of the sponges on wet organ surfaces and triggers the robust immobilization of biomolecules (e.g., proteins and gene vectors), demonstrating their potential for 3D scaffolds as well as drug delivery vehicles. Because fibrous structures are ubiquitous in the human body, these rigid, sticky, 3D fibrous sponges are good candidates for powerful biomaterial systems that functionally mimic a variety of tissue structures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Axial and radial nanostructures in electrospun polymer fibers

NASA Astrophysics Data System (ADS)

Greenfeld, Israel; Camposeo, Andrea; Tantussi, Francesco; Pagliara, Stefano; Fuso, Francesco; Allegrini, Maria; Pisignano, Dario; Zussman, Eyal

2013-03-01

The high tensional stresses during electrospinning of semidilute polymer solutions affect the dynamic conformation of the polymer network within the liquid jet, leaving a distinctive trace in the molecular structure after solidification. We investigated such effects in electrospun nanofibers made of conjugated polymers. Modeling the polymer network evolution during electrospinning showed that as the network stretches axially, it contracts towards the jet core. The model represents the semi-flexible conjugated polymer chains as flexible freely-jointed chains, whose joints are bonding defects. Using the conjugated polymer MEH-PPV dissolved in a mixture of THF and DMF solvents, and taking advantage of its unique photophysical characteristics, we investigated optically the variations in the density and orientation of the polymer macromolecules in electrospun nanofibers. In agreement with our model, we found higher density and axial orientation at the fiber core, while lower density and radial orientation closer to the fiber surface. The non-uniformity of the resulting molecular structure can be tuned and exploited in diverse optical and structural applications. We acknowledge: V. Fasano, G. Potente, S. Girardo and E. Caldi for assistance in measurements; United States-Israel BSF, RBNI Institute, and the Israel Science Foundation for financial support.

Interactions between Surfactants in Solution and Electrospun Protein Fibers: Effects on Release Behavior and Fiber Properties.

PubMed

Stephansen, Karen; García-Díaz, María; Jessen, Flemming; Chronakis, Ioannis S; Nielsen, Hanne M

2016-03-07

Intermolecular interaction phenomena occurring between endogenous compounds, such as proteins and bile salts, and electrospun compounds are so far unreported, despite the exposure of fibers to such biorelevant compounds when applied for biomedical purposes, e.g., tissue engineering, wound healing, and drug delivery. In the present study, we present a systematic investigation of how surfactants and proteins, as physiologically relevant components, interact with insulin-loaded fish sarcoplasmic protein (FSP) electrospun fibers (FSP-Ins fibers) in solution and thereby affect fiber properties such as accessible surface hydrophilicity, physical stability, and release characteristics of an encapsulated drug. Interactions between insulin-loaded protein fibers and five anionic surfactants (sodium taurocholate, sodium taurodeoxycholate, sodium glycocholate, sodium glycodeoxycholate, and sodium dodecyl sulfate), a cationic surfactant (benzalkonium chloride), and a neutral surfactant (Triton X-100) were studied. The anionic surfactants increased the insulin release in a concentration-dependent manner, whereas the neutral surfactant had no significant effect on the release. Interestingly, only minute amounts of insulin were released from the fibers when benzalkonium chloride was present. The FSP-Ins fibers appeared dense after incubation with this cationic surfactant, whereas high fiber porosity was observed after incubation with anionic or neutral surfactants. Contact angle measurements and staining with the hydrophobic dye 8-anilino-1-naphthalenesulfonic acid indicated that the FSP-Ins fibers were hydrophobic, and showed that the fiber surface properties were affected differently by the surfactants. Bovine serum albumin also affected insulin release in vitro, indicating that also proteins may affect the fiber performance in an in vivo setting.

Release of metronidazole from electrospun poly(L-lactide-co-D/L-lactide) fibers for local periodontitis treatment.

PubMed

Reise, Markus; Wyrwa, Ralf; Müller, Ulrike; Zylinski, Matthias; Völpel, Andrea; Schnabelrauch, Matthias; Berg, Albrecht; Jandt, Klaus D; Watts, David C; Sigusch, Bernd W

2012-02-01

We aimed to achieve detailed biomaterials characterization of a drug delivery system for local periodontitis treatment based on electrospun metronidazole-loaded resorbable polylactide (PLA) fibers. PLA fibers loaded with 0.1-40% (w/w) MNA were electrospun and were characterized by SEM and DSC. HPLC techniques were used to analyze the release profiles of metronidazole (MNA) from these fibers. The antibacterial efficacy was determined by measuring inhibition zones of drug-containing aliquots from the same electrospun fiber mats in an agar diffusion test. Three pathogenic periodontal bacterial strains: Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis were studied. Cytotoxicity testing was performed with human gingival fibroblasts by: (i) counting viable cells via live/dead staining methods and (ii) by exposing cells directly onto the surface of MNA-loaded fibers. MNA concentration influenced fiber diameters and thus w/w surface areas: diameter being minimal and area maximal at 20% MNA. HPLC showed that these 20% MNA fibers had the fastest initial MNA release. From the third day, MNA release was slower and nearly linear with time. All fiber mats released 32-48% of their total drug content within the first 7 days. Aliquots of media taken from the fiber mats inhibited the growth of all three bacterial strains. MNA released up to the 28th day from fiber mats containing 40% MNA significantly decreased the viability of F. nucleatum and P. gingivalis and up to the 2nd day also for the resistant A. actinomycetemcomitans. All of the investigated fibers and aliquots showed excellent cytocompatibility. This study shows that MNA-loaded electrospun fiber mats represent an interesting class of resorbable drug delivery systems. Sustained drug release properties and cytocompatibility suggest their potential clinical applicability for the treatment of periodontal diseases. Copyright © 2011 Academy of Dental Materials. Published by Elsevier

Catalytic property of fiber media supported palladium containing alloy nanoparticles and electrospun ceramic fibers biodurability study

NASA Astrophysics Data System (ADS)

Shin, Hyeon Ung

The nanoscale of the supporting fibers may provide enhancements such as restricting the migration of metal catalyst particles. In this work, palladium nanoparticle doped alumina fibers were electrospun into template submicron fibers. These fibers were calcined at temperatures between 650°C and 1150°C to vary the crystal structures of the calcined fibers with the Pd particle size. Higher calcination temperatures led to higher reaction temperatures from 250 to about 450°C for total conversion, indicating the effective reactivity of the fiber-supported catalysts decreased with increase in calcination temperature. Pd-Au alloy nanoparticle doped titania fibers were also fabricated using an electrospinning method and assembled into a fibrous porous medium structure by a vacuum molding process. In reactor tests, the fiber media with Pd-Au alloy nanoparticle catalyst had greater reactivity in conversion of NO and CO gases than that of fiber media with Pd monometallic catalyst alone, attributed to a lower activation energy of the Pd-Au catalyst particles. In carbon monoxide oxidation reaction tests, the results showed that the performance was optimal for a catalyst of composition Pd2Au1 molar ratio that was active at 125°C, which had higher dispersion of active components and better catalytic performance compared to monometallic particle Au/TiO 2 and Pd/TiO2 fiber media. Moreover, the improved reaction activity of Pd2Au1/TiO2 fiber medium was attributed to a decreased in the activation energy. Further experiments were conducted using the electrospun ceramic fibers biodurability study. The properties of nano-sized fiber structures have attracted the attention of recent research on ceramic nanostructures as nonwoven media for applications in hazardous chemical and high temperature environments. However, health and safety concerns of micro and nano scale ceramic materials have not been fully investigated. Little is known about the physicochemical effects of the properties

Development of novel electrospun dual-drug fiber mats loaded with a combination of ampicillin and metronidazole.

PubMed

Schkarpetkin, Dennis; Reise, Markus; Wyrwa, Ralf; Völpel, Andrea; Berg, Albrecht; Schweder, Martina; Schnabelrauch, Matthias; Watts, David C; Sigusch, Bernd W

2016-08-01

Our study was performed with the aim of preparing electrospun polylactide fibers with a combination of ampicillin (AMP) and metronidazole (MNZ) and investigating their drug release behavior and the antibacterial effect on Aggregatibacter actinomycetemcomitans and other oral pathogens. AMP and MNZ were integrated as a combination in two separate fibers (dual fiber mats - DFW mix) of electrospun PLA fiber mats by means of multijet electrospinning and in a single fiber (single fiber mats - SFW mix). HPLC (high-performance liquid chromatography) was used to measure the released drug quantities. Agar diffusion tests were used to determine the antibacterial effect of the eluates on A. actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis and Enterococcus faecalis. The neutral red test was made to examine the cytocompatibility of the eluates with human gingival fibroblasts (hGFs). The release of the active agents varied with the antibiotic concentrations initially used in the fiber mats, but also with the distribution of the active agents in one or two fibers. Of the total quantity of MNZ (AMP), the SFW mix fiber mats released >60% (>70%) within a span of 5min, and 76% (71%) after 96h. With these drug concentrations released by the fiber mats (≥5m%), an antibacterial effect was achieved on A. actinomycetemcomitans and on all other species tested. Fiber mats and their eluates have no cytotoxic influence on human gingival fibroblasts (hGFs). Electrospun AMP/MNZ-loaded polymer fibers are a potential drug delivery system for use in periodontal and endodontic infections. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Trends in polymeric electrospun fibers and their use as oral biomaterials.

PubMed

Meireles, Agnes B; Corrêa, Daniella K; da Silveira, João Vw; Millás, Ana Lg; Bittencourt, Edison; de Brito-Melo, Gustavo Ea; González-Torres, Libardo A

2018-05-01

Electrospinning is one of the techniques to produce structured polymeric fibers in the micro or nano scale and to generate novel materials for biomedical proposes. Electrospinning versatility provides fibers that could support different surgical and rehabilitation treatments. However, its diversity in equipment assembly, polymeric materials, and functional molecules to be incorporated in fibers result in profusion of recent biomaterials that are not fully explored, even though the recognized relevance of the technique. The present article describes the main electrospun polymeric materials used in oral applications, and the main aspects and parameters of the technique. Natural and synthetic polymers, blends, and composites were identified from the available literature and recent developments. Main applications of electrospun fibers were focused on drug delivery systems, tissue regeneration, and material reinforcement or modification, although studies require further investigation in order to enable direct use in human. Current and potential usages as biomaterials for oral applications must motivate the development in the use of electrospinning as an efficient method to produce highly innovative biomaterials, over the next few years. Impact statement Nanotechnology is a challenge for many researchers that look for obtaining different materials behaviors by modifying characteristics at a very low scale. Thus, the production of nanostructured materials represents a very important field in bioengineering, in which the electrospinning technique appears as a suitable alternative. This review discusses and provides further explanation on this versatile technique to produce novel polymeric biomaterials for oral applications. The use of electrospun fibers is incipient in oral areas, mainly because of the unfamiliarity with the technique. Provided disclosure, possibilities and state of the art are aimed at supporting interested researchers to better choose proper materials

Engineered Polymer Composites Through Electrospun Nanofiber Coating of Fiber Tows

NASA Technical Reports Server (NTRS)

Kohlman, Lee W.; Bakis, Charles; Williams, Tiffany S.; Johnston, James C.; Kuczmarski, Maria A.; Roberts, Gary D.

2014-01-01

Composite materials offer significant weight savings in many aerospace applications. The toughness of the interface of fibers crossing at different angles often determines failure of composite components. A method for toughening the interface in fabric and filament wound components using directly electrospun thermoplastic nanofiber on carbon fiber tow is presented. The method was first demonstrated with limited trials, and then was scaled up to a continuous lab scale process. Filament wound tubes were fabricated and tested using unmodified baseline towpreg material and nanofiber coated towpreg.

Delivery of Therapeutic Proteins Using Electrospun Fibers-Recent Developments and Current Challenges.

PubMed

Seif, Salem; Planz, Viktoria; Windbergs, Maike

2017-10-01

Proteins play a vital role within the human body by regulating various functions and even serving as structural constituent of many body parts. In this context, protein-based therapeutics have attracted a lot of attention in the last few decades as potential treatment of different diseases. Due to the steadily increasing interest in protein-based therapeutics, different dosage forms were investigated for delivering such complex macromolecules to the human body. Here, electrospun fibers hold a great potential for embedding proteins without structural damage and for controlled release of the protein for therapeutic applications. This review provides a comprehensive overview of the current state of protein-based carrier systems using electrospun fibers, with special emphasis on discussing their potential and key challenges in developing such therapeutic strategies, along with a prospective view of anticipated future directions. © 2017 Deutsche Pharmazeutische Gesellschaft.

Porous Electrospun Fibers with Self-Sealing Functionality: An Enabling Strategy for Trapping Biomacromolecules.

PubMed

Zhang, Jin; Zheng, Ting; Alarçin, Emine; Byambaa, Batzaya; Guan, Xiaofei; Ding, Jianxun; Zhang, Yu Shrike; Li, Zhongming

2017-12-01

Stimuli-responsive porous polymer materials have promising biomedical application due to their ability to trap and release biomacromolecules. In this work, a class of highly porous electrospun fibers is designed using polylactide as the polymer matrix and poly(ethylene oxide) as a porogen. Carbon nanotubes (CNTs) with different concentrations are further impregnated onto the fibers to achieve self-sealing functionality induced by photothermal conversion upon light irradiation. The fibers with 0.4 mg mL -1 of CNTs exhibit the optimum encapsulation efficiency of model biomacromolecules such as dextran, bovine serum albumin, and nucleic acids, although their photothermal conversion ability is slightly lower than the fibers with 0.8 mg mL -1 of CNTs. Interestingly, reversible reopening of the surface pores is accomplished with the degradation of PLA, affording a further possibility for sustained release of biomacromolecules after encapsulation. Effects of CNT loading on fiber morphology, structure, thermal/mechanical properties, degradation, and cell viability are also investigated. This novel class of porous electrospun fibers with self-sealing capability has great potential to serve as an enabling strategy for trapping/release of biomacromolecules with promising applications in, for example, preventing inflammatory diseases by scavenging cytokines from interstitial body fluids. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Functional electrospun membranes

NASA Astrophysics Data System (ADS)

Ognibene, G.; Fragalà, M. E.; Cristaldi, D. A.; Blanco, I.; Cicala, G.

2016-05-01

In this study we combined electrospun PES nanofibers with ZnO nanostructures in order to obtain a hierarchical nanostructured hybrid material to be use for active water filtration membranes. It benefits of flexibility and high surface area of the polymeric nanofibers as well as of additional functionalities of ZnOnanostructures. First, randomly oriented nanofibers with diameters of 716nm ±365 nm were electrospun on a glass fibers substrate from a solution of PES and DMF-TOL(1:1). ZnO nanorods were grown onto the surface of electrospun PES fibers by a Chemical Bath Deposition (CBD) process. It was preceed by a seeding process necessary to form nucleation sites for the subsequent radially aligned growth of ZnO nanowires. The morfology of the fibers and the effect of the seeding time have been analysed by SEM. The amount of ZnO nanowires grown over electrospun nanofibers was determined as 45% by weight. The high purity and crystallinity of the asobtained products are confirmed by XRD since all reflection peaks can be indexed to hexagonal wurtzite ZnO.

Functionality in Electrospun Nanofibrous Membranes Based on Fiber's Size, Surface Area, and Molecular Orientation

PubMed Central

Matsumoto, Hidetoshi; Tanioka, Akihiko

2011-01-01

Electrospinning is a versatile method for forming continuous thin fibers based on an electrohydrodynamic process. This method has the following advantages: (i) the ability to produce thin fibers with diameters in the micrometer and nanometer ranges; (ii) one-step forming of the two- or three-dimensional nanofiber network assemblies (nanofibrous membranes); and (iii) applicability for a broad spectrum of molecules, such as synthetic and biological polymers and polymerless sol-gel systems. Electrospun nanofibrous membranes have received significant attention in terms of their practical applications. The major advantages of nanofibers or nanofibrous membranes are the functionalities based on their nanoscaled-size, highly specific surface area, and highly molecular orientation. These functionalities of the nanofibrous membranes can be controlled by their fiber diameter, surface chemistry and topology, and internal structure of the nanofibers. This report focuses on our studies and describes fundamental aspects and applications of electrospun nanofibrous membranes. PMID:24957735

Image-based quantification of fiber alignment within electrospun tissue engineering scaffolds is related to mechanical anisotropy.

PubMed

Fee, Timothy; Downs, Crawford; Eberhardt, Alan; Zhou, Yong; Berry, Joel

2016-07-01

It is well documented that electrospun tissue engineering scaffolds can be fabricated with variable degrees of fiber alignment to produce scaffolds with anisotropic mechanical properties. Several attempts have been made to quantify the degree of fiber alignment within an electrospun scaffold using image-based methods. However, these methods are limited by the inability to produce a quantitative measure of alignment that can be used to make comparisons across publications. Therefore, we have developed a new approach to quantifying the alignment present within a scaffold from scanning electron microscopic (SEM) images. The alignment is determined by using the Sobel approximation of the image gradient to determine the distribution of gradient angles with an image. This data was fit to a Von Mises distribution to find the dispersion parameter κ, which was used as a quantitative measure of fiber alignment. We fabricated four groups of electrospun polycaprolactone (PCL) + Gelatin scaffolds with alignments ranging from κ = 1.9 (aligned) to κ = 0.25 (random) and tested our alignment quantification method on these scaffolds. It was found that our alignment quantification method could distinguish between scaffolds of different alignments more accurately than two other published methods. Additionally, the alignment parameter κ was found to be a good predictor the mechanical anisotropy of our electrospun scaffolds. The ability to quantify fiber alignment within and make direct comparisons of scaffold fiber alignment across publications can reduce ambiguity between published results where cells are cultured on "highly aligned" fibrous scaffolds. This could have important implications for characterizing mechanics and cellular behavior on aligned tissue engineering scaffolds. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1680-1686, 2016. © 2016 Wiley Periodicals, Inc.

Neurite Outgrowth On Electrospun PLLA Fibers Is Enhanced By Exogenous Electrical Stimulation

PubMed Central

Koppes, A. N.; Zaccor, N. W.; Rivet, C. J.; Williams, L. A.; Piselli, J. M.; Gilbert, R. J.; Thompson, D. M.

2014-01-01

Objective Both electrical stimuli (endogenous and exogenous) and topographical cues are instructive to axonal extension. This report, for the first time, investigated the relative dominance of directional topographical guidance cues and directional electrical cues to enhance and/or direct primary neurite extension. We hypothesized the combination of electrical stimulation with electrospun fiber topography would induce longer neurite extension from DRG neurons than the presence of electrical stimulation or aligned topography alone. Approach To test the hypothesis, neurite outgrowth was examined on laminin-coated poly-L-lactide (PLLA) films or electrospun fibers (2 μm in diameter) in the presence or absence of electrical stimulation. Immunostained neurons were semi-automatically traced using Neurolucida software and morphology was evaluated. Results Neurite extension increased 74% on the aligned fibers compared to film controls. Stimulation alone increased outgrowth by 32% on films or fibers relative to unstimulated film controls. The co-presentation of topographical (fibers) with biophysical (electrical stimulation) cues resulted in a synergistic 126% increase in outgrowth relative to unstimulated film controls. Field polarity had no influence on the directionality of neurite, indicating topographical cues are responsible to guide neurite extension. Significance Both cues (electrical stimulation and fiber geometry) are modular in nature and can be synergistically applied in conjunction with other common methods in regenerative medicine such as controlled release of growth factors to further influence axonal growth in vivo. The combined application of electrical and aligned fiber topographical guidance cues described herein, if translated in vivo, could provide a more supportive environment for directed and robust axonal regeneration following peripheral nerve injury. PMID:24891494

Neurite outgrowth on electrospun PLLA fibers is enhanced by exogenous electrical stimulation.

PubMed

Koppes, A N; Zaccor, N W; Rivet, C J; Williams, L A; Piselli, J M; Gilbert, R J; Thompson, D M

2014-08-01

Both electrical stimuli (endogenous and exogenous) and topographical cues are instructive to axonal extension. This report, for the first time, investigated the relative dominance of directional topographical guidance cues and directional electrical cues to enhance and/or direct primary neurite extension. We hypothesized the combination of electrical stimulation with electrospun fiber topography would induce longer neurite extension from dorsal root ganglia neurons than the presence of electrical stimulation or aligned topography alone. To test the hypothesis, neurite outgrowth was examined on laminin-coated poly-L-lactide films or electrospun fibers (2 µm in diameter) in the presence or absence of electrical stimulation. Immunostained neurons were semi-automatically traced using Neurolucida software and morphology was evaluated. Neurite extension increased 74% on the aligned fibers compared to film controls. Stimulation alone increased outgrowth by 32% on films or fibers relative to unstimulated film controls. The co-presentation of topographical (fibers) with biophysical (electrical stimulation) cues resulted in a synergistic 126% increase in outgrowth relative to unstimulated film controls. Field polarity had no influence on the directionality of neurites, indicating topographical cues are responsible for guiding neurite extension. Both cues (electrical stimulation and fiber geometry) are modular in nature and can be synergistically applied in conjunction with other common methods in regenerative medicine such as controlled release of growth factors to further influence axonal growth in vivo. The combined application of electrical and aligned fiber topographical guidance cues described herein, if translated in vivo, could provide a more supportive environment for directed and robust axonal regeneration following peripheral nerve injury.

Prediction of thermal conductivity of polyvinylpyrrolidone (PVP) electrospun nanocomposite fibers using artificial neural network and prey-predator algorithm.

PubMed

Khan, Waseem S; Hamadneh, Nawaf N; Khan, Waqar A

2017-01-01

In this study, multilayer perception neural network (MLPNN) was employed to predict thermal conductivity of PVP electrospun nanocomposite fibers with multiwalled carbon nanotubes (MWCNTs) and Nickel Zinc ferrites [(Ni0.6Zn0.4) Fe2O4]. This is the second attempt on the application of MLPNN with prey predator algorithm for the prediction of thermal conductivity of PVP electrospun nanocomposite fibers. The prey predator algorithm was used to train the neural networks to find the best models. The best models have the minimal of sum squared error between the experimental testing data and the corresponding models results. The minimal error was found to be 0.0028 for MWCNTs model and 0.00199 for Ni-Zn ferrites model. The predicted artificial neural networks (ANNs) responses were analyzed statistically using z-test, correlation coefficient, and the error functions for both inclusions. The predicted ANN responses for PVP electrospun nanocomposite fibers were compared with the experimental data and were found in good agreement.

Electrospun Nanofiber Scaffolds with Gradations in Fiber Organization

PubMed Central

Khandalavala, Karl; Jiang, Jiang; Shuler, Franklin D.; Xie, Jingwei

2015-01-01

The goal of this protocol is to report a simple method for generating nanofiber scaffolds with gradations in fiber organization and test their possible applications in controlling cell morphology/orientation. Nanofiber organization is controlled with a new fabrication apparatus that enables the gradual decrease of fiber organization in a scaffold. Changing the alignment of fibers is achieved through decreasing deposition time of random electrospun fibers on a uniaxially aligned fiber mat. By covering the collector with a moving barrier/mask, along the same axis as fiber deposition, the organizational structure is easily controlled. For tissue engineering purposes, adipose-derived stem cells can be seeded to these scaffolds. Stem cells undergo morphological changes as a result of their position on the varied organizational structure, and can potentially differentiate into different cell types depending on their locations. Additionally, the graded organization of fibers enhances the biomimicry of nanofiber scaffolds so they more closely resemble the natural orientations of collagen nanofibers at tendon-to-bone insertion site compared to traditional scaffolds. Through nanoencapsulation, the gradated fibers also afford the possibility to construct chemical gradients in fiber scaffolds, and thereby further strengthen their potential applications in fast screening of cell-materials interaction and interfacial tissue regeneration. This technique enables the production of continuous gradient scaffolds, but it also can potentially produce fibers in discrete steps by controlling the movement of the moving barrier/mask in a discrete fashion. PMID:25938562

Electrospun polystyrene scaffolds as a synthetic substrate for xeno-free expansion and differentiation of human induced pluripotent stem cells.

PubMed

Leong, Meng Fatt; Lu, Hong Fang; Lim, Tze Chiun; Du, Chan; Ma, Nina K L; Wan, Andrew C A

2016-12-01

The use of human induced pluripotent stem cells (hiPSCs) for clinical tissue engineering applications requires expansion and differentiation of the cells using defined, xeno-free substrates. The screening and selection of suitable synthetic substrates however, is tedious, as their performance relies on the inherent material properties. In the present work, we demonstrate an alternative concept for xeno-free expansion and differentiation of hiPSCs using synthetic substrates, which hinges on the structure-function relationship between electrospun polystyrene scaffolds (ESPS) and pluripotent stem cell growth. ESPS of differential porosity was obtained by fusing the fibers at different temperatures. The more porous, loosely fused scaffolds were found to efficiently trap the cells, leading to a large number of three-dimensional (3D) aggregates which were shown to be pluripotent colonies. Immunostaining, PCR analyses, in vitro differentiation and in vivo teratoma formation studies demonstrated that these hiPSC aggregates could be cultured for up to 10 consecutive passages (P10) with maintenance of pluripotency. Flow cytometry showed that more than 80% of the cell population stained positive for the pluripotent marker OCT4 at P1, P5 and P10. P10 cells could be differentiated to neuronal-like cells and cultured within the ESPS for up to 18months. Our results suggest the usefulness of a generic class of synthetic substrates, exemplified by ESPS, for 'trapped aggregate culture' of hiPSCs. To realize the potential of human induced pluripotent stem cells (hiPSCs) in clinical medicine, robust, xeno-free substrates for expansion and differentiation of iPSCs are required. In the existing literature, synthetic materials have been reported that meet the requirement for non-xenogeneic substrates. However, the self-renewal and differentiation characteristics of hiPSCs are affected differently by the biocompatibility and physico-chemical properties of individual substrates. Although

A method to integrate patterned electrospun fibers with microfluidic systems to generate complex microenvironments for cell culture applications

PubMed Central

Wallin, Patric; Zandén, Carl; Carlberg, Björn; Hellström Erkenstam, Nina; Liu, Johan; Gold, Julie

2012-01-01

The properties of a cell’s microenvironment are one of the main driving forces in cellular fate processes and phenotype expression invivo. The ability to create controlled cell microenvironments invitro becomes increasingly important for studying or controlling phenotype expression in tissue engineering and drug discovery applications. This includes the capability to modify material surface properties within well-defined liquid environments in cell culture systems. One successful approach to mimic extra cellular matrix is with porous electrospun polymer fiber scaffolds, while microfluidic networks have been shown to efficiently generate spatially and temporally defined liquid microenvironments. Here, a method to integrate electrospun fibers with microfluidic networks was developed in order to form complex cell microenvironments with the capability to vary relevant parameters. Spatially defined regions of electrospun fibers of both aligned and random orientation were patterned on glass substrates that were irreversibly bonded to microfluidic networks produced in poly-dimethyl-siloxane. Concentration gradients obtained in the fiber containing channels were characterized experimentally and compared with values obtained by computational fluid dynamic simulations. Velocity and shear stress profiles, as well as vortex formation, were calculated to evaluate the influence of fiber pads on fluidic properties. The suitability of the system to support cell attachment and growth was demonstrated with a fibroblast cell line. The potential of the platform was further verified by a functional investigation of neural stem cell alignment in response to orientation of electrospun fibers versus a microfluidic generated chemoattractant gradient of stromal cell-derived factor 1 alpha. The described method is a competitive strategy to create complex microenvironments invitro that allow detailed studies on the interplay of topography, substrate surface properties, and soluble

Electrospun Collagen/Silk Tissue Engineering Scaffolds: Fiber Fabrication, Post-Treatment Optimization, and Application in Neural Differentiation of Stem Cells

NASA Astrophysics Data System (ADS)

Zhu, Bofan

Biocompatible scaffolds mimicking the locally aligned fibrous structure of native extracellular matrix (ECM) are in high demand in tissue engineering. In this thesis research, unidirectionally aligned fibers were generated via a home-built electrospinning system. Collagen type I, as a major ECM component, was chosen in this study due to its support of cell proliferation and promotion of neuroectodermal commitment in stem cell differentiation. Synthetic dragline silk proteins, as biopolymers with remarkable tensile strength and superior elasticity, were also used as a model material. Good alignment, controllable fiber size and morphology, as well as a desirable deposition density of fibers were achieved via the optimization of solution and electrospinning parameters. The incorporation of silk proteins into collagen was found to significantly enhance mechanical properties and stability of electrospun fibers. Glutaraldehyde (GA) vapor post-treatment was demonstrated as a simple and effective way to tune the properties of collagen/silk fibers without changing their chemical composition. With 6-12 hours GA treatment, electrospun collagen/silk fibers were not only biocompatible, but could also effectively induce the polarization and neural commitment of stem cells, which were optimized on collagen rich fibers due to the unique combination of biochemical and biophysical cues imposed to cells. Taken together, electrospun collagen rich composite fibers are mechanically strong, stable and provide excellent cell adhesion. The unidirectionally aligned fibers can accelerate neural differentiation of stem cells, representing a promising therapy for neural tissue degenerative diseases and nerve injuries.

PMMA/PS coaxial electrospinning: core-shell fiber morphology as a function of material parameters

NASA Astrophysics Data System (ADS)

Rahmani, Shahrzad; Arefazar, Ahmad; Latifi, Masoud

2017-03-01

Core-shell fibers of polymethyl methacrylate (PMMA) and polystyrene (PS) have been successfully electrospun by coaxial electrospinning. To evaluate the influence of the solvent on the final fiber morphology, four types of organic solvents were used in the shell solution while the core solvent was preserved. Morphological observations with scanning electron microscopy, transmission electron microscopy and optical microscopy revealed that both core and shell solvent properties were involved in the final fiber morphology. To explain this involvement, alongside a discussion of the Bagley solubility graph of PS and PMMA, a novel criterion based on solvent physical properties was introduced. A theoretical model based on the momentum conservation principle was developed and applied for describing the dependence of the core and shell diameters to their solvent combinations. Different concentrations of core and shell were also investigated in the coaxial electrospinning of PMMA/PS. The core-shell fiber morphologies with different core and shell concentrations were compared with their single electrospun fibers.

Morphology, drug release, antibacterial, cell proliferation, and histology studies of chamomile-loaded wound dressing mats based on electrospun nanofibrous poly(ɛ-caprolactone)/polystyrene blends.

PubMed

Motealleh, Behrooz; Zahedi, Payam; Rezaeian, Iraj; Moghimi, Morvarid; Abdolghaffari, Amir Hossein; Zarandi, Mohammad Amin

2014-07-01

For the first time, it has been tried to achieve optimum conditions for electrospun poly(ε-caprolactone)/polystyrene (PCL/PS) nanofibrous samples as active wound dressings containing chamomile via D-optimal design approach. In this work, systematic in vitro and in vivo studies were carried out by drug release rate, antibacterial and antifungal evaluations, cell culture, and rat wound model along with histology observation. The optimized samples were prepared under the following electrospinning conditions: PCL/PS ratio (65/35), PCL concentration 9%(w/v), PS concentration 14%(w/v), distance between the syringe needle tip and the collector 15.5 cm, applied voltage 18 kV, and solution flow rate 0.46 mL h(-1) . The FE-SEM micrographs showed electrospun PCL/PS (65/35) nanofibrous sample containing 15% chamomile had a minimum average diameter (∼175 nm) compared to the neat samples (∼268 nm). The drug released resulted in a gradual and high amount of chamomile from the optimized PCL/PS nanofibrous sample (∼70%) in respect to PCL and PS nanofibers after 48 h. This claim was also confirmed by antibacterial and antifungal evaluations in which an inhibitory zone with a diameter of about 7.6 mm was formed. The rat wound model results also indicated that the samples loaded with 15% chamomile extract were remarkably capable to heal the wounds up to 99 ± 0.5% after 14 days post-treatment periods. The adhesion of mesenchymal stem cells and their viability on the optimized samples were confirmed by MTT analysis. Also, the electrospun nanofibrous mats based on PCL/PS (65/35) showed a high efficiency in the wound closure and healing process compared to the reference sample, PCL/PS nanofibers without chamomile. Finally, the histology analysis revealed that the formation of epithelial tissues, the lack of necrosis and collagen fibers accumulation in the dermis tissues for the above optimized samples. © 2013 Wiley Periodicals, Inc.

Antibacterial poly(lactic acid) (PLA) films grafting electrospun PLA/Ally isothioscyanate (AITC) fibers for food packaging

USDA-ARS?s Scientific Manuscript database

Poly(lactic acid) (PLA) fibers of submicron sizes encapsulating allyl isothiocyanate (AITC) (PfA) were made and electrospun onto the surfaces of PLA films (PfA-g-film). SEM examination confirmed that the fibers were grafted to the PLA film after the (PfA-g-film) underwent air blowing and water washi...

Electrospun fiber membranes enable proliferation of genetically modified cells

PubMed Central

Borjigin, Mandula; Eskridge, Chris; Niamat, Rohina; Strouse, Bryan; Bialk, Pawel; Kmiec, Eric B

2013-01-01

Polycaprolactone (PCL) and its blended composites (chitosan, gelatin, and lecithin) are well-established biomaterials that can enrich cell growth and enable tissue engineering. However, their application in the recovery and proliferation of genetically modified cells has not been studied. In the study reported here, we fabricated PCL-biomaterial blended fiber membranes, characterized them using physicochemical techniques, and used them as templates for the growth of genetically modified HCT116-19 colon cancer cells. Our data show that the blended polymers are highly miscible and form homogenous electrospun fiber membranes of uniform texture. The aligned PCL nanofibers support robust cell growth, yielding a 2.5-fold higher proliferation rate than cells plated on standard plastic plate surfaces. PCL-lecithin fiber membranes yielded a 2.7-fold higher rate of proliferation, while PCL-chitosan supported a more modest growth rate (1.5-fold higher). Surprisingly, PCL-gelatin did not enhance cell proliferation when compared to the rate of cell growth on plastic surfaces. PMID:23467983

Effects of the glycerophosphate-polylactic copolymer formation on electrospun fibers

NASA Astrophysics Data System (ADS)

Shen, Wen; Zhang, Guanghua; Li, YaLi; Fan, Guodong

2018-06-01

Poly-lactic (PLA) porous fibers are widely used in tissue engineering scaffolds and many other fields. Non-solvent induced phase separation is one of the best way for preparation of porous fiber. It is difficult to obtain the PLA electrospun porous fibers by phase separation. In this paper, glycerophosphate-polylactic copolymer (GP-PLA) are synthesized with sodium glyceryl phosphate and L-lactide to produce porous fibers. Furthermore, the Gel permeation chromatography (GPC), FT-IR and 1H-NMR are applied for characterizing the obtained copolymers. Thermogravimetric (TG) measurements indicate that the thermal stability of GP-PLA is lower than that of linear PLA. Under 30% humidity, porous GP-PLA fibers are obtained by electrospinning method, the scanning electron microscopy (SEM) refers that through the modification of the molecular structure, GP-PLA fibers are more porous under the same condition. The water contact angle is increased coming with the increase of GP contents. Hydrophilic porous GP-PLA fibers are obtained via solvent phase separation. The relationship between hydrophilicity and surface morphology of materials is further explained by Atomic Force Microscope (AFM). GP-PLA has a potential application in the field of scaffold for tissue engineering.

Direct Piezoelectricity of Soft Composite Electrospun Fibers

NASA Astrophysics Data System (ADS)

Varga, Michael; Morvan, Jason; Diorio, Nick; Buyuktanir, Ebru; Harden, John; West, John; Jakli, Antal

2013-03-01

Recently soft fiber mats electrospun from solutions of Barium Titanate (BT) ferroelectric ceramics particles and poly lactic acid (PLA) were found to have large (d33 1nm/V) converse piezoelectric signals offering a myriad of applications ranging from active implants to smart textiles. Here we report direct piezoelectric measurements (electric signals due to mechanical stress) of the BT/PLA composite fiber mats at various BT concentrations. A testing apparatus was designed and constructed solely for these measurements involving AC stresses provided by a speaker in 10Hz-10kHz frequency range. The piezoelectric constant d33 ~1nC/N was found to be in agreement with the prior converse piezoelectric measurements. The largest signals were obtained with 6% BT/PLA composites, probably because the BT particles at higher concentrations could not be dispersed homogeneously. Importantly the direct piezoelectric signal is large enough to power a small LCD by simply pressing a 0.2mm thick 2 cm2 area mat by a finger. We expect to use these mats in active Braille cells and in liquid crystal writing tablets.

In situ growth of hydroxyapatite within electrospun poly(DL-lactide) fibers.

PubMed

Cui, Wenguo; Li, Xiaohong; Zhou, Shaobing; Weng, Jie

2007-09-15

Development of nanocomposites of hydroxyapatite (HA) and polylactic acid (PLA) is attractive, as the advantageous properties of the two types of materials can be combined to suit better the mechanical and biological demands for biomedical uses. To solve the problematic issue of agglomeration of HA crystallites in the PLA matrix, a novel method is introduced in the present study to use electrospun nanofibers as the reaction confinement for composite fabrication. Poly(DL-lactide) ultrafine fibers with calcium nitrate entrapment were prepared by electrospinning and then incubated in phosphate solution to form in situ calcium phosphate on the polymer matrix. The formation of nonstoichiometric nanostructured HA and well dispersion of HA particles on the electrospun fibers were observed. Higher crystalline HA phase was indicated in samples after sintering at 1200 degrees C. The formation of the calcium-phosphate phase was dependent upon the precipitation conditions, and the effects of the incubation time, temperature, and the pH values of the incubation medium were investigated on the spontaneous precipitation and amorphous-crystalline transformation of HA in the current study. Considering the biodegradability of matrix polymer and the crystallinity and uniform dispersal of HA, optimal conditions for composite preparation were incubating calcium-containing ultrafine fibers at 37 degrees C in pH 7.4 or at 25 degrees C in pH 9.0 of diammonium hydrogen phosphate solutions for 7 days. Around 25%-34% of mineral contents can be synthesized in the resulting composites, which was higher than the theoretical value due to the nonstoichiometric HA formed in the composite, and the fiber degradation and partial calcium nitrate involved in the HA formation. Copyright 2007 Wiley Periodicals, Inc.

Post-processing optimization of electrospun submicron poly(3-hydroxybutyrate) fibers to obtain continuous films of interest in food packaging applications.

PubMed

Cherpinski, Adriane; Torres-Giner, Sergio; Cabedo, Luis; Lagaron, Jose M

2017-10-01

Polyhydroxyalkanoates (PHAs) are one of the most researched family of biodegradable polymers based on renewable materials due to their thermoplastic nature and moisture resistance. The present study was targeted to investigate the preparation and characterization of poly(3-hydroxybutyrate) (PHB) films obtained through the electrospinning technique. To convert them into continuous films and then to increase their application interest in packaging, the electrospun fiber mats were subsequently post-processed by different physical treatments. Thus, the effect of annealing time and cooling method on morphology, molecular order, thermal, optical, mechanical, and barrier properties of the electrospun submicron PHB fibers was studied. Annealing at 160°C, well below the homopolyester melting point, was found to be the minimum temperature at which homogeneous transparent films were produced. The film samples that were cooled slowly after annealing showed the lowest permeability to oxygen, water vapor, and limonene. The optimally post-processed electrospun PHB fibers exhibited similar rigidity to conventional compression-molded PHA films, but with enhanced elongation at break and toughness. Films made by this electrospinning technique have many potential applications, such as in the design of barrier layers, adhesive interlayers, and coatings for fiber- and plastic-based food packaging materials.

Aligned and Electrospun Piezoelectric Polymer Fiber Assembly and Scaffold

NASA Technical Reports Server (NTRS)

Holloway, Nancy M. (Inventor); Scott-Carnell, Lisa A. (Inventor); Siochi, Emilie J. (Inventor); Leong, Kam W. (Inventor); Kulangara, Karina (Inventor)

2015-01-01

A scaffold assembly and related methods of manufacturing and/or using the scaffold for stem cell culture and tissue engineering applications are disclosed which at least partially mimic a native biological environment by providing biochemical, topographical, mechanical and electrical cues by using an electroactive material. The assembly includes at least one layer of substantially aligned, electrospun polymer fiber having an operative connection for individual voltage application. A method of cell tissue engineering and/or stem cell differentiation uses the assembly seeded with a sample of cells suspended in cell culture media, incubates and applies voltage to one or more layers, and thus produces cells and/or a tissue construct. In another aspect, the invention provides a method of manufacturing the assembly including the steps of providing a first pre-electroded substrate surface; electrospinning a first substantially aligned polymer fiber layer onto the first surface; providing a second pre-electroded substrate surface; electrospinning a second substantially aligned polymer fiber layer onto the second surface; and, retaining together the layered surfaces with a clamp and/or an adhesive compound.

Aligned and Electrospun Piezoelectric Polymer Fiber Assembly and Scaffold

NASA Technical Reports Server (NTRS)

Kulangara, Karina (Inventor); Scott Carnell, Lisa A. (Inventor); Holloway, Nancy M. (Inventor); Leong, Kam W. (Inventor); Siochi, Emilie J. (Inventor)

2017-01-01

A method of manufacturing and/or using a scaffold assembly for stem cell culture and tissue engineering applications is disclosed. The scaffold at least partially mimics a native biological environment by providing biochemical, topographical, mechanical and electrical cues by using an electroactive material. The assembly includes at least one layer of substantially aligned, electrospun polymer fiber having an operative connection for individual voltage application. A method of cell tissue engineering and/or stem cell differentiation that uses the assembly seeded with a sample of cells suspended in cell culture media, incubates and applies voltage to one or more layers, and thus produces cells and/or a tissue construct. In another aspect, the invention provides a method of manufacturing the assembly including the steps of providing a first pre-electroded substrate surface; electrospinning a first substantially aligned polymer fiber layer onto the first surface; providing a second pre-electroded substrate surface; electrospinning a second substantially aligned polymer fiber layer onto the second surface; and, retaining together the layered surfaces with a clamp and/or an adhesive compound.

Nitroxyl radical incorporated electrospun biodegradable poly(ester Amide) nanofiber membranes.

PubMed

Li, Lei; Chu, Chih-Chang

2009-01-01

Biodegradable amino-acid-based poly(ester amide) (PEA) ultra-fine fibers pre-loaded with a nitroxyl radical model compound, 4-amino-2.2.6.6-tetramethylpiperidine-1-oxy (4-amino-TEMPO), were prepared by electrospinning. The fiber size and morphology were shown to be greatly affected by the composition ratio of the solvent mixture (chloroform to DMF) prepared for electrospinning. Nano-size PEA fibers (approx. 640 nm) were obtained when PEA dope was electrospun from the chloroform/DMF solvent mixture at a volume ratio of 2 to 1 vs. 3.5 mum size PEA fibers obtained from chloroform-based electrospun dope. Due to the low glass transition temperature and completely amorphous structures, the PEA electrospun fibrous membranes gradually lost their fiber characteristic during 1 month incubation in PBS buffer at 37 degrees C. The glass transition temperature and heat of fusion of PEA electrospun fibers increased with an increasing incubation time and the most significant change occurred in the first day of incubation in PBS. A sustained release of 4-amino-TEMPO from the electrospun PEA nanofiber membranes was observed over the 1-month incubation period in PBS buffer at 37 degrees C and 38% of the incorporated 4-amino-TEMPO (initial loading level 10 mg/g PEA fibers) was released in one month. During this 1 month incubation in PBS buffer, there were only 1.2% weight loss and 11.7% molecular weight reduction for the electrospun PEA fibrous membranes. In an alpha-chymotrypsin medium (0.1 mg/ml PBS), however, the same electrospun PEA fibrous membranes showed more than 80% weight loss within 6 days and a complete release of encapsulated 4-amino-TEMPO within 5 days.

Morphology and properties of wood-fiber reinforced blends of recycled polystyrene and polyethylene

Treesearch

John Simonsen; Timothy G. Rials

1996-01-01

Material properties of composites produced from recycled plastics and recycled wood fiber were compared. A blend of high-density polyethylene and polystyrene was used as a simulated mixed plastic. Stiffness was generally improved by the addition of fiber, as expected, but brittleness also increased. Pre-treatment of the wood filler with phenol-formaldehyde resins did...

Junction-Free Electrospun Ag Fiber Electrodes for Flexible Organic Light-Emitting Diodes.

PubMed

Choi, Junhee; Shim, Yong Sub; Park, Cheol Hwee; Hwang, Ha; Kwack, Jin Ho; Lee, Dong Jun; Park, Young Wook; Ju, Byeong-Kwon

2018-02-01

Fabrication of junction-free Ag fiber electrodes for flexible organic light-emitting diodes (OLEDs) is demonstrated. The junction-free Ag fiber electrodes are fabricated by electrospun polymer fibers used as an etch mask and wet etching of Ag thin film. This process facilitates surface roughness control, which is important in transparent electrodes based on metal wires to prevent electrical instability of the OLEDs. The transmittance and resistance of Ag fiber electrodes can be independently adjusted by controlling spinning time and Ag deposition thickness. The Ag fiber electrode shows a transmittance of 91.8% (at 550 nm) at a sheet resistance of 22.3 Ω □ -1 , leading to the highest OLED efficiency. In addition, Ag fiber electrodes exhibit excellent mechanical durability, as shown by measuring the change in resistance under repeatable mechanical bending and various bending radii. The OLEDs with Ag fiber electrodes on a flexible substrate are successfully fabricated, and the OLEDs show an enhancement of EQE (≈19%) compared to commercial indium tin oxide electrodes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Distributed feedback imprinted electrospun fiber lasers.

PubMed

Persano, Luana; Camposeo, Andrea; Del Carro, Pompilio; Fasano, Vito; Moffa, Maria; Manco, Rita; D'Agostino, Stefania; Pisignano, Dario

2014-10-01

Imprinted, distributed feedback lasers are demonstrated on individual, active electrospun polymer nanofibers. In addition to advantages related to miniaturization, optical confinement and grating nanopatterning lead to a significant threshold reduction compared to conventional thin-film lasers. The possibility of imprinting arbitrary photonic crystal geometries on electrospun lasing nanofibers opens new opportunities for realizing optical circuits and chips. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrospun microcrimped fibers with nonlinear mechanical properties enhance ligament fibroblast phenotype.

PubMed

Grace Chao, Pen-hsiu; Hsu, Hsiang-Yi; Tseng, Hsiao-Yun

2014-09-01

Fiber structure and order greatly impact the mechanical behavior of fibrous materials. In biological tissues, the nonlinear mechanics of fibrous scaffolds contribute to the functionality of the material. The nonlinear mechanical properties of the wavy structure (crimp) in collagen allow tissue flexibility while preventing over-extension. A number of approaches have tried to recreate this complex mechanical functionality. We generated microcrimped fibers by briefly heating electrospun parallel fibers over the glass transition temperature or by ethanol treatment. The crimp structure is similar to those of collagen fibers found in native aorta, intestines, or ligaments. Using poly-L-lactic acid fibers, we demonstrated that the bulk materials exhibit changed stress-strain behaviors with a significant increase in the toe region in correlation to the degree of crimp, similar to those observed in collagenous tissues. In addition to mimicking the stress-strain behavior of biological tissues, the microcrimped fibers are instructive in cell morphology and promote ligament phenotypic gene expression. This effect can be further enhanced by dynamic tensile loading, a physiological perturbation in vivo. This rapid and economical approach for microcrimped fiber production provides an accessible platform to study structure-function relationships and a novel functional scaffold for tissue engineering and cell mechanobiology studies.

Synthesis of High-Impact Polystyrene Fibers using Electrospinning

NASA Astrophysics Data System (ADS)

Zulfi, A.; Fauzi, A.; Edikresnha, D.; Munir, M. M.; Khairurrijal

2017-05-01

Synthesis of fibers from waste high-impact polystyrene (HIPS) have been successfully done using electrospinning method. The HIPS solutions were made with a single solvent (DMF or d-limonene), a mixed solvent (d-limonene/DMF), and with the addition of acetone to the previously stated solvents. The effects of HIPS concentration, a mix of solvent, and the addition of acetone on the morphology and the diameter of fibers were observed. The morphological change from particles to fibers took place along with the increasing concentration of HIPS in d-limonene. For other precursor solutions using DMF solvent, bead free fibers could be obtained even at low levels. The average diameter of fibers increased along with the increase of the HIPS concentration in DMF. At the concentrations of 15, 20, 25, 30, and 35 wt.%, the average diameters were 1.85, 2.09, 2.66, 3.59, and 7.38 μm, respectively. For the precursor solutions with the combination of different solvents (HIPS/DMF), the existence of beads was influenced by the ratio of solvents. When the ratio of d-limonene/DMF was 75:25, the obtained beaded fibers had a relatively large amount of beads. At the ratio of 50:50, fewer beads were found. Bead-free fibers were finally reached when the ratio of HIPS / DMF was 25:75. The addition of acetone reduced the diameter of the produced fibers. However, too much addition of acetone caused the fibers to be wet. Additionally, the diameter became larger if the addition of acetone surpassed a certain amount of volume.

Phospholipid Nonwoven Electrospun Membranes

NASA Astrophysics Data System (ADS)

McKee, Matthew G.; Layman, John M.; Cashion, Matthew P.; Long, Timothy E.

2006-01-01

Nonwoven fibrous membranes were formed from electrospinning lecithin solutions in a single processing step. As the concentration of lecithin increased, the micellar morphology evolved from spherical to cylindrical, and at higher concentrations the cylindrical micelles overlapped and entangled in a fashion similar to polymers in semi-dilute or concentrated solutions. At concentrations above the onset of entanglements of the wormlike micelles, electrospun fibers were fabricated with diameters on the order of 1 to 5 micrometers. The electrospun phospholipid fibers offer the potential for direct fabrication of biologically based, high-surface-area membranes without the use of multiple synthetic steps, complicated electrospinning designs, or postprocessing surface treatments.

Laser-treated electrospun fibers loaded with nano-hydroxyapatite for bone tissue engineering.

PubMed

Aragon, Javier; Navascues, Nuria; Mendoza, Gracia; Irusta, Silvia

2017-06-15

Core-shell polycaprolactone/polycaprolactone (PCL/PCL) and polycaprolactone/polyvinyl acetate (PCL/PVAc) electrospun fibers loaded with synthesized nanohydroxyapatite (HAn) were lased treated to create microporosity. The prepared materials were characterized by XRD, FTIR, TEM and SEM. Uniform and randomly oriented beadless fibrous structures were obtained in all cases. Fibers diameters were in the 150-300nm range. Needle-like HAn nanoparticles with mean diameters of 20nm and length of approximately 150nm were mostly encase inside the fibers. Laser treated materials present micropores with diameters in the range 70-120μm for PCL-HAn/PCL fibers and in the 50-90μm range for PCL-HAn/PVAC material. Only samples containing HAn presented bioactivity after incubation during 30days in simulated body fluid. All scaffolds presented high viability, very low mortality, and human osteoblast proliferation. Biocompatibility was increased by laser treatment due to the surface and porosity modification. Copyright © 2017 Elsevier B.V. All rights reserved.

The formation of web-like connection among electrospun chitosan/PVA fiber network by the reinforcement of ellipsoidal calcium carbonate.

PubMed

Sambudi, Nonni Soraya; Kim, Minjeong G; Park, Seung Bin

2016-03-01

The electrospun fibers consist of backbone fibers and nano-branch network are synthesized by loading of ellipsoidal calcium carbonate in the mixture of chitosan/poly(vinyl alcohol) (PVA) followed by electrospinning. The synthesized ellipsoidal calcium carbonate is in submicron size (730.7±152.4 nm for long axis and 212.6±51.3 nm for short axis). The electrospun backbone fibers experience an increasing in diameter by loading of calcium carbonate from 71.5±23.4 nm to 281.9±51.2 nm. The diameters of branch fibers in the web-network range from 15 nm to 65 nm with most distributions of fibers are in 30-35 nm. Calcium carbonate acts as reinforcing agent to improve the mechanical properties of fibers. The optimum value of Young's modulus is found at the incorporation of 3 wt.% of calcium carbonate in chitosan/PVA fibers, which is enhanced from 15.7±3 MPa to 432.4±94.3 MPa. On the other hand, the ultimate stress of fibers experiences a decrease. This result shows that the fiber network undergoes changes from flexible to more stiff by the inclusion of calcium carbonate. The thermal analysis results show that the crystallinity of polymer is changed by the existence of calcium carbonate in the fiber network. The immersion of fibers in simulated body fluid (SBF) results in the formation of apatite on the surface of fibers. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of fiber diameter and orientation on fibroblast morphology and proliferation on electrospun poly(D,L-lactic-co-glycolic acid) meshes.

PubMed

Bashur, Chris A; Dahlgren, Linda A; Goldstein, Aaron S

2006-11-01

Engineered ligament tissues are promising materials for the repair of tears and ruptures, but require the development of biomaterial scaffolds that not only support physiologically relevant loads, but also possess architectures capable of orienting cell adhesion and extracellular matrix deposition. Based on evidence that micron-scale topographic features induce cell orientation through a contact guidance phenomenon, we postulate that oriented micron-scale fiber meshes-formed by the electrospinning process-can regulate cell morphology. To test this, fused fiber meshes of poly(d,l-lactic-co-glycolic acid) (PLGA) were electrospun onto rigid supports under conditions that produced mean fiber diameters of 0.14-3.6 microm, and angular standard deviations of 31-60 degrees . Analysis of the morphology of adherent NIH 3T3 fibroblasts indicated that projected cell area and aspect ratio increased systematically with both increasing fiber diameter and degree of fiber orientation. Importantly, cell morphology on 3.6 microm fibers was similar to that on spincoated PLGA films. Finally, cell densities on electrospun meshes were not significantly different from spincoated PLGA, indicating that cell proliferation is not sensitive to fiber diameter or orientation.

Photocatalytic antibacterial effect of ZnO nanoparticles into coaxial electrospun PCL fibers to prevent infections from skin injuries

NASA Astrophysics Data System (ADS)

Prado-Prone, G.; Silva-Bermúdez, P.; García-Macedo, J. A.; Almaguer-Flores, A.; Ibarra, C.; Velasquillo-Martínez, C.

2017-02-01

Antibacterial studies of inorganic nanoparticles (nps) have become important due to the increased bacterial resistance against antibiotics. We used Zinc oxide nanoparticles (ZnO nps), which possess excellent photocatalytic properties with a wide band gap (Eg), are listed as "generally recognized as safe" by the Food and Drug Administration (FDA) and have shown antibacterial activity (AA) against many bacterial strains. The AA of ZnO nps is partly attributed to the production of Reactive Oxygen Species (ROS) by photocatalysis. When ZnO nps in aqueous media are illuminated with an energy fibers obtained by electrospinning technique. To optimize the use of ZnO nps concentration, we developed coreshell coaxial electrospun fibers where the core corresponded to PCL and the shell to a mixture of ZnO nps/PCL. Thus, ZnO nps were only dispersed on the surface of the fibers increasing its superficial contact area. We evaluated the AA against E. coli of different electrospun ZnO nps/PCL fibers under two different conditions: UVA pre-illumination and darkness. Preliminary results suggest that the AA against E. coli is better when electrospun ZnO nps/PCL were preilluminated with UVA than under darkness conditions.

Study on selective laser sintering of glass fiber reinforced polystyrene

NASA Astrophysics Data System (ADS)

Yang, Laixia; Wang, Bo; Zhou, Wenming

2017-12-01

In order to improve the bending strength of Polystyrene (PS) sintered parts by selective laser sintering, Polystyrene/glass fiber (PS/GF) composite powders were prepared by mechanical mixing method. The size distribution of PS/GF composite powders was characterized by laser particle size analyzer. The optimum ratio of GF was determined by proportioning sintering experiments. The influence of process parameters on the bending strength of PS and PS/GF sintered parts was studied by orthogonal test. The result indicates that the particle size of PS/GF composite powder is mainly distributed in 24.88 μm~139.8 μm. When the content of GF is 10%, it has better strengthen effect. Finally, the article used the optimum parameter of the two materials to sinter prototype, it is found that the PS/GF prototype has the advantages of good accuracy and high strength.

Fiber Angle and Aspect Ratio Influence the Shear Mechanics of Oriented Electrospun Nanofibrous Scaffolds

PubMed Central

Driscoll, Tristan P.; Nerurkar, Nandan L.; Jacobs, Nathan T.; Elliott, Dawn M.; Mauck, Robert L.

2011-01-01

Fibrocartilages, including the knee meniscus and the annulus fibrosus (AF) of the intervertebral disc, play critical mechanical roles in load transmission across joints and their function is dependent upon well-defined structural hierarchies, organization, and composition. All, however, are compromised in the pathologic transformations associated with tissue degeneration. Tissue engineering strategies that address these key features, for example, aligned nanofibrous scaffolds seeded with mesenchymal stem cells (MSCs), represent a promising approach for the regeneration of these fibrous structures. While such engineered constructs can replicate native tissue structure and uniaxial tensile properties, the multidirectional loading encountered by these tissues in vivo necessitates that they function adequately in other loading modalities as well, including shear. As previous findings have shown that native tissue tensile and shear properties are dependent on fiber angle and sample aspect ratio, respectively, the objective of the present study was to evaluate the effects of a changing fiber angle and sample aspect ratio on the shear properties of aligned electrospun poly(ε-caprolactone) (PCL) scaffolds, and to determine how extracellular matrix deposition by resident MSCs modulates the measured shear response. Results show that fiber orientation and sample aspect ratio significantly influence the response of scaffolds in shear, and that measured shear strains can be predicted by finite element models. Furthermore, acellular PCL scaffolds possessed a relatively high shear modulus, 2–4 fold greater than native tissue, independent of fiber angle and aspect ratio. It was further noted that under testing conditions that engendered significant fiber stretch, the aggregate resistance to shear was higher, indicating a role for fiber stretch in the overall shear response. Finally, with time in culture, the shear modulus of MSC laden constructs increased, suggesting that

Guidance of neurite outgrowth on aligned electrospun polypyrrole/poly(styrene-beta-isobutylene-beta-styrene) fiber platforms.

PubMed

Liu, Xiao; Chen, Jun; Gilmore, Kerry J; Higgins, Michael J; Liu, Yong; Wallace, Gordon G

2010-09-15

The purpose of this work was to investigate the potential biomedical application of novel aligned electrospun polypyrrole (PPy)/poly(styrene-beta-isobutylene-beta-styrene) (SIBS) fibers. After successfully aligning the electroactive PPy/SIBS fibers based on our modified electrospinning method, we demonstrated that neurite outgrowth from PC12 cells could be highly orientated parallel to the aligned PPy/SIBS fibers. Physical interactions between the nerve cells and PPy/SIBS fibers through filopodia "sensing" were observed using atomic force microscopy. These observations indicate a role of contact guidance as a mechanism for the observed alignment. This work highlights the capacity for electroactive PPy/SIBS fibers to support and guide nerve cell differentiation through topographic cues, which is a highly desirable characteristic in medical implants for neurological applications. (c) 2010 Wiley Periodicals, Inc.

Use of lecithin to control fiber morphology in electrospun poly (ɛ-caprolactone) scaffolds for improved tissue engineering applications.

PubMed

Coverdale, Benjamin D M; Gough, Julie E; Sampson, William W; Hoyland, Judith A

2017-10-01

We elucidate the effects of incorporating surfactants into electrospun poly (ɛ-caprolactone) (PCL) scaffolds on network homogeneity, cellular adherence and osteogenic differentiation. Lecithin was added with a range of concentrations to PCL solutions, which were electrospun to yield functionalized scaffolds. Addition of lecithin yielded a dose-dependent reduction in scaffold hydrophobicity, whilst reducing fiber width and hence increasing specific surface area. These changes in scaffold morphology were associated with increased cellular attachment of Saos-2 osteoblasts 3-h postseeding. Furthermore, cells on scaffolds showed comparable proliferation over 14 days of incubation to TCP controls. Through model-based interpretation of image analysis combined with gravimetric estimates of porosity, lecithin is shown to reduce scaffold porosity and mean pore size. Additionally, lecithin incorporation is found to reduce fiber curvature, resulting in increased scaffold specific elastic modulus. Low concentrations of lecithin were found to induce upregulation of several genes associated with osteogenesis in primary mesenchymal stem cells. The results demonstrate that functionalization of electrospun PCL scaffolds with lecithin can increase the biocompatibility and regenerative potential of these networks for bone tissue engineering applications. © 2017 The Authors Journal of Biomedical Materials Research Part A Published by Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2865-2874, 2017. © 2017 The Authors Journal of Biomedical Materials Research Part A Published by Wiley Periodicals, Inc.

A highly flexible piezoelectret-fiber pressure sensor based on highly aligned P(VDF-TrFE) electrospun fibers

NASA Astrophysics Data System (ADS)

Ke, Jun-Yi; Chu, Hsin-Jung; Hsu, Yu-Hsiang; Lee, Chih-Kung

2017-04-01

P(VDF-TrFE) is a ferroelectric material having a strong piezoelectric effect, a good chemical stability, chemical resistance and biocompatibility. Therefore, it is suitable for the development of flexible pressure sensors in biological applications. Using electrospinning method and a drum collector, P(VDF-TrFE) nanofibers are aligned and formed an ultrathin film sheet with a thickness of 15 to 30 μm. A 140 °C annealing process and a corona discharge poling process are conducted to increase the performance of β phase piezoelectricity. Based on this technology, a highly flexible piezoelectret pressure sensor is developed for measuring muscle movement on the surface of human body. The orientation of electrospun P(VDFTrFE) fibers and poling direction are studied to enhance the sensitivity of the piezoelectret-fiber pressure sensor. Preliminary study shows that the sensitivity of piezoelectret-fiber pressure sensor can be 110.37 pC/Pa with a high signal to noise ratio. Sensor design, experimental studies, and biological application are detailed in this paper.

Fabrication and Evaluation of Electrospun, 3D-Bioplotted, and Combination of Electrospun/3D-Bioplotted Scaffolds for Tissue Engineering Applications

PubMed Central

Mellor, Liliana F.; Huebner, Pedro; Cai, Shaobo; Taylor, Michael A.; Spang, Jeffrey

2017-01-01

Electrospun scaffolds provide a dense framework of nanofibers with pore sizes and fiber diameters that closely resemble the architecture of native extracellular matrix. However, it generates limited three-dimensional structures of relevant physiological thicknesses. 3D printing allows digitally controlled fabrication of three-dimensional single/multimaterial constructs with precisely ordered fiber and pore architecture in a single build. However, this approach generally lacks the ability to achieve submicron resolution features to mimic native tissue. The goal of this study was to fabricate and evaluate 3D printed, electrospun, and combination of 3D printed/electrospun scaffolds to mimic the native architecture of heterogeneous tissue. We assessed their ability to support viability and proliferation of human adipose derived stem cells (hASC). Cells had increased proliferation and high viability over 21 days on all scaffolds. We further tested implantation of stacked-electrospun scaffold versus combined electrospun/3D scaffold on a cadaveric pig knee model and found that stacked-electrospun scaffold easily delaminated during implantation while the combined scaffold was easier to implant. Our approach combining these two commonly used scaffold fabrication technologies allows for the creation of a scaffold with more close resemblance to heterogeneous tissue architecture, holding great potential for tissue engineering and regenerative medicine applications of osteochondral tissue and other heterogeneous tissues. PMID:28536700

Investigation of Electrospun Poly Vinyl Alcohol Fibers Towards the Development of Manufacturable Wound Dressings

NASA Astrophysics Data System (ADS)

Vora, Asad

Polymers such as polyvinyl alcohol, chitosan, and starch have excellent bio-compatible and bio-degradable properties. Their applications in drug delivery, wound dressings, artificial cartilage materials have increased dramatically due to their much sought-after renewable and biological properties. Hence, polyvinyl alcohol has been chosen for this study to test the feasibility of polyvinyl alcohol nanofibers towards the manufacturable wound dressings. Polyvinyl alcohol nanofibers are prepared via electrospinning technique, where different wt% polyvinyl alcohol solutions are prepared. The fibers were optimized by varying important electrospninning parameters which include voltage applied, the collector-needle distance and flow rate. Morphology and structure of the electrospun fibers are analysed using scanning electron microscopy and fourier transform infrared respectively. The diameter of fibers obtained was found to be in the range of 100 nm-160 nm. Thermal stability was examined using DSC and TGA characterization technique and fibers are found to be stable up to 220oC. Finally, each weight sample of PVA fibers are analysed by goniometer for wettability and is found to be hydrophilic.

κ-Carrageenan Enhances the Biomineralization and Osteogenic Differentiation of Electrospun Polyhydroxybutyrate and Polyhydroxybutyrate Valerate Fibers.

PubMed

Goonoo, Nowsheen; Khanbabaee, Behnam; Steuber, Marc; Bhaw-Luximon, Archana; Jonas, Ulrich; Pietsch, Ullrich; Jhurry, Dhanjay; Schönherr, Holger

2017-05-08

Novel electrospun materials for bone tissue engineering were obtained by blending biodegradable polyhydroxybutyrate (PHB) or polyhydroxybutyrate valerate (PHBV) with the anionic sulfated polysaccharide κ-carrageenan (κ-CG) in varying ratios. In both systems, the two components phase separated as shown by FTIR, DSC and TGA. According to the contact angle data, κ-CG was localized preferentially at the fiber surface in PHBV/κ-CG blends in contrast to PHB/κ-CG, where the biopolymer was mostly found within the fiber. In contrast to the neat polyester fibers, the blends led to the formation of much smaller apatite crystals (800 nm vs 7 μm). According to the MTT assay, NIH3T3 cells grew in higher density on the blend mats in comparison to neat polyester mats. The osteogenic differentiation potential of the fibers was determined by SaOS-2 cell culture for 2 weeks. Alizarin red-S staining suggested an improved mineralization on the blend fibers. Thus, PHBV/κ-CG fibers resulted in more pronounced bioactive and osteogenic properties, including fast apatite-forming ability and deposition of nanosized apatite crystals.

Bacterial response to different surface chemistries fabricated by plasma polymerization on electrospun nanofibers.

PubMed

Abrigo, Martina; Kingshott, Peter; McArthur, Sally L

2015-12-06

Control over bacterial attachment and proliferation onto nanofibrous materials constitutes a major challenge for a variety of applications, including filtration membranes, protective clothing, wound dressings, and tissue engineering scaffolds. To develop effective devices, the interactions that occur between bacteria and nanofibers with different morphological and physicochemical properties need to be investigated. This paper explores the influence of fiber surface chemistry on bacterial behavior. Different chemical functionalities were generated on the surface of electrospun polystyrene nanofibers through plasma polymerization of four monomers (acrylic acid, allylamine, 1,7-octadiene, and 1,8-cineole). The interactions of Escherichia coli with the surface modified fibers were investigated through a combination of scanning electron microscopy and confocal laser scanning microscopy. Fiber wettability, surface charge, and chemistry were found to affect the ability of bacterial cells to attach and proliferate throughout the nanofiber meshes. The highest proportion of viable cells attachment occurred on the hydrophilic amine rich coating, followed by the hydrophobic octadiene. The acrylic acid coating rich in carboxyl groups showed a significantly lower attraction of bacterial cells. The 1,8-cineole retained the antibacterial activity of the monomer, resulting with a high proportion of dead isolated cells attached onto the fibers. Results showed that the surface chemistry properties of nanofibrous membranes can be strategically tuned to control bacterial behavior.

Electrodynamic tailoring of self-assembled three-dimensional electrospun constructs

NASA Astrophysics Data System (ADS)

Reis, Tiago C.; Correia, Ilídio J.; Aguiar-Ricardo, Ana

2013-07-01

The rational design of three-dimensional electrospun constructs (3DECs) can lead to striking topographies and tailored shapes of electrospun materials. This new generation of materials is suppressing some of the current limitations of the usual 2D non-woven electrospun fiber mats, such as small pore sizes or only flat shaped constructs. Herein, we pursued an explanation for the self-assembly of 3DECs based on electrodynamic simulations and experimental validation. We concluded that the self-assembly process is driven by the establishment of attractive electrostatic forces between the positively charged aerial fibers and the already collected ones, which tend to acquire a negatively charged network oriented towards the nozzle. The in situ polarization degree is strengthened by higher amounts of clustered fibers, and therefore the initial high density fibrous regions are the preliminary motifs for the self-assembly mechanism. As such regions increase their in situ polarization electrostatic repulsive forces will appear, favoring a competitive growth of these self-assembled fibrous clusters. Highly polarized regions will evidence higher distances between consecutive micro-assembled fibers (MAFs). Different processing parameters - deposition time, electric field intensity, concentration of polymer solution, environmental temperature and relative humidity - were evaluated in an attempt to control material's design.The rational design of three-dimensional electrospun constructs (3DECs) can lead to striking topographies and tailored shapes of electrospun materials. This new generation of materials is suppressing some of the current limitations of the usual 2D non-woven electrospun fiber mats, such as small pore sizes or only flat shaped constructs. Herein, we pursued an explanation for the self-assembly of 3DECs based on electrodynamic simulations and experimental validation. We concluded that the self-assembly process is driven by the establishment of attractive

Effect of fiber orientation of collagen-based electrospun meshes on human fibroblasts for ligament tissue engineering applications.

PubMed

Full, Sean Michael; Delman, Connor; Gluck, Jessica M; Abdmaulen, Raushan; Shemin, Richard J; Heydarkhan-Hagvall, Sepideh

2015-01-01

Within the past two decades polylactic-co-glycolic acid (PLGA) has gained considerable attention as a biocompatible and biodegradable polymer that is suitable for tissue engineering and regenerative medicine. In this present study, we have investigated the potential of PLGA, collagen I (ColI), and polyurethane (PU) scaffolds for ligament tissue regeneration. Two different ratios of PLGA (50:50 and 85:15) were used to determine the effects on mechanical tensile properties and cell adhesion. The Young's modulus, tensile stress at yield, and ultimate tensile strain of PLGA(50:50)-ColI-PU scaffolds demonstrated similar tensile properties to that of ligaments found in the knee. Whereas, scaffolds composed of PLGA(85:15)-ColI-PU had lower tensile properties than that of ligaments. Furthermore, we investigated the effect of fiber orientation on mechanical properties and our results indicate that aligned fiber scaffolds demonstrate higher tensile properties than scaffolds with random fiber orientation. Also, human fibroblasts attached and proliferated with no need for additional surface modifications to the presented electrospun scaffolds in both categories. Collectively, our investigation demonstrates the effectiveness of electrospun PLGA scaffolds as a suitable candidate for regenerative medicine, capable of being manipulated and combined with other polymers to create three-dimensional microenvironments with adjustable tensile properties to mimic native tissues. © 2014 Wiley Periodicals, Inc.

Effect of Electromechanical Stimulation on the Maturation of Myotubes on Aligned Electrospun Fibers

PubMed Central

Liao, I-Chien; Liu, Jason B.; Bursac, Nenad; Leong, Kam W.

2009-01-01

Tissue engineering may provide an alternative to cell injection as a therapeutic solution for myocardial infarction. A tissue-engineered muscle patch may offer better host integration and higher functional performance. This study examined the differentiation of skeletal myoblasts on aligned electrospun polyurethane (PU) fibers and in the presence of electromechanical stimulation. Skeletal myoblasts cultured on aligned PU fibers showed more pronounced elongation, better alignment, higher level of transient receptor potential cation channel-1 (TRPC-1) expression, upregulation of contractile proteins and higher percentage of striated myotubes compared to those cultured on random PU fibers and film. The resulting tissue constructs generated tetanus forces of 1.1 mN with a 10-ms time to tetanus. Additional mechanical, electrical, or synchronized electromechanical stimuli applied to myoblasts cultured on PU fibers increased the percentage of striated myotubes from 70 to 85% under optimal stimulation conditions, which was accompanied by an upregulation of contractile proteins such as α-actinin and myosin heavy chain. In describing how electromechanical cues can be combined with topographical cue, this study helped move towards the goal of generating a biomimetic microenvironment for engineering of functional skeletal muscle. PMID:19774099

Novel Technique for Quantitative Fast Scanning Calorimetry on Electrospun Fibers

NASA Astrophysics Data System (ADS)

Thomas, David; Govinna, Nelaka; Schick, Christoph; Cebe, Peggy

Fast scanning chip calorimetry allows for the study of polymers which have rapid nucleation and/or crystallization kinetics, or degrade within their melting range. Heating rates used, up to 4000 K/s, allow studies of hetero and homogeneous nucleation at time scales inaccessible with conventional calorimeters, whose rates are typically <0.5 K/s. Polyethylene terephthalate (PET) and polyvinyl alcohol (PVA) were chosen in the development of a new methodology to obtain quantitative fast scanning thermal data from electrospun nanofibers using a Flash DSC1. The structure of nanofibers requires special methods to load nanogram-sized samples onto a UFSC1 sensor. Fibers were directly spun onto TEM grids which provide a durable substrate to support bundles of nanofibers and possess excellent thermal conductivity allowing for a strong, repeatable signal and ensure good sample to sensor contact. As spun samples were held isothermally at temperatures ranging from Tg to Tm then heated at 2,000 K/s to assess as-spun crystallinity and cold crystallization behaviors. Above Tm the fibers break up into micro- and nano-droplets. On these samples, melt crystallization experiments were performed to study nucleation and crystallization of polymer confined to nanodroplet morphology. NSF DMR-1608125.

Long-term Controlled Drug Release from bi-component Electrospun Fibers

NASA Astrophysics Data System (ADS)

Xu, Shanshan; Zhang, Zixin; Xia, Qinghua; Han, Charles

Multi-drug delivery systems with timed programmed release are hard to be produced due to the complex drug release kinetics which mainly refers to the diffusion of drug molecules from the fiber and the degradation of the carrier. This study focused on the whole life-time story of the long-term drug releasing fibrous systems. Electrospun membrane utilizing FDA approved polymers and broad-spectrum antibiotics showed specific drug release profiles which could be divided into three stages based on the profile slope. With throughout morphology observation, cumulative release amount and releasing duration, releasing kinetics and critical factors were fully discussed during three stages. Through changing the second component, approximately linear drug release profile and a drug release duration about 13 days was prepared, which is perfect for preventing post-operative infection. The addition of this semi-crystalline polymer in turn influenced the fiber swelling and created drug diffusion channels. In conclusion, through adjusting and optimization of the blending component, initial burst release, delayed release for certain duration, and especially the sustained release profile could all be controlled, as well as specific anti-bacterial behavior could be obtained.

Denaturing of single electrospun fibrinogen fibers studied by deep ultraviolet fluorescence microscopy.

PubMed

Kim, Jeongyong; Song, Hugeun; Park, Inho; Carlisle, Christine R; Bonin, Keith; Guthold, Martin

2011-03-01

Deep ultraviolet (DUV) microscopy is a fluorescence microscopy technique to image unlabeled proteins via the native fluorescence of some of their amino acids. We constructed a DUV fluorescence microscope, capable of 280 nm wavelength excitation by modifying an inverted optical microscope. Moreover, we integrated a nanomanipulator-controlled micropipette into this instrument for precise delivery of picoliter amounts of fluid to selected regions of the sample. In proof-of-principle experiments, we used this instrument to study, in situ, the effect of a denaturing agent on the autofluorescence intensity of single, unlabeled, electrospun fibrinogen nanofibers. Autofluorescence emission from the nanofibers was excited at 280 nm and detected at ∼350 nm. A denaturant solution was discretely applied to small, select sections of the nanofibers and a clear local reduction in autofluorescence intensity was observed. This reduction is attributed to the dissolution of the fibers and the unfolding of proteins in the fibers. Copyright © 2010 Wiley-Liss, Inc.

Synthesis of continuous boron nitride nanofibers by solution coating electrospun template fibers

NASA Astrophysics Data System (ADS)

Qiu, Yejun; Yu, Jie; Yin, Jing; Tan, Cuili; Zhou, Xiaosong; Bai, Xuedong; Wang, Enge

2009-08-01

Continuous boron nitride nanofibers (BNNFs) have been synthesized from boric oxide (B2O3) coatings deposited on stabilized electrospun polyacrylonitrile fibers (S-PANFs). The B2O3 overcoatings were prepared by impregnating the S-PANFs with B2O3 ethanol solutions. By successive heat treatments at 800 °C in NH3/O2 mixture, 1100 °C in pure NH3, and 1500 °C in N2, the S-PANFs were fully removed and the B2O3 coatings deflate to form solid fibers and transform into the BNNFs. The S-PANF template was fully removed by introducing O2 during nitridation, and thus resulted in the formation of the BNNFs. The diameter of the BNNFs can be effectively controlled by changing the mass concentration of the B2O3 solution, and diameters from 43 to 230 nm were obtained by changing the B2O3 mass concentration from 0.25% to 4.8%. The obtained BNNFs are crystallized with the (002) planes oriented in parallel to the fiber axis. This method provides a powerful tool for obtaining BNNFs with controllable diameters, especially extremely thin BNNFs.

Synthesis of continuous boron nitride nanofibers by solution coating electrospun template fibers.

PubMed

Qiu, Yejun; Yu, Jie; Yin, Jing; Tan, Cuili; Zhou, Xiaosong; Bai, Xuedong; Wang, Enge

2009-08-26

Continuous boron nitride nanofibers (BNNFs) have been synthesized from boric oxide (B(2)O(3)) coatings deposited on stabilized electrospun polyacrylonitrile fibers (S-PANFs). The B(2)O(3) overcoatings were prepared by impregnating the S-PANFs with B(2)O(3) ethanol solutions. By successive heat treatments at 800 degrees C in NH(3)/O(2) mixture, 1100 degrees C in pure NH(3), and 1500 degrees C in N(2), the S-PANFs were fully removed and the B(2)O(3) coatings deflate to form solid fibers and transform into the BNNFs. The S-PANF template was fully removed by introducing O(2) during nitridation, and thus resulted in the formation of the BNNFs. The diameter of the BNNFs can be effectively controlled by changing the mass concentration of the B(2)O(3) solution, and diameters from 43 to 230 nm were obtained by changing the B(2)O(3) mass concentration from 0.25% to 4.8%. The obtained BNNFs are crystallized with the (002) planes oriented in parallel to the fiber axis. This method provides a powerful tool for obtaining BNNFs with controllable diameters, especially extremely thin BNNFs.

Electrospun Fiber Pads of Cellulose Acetate and Essential Oils with Antimicrobial Activity.

PubMed

Liakos, Ioannis L; Holban, Alina Maria; Carzino, Riccardo; Lauciello, Simone; Grumezescu, Alexandru Mihai

2017-04-12

The method of electrospinning was used to create nanofibers made of cellulose acetate (CA) and essential oils (EOs). CA polymer at 15% w / v was dissolved in acetone and then 1% or 5% v / v of EOs was added to the polymer solution. The utilized essential oils were rosemary and oregano oils. Then, the CA/EOs in acetone solution were electrospun, creating micro/nanofibers, approximately 700-1500 nm in diameter. Raman spectroscopy was used to detect the attachment of the EOs in the CA electrospun fibers (ESFs). Scanning electron microscopy was used to study the morphology, topography and dimensions of the ESFs. The formed CA/EOs ESFs are found to have good antimicrobial properties against three common microbial species, frequently found in difficult to treat infections: Bacteria species Staphylococcus aureus , Escherichia coli and the yeast Candida albicans . ESFs with 5% v / v oregano oil with respect to the initial solution, showed the best antimicrobial and anti-biofilm effects due to the potency of this EO against bacteria and fungi, especially for Escherichia coli and Candida albicans . This work describes an effective and simple method to prepare CA/EOs ESFs and opens up many new applications of micro/nanofibers such as improved antimicrobial wound dressings, anti-biofilm surfaces, sensors and packaging alternatives.

Electrospun polylactic acid and polyvinyl alcohol fibers as efficient and stable nanomaterials for immobilization of lipases.

PubMed

Sóti, Péter Lajos; Weiser, Diana; Vigh, Tamás; Nagy, Zsombor Kristóf; Poppe, László; Marosi, György

2016-03-01

Electrospinning was applied to create easy-to-handle and high-surface-area membranes from continuous nanofibers of polyvinyl alcohol (PVA) or polylactic acid (PLA). Lipase PS from Burkholderia cepacia and Lipase B from Candida antarctica (CaLB) could be immobilized effectively by adsorption onto the fibrous material as well as by entrapment within the electrospun nanofibers. The biocatalytic performance of the resulting membrane biocatalysts was evaluated in the kinetic resolution of racemic 1-phenylethanol (rac-1) and 1-phenylethyl acetate (rac-2). Fine dispersion of the enzymes in the polymer matrix and large surface area of the nanofibers resulted in an enormous increase in the activity of the membrane biocatalyst compared to the non-immobilized crude powder forms of the lipases. PLA as fiber-forming polymer for lipase immobilization performed better than PVA in all aspects. Recycling studies with the various forms of electrospun membrane biocatalysts in ten cycles of the acylation and hydrolysis reactions indicated excellent stability of this forms of immobilized lipases. PLA-entrapped lipases could preserve lipase activity and enantiomer selectivity much better than the PVA-entrapped forms. The electrospun membrane forms of CaLB showed high mechanical stability in the repeated acylations and hydrolyses than commercial forms of CaLB immobilized on polyacrylamide beads (Novozyme 435 and IMMCALB-T2-150).

Molecular orientation in aligned electrospun polyimide nanofibers by polarized FT-IR spectroscopy.

PubMed

Yang, Haoqi; Jiang, Shaohua; Fang, Hong; Hu, Xiaowu; Duan, Gaigai; Hou, Haoqing

2018-07-05

Quantitative explanation on the improved mechanical properties of aligned electrospun polyimide (PI) nanofibers as the increased imidization temperatures is highly required. In this work, polarized FT-IR spectroscopy is applied to solve this problem. Based on the polarized FT-IR spectroscopy and the molecular model in the fibers, the length of the repeat unit of PI molecule, the angle between the fiber axis and the symmetric stretching direction of carbonyl group on the imide ring, and the angle between the PI molecular axis and fiber axis are all investigated. The Mark-Howink equation is used to calculate the number-average molar mass of PI molecules. The orientation states of PI molecules in the electrospun nanofibers are studied from the number-average molar mass of PI molecules and the average fiber diameter. Quantitative analysis of the orientation factor of PI molecules in the electrospun nanofibers is performed by polarized FT-IR spectroscopy. Copyright © 2018 Elsevier B.V. All rights reserved.

Fabrication and characterization of polycaprolactone-graphene powder electrospun nanofibers

NASA Astrophysics Data System (ADS)

Ginestra, Paola; Ghazinejad, Maziar; Madou, Marc; Ceretti, Elisabetta

2016-09-01

Porous fibrous membranes having multiple scales geometries and tailored properties have become attractive microfabrication materials in recent years. Due to the feasibility of incorporating graphene in electrospun nanofibres and the growing interest on these nanomaterials, the present paper focuses on the electrospinning of Poly (ɛ-Caprolactone) (PCL) solutions in the presence of different amounts of Graphene platelets. Electrospinning is a process whereby ultrafine fibers are formed in a high-voltage electrostatic field. The morphological appearance, fiber diameter, and structure of PCL nanofibers produced by the electrospinning process were studied in the presence of different concentration of graphene. Moreover, the effect of a successful incorporation of graphene nanosheets into PCL polymer nanofibers was analyzed. Scanning electron microscope micrographs of the electrospun fibers showed that the average fiber diameter increases in the presence of graphene. Furthermore, the intrinsic properties developed due to the interactions of graphene and PCL improved the mechanical properties of the nanofibers. The results reveal the effect of various graphene concentrations on PCL and the strong interfacial interactions between the graphene platelets phase and the polymer matrix. The functional complexity of the electrospun fibers provides significant advantages over other techniques and shows the promise of these fibers for many applications including air/water filters, sensors, organic solar cells, smart textiles, biocompatible scaffolds for tissue engineering and load-bearing applications. Optimizing deposition efficiency, however, is a necessary milestone for the widespread use of this technique.

Controlled Antibiotics Release System through Simple Blended Electrospun Fibers for Sustained Antibacterial Effects.

PubMed

Zhang, Zixin; Tang, Jianxiong; Wang, Heran; Xia, Qinghua; Xu, Shanshan; Han, Charles C

2015-12-09

Implantation of sustained antibacterial system after abdominal surgery could effectively prevent complicated intra-abdominal infection. In this study, a simple blended electrospun membrane made of poly(D,L-lactic-co-glycolide) (PLGA)/poly(dioxanone) (PDO)/Ciprofloxacin hydrochloride (CiH) could easily result in approximately linear drug release profile and sustained antibacterial activity against both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The addition of PDO changed the stack structure of PLGA, which in turn influenced the fiber swelling and created drug diffusion channels. It could be a good candidate for reducing postoperative infection or be associated with other implant to resist biofilm formation.

Tunable Engineered Skin Mechanics via Coaxial Electrospun Fiber Core Diameter

PubMed Central

Blackstone, Britani Nicole; Drexler, Jason William

2014-01-01

Autologous engineered skin (ES) offers promise as a treatment for massive full thickness burns. Unfortunately, ES is orders of magnitude weaker than normal human skin causing it to be difficult to apply surgically and subject to damage by mechanical shear in the early phases of engraftment. In addition, no manufacturing strategy has been developed to tune ES biomechanics to approximate the native biomechanics at different anatomic locations. To enhance and tune ES biomechanics, a coaxial (CoA) electrospun scaffold platform was developed from polycaprolactone (PCL, core) and gelatin (shell). The ability of the coaxial fiber core diameter to control both scaffold and tissue mechanics was investigated along with the ability of the gelatin shell to facilitate cell adhesion and skin development compared to pure gelatin, pure PCL, and a gelatin-PCL blended fiber scaffold. CoA ES exhibited increased cellular adhesion and metabolism versus PCL alone or gelatin-PCL blend and promoted the development of well stratified skin with a dense dermal layer and a differentiated epidermal layer. Biomechanics of the scaffold and ES scaled linearly with core diameter suggesting that this scaffold platform could be utilized to tailor ES mechanics for their intended grafting site and reduce graft damage in vitro and in vivo. PMID:24712409

Tunable engineered skin mechanics via coaxial electrospun fiber core diameter.

PubMed

Blackstone, Britani Nicole; Drexler, Jason William; Powell, Heather Megan

2014-10-01

Autologous engineered skin (ES) offers promise as a treatment for massive full thickness burns. Unfortunately, ES is orders of magnitude weaker than normal human skin causing it to be difficult to apply surgically and subject to damage by mechanical shear in the early phases of engraftment. In addition, no manufacturing strategy has been developed to tune ES biomechanics to approximate the native biomechanics at different anatomic locations. To enhance and tune ES biomechanics, a coaxial (CoA) electrospun scaffold platform was developed from polycaprolactone (PCL, core) and gelatin (shell). The ability of the coaxial fiber core diameter to control both scaffold and tissue mechanics was investigated along with the ability of the gelatin shell to facilitate cell adhesion and skin development compared to pure gelatin, pure PCL, and a gelatin-PCL blended fiber scaffold. CoA ES exhibited increased cellular adhesion and metabolism versus PCL alone or gelatin-PCL blend and promoted the development of well stratified skin with a dense dermal layer and a differentiated epidermal layer. Biomechanics of the scaffold and ES scaled linearly with core diameter suggesting that this scaffold platform could be utilized to tailor ES mechanics for their intended grafting site and reduce graft damage in vitro and in vivo.

Processing and characterization of α-elastin electrospun membranes

NASA Astrophysics Data System (ADS)

Araujo, J.; Padrão, J.; Silva, J. P.; Dourado, F.; Correia, D. M.; Botelho, G.; Gomez Ribelles, J. L.; Lanceros-Méndez, S.; Sencadas, V.

2014-06-01

Elastin isolated from fresh bovine ligaments was dissolved in a mixture of 1,1,1,3,3,3-Hexafluoro-2-propanol and water were electrospun into fiber membranes under different processing conditions. Fiber mats of randomly and aligned fibers were obtained with fixed and rotating ground collectors and fibrils were composed by thin ribbons whose width depends on electrospinning conditions; fibrils with 721 nm up to 2.12 μm width were achieved. After cross-linking with glutaraldehyde, α-elastin can uptake as much as 1700 % of PBS solution and a slight increase on fiber thickness was observed. The glass transition temperature of electrospun fiber mats was found to occur at ˜80 °C. Moreover, α-Elastin showed to be a perfect elastomeric material, and no mechanical hysteresis was found in cycle mechanical measurements. The elastic modulus obtained for random and aligned fibers mats in a PBS solution was 330±10 kPa and 732±165 kPa, respectively. Finally, the electrospinning and cross-linking process does not inhibit MC-3T3-E1 cell adhesion. Cell culture results showed good cell adhesion and proliferation in the cross-linked elastin fiber mats.

Effect of Sterilization Methods on Electrospun Poly(lactic acid) (PLA) Fiber Alignment for Biomedical Applications.

PubMed

Valente, T A M; Silva, D M; Gomes, P S; Fernandes, M H; Santos, J D; Sencadas, V

2016-02-10

Medically approved sterility methods should be a major concern when developing a polymeric scaffold, mainly when commercialization is envisaged. In the present work, poly(lactic acid) (PLA) fiber membranes were processed by electrospinning with random and aligned fiber alignment and sterilized under UV, ethylene oxide (EO), and γ-radiation, the most common ones for clinical applications. It was observed that UV light and γ-radiation do not influence fiber morphology or alignment, while electrospun samples treated with EO lead to fiber orientation loss and morphology changing from cylindrical fibers to ribbon-like structures, accompanied to an increase of polymer crystallinity up to 28%. UV light and γ-radiation sterilization methods showed to be less harmful to polymer morphology, without significant changes in polymer thermal and mechanical properties, but a slight increase of polymer wettability was detected, especially for the samples treated with UV radiation. In vitro results indicate that both UV and γ-radiation treatments of PLA membranes allow the adhesion and proliferation of MG 63 osteoblastic cells in a close interaction with the fiber meshes and with a growth pattern highly sensitive to the underlying random or aligned fiber orientation. These results are suggestive of the potential of both γ-radiation sterilized PLA membranes for clinical applications in regenerative medicine, especially those where customized membrane morphology and fiber alignment is an important issue.

Chain Confinement in Electrospun Nanocomposites: using Thermal Analysis to Investigate Polymer-Filler Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Q Ma; B Mao; P Cebe

2011-12-31

We investigate the interaction of the polymer matrix and filler in electrospun nanofibers using advanced thermal analysis methods. In particular, we study the ability of silicon dioxide nanoparticles to affect the phase structure of poly(ethylene terephthalate), PET. SiO{sub 2} nanoparticles (either unmodified or modified with silane) ranging from 0 to 2.0 wt% in PET were electrospun from hexafluoro-2-propanol solutions. The morphologies of both the electrospun (ES) nanofibers and the SiO{sub 2} powders were observed by scanning and transmission electron microscopy, while the amorphous or crystalline nature of the fibers was determined by real-time wide-angle X-ray scattering. The fractions of themore » crystal, mobile amorphous, and rigid amorphous phases of the non-woven, nanofibrous composite mats were quantified by using heat capacity measurements. The amount of the immobilized polymer layer, the rigid amorphous fraction, was obtained from the specific reversing heat capacity for both as-spun amorphous fibers and isothermally crystallized fibers. Existence of the rigid amorphous phase in the absence of crystallinity was verified in nanocomposite fibers, and two origins for confinement of the rigid amorphous fraction are proposed. Thermal analysis of electrospun fibers, including quasi-isothermal methods, provides new insights to quantitatively characterize the polymer matrix phase structure and thermal transitions, such as devitrification of the rigid amorphous fraction.« less

Electrospun core-shell fibers for robust silicon nanoparticle-based lithium ion battery anodes.

PubMed

Hwang, Tae Hoon; Lee, Yong Min; Kong, Byung-Seon; Seo, Jin-Seok; Choi, Jang Wook

2012-02-08

Because of its unprecedented theoretical capacity near 4000 mAh/g, which is approximately 10-fold larger compared to those of the current commercial graphite anodes, silicon has been the most promising anode for lithium ion batteries, particularly targeting large-scale energy storage applications including electrical vehicles and utility grids. Nevertheless, Si suffers from its short cycle life as well as the limitation for scalable electrode fabrication. Herein, we develop an electrospinning process to produce core-shell fiber electrodes using a dual nozzle in a scalable manner. In the core-shell fibers, commercially available nanoparticles in the core are wrapped by the carbon shell. The unique core-shell structure resolves various issues of Si anode operations, such as pulverization, vulnerable contacts between Si and carbon conductors, and an unstable sold-electrolyte interphase, thereby exhibiting outstanding cell performance: a gravimetric capacity as high as 1384 mAh/g, a 5 min discharging rate capability while retaining 721 mAh/g, and cycle life of 300 cycles with almost no capacity loss. The electrospun core-shell one-dimensional fibers suggest a new design principle for robust and scalable lithium battery electrodes suffering from volume expansion. © 2011 American Chemical Society

Fabrication, Polarization of Electrospun Polyvinylidene Fluoride Electret Fibers and Effect on Capturing Nanoscale Solid Aerosols †

PubMed Central

Lolla, Dinesh; Lolla, Manideep; Abutaleb, Ahmed; Shin, Hyeon U.; Reneker, Darrell H.; Chase, George G.

2016-01-01

Electrospun polyvinylidene fluoride (PVDF) fiber mats with average fiber diameters (≈200 nm, ≈2000 nm) were fabricated by controlled electrospinning conditions. These fiber mats were polarized using a custom-made device to enhance the formation of the electret β-phase ferroelectric property of the fibers by simultaneous uniaxial stretching of the fiber mat and heating the mat to the Curie temperature of the PVDF polymer in a strong electric field of 2.5 kV/cm. Scanning electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, differential scanning calorimetry and Brunauer-Emmett-Teller (BET) surface area analyses were performed to characterize both the internal and external morphologies of the fiber mat samples to study polarization-associated changes. MATLAB simulations revealed the changes in the paths of the electric fields and the magnetic flux inside the polarization field with inclusion of the ferroelectric fiber mats. Both polarized and unpolarized fiber mats were challenged as filters against NaCl particles with average particle diameters of about 150 nm using a TSI 8130 to study capture efficiencies and relative pressure drops. Twelve filter experiments were conducted on each sample at one month time intervals between experiments to evaluate the reduction of the polarization enhancement over time. The results showed negligible polarization loss for the 200-nm fiber sample. The polarized mats had the highest filter efficiencies and lowest pressure drops. PMID:28773798

Development of electrospun beaded fibers from Thai silk fibroin and gelatin for controlled release application.

PubMed

Somvipart, Siraporn; Kanokpanont, Sorada; Rangkupan, Rattapol; Ratanavaraporn, Juthamas; Damrongsakkul, Siriporn

2013-04-01

Thai silk fibroin and gelatin are attractive biomaterials for tissue engineering and controlled release applications due to their biocompatibility, biodegradability, and bioactive properties. The development of electrospun fiber mats from silk fibroin and gelatin were reported previously. However, burst drug release from such fiber mats remained the problem. In this study, the formation of beads on the fibers aiming to be used for the sustained release of drug was of our interest. The beaded fiber mats were fabricated using electrospinning technique by controlling the solution concentration, weight blending ratio of Thai silk fibroin/gelatin blend, and applied voltage. It was found that the optimal conditions including the solution concentration and the weight blending ratio of Thai silk fibroin/gelatin at 8-10% (w/v) and 70/30, respectively, with the applied voltage at 18 kV provided the fibers with homogeneous formation of beads. Then, the beaded fiber mats obtained were crosslinked by the reaction of carbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS). Methylene blue as a model active compound was loaded on the fiber mats. The release test of methylene blue from the beaded fiber mats was carried out in comparison to that of the smooth fiber mats without beads. It was found that the beaded fiber mats could prolong the release of methylene blue, comparing to the smooth fiber mats without beads. This was possibly due to the beaded fiber mats that would absorb and retain higher amount of methylene blue than the fiber mats without beads. Thai silk fibroin/gelatin beaded fiber mats were established as an effective carrier for the controlled release applications. Copyright © 2013 Elsevier B.V. All rights reserved.

Solid polystyrene and deuterated polystyrene light output response to fast neutrons

NASA Astrophysics Data System (ADS)

Simpson, R.; Danly, C.; Glebov, V. Yu.; Hurlbut, C.; Merrill, F. E.; Volegov, P. L.; Wilde, C.

2016-04-01

The Neutron Imaging System has proven to be an important diagnostic in studying DT implosion characteristics at the National Ignition Facility. The current system depends on a polystyrene scintillating fiber array, which detects fusion neutrons born in the DT hotspot as well as neutrons that have scattered to lower energies in the surrounding cold fuel. Increasing neutron yields at NIF, as well as a desire to resolve three-dimensional information about the fuel assembly, have provided the impetus to build and install two additional next-generation neutron imaging systems. We are currently investigating a novel neutron imaging system that will utilize a deuterated polystyrene (CD) fiber array instead of standard hydrogen-based polystyrene (CH). Studies of deuterated xylene or deuterated benzene liquid scintillator show an improvement in imaging resolution by a factor of two [L. Disdier et al., Rev. Sci. Instrum. 75, 2134 (2004)], but also a reduction in light output [V. Bildstein et al., Nucl. Instrum. Methods Phys. Res., Sect. A 729, 188 (2013); M. I. Ojaruega, Ph.D. thesis, University of Michigan, 2009; M. T. Febbraro, Ph.D. thesis, University of Michigan, 2014] as compared to standard plastic. Tests of the relative light output of deuterated polystyrene and standard polystyrene were completed using 14 MeV fusion neutrons generated through implosions of deuterium-tritium filled capsules at the OMEGA laser facility. In addition, we collected data of the relative response of these two scintillators to a wide energy range of neutrons (1-800 MeV) at the Weapons Neutrons Research Facility. Results of these measurements are presented.

Solid polystyrene and deuterated polystyrene light output response to fast neutrons.

PubMed

Simpson, R; Danly, C; Glebov, V Yu; Hurlbut, C; Merrill, F E; Volegov, P L; Wilde, C

2016-04-01

The Neutron Imaging System has proven to be an important diagnostic in studying DT implosion characteristics at the National Ignition Facility. The current system depends on a polystyrene scintillating fiber array, which detects fusion neutrons born in the DT hotspot as well as neutrons that have scattered to lower energies in the surrounding cold fuel. Increasing neutron yields at NIF, as well as a desire to resolve three-dimensional information about the fuel assembly, have provided the impetus to build and install two additional next-generation neutron imaging systems. We are currently investigating a novel neutron imaging system that will utilize a deuterated polystyrene (CD) fiber array instead of standard hydrogen-based polystyrene (CH). Studies of deuterated xylene or deuterated benzene liquid scintillator show an improvement in imaging resolution by a factor of two [L. Disdier et al., Rev. Sci. Instrum. 75, 2134 (2004)], but also a reduction in light output [V. Bildstein et al., Nucl. Instrum. Methods Phys. Res., Sect. A 729, 188 (2013); M. I. Ojaruega, Ph.D. thesis, University of Michigan, 2009; M. T. Febbraro, Ph.D. thesis, University of Michigan, 2014] as compared to standard plastic. Tests of the relative light output of deuterated polystyrene and standard polystyrene were completed using 14 MeV fusion neutrons generated through implosions of deuterium-tritium filled capsules at the OMEGA laser facility. In addition, we collected data of the relative response of these two scintillators to a wide energy range of neutrons (1-800 MeV) at the Weapons Neutrons Research Facility. Results of these measurements are presented.

Thermal, Electrical and Surface Hydrophobic Properties of Electrospun Polyacrylonitrile Nanofibers for Structural Health Monitoring

PubMed Central

Alarifi, Ibrahim M.; Alharbi, Abdulaziz; Khan, Waseem S.; Swindle, Andrew; Asmatulu, Ramazan

2015-01-01

This paper presents an idea of using carbonized electrospun Polyacrylonitrile (PAN) fibers as a sensor material in a structural health monitoring (SHM) system. The electrospun PAN fibers are lightweight, less costly and do not interfere with the functioning of infrastructure. This study deals with the fabrication of PAN-based nanofibers via electrospinning followed by stabilization and carbonization in order to remove all non-carbonaceous material and ensure pure carbon fibers as the resulting material. Electrochemical impedance spectroscopy was used to determine the ionic conductivity of PAN fibers. The X-ray diffraction study showed that the repeated peaks near 42° on the activated nanofiber film were α and β phases, respectively, with crystalline forms. Contact angle, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were also employed to examine the surface, thermal and chemical properties of the carbonized electrospun PAN fibers. The test results indicated that the carbonized PAN nanofibers have superior physical properties, which may be useful for structural health monitoring (SHM) applications in different industries. PMID:28793615

Interaction of gelatin with polyenes modulates antifungal activity and biocompatibility of electrospun fiber mats

PubMed Central

Lakshminarayanan, Rajamani; Sridhar, Radhakrishnan; Loh, Xian Jun; Nandhakumar, Muruganantham; Barathi, Veluchamy Amutha; Kalaipriya, Madhaiyan; Kwan, Jia Lin; Liu, Shou Ping; Beuerman, Roger Wilmer; Ramakrishna, Seeram

2014-01-01

Topical application of antifungals does not have predictable or well-controlled release characteristics and requires reapplication to achieve therapeutic local concentration in a reasonable time period. In this article, the efficacy of five different US Food and Drug Administration-approved antifungal-loaded (amphotericin B, natamycin, terbinafine, fluconazole, and itraconazole) electrospun gelatin fiber mats were compared. Morphological studies show that incorporation of polyenes resulted in a two-fold increase in fiber diameter and the mats inhibit the growth of yeasts and filamentous fungal pathogens. Terbinafine-loaded mats were effective against three filamentous fungal species. Among the two azole antifungals compared, the itraconazole-loaded mat was potent against Aspergillus strains. However, activity loss was observed for fluconazole-loaded mats against all of the test organisms. The polyene-loaded mats displayed rapid candidacidal activities as well. Biophysical and rheological measurements indicate strong interactions between polyene antifungals and gelatin matrix. As a result, the polyenes stabilized the triple helical conformation of gelatin and the presence of gelatin decreased the hemolytic activity of polyenes. The polyene-loaded fiber mats were noncytotoxic to primary human corneal and sclera fibroblasts. The reduction of toxicity with complete retention of activity of the polyene antifungal-loaded gelatin fiber mats can provide new opportunities in the management of superficial skin infections. PMID:24920895

Picosecond laser ablation of polyamide electrospun nanofibers

NASA Astrophysics Data System (ADS)

Götze, Marco; Krimig, Olaf; Kürbitz, Tobias; Henning, Sven; Heilmann, Andreas; Hillrichs, Georg

2017-02-01

Electrospun nanofibers mats have a great potential in tissue engineering and regenerative medicine. Their high porosity and enormous volume to surface ratio stimulate the growth and adhesion of mammalian cells and serve as a stable support structure. These suitable properties can be further optimized by structuring of the nanofibers. Ultrashort pulsed lasers can be used for modifying of the electrospun nanofibers without significant heat exposure. It seems also possible to generate very fine cuts from the fiber mats. In this study, polyamide electrospun nanofibers samples were processed with picosecond UV-laser irradiation (λ = 355 nm, τ = 15 ps). The samples were processed in dry, wet and immersed condition. To optimize cutting and structuring of nanofiber tissue flakes, the influence of different laser parameters on line widths, edge quality, heat-affected zone (HAZ) and the contamination of the fibers by ablated particles (debris) were examined. One additional aim was the minimization of the flake size. It was possible to generate nanofiber flakes in the sub-millimeter range. The quality of the nanofiber flakes could be improved by ablation near the ablation threshold of the material. For cutting under wet conditions shrinking of the flakes has to be taken into account.

Enhanced Differentiation of Human Preosteoblasts on Electrospun Blend Fiber Mats of Polydioxanone and Anionic Sulfated Polysaccharides

PubMed Central

2017-01-01

The viability and differentiation of SaOS-2 preosteoblasts on fiber mats of blends comprising of the biodegradable poly(ester-ether) polydioxanone (PDX) and the sulfate-containing anionic polysaccharides kappa-carrageenan (KCG) and fucoidan (FUC) were investigated for a range of different blend compositions. The detailed analysis of the blend nanofiber properties revealed a different degree of miscibility of PDX and the polysaccharide leading to a different enrichment at the surface of the blend nanofibers, which were observed to be stable in phosphate buffer solution (PBS) for up to 5 weeks. The fibrous mats of PDX/FUC led to the highest osteogenic differentiation with very good cell viability. The electrospun blend fibers also supported human-induced pluripotent stem (iPS) cells and iPS cell-derived embryoid bodies with high cell viability, which underlines the potential of these novel blend fiber systems for optimized performance in bone tissue engineering applications. PMID:29285521

Long-term drug release from electrospun fibers for in vivo inflammation prevention in the prevention of peritendinous adhesions.

PubMed

Hu, Changmin; Liu, Shen; Zhang, Yang; Li, Bin; Yang, Huilin; Fan, Cunyi; Cui, Wenguo

2013-07-01

Physical barriers such as electrospun fibrous membranes are potentially useful in preventing peritendinous adhesions after surgery. However, inflammatory responses caused by degradation of barrier materials remain a major challenge. This study aimed to fabricate electrospun composite fibrous membranes based on drug-loaded modified mesoporous silica (MMS) and poly (l-lactic acid) (PLLA). Using a co-solvent-based electrospinning method ibuprofen (IBU)-loaded MMS was successfully and uniformly encapsulated in the PLLA fibers. The electrospun PLLA-MMS-IBU composite fibrous membranes showed significantly lower initial burst release (6% release in the first 12h) compared with that of electrospun PLLA-IBU fibrous membranes (46% release in the first 12h) in in vitro release tests. Moreover, the release from PLLA-MMS-IBU was also for significantly longer than that from PLLA-IBU (100 vs. 20days). In animal studies both PLLA-IBU and PLLA-MMS-IBU showed improved anti-adhesion properties and anti-inflammatory effects compared with PLLA fibrous membrane alone 4weeks after implantation. Further, animals implanted with PLLA-MMS-IBU for 8weeks showed the lowest inflammation and best recovery compared with those implanted with PLLA-IBU and PLLA, most likely as a result of its long-term IBU release profile. Therefore, this study provides a platform technique for fabricating fibrous membranes with long-term sustained drug release characteristics which may function as a novel carrier for long-term anti-inflammation and anti-adhesion to prevent peritendinous adhesions. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Current strategies for sustaining drug release from electrospun nanofibers

PubMed Central

Chou, Shih-Feng; Carson, Daniel; Woodrow, Kim A.

2017-01-01

Electrospun drug-eluting fibers are emerging as a novel dosage form for multipurpose prevention against sexually transmitted infections, including HIV, and unintended pregnancy. Previous work from our lab and others show the versatility of this platform to deliver large doses of physico-chemically diverse agents. However, there is still an unmet need to develop practical fiber formulations for water-soluble small molecule drugs needed at high dosing due to intrinsic low potency or desire for sustained prevention. To date, most sustained release fibers have been restricted to the delivery of biologics or hydrophobic small molecules at low drug loading of typically < 1 wt.%, which is often impractical for most clinical applications. For hydrophilic small molecule drugs, their high aqueous solubility and poor partitioning and incompatibility with insoluble polymers make long-term release even more challenging. Here we investigate several existing strategies to sustain release of hydrophilic small molecule drugs that are highly-loaded in electrospun fibers. In particular, we investigate what is known about the design constraints required to realize multi-day release from fibers fabricated from uniaxial and coaxial electrospinning. PMID:26363300

Effect of clay content on morphology and processability of electrospun keratin/poly(lactic acid) nanofiber.

PubMed

Isarankura Na Ayutthaya, Siriorn; Tanpichai, Supachok; Sangkhun, Weradesh; Wootthikanokkhan, Jatuphorn

2016-04-01

This research work has concerned the development of volatile organic compounds (VOCs) removal filters from biomaterials, based on keratin extracted from chicken feather waste and poly(lactic acid) (PLA) (50/50%w/w) blend. Clay (Na-montmorillonite) was also added to the blend solution prior to carrying out an electro-spinning process. The aim of this study was to investigate the effect of clay content on viscosity, conductivity, and morphology of the electrospun fibers. Scanning electron micrographs showed that smooth and bead-free fibers were obtained when clay content used was below 2 pph. XRD patterns of the electrospun fibers indicated that the clay was intercalated and exfoliated within the polymers matrix. Percentage crystallinity of keratin in the blend increased after adding the clay, as evidenced from FTIR spectra and DSC thermograms. Transmission electron micrographs revealed a kind of core-shell structure with clay being predominately resided within the keratin rich shell and at the interfacial region. Filtration performance of the electrospun keratin/PLA fibers, described in terms of pressure drop and its capability of removing methylene blue, were also explored. Overall, our results demonstrated that it was possible to improve process-ability, morphology and filtration efficiency of the electrospun keratin fibers by adding a suitable amount of clay. Copyright © 2016 Elsevier B.V. All rights reserved.

Solid polystyrene and deuterated polystyrene light output response to fast neutrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simpson, R., E-mail: raspberry@lanl.gov; Danly, C.; Merrill, F. E.

The Neutron Imaging System has proven to be an important diagnostic in studying DT implosion characteristics at the National Ignition Facility. The current system depends on a polystyrene scintillating fiber array, which detects fusion neutrons born in the DT hotspot as well as neutrons that have scattered to lower energies in the surrounding cold fuel. Increasing neutron yields at NIF, as well as a desire to resolve three-dimensional information about the fuel assembly, have provided the impetus to build and install two additional next-generation neutron imaging systems. We are currently investigating a novel neutron imaging system that will utilize amore » deuterated polystyrene (CD) fiber array instead of standard hydrogen-based polystyrene (CH). Studies of deuterated xylene or deuterated benzene liquid scintillator show an improvement in imaging resolution by a factor of two [L. Disdier et al., Rev. Sci. Instrum. 75, 2134 (2004)], but also a reduction in light output [V. Bildstein et al., Nucl. Instrum. Methods Phys. Res., Sect. A 729, 188 (2013); M. I. Ojaruega, Ph.D. thesis, University of Michigan, 2009; M. T. Febbraro, Ph.D. thesis, University of Michigan, 2014] as compared to standard plastic. Tests of the relative light output of deuterated polystyrene and standard polystyrene were completed using 14 MeV fusion neutrons generated through implosions of deuterium-tritium filled capsules at the OMEGA laser facility. In addition, we collected data of the relative response of these two scintillators to a wide energy range of neutrons (1-800 MeV) at the Weapons Neutrons Research Facility. Results of these measurements are presented.« less

Thermomechanical Properties of Lignin-Based Electrospun Nanofibers and Films Reinforced with Cellulose Nanocrystals: A Dynamic Mechanical and Nanoindentation Study

Treesearch

Mariko Ago; Joseph E. Jakes; Orlando J. Rojas

2013-01-01

We produced defect-free electrospun fibers from aqueous dispersions of lignin, poly(vinyl alcohol) (PVA), and cellulose nanocrystals (CNCs), which were used as reinforcing nanoparticles. The thermomechanical performance of the lignin-based electrospun fibers and the spin-coated thin films was improved when they were embedded with CNCs. Isochronal dynamic mechanical...

Align and random electrospun mat of PEDOT:PSS and PEDOT:PSS/RGO

NASA Astrophysics Data System (ADS)

Sarabi, Ghazale Asghari; Latifi, Masoud; Bagherzadeh, Roohollah

2018-01-01

In this research work we fabricated two ultrafine conductive nanofibrous layers to investigate the materilas composition and their properties for the preparation of supercapacitor materials application. In first layer, a polymer and a conductive polymer were used and second layer was a composition of polymer, conductive polymer and carbon-base material. In both cases align and randomized mat of conductive nanofibers were fabricated using electrospinning set up. Conductive poly (3,4-ethylenedioxythiophene)/ polystyrene sulfonate (PEDOT:PSS) nanofibers were electrospun by dissolving fiber-forming polymer and polyvinyl alcohol (PVA) in an aqueous dispersion of PEDOT:PSS. The effect of addition of reduced graphene oxide (RGO) was considered for nanocomposite layer. The ultrafine conductive polymer fibers and conductive nanocomposite fibrous materials were also fabricated using an electrospinning process. A fixed collector and a rotating drum were used for random and align nanofibers production, respectively. The resulted fibers were characterized and analyzed by SEM, FTIR and two-point probe conductivity test. The average diameter of nanofibers measured by ImageJ software indicated that the average fiber diameter for first layer was 100 nm and for nanocomposite layer was about 85 nm. The presence of PEDOT:PSS and RGO in the nanofibers was confirmed by FT-IR spectroscopy. The conductivity of align and random layers was characterized. The conductivity of PEDOT:PSS nanofibers showed higher enhancement by addition of RGO in aqueous dispersion. The obtained results showed that alignment of fibrous materials can be considered as an engineering tool for tuning the conductivity of fibrous materials for many different applications such as supercapacitors, conductive and transparent materials.

Desalination by Membrane Distillation using Electrospun Polyamide Fiber Membranes with Surface Fluorination by Chemical Vapor Deposition.

PubMed

Guo, Fei; Servi, Amelia; Liu, Andong; Gleason, Karen K; Rutledge, Gregory C

2015-04-22

Fibrous membranes of poly(trimethyl hexamethylene terephthalamide) (PA6(3)T) were fabricated by electrospinning and rendered hydrophobic by applying a conformal coating of poly(1H,1H,2H,2H-perfluorodecyl acrylate) (PPFDA) using initiated chemical vapor deposition (iCVD). A set of iCVD-treated electrospun PA6(3)T fiber membranes with fiber diameters ranging from 0.25 to 1.8 μm were tested for desalination using the air gap membrane distillation configuration. Permeate fluxes of 2-11 kg/m2/h were observed for temperature differentials of 20-45 °C between the feed stream and condenser plate, with rejections in excess of 99.98%. The liquid entry pressure was observed to increase dramatically, from 15 to 373 kPa with reduction in fiber diameter. Contrary to expectation, for a given feed temperature the permeate flux was observed to increase for membranes of decreasing fiber diameter. The results for permeate flux and salt rejection show that it is possible to construct membranes for membrane distillation even from intrinsically hydrophilic materials after surface modification by iCVD and that the fiber diameter is shown to play an important role on the membrane distillation performance in terms of permeate flux, salt rejection, and liquid entry pressure.

Tunable Mechanics in Electrospun Composites via Hierarchical Organization.

PubMed

Wanasekara, Nandula D; Matolyak, Lindsay E; Korley, LaShanda T J

2015-10-21

Design strategies from nature provide vital clues for the development of synthetic materials with tunable mechanical properties. Employing the concept of hierarchy and controlled percolation, a new class of polymer nanocomposites containing a montmorillonite (MMT)-reinforced electrospun poly(vinyl alcohol) (PVA) filler embedded within a polymeric matrix of either poly(vinyl acetate) (PVAc) or ethylene oxide-epichlorohydrin copolymer (EO-EPI) were developed to achieve a tunable mechanical response upon exposure to specific stimuli. Mechanical response and switching times upon hydration were shown to be dependent on the weight-fraction of MMT in the PVA electrospun fibers and type of composite matrix. PVA/MMT.PVAc composite films retained excellent two-way switchability for all MMT fractions; however, the switching time upon hydration was decreased dramatically as the MMT content was increased due to the highly hydrophilic nature of MMT. Additionally, for the first time, significant two-way switchability of PVA/MMT.EO-EPI composites was achieved for higher weight fractions (12 wt %) of MMT. An extensive investigation into the effects of fiber diameter, crystallinity, and MMT content revealed that inherent rigidity of MMT platelets plays an important role in controlling the mechanical response of these hierarchical electrospun composites.

[Experimental study on long-term prevention effect of chitosan electrospun membrane on cerebrospinal fluid leakage].

PubMed

Guo, Xingfeng; Hou, Chunlin; Dou, Yuandong; Lin, Ye; Lei, Deqiao

2014-08-01

To study the long-term prevention effect of self-developed chitosan electrospun membrane on cerebrospinal fluid leakage. Twenty-five healthy adult New Zealand rabbits were selected to prepare the bilateral dural defect (0.8 cem x 0.8 cm in size) via midline incision of head. Defect of the right was repaired with chitosan electrospun membrane as the experimental group; defect of the left was not repaired as the control group. At 2-16 weeks after operation, one rabbit was sacrificed for the general observation of inflammatory response surrounding bone window and absorption of chitosan electrospun membrane; at 3 and 6 weeks after operation, 5 rabbits were sacrificed for sampling to observe histological change and collagen expression by_HE and Masson staining, and to measure the expressions of epidermal growth factor receptor (EGFR) and basic fibroblast growth factor (bFGF) by immunohistochemical staining. No inflammatory reaction of swelling, exudation, and sppuration appeared in the skin and subcutaneous tissue after operation in 2 groups. There was no adhesion around the chitosan electrospun membrane, and new fiber membrane formed under the chitosan electrospun membrane in the experimental group; no cerebrospinal fluid leakage happened; the chitosan electrospun membrane was gradually degraded with time, and was completely absorbed at 16 weeks. There was uneven scar around the dural detect in control group. Histological observation showed less inflammatory cell infiltration in the experimental group, showing significant difference in the number of inflammatory cells compared with control group at 3, 6 weeks (P < 0.05); capillary, granulation tissue and collagen fiber massively proliferated; collagen fiber arranged in line, and there was a clear borderline between chitosan electrospurn membrane and adjacent collagen fiber. The immunohistochemical staining showed that there were high expressions of bFGF and EGFR in the experimental group, and low expressions of b

Carbon Microfibers with Hierarchical Porous Structure from Electrospun Fiber-Like Natural Biopolymer

NASA Astrophysics Data System (ADS)

Liang, Yeru; Wu, Dingcai; Fu, Ruowen

2013-01-01

Electrospinning offers a powerful route for building one-dimensional (1D) micro/nanostructures, but a common requirement for toxic or corrosive organic solvents during the preparation of precursor solution has limited their large scale synthesis and broad applications. Here we report a facile and low-cost way to prepare 1D porous carbon microfibers by using an electrospun fiber-like natural product, i.e., silk cocoon, as precursor. We surprisingly found that by utilizing a simple carbonization treatment, the cocoon microfiber can be directly transformed into 1D carbon microfiber of ca. 6 μm diameter with a unique three-dimensional porous network structure composed of interconnected carbon nanoparticles of 10~40 nm diameter. We further showed that the as-prepared carbon product presents superior electrochemical performance as binder-free electrodes of supercapacitors and good adsorption property toward organic vapor.

Effect of electrospun nanofibers on flexural properties of fiberglass composites

NASA Astrophysics Data System (ADS)

White, Fatima T.

In the present study, sintered electrospun TEOS nanofibers were interleaved in S2 fiberglass woven fabric layers, and composite panels were fabricated using the heated vacuum assisted resin transfer molding (H-VARTM) process. Cured panels were water jet cut to obtain the flexural test coupons. Flexural coupons were then tested using ASTM D7264 standard. The mechanical properties such as flexural strength, ultimate flexural failure strains, flexural modulus, and fiber volume fraction were measured. The S-2 fiberglass composite with the sintered TEOS electrospun nanofibers displayed lower flexural stiffness and strength as compared to the composites that were fabricated using S-2 fiberglass composite without the TEOS electrospun nanofibers. The present study also indicated that the composites fabricated with sintered TEOS electrospun nanofibers have larger failure strains as compared to the ones that were fabricated without the presence of electrospun nanofibers. The study indicates that the nanoengineered composites have better energy absorbing mechanism under flexural loading as compared to conventional fiberglass composites without presence of nanofibers.

Release of tetracycline hydrochloride from electrospun poly(ethylene-co-vinylacetate), poly(lactic acid), and a blend.

PubMed

Kenawy, El-Refaie; Bowlin, Gary L; Mansfield, Kevin; Layman, John; Simpson, David G; Sanders, Elliot H; Wnek, Gary E

2002-05-17

Electrospun fiber mats are explored as drug delivery vehicles using tetracycline hydrochloride as a model drug. The mats were made either from poly(lactic acid) (PLA), poly(ethylene-co-vinyl acetate) (PEVA), or from a 50:50 blend of the two. The fibers were electrospun from chloroform solutions containing a small amount of methanol to solubilize the drug. The release of the tetracycline hydrochloride from these new drug delivery systems was followed by UV-VIS spectroscopy. Release profiles from the electrospun mats were compared to a commercially available drug delivery system, Actisite (Alza Corporation, Palo Alto, CA), as well as to cast films of the various formulations.

Current strategies for sustaining drug release from electrospun nanofibers.

PubMed

Chou, Shih-Feng; Carson, Daniel; Woodrow, Kim A

2015-12-28

Electrospun drug-eluting fibers are emerging as a novel dosage form for multipurpose prevention against sexually transmitted infections, including HIV, and unintended pregnancy. Previous work from our lab and others show the versatility of this platform to deliver large doses of physico-chemically diverse agents. However, there is still an unmet need to develop practical fiber formulations for water-soluble small molecule drugs needed at high dosing due to intrinsic low potency or desire for sustained prevention. To date, most sustained release fibers have been restricted to the delivery of biologics or hydrophobic small molecules at low drug loading of typically <1 wt.%, which is often impractical for most clinical applications. For hydrophilic small molecule drugs, their high aqueous solubility and poor partitioning and incompatibility with insoluble polymers make long-term release even more challenging. Here we investigate several existing strategies to sustain release of hydrophilic small molecule drugs that are highly-loaded in electrospun fibers. In particular, we investigate what is known about the design constraints required to realize multi-day release from fibers fabricated from uniaxial and coaxial electrospinning. Copyright © 2015 Elsevier B.V. All rights reserved.

Cellulose Acetate Modified Titanium Dioxide (TiO2) Nanoparticles Electrospun Composite Membranes: Fabrication and Characterization

NASA Astrophysics Data System (ADS)

Das, Chandan; Gebru, Kibrom Alebel

2017-12-01

Hybrid membranes from Cellulose Acetate (CA) and titanium oxide (TiO2) nanoparticles were fabricated using electrospinning technique. The electrospun hybrid membranes were characterized using field emission scanning electron microscopy, high energy electrons of the energy dispersive X-ray spectroscopy, X-ray diffraction patterns, atomic force microscopy, zeta potential (ζ), and thermo gravimetric analysis. The impact of TiO2 contents on the electrospun membranes matrix was studied in detail. All these characterization results indicated that TiO2 were uniformly distributed within the CA electrospun membrane's matrix. The addition of TiO2 caused formation of largely interconnected fiber networks which in turn have a positive effect on the enhancement of the membrane pore structures. As the amount of TiO2 addition was raised from 0 to 6.5 wt%, the entanglements of the fibers and the spider-net like network among fibers were increased.

A review of evolution of electrospun tissue engineering scaffold: From two dimensions to three dimensions.

PubMed

Ngadiman, Nor Hasrul Akhmal; Noordin, M Y; Idris, Ani; Kurniawan, Denni

2017-07-01

The potential of electrospinning process to fabricate ultrafine fibers as building blocks for tissue engineering scaffolds is well recognized. The scaffold construct produced by electrospinning process depends on the quality of the fibers. In electrospinning, material selection and parameter setting are among many factors that contribute to the quality of the ultrafine fibers, which eventually determine the performance of the tissue engineering scaffolds. The major challenge of conventional electrospun scaffolds is the nature of electrospinning process which can only produce two-dimensional electrospun mats, hence limiting their applications. Researchers have started to focus on overcoming this limitation by combining electrospinning with other techniques to fabricate three-dimensional scaffold constructs. This article reviews various polymeric materials and their composites/blends that have been successfully electrospun for tissue engineering scaffolds, their mechanical properties, and the various parameters settings that influence the fiber morphology. This review also highlights the secondary processes to electrospinning that have been used to develop three-dimensional tissue engineering scaffolds as well as the steps undertaken to overcome electrospinning limitations.

Development and characterization of coaxially electrospun gelatin coated poly (3-hydroxybutyric acid) thin films as potential scaffolds for skin regeneration.

PubMed

Nagiah, Naveen; Madhavi, Lakshmi; Anitha, R; Anandan, C; Srinivasan, Natarajan Tirupattur; Sivagnanam, Uma Tirichurapalli

2013-10-01

The morphology of fibers synthesized through electrospinning has been found to mimic extracellular matrix. Coaxially electrospun fibers of gelatin (sheath) coated poly (3-hydroxybutyric acid) (PHB) (core) was developed using 2,2,2 trifluoroethanol(TFE) and 1,1,1,3,3,3 hexafluoro-2-propanol(HFIP) as solvents respectively. The coaxial structure and coating of gelatin with PHB fibers was confirmed through transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Thermal stability of the coaxially electrospun fibers was analyzed using thermogravimetric analysis(TGA), differential scanning calorimetry(DSC) and differential thermogravimetric analysis(DTA). Complete evaporation of solvent and gelatin grafting over PHB fibers was confirmed through attenuated total reflection-Fourier transformed infrared spectroscopy (ATR-FTIR). The coaxially electrospun fibers exhibited competent tensile properties for skin regeneration with high surface area and porosity. In vitro degradation studies proved the stability of fibers and its potential applications in tissue engineering. The fibers supported the growth of human dermal fibroblasts and keratinocytes with normal morphology indicating its potential as a scaffold for skin regeneration. © 2013.

Stem cell responses to plasma surface modified electrospun polyurethane scaffolds.

PubMed

Zandén, Carl; Hellström Erkenstam, Nina; Padel, Thomas; Wittgenstein, Julia; Liu, Johan; Kuhn, H Georg

2014-07-01

The topographical effects from functional materials on stem cell behavior are currently of interest in tissue engineering and regenerative medicine. Here we investigate the influence of argon, oxygen, and hydrogen plasma surface modification of electrospun polyurethane fibers on human embryonic stem cell (hESC) and rat postnatal neural stem cell (NSC) responses. The plasma gases were found to induce three combinations of fiber surface functionalities and roughness textures. On randomly oriented fibers, plasma treatments lead to substantially increased hESC attachment and proliferation as compared to native fibers. Argon plasma was found to induce the most optimal combination of surface functionality and roughness for cell expansion. Contact guided migration of cells and alignment of cell processes were observed on aligned fibers. Neuronal differentiation around 5% was found for all samples and was not significantly affected by the induced variations of surface functional group distribution or individual fiber topography. In this study the influence of argon, oxygen, and hydrogen plasma surface modification of electrospun polyurethane fibers on human embryonic stem cell and rat postnatal neural stem cell (NSC) responses is studied with the goal of clarifying the potential effects of functional materials on stem cell behavior, a topic of substantial interest in tissue engineering and regenerative medicine. Copyright © 2014 Elsevier Inc. All rights reserved.

Electrospun PVA/HAp nanocomposite nanofibers: biomimetics of mineralized hard tissues at a lower level of complexity.

PubMed

Kim, Gyeong-Man; Asran, Ashraf Sh; Michler, Georg H; Simon, Paul; Kim, Jeong-Sook

2008-12-01

Based on the biomimetic approaches the present work describes a straightforward technique to mimic not only the architecture (the morphology) but also the chemistry (the composition) of the lowest level of the hierarchical organization of bone. This technique uses an electrospinning (ES) process with polyvinyl alcohol (PVA) and hydroxyapatite (HAp) nanoparticles. To determine morphology, crystalline structures and thermal properties of the resulting electrospun fibers with the pure PVA and PVA/HAp nanocomposite (NC) before electrospinning various techniques were employed, including transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In addition, FT-IR spectroscopy was carried out to analyze the complex structural changes upon undergoing electrospinning as well as interactions between HAp and PVA. The morphological and crystallographic investigations revealed that the rod-like HAp nanoparticles exhibit a nanoporous morphology and are embedded within the electrospun fibers. A large number of HAp nanorods are preferentially oriented parallel to the longitudinal direction of the electrospun PVA fibers, which closely resemble the naturally mineralized hard tissues of bones. Due to abundant OH groups present in PVA and HAp nanorods, they strongly interact via hydrogen bonding within the electrospun PVA/HAp NC fibers, which results in improved thermal properties. The unique physiochemical features of the electrospun PVA/HAp NC nanofibers prepared by the ES process will open up a wide variety of future applications related to hard tissue replacement and regeneration (bone and dentin), not limited to coating implants.

Electrospun Ceramic Nanofiber Mats Today: Synthesis, Properties, and Applications

PubMed Central

Esfahani, Hamid; Ramakrishna, Seeram

2017-01-01

Ceramic nanofibers (NFs) have recently been developed for advanced applications due to their unique properties. In this article, we review developments in electrospun ceramic NFs with regard to their fabrication process, properties, and applications. We find that surface activity of electrospun ceramic NFs is improved by post pyrolysis, hydrothermal, and carbothermal processes. Also, when combined with another surface modification methods, electrospun ceramic NFs result in the advancement of properties and widening of the application domains. With the decrease in diameter and length of a fiber, many properties of fibrous materials are modified; characteristics of such ceramic NFs are different from their wide and long (bulk) counterparts. In this article, electrospun ceramic NFs are reviewed with an emphasis on their applications as catalysts, membranes, sensors, biomaterials, fuel cells, batteries, supercapacitors, energy harvesting systems, electric and magnetic parts, conductive wires, and wearable electronic textiles. Furthermore, properties of ceramic nanofibers, which enable the above applications, and techniques to characterize them are briefly outlined. PMID:29077074

Electrospun Ceramic Nanofiber Mats Today: Synthesis, Properties, and Applications.

PubMed

Esfahani, Hamid; Jose, Rajan; Ramakrishna, Seeram

2017-10-27

Ceramic nanofibers (NFs) have recently been developed for advanced applications due to their unique properties. In this article, we review developments in electrospun ceramic NFs with regard to their fabrication process, properties, and applications. We find that surface activity of electrospun ceramic NFs is improved by post pyrolysis, hydrothermal, and carbothermal processes. Also, when combined with another surface modification methods, electrospun ceramic NFs result in the advancement of properties and widening of the application domains. With the decrease in diameter and length of a fiber, many properties of fibrous materials are modified; characteristics of such ceramic NFs are different from their wide and long (bulk) counterparts. In this article, electrospun ceramic NFs are reviewed with an emphasis on their applications as catalysts, membranes, sensors, biomaterials, fuel cells, batteries, supercapacitors, energy harvesting systems, electric and magnetic parts, conductive wires, and wearable electronic textiles. Furthermore, properties of ceramic nanofibers, which enable the above applications, and techniques to characterize them are briefly outlined.

Method for Coating a Tow with an Electrospun Nanofiber

NASA Technical Reports Server (NTRS)

Kohlman, Lee W. (Inventor); Roberts, Gary D. (Inventor)

2015-01-01

Method and apparatus for enhancing the durability as well as the strength and stiffness of prepreg fiber tows of the sort used in composite materials are disclosed. The method involves adhering electrospun fibers onto the surface of such composite materials as filament-wound composite objects and the surface of prepreg fiber tows of the sort that are subsequently used in the production of composite materials of the filament-wound, woven, and braided sorts. The apparatus performs the methods described herein.

Electrospun Poly(lactic acid-co-glycolic acid) Scaffolds for Skin Tissue Engineering

PubMed Central

Kumbar, Sangamesh G.; Nukavarapu, Syam Prasad; James, Roshan; Nair, Lakshmi S.; Laurencin, Cato T.

2008-01-01

Electrospun fiber matrices composed of scaffolds of varying fiber diameters were investigated for potential application of severe skin loss. Few systematic studies have been performed to examine the effect of varying fiber diameter electrospun fiber matrices for skin regeneration. The present study reports the fabrication of poly[lactic acid-co-glycolic acid] (PLAGA) matrices with fiber diameters of 150–225, 200–300, 250–467, 500–900, 600–1200, 2500–3000 and 3250–6000 nm via electrospinning. All fiber matrices found to have a tensile modulus from 39.23 ± 8.15 to 79.21 ± 13.71 MPa which falls in the range for normal human skin. Further, the porous fiber matrices have porosity between 38–60 % and average pore diameters between 10–14µm. We evaluated the efficacy of these biodegradable fiber matrices as skin substitutes by seeding them with human skin fibroblasts (hSF). Human skin fibroblasts acquired a well spread morphology and showed significant progressive growth on fiber matrices in the 350–1100 nm diameter range. Collagen type III gene expression was significantly up-regulated in hSF seeded on matrices with fiber diameters in the range of 350–1100 nm. Based on the need, the proposed fiber skin substitutes can be successfully fabricated and optimized for skin fibroblast attachment and growth. PMID:18639927

Nanospot soldering polystyrene nanoparticles with an optical fiber probe laser irradiating a metallic AFM probe based on the near-field enhancement effect.

PubMed

Cui, Jianlei; Yang, Lijun; Wang, Yang; Mei, Xuesong; Wang, Wenjun; Hou, Chaojian

2015-02-04

With the development of nanoscience and nanotechnology for the bottom-up nanofabrication of nanostructures formed from polystyrene nanoparticles, joining technology is an essential step in the manufacturing and assembly of nanodevices and nanostructures in order to provide mechanical integration and connection. To study the nanospot welding of polystyrene nanoparticles, we propose a new nanospot-soldering method using the near-field enhancement effect of a metallic atomic force microscope (AFM) probe tip that is irradiated by an optical fiber probe laser. On the basis of our theoretical analysis of the near-field enhancement effect, we set up an experimental system for nanospot soldering; this approach is carried out by using an optical fiber probe laser to irradiate the AFM probe tip to sinter the nanoparticles, providing a promising technical approach for the application of nanosoldering in nanoscience and nanotechnology.

Electrospun cross linked rosin fibers

NASA Astrophysics Data System (ADS)

Baek, Woo-il; Nirmala, R.; Barakat, Nasser A. M.; El-Newehy, Mohamed H.; Al-Deyab, Salem S.; Kim, Hak Yong

2011-12-01

In this study, we describe the first reported preparation of rosin in fiber form through use of an electrospinning technique utilizing various solvent systems. The polymer concentration of the formed fiber was studied by using various solvents such as chloroform, ethanol, N-N dimethylformamide (DMF), tetrahydrofuran (THF), acetone, and methylene chloride (MC). An electrospray of the solution resulted in the beaded form of the rosin. By varying the polymer concentration with MC, we were then able to obtain uniform fibers. However, the fibers exhibited large diameter. We believe that it is possible to reduce the diameter of the rosin fibers through appropriate selection of electrospinning parameters. In addition, the morphological transitions from beads, to beaded fiber, to fiber were studied at different polymer concentrations. We propose a possible physical cross linking mechanism for the formation of rosin fibers during the electrospinning process. Our results demonstrate the feasibility of producing fiber nanostructures of rosin by using an electrospinning technique.

Study on structure, mechanical property and cell cytocompatibility of electrospun collagen nanofibers crosslinked by common agents.

PubMed

Luo, Xueshi; Guo, Zhenzhao; He, Ping; Chen, Tian; Li, Lihua; Ding, Shan; Li, Hong

2018-07-01

Collagen electrospun scaffolds properly reproduce the framework of the extracellular matrix (ECM) of tissues that are natural with the fibrous morphology of the protein by coupling large biomimetism of the biological material. However, traditional solvents employed for collagen electrospinning lead to poor mechanical attributes and bad hydro-stability. In this work, by N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride with N-hydroxysulfosuccinimide (EDC-NHS), glutaraldehyde (GTA) and genipin (GP) respectively, electrospun collagen fibers cross-linked, effectively stabilized the fiber morphology over 2months and improved the mechanical properties in both dry and wet state, especially EDC-NHS with large ultimate tensile stress and ε b . The secondary structure of collagen structure still remained and had no obvious difference among various crosslinked samples according to FTIR. On the cell assessment, electrospun collagen fibers crosslinked by EDC-NHS, GTA and GP, were found to support cell adhesion, spreading and proliferation of MC3T3-E1. By contrast, GTA was more effective in preserving explicit fibrous morphology with a relatively lower cell viability both in FBS and BSA soaked mats. Interestingly, GP also had the similar cytocompatibility of MC3T3-E1 as EDC-NHS did. The study proved the feasibility of chemical crosslinker to electrospun collagen for biomedical application. Copyright © 2018. Published by Elsevier B.V.

Surface Entrapment of Fibronectin on Electrospun PLGA Scaffolds for Periodontal Tissue Engineering

PubMed Central

Gritsch, Kerstin; Salles, Vincent; Attik, Ghania N.; Grosgogeat, Brigitte

2014-01-01

Abstract Nowadays, the challenge in the tissue engineering field consists in the development of biomaterials designed to regenerate ad integrum damaged tissues. Despite the current use of bioresorbable polyesters such as poly(l-lactide) (PLA), poly(d,l-lactide-co-glycolide) (PLGA), and poly-ɛ-caprolactone in soft tissue regeneration researches, their hydrophobic properties negatively influence the cell adhesion. Here, to overcome it, we have developed a fibronectin (FN)-functionalized electrospun PLGA scaffold for periodontal ligament regeneration. Functionalization of electrospun PLGA scaffolds was performed by alkaline hydrolysis (0.1 or 0.01 M NaOH). Then, hydrolyzed scaffolds were coated by simple deposition of an FN layer (10 μg/mL). FN coating was evidenced by X-ray photoelectron analysis. A decrease of contact angle and greater cell adhesion to hydrolyzed, FN-coated PLGA scaffolds were noticed. Suitable degradation behavior without pH variations was observed for all samples up to 28 days. All treated materials presented strong shrinkage, fiber orientation loss, and collapsed fibers. However, functionalization process using 0.01 M NaOH concentration resulted in unchanged scaffold porosity, preserved chemical composition, and similar mechanical properties compared with untreated scaffolds. The proposed simplified method to functionalize electrospun PLGA fibers is an efficient route to make polyester scaffolds more biocompatible and shows potential for tissue engineering. PMID:24940563

Antibacterial and Barrier Properties of Gelatin Coated by Electrospun Polycaprolactone Ultrathin Fibers Containing Black Pepper Oleoresin of Interest in Active Food Biopackaging Applications

PubMed Central

Castro-Mayorga, Jinneth Lorena

2018-01-01

The present study evaluated the effect of using electrospun polycaprolactone (PCL) as a barrier coating and black pepper oleoresin (OR) as a natural extract on the morphology, thermal, mechanical, antimicrobial, oxygen, and water vapor barrier properties of solvent cast gelatin (GEL). The antimicrobial activity of the developed multilayer system obtained by the so-called electrospinning coating technique was also evaluated against Staphylococcus aureus strains for 10 days. The results showed that the multilayer system containing PCL and OR increased the thermal resistance, elongated the GEL film, and significantly diminished its permeance to water vapor. Active multilayer systems stored in hermetically closed bottles increased their antimicrobial activity after 10 days by inhibiting the growth of Staphylococcus aureus. This study demonstrates that addition of electrospun PCL ultrathin fibers and OR improved the properties of GEL films, which promoted its potential use in active food packaging applications. PMID:29597268

Strong size-dependent stress relaxation in electrospun polymer nanofibers

NASA Astrophysics Data System (ADS)

Wingert, Matthew C.; Jiang, Zhang; Chen, Renkun; Cai, Shengqiang

2017-01-01

Electrospun polymer nanofibers have garnered significant interest due to their strong size-dependent material properties, such as tensile moduli, strength, toughness, and glass transition temperatures. These properties are closely correlated with polymer chain dynamics. In most applications, polymers usually exhibit viscoelastic behaviors such as stress relaxation and creep, which are also determined by the motion of polymer chains. However, the size-dependent viscoelasticity has not been studied previously in polymer nanofibers. Here, we report the first experimental evidence of significant size-dependent stress relaxation in electrospun Nylon-11 nanofibers as well as size-dependent viscosity of the confined amorphous regions. In conjunction with the dramatically increasing stiffness of nano-scaled fibers, this strong relaxation enables size-tunable properties which break the traditional damping-stiffness tradeoff, qualifying electrospun nanofibers as a promising set of size-tunable materials with an unusual and highly desirable combination of simultaneously high stiffness and large mechanical energy dissipation.

Strong size-dependent stress relaxation in electrospun polymer nanofibers

DOE PAGES

Wingert, Matthew C.; Jiang, Zhang; Chen, Renkun; ...

2017-01-04

Here, electrospun polymer nanofibers have garnered significant interest due to their strong size-dependent material properties, such as tensile moduli, strength, toughness, and glass transition temperatures. These properties are closely correlated with polymer chain dynamics. In most applications, polymers usually exhibit viscoelastic behaviors such as stress relaxation and creep, which are also determined by the motion of polymer chains. However, the size-dependent viscoelasticity has not been studied previously in polymer nanofibers. Here, we report the first experimental evidence of significant size-dependent stress relaxation in electrospun Nylon-11 nanofibers as well as size-dependent viscosity of the confined amorphous regions. In conjunction with themore » dramatically increasing stiffness of nano-scaled fibers, this strong relaxation enables size-tunable properties which break the traditional damping-stiffness tradeoff, qualifying electrospun nanofibers as a promising set of size-tunable materials with an unusual and highly desirable combination of simultaneously high stiffness and large mechanical energy dissipation.« less

Development of a novel polystyrene/metal-organic framework-199 electrospun nanofiber adsorbent for thin film microextraction of aldehydes in human urine.

PubMed

Liu, Feilong; Xu, Hui

2017-01-01

In this work, electrospun polystyrene/metal-organic frameworks-199 (PS/MOF-199) nanofiber film was synthesized and investigated as a novel adsorbent for thin film microextraction (TFME) of aldehydes in human urine. Some properties of the prepared PS/MOF-199 nanofiber film, including morphology, structure, wettability, solvent stability and extraction performance were studied systematically. Porous fibrous structure, large surface area, good stability, strong hydrophobicity and excellent extraction efficiency were obtained for the film. Based on the PS/MOF-199 film, a thin film microextraction-high performance liquid chromatography (TFME-HPLC) method was developed, and the experimental parameters that affected the extraction and desorption were optimized. Under the optimal conditions, the limits of detection (LODs) were in the range of 4.2-17.3nmolL -1 for the analysis of six aldehydes. Good linearity was achieved with correlation coefficients (R 2 ) being lager than 0.9943. Satisfactory recovery (82-112%) and acceptable reproducibility (relative standard deviation: 2.1-13.3%) were also obtained for the method. The developed TFME-HPLC method has been successfully applied to the analysis of aldehyde metabolites in the urine samples of lung cancer patients and healthy people. The method possesses the advantages of simplicity, rapidity, cost-effective, sensitivity and non-invasion, it provides an alternative tool for the determination of aldehydes in complex sample matrices. Copyright © 2016 Elsevier B.V. All rights reserved.

Bioactivity of cellulose acetate/hydroxyapatite nanoparticle composite fiber by an electro-spinning process.

PubMed

Kwak, Dae Hyun; Lee, Eun Ju; Kim, Deug Joong

2014-11-01

Hydroxyapatite/cellulose acetate composite webs were fabricated by an electro-spinning process. This electro-spinning process makes it possible to fabricate complex three-dimensional shapes. Nano fibrous web consisting of cellulose acetate and hydroxyapatite was produced from their mixture solution by using an electro-spinning process under high voltage. The surface of the electro-spun fiber was modified by a plasma and alkaline solution in order to increase its bioactivity. The structure, morphology and properties of the electro-spun fibers were investigated and an in-vitro bioactivity test was evaluated in simulated body fluid (SBF). Bioactivity of the electro-spun web was enhanced with the filler concentration and surface treatment. The surface changes of electro-spun fibers modified by plasma and alkaline solution were investigated by FT-IR (Fourier Transform Infrared Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy).

Vascularization and Cellular Isolation Potential of a Novel Electrospun Cell Delivery Vehicle

PubMed Central

Krishnan, Laxminarayanan; Touroo, Jeremy; Reed, Robert; Boland, Eugene; Hoying, James B.; Williams, Stuart K.

2014-01-01

A clinical need exists for a cell delivery device that supports long term cell viability, cell retention within the device and retrieval of delivered cells if necessary. Previously, cell isolation devices have been based on hollow fiber membranes, porous polymer scaffolds, alginate systems, or micro-machined membranes. We present the development and characterization of a novel dual porosity electrospun membrane based device, which supports cellular infiltration and vascularization of its outer porous layer and maintains cellular isolation within a lumen bounded by an inner low porosity layer. Electrospinning conditions were initially established to support electrospun fiber deposition onto nonconductive silicone surfaces. With these parameters established, devices for in vivo evaluations were produced using nylon as a nonconductive scaffold for deposition of dual porosity electrospun fibers. The outer porous layer supported the development of a penetrating microcirculation and the membrane supported the transfer of insulin from encapsulated sustained release pellets for four weeks. Viable cells implanted within the device could be identified after two weeks of implantation. Through the successful demonstration of survival and cellular isolation of human epithelial cells within the implanted devices and the ability to use the device to deliver insulin, we have established the utility of this device toward localized cell transplantation. The Cell Delivery Device establishes a platform to test the feasibility of approaches to cell dose control and cell localization at the site of implantation in the clinical use of modified autologous or allogeneic cells. PMID:23913805

Cell infiltration and growth in a low density, uncompressed three-dimensional electrospun nanofibrous scaffold.

PubMed

Blakeney, Bryan A; Tambralli, Ajay; Anderson, Joel M; Andukuri, Adinarayana; Lim, Dong-Jin; Dean, Derrick R; Jun, Ho-Wook

2011-02-01

A limiting factor of traditional electrospinning is that the electrospun scaffolds consist entirely of tightly packed nanofiber layers that only provide a superficial porous structure due to the sheet-like assembly process. This unavoidable characteristic hinders cell infiltration and growth throughout the nanofibrous scaffolds. Numerous strategies have been tried to overcome this challenge, including the incorporation of nanoparticles, using larger microfibers, or removing embedded salt or water-soluble fibers to increase porosity. However, these methods still produce sheet-like nanofibrous scaffolds, failing to create a porous three-dimensional scaffold with good structural integrity. Thus, we have developed a three-dimensional cotton ball-like electrospun scaffold that consists of an accumulation of nanofibers in a low density and uncompressed manner. Instead of a traditional flat-plate collector, a grounded spherical dish and an array of needle-like probes were used to create a Focused, Low density, Uncompressed nanoFiber (FLUF) mesh scaffold. Scanning electron microscopy showed that the cotton ball-like scaffold consisted of electrospun nanofibers with a similar diameter but larger pores and less-dense structure compared to the traditional electrospun scaffolds. In addition, laser confocal microscopy demonstrated an open porosity and loosely packed structure throughout the depth of the cotton ball-like scaffold, contrasting the superficially porous and tightly packed structure of the traditional electrospun scaffold. Cells seeded on the cotton ball-like scaffold infiltrated into the scaffold after 7 days of growth, compared to no penetrating growth for the traditional electrospun scaffold. Quantitative analysis showed approximately a 40% higher growth rate for cells on the cotton ball-like scaffold over a 7 day period, possibly due to the increased space for in-growth within the three-dimensional scaffolds. Overall, this method assembles a nanofibrous scaffold

Increasing the pore sizes of bone-mimetic electrospun scaffolds comprised of polycaprolactone, collagen I and hydroxyapatite to enhance cell infiltration

PubMed Central

Phipps, Matthew C.; Clem, William C.; Grunda, Jessica M.; Clines, Gregory A.; Bellis, Susan L.

2012-01-01

Bone-mimetic electrospun scaffolds consisting of polycaprolactone (PCL), collagen I and nanoparticulate hydroxyapatite (HA) have previously been shown to support the adhesion, integrin-related signaling and proliferation of mesenchymal stem cells (MSCs), suggesting these matrices serve as promising degradable substrates for osteoregeneration. However, the small pore sizes in electrospun scaffolds hinder cell infiltration in vitro and tissue-ingrowth into the scaffold in vivo, limiting their clinical potential. In this study, three separate techniques were evaluated for their capability to increase the pore size of the PCL/col I/nanoHA scaffolds: limited protease digestion, decreasing the fiber packing density during electro-spinning, and inclusion of sacrificial fibers of the water-soluble polymer PEO. The PEO sacrificial fiber approach was found to be the most effective in increasing scaffold pore size. Furthermore, the use of sacrificial fibers promoted increased MSC infiltration into the scaffolds, as well as greater infiltration of endogenous cells within bone upon placement of scaffolds within calvarial organ cultures. These collective findings support the use of sacrificial PEO fibers as a means to increase the porosity of complex, bone-mimicking electrospun scaffolds, thereby enhancing tissue regenerative processes that depend upon cell infiltration, such as vascularization and replacement of the scaffold with native bone tissue. PMID:22014462

Mechanical and transport properties of layer-by-layer electrospun composite proton exchange membranes for fuel cell applications.

PubMed

Mannarino, Matthew M; Liu, David S; Hammond, Paula T; Rutledge, Gregory C

2013-08-28

Composite membranes composed of highly conductive and selective layer-by-layer (LbL) films and electrospun fiber mats were fabricated and characterized for mechanical strength and electrochemical selectivity. The LbL component consists of a proton-conducting, methanol-blocking poly(diallyl dimethyl ammonium chloride)/sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (PDAC/sPPO) thin film. The electrospun fiber component consists of poly(trimethyl hexamethylene terephthalamide) (PA 6(3)T) fibers in a nonwoven mat of 60-90% porosity. The bare mats were annealed to improve their mechanical properties, which improvements are shown to be retained in the composite membranes. Spray LbL assembly was used as a means for the rapid formation of proton-conducting films that fill the void space throughout the porous electrospun matrix and create a fuel-blocking layer. Coated mats as thin as 15 μm were fabricated, and viable composite membranes with methanol permeabilities 20 times lower than Nafion and through-plane proton selectivity five and a half times greater than Nafion are demonstrated. The mechanical properties of the spray coated electrospun mats are shown to be superior to the LbL-only system and possess intrinsically greater dimensional stability and lower mechanical hysteresis than Nafion under hydrated conditions. The composite proton exchange membranes fabricated here were tested in an operational direct methanol fuel cell. The results show the potential for higher open circuit voltages (OCV) and comparable cell resistances when compared to fuel cells based on Nafion.

Fabricating and Characterizing Physical Properties of Electrospun Polypeptide-based Nanofibers

NASA Astrophysics Data System (ADS)

Khadka, Dhan Bahadur

pH values. Variations in fiber morphology, elemental composition and stability have been studied by microscopy and energy-dispersive X-ray spectroscopy (EDX), following the treatment of samples at different pH values in the 2-12 range. Fiber stability has been interpreted with reference to the pH dependence of the UV absorbance and fluorescence of PLEY chains in solution. The data show that fiber stability is crucially dependent on the extent of side chain ionization, even after crosslinking. Self-organization kinetics of electrospun PLO and PLEY fibers during solvent annealing has been studied. After being crosslinked in situ , fibers were annealed in water at 22 °C. Analysis by Fourier transform infrared spectroscopy (FTIR) has revealed that annealing involved fiber restructuring with an overall time constant of 29 min for PLO and 63 min for PLEY, and that changes in the distribution of polymer conformations occurred during the first 13 min of annealing. There was a substantial decrease in the amount of Na+ bound to PLEY fibers during annealing. Kinetic modeling has indicated that two parallel pathways better account for the annealing trajectory than a single pathway with multiple transition states. Taken together, the results will advance the rational design of polypeptides for peptide-based materials, especially materials prepared by electrospinning. It is believed that this research will increase basic knowledge of polymer electrospinning and advance the development of electrospun materials, especially in medicine and biotechnology. The study has yielded two advances on previous work in the area: avoidance of an animal source of peptides and avoidance of inorganic solvent. The present results thus advance the growing field of peptide-based materials. Non-woven electrospun fiber mats made of polypeptides are increasingly considered attractive for basic research and technology development in biotechnology, medicine and other areas. (Abstract shortened by UMI.)

Composite vascular scaffold combining electrospun fibers and physically-crosslinked hydrogel with copper wire-induced grooves structure.

PubMed

Liu, Yuanyuan; Jiang, Chen; Li, Shuai; Hu, Qingxi

2016-08-01

While the field of tissue engineered vascular grafts has greatly advanced, many inadequacies still exist. Successfully developed scaffolds require mechanical and structural properties that match native vessels and optimal microenvironments that foster cell integration, adhesion and growth. We have developed a small diameter, three-layered composite vascular scaffold which consists of electrospun fibers and physically-crosslinked hydrogel with copper wire-induced grooves by combining the electrospinning and dip-coating methods. Scaffold morphology and mechanics were assessed, quantified and compared to native vessels. Scaffolds were seeded with Human Umbilical Vein Endothelial Cells (HUVECs), cultured in vitro for 3 days and were evaluated for cell viability and morphology. The results showed that composite scaffolds had adjustable mechanical strength and favorable biocompatibility, which is important in the future clinical application of Tissue-engineered vascular grafts (TEVGs). Copyright © 2016 Elsevier Ltd. All rights reserved.

Poly(ɛ-caprolactone)/gelatin composite electrospun scaffolds with porous crater-like structures for tissue engineering.

PubMed

Hwang, Patrick T J; Murdock, Kyle; Alexander, Grant C; Salaam, Amanee D; Ng, Joshua I; Lim, Dong-Jin; Dean, Derrick; Jun, Ho-Wook

2016-04-01

Electrospinning has been widely used to fabricate scaffolds imitating the structure of natural extracellular matrix (ECM). However, conventional electrospinning produces tightly compacted nanofiber layers with only small superficial pores and a lack of bioactivity, which limit the usefulness of electrospinning in biomedical applications. Thus, a porous poly(ε-caprolactone) (PCL)/gelatin composite electrospun scaffold with crater-like structures was developed. Porous crater-like structures were created on the scaffold by a gas foaming/salt leaching process; this unique fiber structure had more large pore areas and higher porosity than the conventional electrospun fiber network. Various ratios of PCL/gelatin (concentration ratios: 100/0, 75/25, and 50/50) composite electrospun scaffolds with and without crater-like structures were characterized by their microstructures, surface chemistry, degradation, mechanical properties, and ability to facilitate cell growth and infiltration. The combination of PCL and gelatin endowed the scaffold with both structural stability of PCL and bioactivity of gelatin. All ratios of scaffolds with crater-like structures showed fairly similar surface chemistry, degradation rates, and mechanical properties to equivalent scaffolds without crater-like structures; however, craterized scaffolds displayed higher human mesenchymal stem cell (hMSC) proliferation and infiltration throughout the scaffolds after 7-day culture. Therefore, these results demonstrated that PCL/gelatin composite electrospun scaffolds with crater-like structures can provide a structurally and biochemically improved three-dimensional ECM-mimicking microenvironment. © 2016 Wiley Periodicals, Inc.

Poly(ε-caprolactone)/gelatin composite electrospun scaffolds with porous crater-like structures for tissue engineering

PubMed Central

Hwang, Patrick T.J.; Murdock, Kyle; Alexander, Grant C.; Salaam, Amanee D.; Ng, Joshua I.; Lim, Dong-Jin; Dean, Derrick; Jun, Ho-Wook

2016-01-01

Electrospinning has been widely used to fabricate scaffolds imitating the structure of natural extracellular matrix (ECM). However, conventional electrospinning produces tightly compacted nanofiber layers with only small superficial pores and a lack of bioactivity, which limit the usefulness of electrospinning in biomedical applications. Thus, a porous poly(ε-caprolactone) (PCL)/gelatin composite electrospun scaffold with crater-like structures was developed. Porous crater-like structures were created on the scaffold by a gas foaming/salt leaching process; this unique fiber structure had more large pore areas and higher porosity than the conventional electrospun fiber network. Various ratios of PCL/gelatin (concentration ratios: 100/0, 75/25, and 50/50) composite electrospun scaffolds with and without crater-like structures were characterized by their microstructures, surface chemistry, degradation, mechanical properties, and ability to facilitate cell growth and infiltration. The combination of PCL and gelatin endowed the scaffold with both structural stability of PCL and bioactivity of gelatin. All ratios of scaffolds with crater-like structures showed fairly similar surface chemistry, degradation rates, and mechanical properties to equivalent scaffolds without crater-like structures; however, craterized scaffolds displayed higher human mesenchymal stem cell (hMSC) proliferation and infiltration throughout the scaffolds after 7-day culture. Therefore, these results demonstrated that PCL/gelatin composite electrospun scaffolds with crater-like structures can provide a structurally and biochemically improved three-dimensional ECM-mimicking microenvironment. PMID:26567028

Modulation of gene expression using electrospun scaffolds with templated architecture.

PubMed

Karchin, A; Wang, Y-N; Sanders, J E

2012-06-01

The fabrication of biomimetic scaffolds is a critical component to fulfill the promise of functional tissue-engineered materials. We describe herein a simple technique, based on printed circuit board manufacturing, to produce novel templates for electrospinning scaffolds for tissue-engineering applications. This technique facilitates fabrication of electrospun scaffolds with templated architecture, which we defined as a scaffold's bulk mechanical properties being driven by its fiber architecture. Electrospun scaffolds with templated architectures were characterized with regard to fiber alignment and mechanical properties. Fast Fourier transform analysis revealed a high degree of fiber alignment along the conducting traces of the templates. Mechanical testing showed that scaffolds demonstrated tunable mechanical properties as a function of templated architecture. Fibroblast-seeded scaffolds were subjected to a peak strain of 3 or 10% at 0.5 Hz for 1 h. Exposing seeded scaffolds to the low strain magnitude (3%) significantly increased collagen I gene expression compared to the high strain magnitude (10%) in a scaffold architecture-dependent manner. These experiments indicate that scaffolds with templated architectures can be produced, and modulation of gene expression is possible with templated architectures. This technology holds promise for the long-term goal of creating tissue-engineered replacements with the biomechanical and biochemical make-up of native tissues. Copyright © 2012 Wiley Periodicals, Inc.

Shape Memory Composites Based on Electrospun Poly(vinyl alcohol) Fibers and a Thermoplastic Polyether Block Amide Elastomer.

PubMed

Shirole, Anuja; Sapkota, Janak; Foster, E Johan; Weder, Christoph

2016-03-01

The present study aimed at developing new thermally responsive shape-memory composites, that were fabricated by compacting mats of electrospun poly(vinyl alcohol) (PVA) fibers and sheets of a thermoplastic polyether block amide elastomer (PEBA). This design was based on the expectation that the combination of the rubber elasticity of the PEBA matrix and the mechanical switching exploitable through the reversible glass transition temperature (Tg) of the PVA filler could be combined to create materials that display shape memory characteristics as an emergent effect. Dynamic mechanical analyses (DMA) show that, upon introduction of 10-20% w/w PVA fibers, the room-temperature storage modulus (E') increased by a factor of 4-5 in comparison to the neat PEBA, and they reveal a stepwise reduction of E' around the Tg of PVA (85 °C). This transition could indeed be utilized to fix a temporary shape and recover the permanent shape. At low strain, the fixity was 66 ± 14% and the recovery was 98 ± 2%. Overall, the data validate a simple and practical strategy for the fabrication of shape memory composites that involves a melt compaction process and employs two commercially available polymers.

Nanostructured biomaterials from electrospun demineralized bone matrix: a survey of processing and crosslinking strategies.

PubMed

Leszczak, Victoria; Place, Laura W; Franz, Natalee; Popat, Ketul C; Kipper, Matt J

2014-06-25

In the design of scaffolds for tissue engineering biochemical function and nanoscale features are of particular interest. Natural polymers provide a wealth of biochemical function, but do not have the processability of synthetic polymers, limiting their ability to mimic the hierarchy of structures in the natural extracellular matrix. Thus, they are often combined with synthetic carrier polymers to enable processing. Demineralized bone matrix (DBM), a natural polymer, is allograft bone with inorganic material removed. DBM contains the protein components of bone, which includes adhesion ligands and osteoinductive signals, such as important growth factors. Herein we describe a novel method for tuning the nanostructure of DBM through electrospinning without the use of a carrier polymer. This work surveys solvents and solvent blends for electrospinning DBM. Blends of hexafluoroisopropanol and trifluoroacetic acid are studied in detail. The effects of DBM concentration and dissolution time on solution viscosity are also reported and correlated to observed differences in electrospun fiber morphology. We also present a survey of techniques to stabilize the resultant fibers with respect to aqueous environments. Glutaraldehyde vapor treatment is successful at maintaining both macroscopic and microscopic structure of the electrospun DBM fibers. Finally, we report results from tensile testing of stabilized DBM nanofiber mats, and preliminary evaluation of their cytocompatibility. The DBM nanofiber mats exhibit good cytocompatibility toward human dermal fibroblasts (HDF) in a 4-day culture; neither the electrospun solvents nor the cross-linking results in any measurable residual cytotoxicity toward HDF.

The properties of the wood-polystyrene interphase determined by inverse gas chromatography

Treesearch

John Simonsen; Zhenqiu Hong; Timothy G. Rials

1997-01-01

The properties of the interphase in wood-polymer composites are important determinants of the properties of the final composite. This study used inverse gas chromatography (IGC) to measure interphasal properties of composites of polystyrene and two types of wood fiber fillers and an inoranic substrate (CW) with varying amounts of surface coverage of polystyrene. Glass...

Influence of electrospun scaffolds prepared from distinct polymers on proliferation and viability of endothelial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matveeva, V. G., E-mail: matveeva-vg@mail.ru; Antonova, L. V., E-mail: antonova.la@mail.ru; Velikanova, E. A.

We compared electrospun nonwoven scaffolds from polylactic acid (PLA), polycaprolactone (PCL), and polyhydroxybutyrate/valerate (PHBV)/polycaprolactone (PHBV/PCL). The surface of PHBV/PCL and PCL scaffolds was highly porous and consisted of randomly distributed fibers, whilst the surface of PLA scaffolds consisted of thin straight fibers, which located more sparsely, forming large pores. Culture of EA.hy 926 endothelial cells on these scaffolds during 7 days and further fluorescent microscopy demonstrated that the surface of PHBV/PCL scaffolds was most favorable for efficient adhesion, proliferation, and viability of endothelial cells. The lowest proliferation rate and cell viability were detected on PLA scaffolds. Therefore, PHBV/PCL electrospun nonwovenmore » scaffolds demonstrated the best results regarding endothelial cell proliferation and viability as compared to PCL and PLA scaffolds.« less

Elastin-PLGA hybrid electrospun nanofiber scaffolds for salivary epithelial cell self-organization and polarization.

PubMed

Foraida, Zahraa I; Kamaldinov, Tim; Nelson, Deirdre A; Larsen, Melinda; Castracane, James

2017-10-15

Development of electrospun nanofibers that mimic the structural, mechanical and biochemical properties of natural extracellular matrices (ECMs) is a promising approach for tissue regeneration. Electrospun fibers of synthetic polymers partially mimic the topography of the ECM, however, their high stiffness, poor hydrophilicity and lack of in vivo-like biochemical cues is not optimal for epithelial cell self-organization and function. In search of a biomimetic scaffold for salivary gland tissue regeneration, we investigated the potential of elastin, an ECM protein, to generate elastin hybrid nanofibers that have favorable physical and biochemical properties for regeneration of the salivary glands. Elastin was introduced to our previously developed poly-lactic-co-glycolic acid (PLGA) nanofiber scaffolds by two methods, blend electrospinning (EP-blend) and covalent conjugation (EP-covalent). Both methods for elastin incorporation into the nanofibers improved the wettability of the scaffolds while only blend electrospinning of elastin-PLGA nanofibers and not surface conjugation of elastin to PLGA fibers, conferred increased elasticity to the nanofibers measured by Young's modulus. After two days, only the blend electrospun nanofiber scaffolds facilitated epithelial cell self-organization into cell clusters, assessed with nuclear area and nearest neighbor distance measurements, leading to the apicobasal polarization of salivary gland epithelial cells after six days, which is vital for cell function. This study suggests that elastin electrospun nanofiber scaffolds have potential application in regenerative therapies for salivary glands and other epithelial organs. Regenerating the salivary glands by mimicking the extracellular matrix (ECM) is a promising approach for long term treatment of salivary gland damage. Despite their topographic similarity to the ECM, electrospun fibers of synthetic polymers lack the biochemical complexity, elasticity and hydrophilicity of the

p - n junction diodes fabricated from isolated electrospun fibers of (P(NDI2ODT2)) and an inorganic p-doped semiconductor

NASA Astrophysics Data System (ADS)

Rosado, Alexander; Pinto, Nicholas

2013-03-01

A simple method to fabricate, under ambient conditions and within seconds, p - n diodes using an individual electrospun poly{[N, N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)}-(P(NDI2ODT2)) fiber and a commercially available p-doped Si/SiO2 substrate is presented. Band bending at the fiber/Si+ interface leads to asymmetric I-V characteristic curves resembling that of a diode. The diode turn-on voltage was in the range 1V and was unaffected via UV light irradiation. The rectification ratio however could be tuned reversibly thereby making this device multifunctional. In addition to being a rectifier, the advantage of our design is the complete exposure of the rectifying junction to the surrounding environment. This has the advantage of making them attractive candidates in the potential fabrication of low power, sensitive and rapid response photo-sensors. NSF

Electrospun Fibers for Composites Applications

DTIC Science & Technology

2014-02-01

so designated by other authorized documents. Citation of manufacturer’s or trade names does not constitute an official endorsement or approval of...and tensile testing . While the nanofibers did not dramatically stiffen the resulting composites, they provided insight as to the impact of the...of suitable fiber mats for this study limited the scope and accessibility of test specimens, the results from the examination of fiber-matrix

Electrospun nanofibers: Formation, characterization, and evaluation for nerve tissue engineering applications

NASA Astrophysics Data System (ADS)

Zander, Nicole E.

The effects of fiber alignment and surface chemistry, including the covalent attachment and physical adsorption of the extracellular matrix (ECM) proteins laminin and collagen, on the neurite outgrowth of neuron-like PC12 cells were examined. Neuron-like PC12 cells responded to fiber orientation, and were successfully contact-guided by aligned electrospun nanofibers. In addition, fibers with attached protein, either physically adsorbed or covalently attached, improved neurite outgrowth lengths. Furthermore, aligning the fibers and attaching the ECM protein laminin, in particular, significantly improved neurite outgrowth over randomly oriented fibers with laminin. Since this research suggested that protein concentration on the fibers was the dominant driving force for improved neurite outgrowth, the effect of protein concentration, incorporated onto the surface of the nanofibers, on neurite outgrowth was examined. Two ways to control protein concentration on the fibers were explored—the variation of the fiber-protein reaction time and the variation of the protein soaking solution concentration. In addition, analytical methods to quantify the concentration of protein, as well as the protein coverage, on the surface of the fibers were developed. Although most of the fiber mats had multilayer protein coverage, and hence physically adsorbed proteins which could potentially mean a loss in bioactivity, the neuron-like PC12 cell neurites responded in a dose-dependent manner with increased neurite lengths on scaffolds with higher protein concentrations. The work was extended further by forming protein gradients on the fiber mats in hopes of locally directing neurite outgrowth and orientation. Fiber mats with both linear gradients (continuous change in protein concentration) and step gradients (six regions of uniform protein coverage, with protein concentration increasing from region to region) were fabricated and analyzed. The step gradients formed in the aligned fiber

Interactions between Chloramphenicol, Carrier Polymers, and Bacteria-Implications for Designing Electrospun Drug Delivery Systems Countering Wound Infection.

PubMed

Preem, Liis; Mahmoudzadeh, Mohammad; Putrinš, Marta; Meos, Andres; Laidmäe, Ivo; Romann, Tavo; Aruväli, Jaan; Härmas, Riinu; Koivuniemi, Artturi; Bunker, Alex; Tenson, Tanel; Kogermann, Karin

2017-12-04

Antibacterial drug-loaded electrospun nano- and microfibrous dressings are of major interest as novel topical drug delivery systems in wound care. In this study, chloramphenicol (CAM)-loaded polycaprolactone (PCL) and PCL/poly(ethylene oxide) (PEO) fiber mats were electrospun and characterized in terms of morphology, drug distribution, physicochemical properties, drug release, swelling, cytotoxicity, and antibacterial activity. Computational modeling together with physicochemical analysis helped to elucidate possible interactions between the drug and carrier polymers. Strong interactions between PCL and CAM together with hydrophobicity of the system resulted in much slower drug release compared to the hydrophilic ternary system of PCL/PEO/CAM. Cytotoxicity studies confirmed safety of the fiber mats to murine NIH 3T3 cells. Disc diffusion assay demonstrated that both fast and slow release fiber mats reached effective concentrations and had similar antibacterial activity. A biofilm formation assay revealed that both blank matrices are good substrates for the bacterial attachment and formation of biofilm. Importantly, prolonged release of CAM from drug-loaded fibers helps to avoid biofilm formation onto the dressing and hence avoids the treatment failure.

Enzyme Prodrug Therapy Engineered into Electrospun Fibers with Embedded Liposomes for Controlled, Localized Synthesis of Therapeutics.

PubMed

Chandrawati, Rona; Olesen, Morten T J; Marini, Thatiane C C; Bisra, Gurpal; Guex, Anne Géraldine; de Oliveira, Marcelo G; Zelikin, Alexander N; Stevens, Molly M

2017-09-01

Enzyme prodrug therapy (EPT) enables localized conversion of inert prodrugs to active drugs by enzymes. Performance of EPT necessitates that the enzyme remains active throughout the time frame of the envisioned therapeutic application. β-glucuronidase is an enzyme with historically validated performance in EPT, however it retains its activity in biomaterials for an insufficiently long period of time, typically not exceeding 7 d. Herein, the encapsulation of β-glucuronidase in liposomal subcompartments within poly(vinyl alcohol) electrospun fibers is reported, leading to the assembly of biocatalytically active materials with activity of the enzyme sustained over at least seven weeks. It is further shown that liposomes provide the highly beneficial stabilization of the enzyme when incubated in cell culture media. The assembled biocatalytic materials successfully produce antiproliferative drugs (SN-38) using externally administered prodrugs (SN-38-glucuronide) and effectively suppress cell proliferation, with envisioned utility in the design of cardiovascular grafts. © 2017 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermoresponsive electrospun fibers for water harvesting applications

NASA Astrophysics Data System (ADS)

Thakur, Neha; Baji, Avinash; Ranganath, Anupama Sargur

2018-03-01

Temperature triggered switchable cellulose acetate-poly(N-isopropylacrylamide) (CA-PNIPAM) core-shell and blend nanofibers are fabricated for controlled moisture harvesting applications. Core-shell fibers are fabricated using a co-axial electrospinning setup whereas the conventional electrospinning setup is employed for fabricating the blend fibers. Investigation of their wettability behaviour demonstrated that the blend fibers are superhydrophilic whereas the core-shell fibers are hydrophilic at ambient temperature. Furthermore, both the samples have an ability to switch between the two states viz. hydrophilic to hydrophobic state based on thermal stimulus. The core-shell fibers are shown to have higher moisture sorption ability compared to the blend fibers. This study investigates the mechanism behind the switchable wettability behaviour of the core-shell fibers and demonstrates the crucial role played by the functional groups present on the surface layer of fibers in governing their moisture collection efficiency.

Transition Metal Ions Enable the Transition from Electrospun Prolamin Protein Fibers to Nitrogen-Doped Freestanding Carbon Films for Flexible Supercapacitors.

PubMed

Wang, Yixiang; Yang, Jingqi; Du, Rongbing; Chen, Lingyun

2017-07-19

Flexible carbon ultrafine fibers are highly desirable in energy storage and conversion devices. Our previous finding showed that electrospun hordein/zein fibers stabilized by Ca 2+ were successfully transferred into nitrogen-doped carbon ultrafine fibers for supercapacitors. However, their relatively brittle nature needed to be improved. Inspired by this stabilizing effect of Ca 2+ , in this work, four transition metal divalent cations were used to assist the formation of flexible hordein/zein-derived carbon ultrafine fibers. Without alteration of the electrospinnability, adequate amounts of zinc acetate and cobalt acetate supported the fibrous structure during pyrolysis. This resulted in flexible freestanding carbon films consisting of well-defined fibers with nitrogen-doped graphitic layers and hierarchical pores. These carbon films were easily cut into small square pieces and directly applied as working electrode in the three-electrode testing system without the need for polymer binders or conducting agents. Notably, the hz-Zn0.3-p electrode, synthesized with 0.3 mol/L Zn 2+ and post-acid treatment, exhibited a specific capacitance of 393 F/g (at 1 A/g), a large rate capability (72.3% remained at 20 A/g), and a capacitance retention of ∼98% after 2000 charging-discharging cycles at 10 A/g. These superior electrochemical properties were attributed to the synergistic effects of the well-developed graphitic layers induced by Zn 2+ , the nitrogen-decorated carbon structure, and the interconnected channels generated by HCl treatment. This research advances potential applications for prolamin proteins as nitrogen-containing raw materials in developing carbon structures for high-performance supercapacitors.

Cellulose acetate based 3-dimensional electrospun scaffolds for skin tissue engineering applications.

PubMed

Atila, Deniz; Keskin, Dilek; Tezcaner, Ayşen

2015-11-20

Skin defects that are not able to regenerate by themselves are among the major problems faced. Tissue engineering approach holds promise for treating such defects. Development of tissue-mimicking-scaffolds that can promote healing process receives an increasing interest in recent years. In this study, 3-dimensional electrospun cellulose acetate (CA) pullulan (PULL) scaffolds were developed for the first time. PULL was intentionally used to obtain 3D structures with adjustable height. It was removed from the electrospun mesh to increase the porosity and biostability. Different ratios of the polymers were electrospun and analyzed with respect to degradation, porosity, and mechanical properties. It has been observed that fiber diameter, thickness and porosity of scaffolds increased with increased PULL content, on the other hand this resulted with higher degradation of scaffolds. Mechanical strength of scaffolds was improved after PULL removal suggesting their suitability as cell carriers. Cell culture studies were performed with the selected scaffold group (CA/PULL: 50/50) using mouse fibroblastic cell line (L929). In vitro cell culture tests showed that cells adhered, proliferated and populated CA/PULL (50/50) scaffolds showing that they are cytocompatible. Results suggest that uncrosslinked CA/PULL (50/50) electrospun scaffolds hold potential for skin tissue engineering applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electrospun materials for affinity-based engineering and drug delivery

NASA Astrophysics Data System (ADS)

Sill, T. J.; von Recum, H. A.

2015-10-01

Electrospinning is a process which can quickly and cheaply create materials of high surface to volume and aspect ratios from many materials, however in application toward drug delivery this can be a strong disadvantage as well. Diffusion of drug is proportional to the thickness of that device. In moving from macro to micro to nano-sized electrospun materials drug release rates change to profiles that are too fast to be therapeutically beneficial. In this work we use molecular interactions to further control the rate of release beyond that capable of diffusion alone. To do this we create materials with molecular pockets, which can "hold" therapeutic drugs through a reversible interaction such as a host/guest complexation. Through these complexes we show we are able to impact delivery of drug from electrospun materials, and also apply them in tissue engineering for the reversible presentation of biomolecules on a fiber surface.

Physical properties and morphology of electrospun composite fiber mats of polyhydroxyalkanoate containing nanoclay and tricalcium phosphate additives

NASA Astrophysics Data System (ADS)

Tanadchangsaeng, N.; Boonyagul, S.

2018-05-01

Recently, nanofiber research has gained substantial attention from scientists. In this study, the main component of the nanofiber sheet is polyhydroxyalkanoate (PHA) polymer, which is strong, ductile, flexible and adhesive to human skin. Two major additives of nanofiber sheet that we applied are nanoclay and tricalcium phosphate. The additives are generally synthetic substances that can be chemically synthesized and compatible with tissues body. Nanoclay has a low density, strong, durable to compressive strength and humidity. While, tricalcium phosphate is a calcium phosphate ceramic that is biocompatible to human tissue. From the reasons above, we proposed to choose both nanoclay and tricalcium phosphate for adding into PHA nanofibers for film formation. Thus, this study aims to investigate the morphological and mechanical properties of the fiber mat by using PHA added with various amount of nanoclay and tricalcium phosphate at 0.1%, 1% and 10% by weight, and fabricate nanofiber samples by electrospinning technique. The tested results of scanning electron microscope (SEM) morphology show that the fibers have a uniformed pattern. The PHA containing nanoclay of all additive contents exhibited micrometer diameter distributions, while PHA loaded with 1% tricalcium phosphate still had the nano-scale diameter range, and might be the optimum additive load for further nanometer medical applications. A tensile test was performed to determine the effect of nanoclay and tricalcium phosphate contents on the mechanical properties of the electrospun PHA films, and reflect the level of modularity. With nanoclay components being integrated into the polymer matrix, subsequent reduction in fiber crystallinity was occurred after addition of nanoclay with an increase of modulus value. The results confirmed that PHA fiber mat containing 1% nanoclay may have a potential for using as a rigid scaffold which bearing force loading in human organ system. Whereas, it can be indicated that

Interfacial Properties of Lignin-Based Electrospun Nanofibers and Films Reinforced with Cellulose Nanocrystals

Treesearch

Mariko Ago; Joseph E. Jakes; Leena-Sisko Johansson; Sunkyu Park; Orlando J. Rojas

2012-01-01

Sub-100 nm resolution local thermal analysis, X-ray photoelectron spectroscopy (XPS), and water contact angle (WCA) measurements were used to relate surface polymer distribution with the composition of electrospun fiber mats and spin coated films obtained from aqueous dispersions of lignin, polyvinyl alcohol (PVA), and cellulose nanocrystal (CNC). Defect-free lignin/...

An aligned porous electrospun fibrous membrane with controlled drug delivery - An efficient strategy to accelerate diabetic wound healing with improved angiogenesis.

PubMed

Ren, Xiaozhi; Han, Yiming; Wang, Jie; Jiang, Yuqi; Yi, Zhengfang; Xu, He; Ke, Qinfei

2018-04-01

A chronic wound in diabetic patients is usually characterized by poor angiogenesis and delayed wound closure. The exploration of efficient strategy to significantly improve angiogenesis in the diabetic wound bed and thereby accelerate wound healing is still a significant challenge. Herein, we reported a kind of aligned porous poly (l-lactic acid) (PlLA) electrospun fibrous membranes containing dimethyloxalylglycine (DMOG)-loaded mesoporous silica nanoparticles (DS) for diabetic wound healing. The PlLA electrospun fibers aligned in a single direction and there were ellipse-shaped nano-pores in situ generated onto the surface of fibers, while the DS were well distributed in the fibers and the DMOG as well as Si ion could be controlled released from the nanopores on the fibers. The in vitro results revealed that the aligned porous composite membranes (DS-PL) could stimulate the proliferation, migration and angiogenesis-related gene expression of human umbilical vein endothelial cells (HUVECs) compared with the pure PlLA membranes. The in vivo study further demonstrated that the prepared DS-PL membranes significantly improved neo-vascularization, re-epithelialization and collagen formation as well as inhibited inflammatory reaction in the diabetic wound bed, which eventually stimulated the healing of the diabetic wound. Collectively, these results suggest that the combination of hierarchical structures (nanopores on the aligned fibers) with the controllable released DMOG drugs as well as Si ions from the membranes, which could create a synergetic effect on the rapid stimulation of angiogenesis in the diabetic wound bed, is a potential novel therapeutic strategy for highly efficient diabetic wound healing. A chronic wound in diabetic patients is usually characterized by the poor angiogenesis and the delayed wound closure. The main innovation of this study is to design a new kind of skin tissue engineered scaffold, aligned porous poly (l-lactic acid) (PlLA) electrospun

Investigating the potential of electrospun gelatin and collagen scaffolds for tissue engineering applications

NASA Astrophysics Data System (ADS)

Sisson, Kristin M.

Electrospinning provides an avenue to explore tissue engineering with the ability to produce nano- and micro-sized fibers in a non-woven construct with properties ideal for a tissue engineered scaffold including: small diameter fibers, which create a large surface to volume ratio, and an interconnected porous network that enables cell migration, good mechanical integrity and a three-dimensional structure. A tissue engineered scaffold also must be biocompatible, biodegradable, non-toxic and able to be sterilized. All of these requirements can be satisfied by choosing an appropriate polymer and solvent system for electrospinning. The main objective of this research is to create a non-toxic, flat, bone tissue engineered scaffold to place into a non-immune compromised mouse. The current bone tissue repair and replacement methodologies include using metal and ceramic replacements or autologous and autogenous bone grafts. Each of these has its own set of disadvantages. Autologous grafts are bone harvested in one location in a patient and used in another location. This procedure is expensive, often results in pain and infection at the replacement site, and the actual harvesting procedure can cause problems for the patient. Autogenous grafts are bone harvested in one patient and used in another patient. The shortcomings include low donor availability and the possibility of rejection of the implant. The other options include using metal and ceramics to create replacement bone. However, metals provide good mechanical stability but can fail due to infection and also have poor integration into natural tissue. Ceramics, on the other hand, are brittle and have very low tensile strength. The natural extracellular matrix (ECM) of bone consists mainly of collagen type I. Electrospun fiber diameters closely resemble those of the natural ECM of bone. Thus, electrospinning a natural polymer like collagen type I for bone tissue engineering could make sense. Applications for these

Electrospun Polymer Fibers for Electronic Applications

PubMed Central

Luzio, Alessandro; Canesi, Eleonora Valeria; Bertarelli, Chiara; Caironi, Mario

2014-01-01

Nano- and micro- fibers of conjugated polymer semiconductors are particularly interesting both for applications and for fundamental research. They allow an investigation into how electronic properties are influenced by size confinement and chain orientation within microstructures that are not readily accessible within thin films. Moreover, they open the way to many applications in organic electronics, optoelectronics and sensing. Electro-spinning, the technique subject of this review, is a simple method to effectively form and control conjugated polymer fibers. We provide the basics of the technique and its recent advancements for the formation of highly conducting and high mobility polymer fibers towards their adoption in electronic applications. PMID:28788493

Electrospun Blends of Gelatin and Gelatin-dendrimer Conjugates as a Wound Dressing and Drug Delivery Platform

PubMed Central

Dongargaonkar, Alpana A.; Bowlin, Gary L.; Yang, Hu

2013-01-01

In this work, we report a new nanofiber construct based on electrospun blends of gelatin and gelatin-dendrimer conjugates. Highly branched star-shaped polyamidoamine (PAMAM) dendrimer G3.5 was covalently conjugated to gelatin via EDC/NHS chemistry. Blends of gelatin and gelatin-dendrimer conjugates mixed with various loading levels of silver acetate (0, 0.83, 1.65, and 3.30% w/w) were successfully electrospun into nanofiber constructs (NCs). The NCs were further converted into semi-interpenetrating networks (sIPNs) with photoreactive polyethylene glycol diacrylate (Mn=575 gmol-1) (PEG DA575). They were characterized in terms of fiber morphology, diameter, pore size, permeability, degradation, and mechanical properties. The resulting sIPN NCs retained nanofiber morphology, possessed similar fiber diameters to counterpart NCs, and gained improved structural stability. The sIPN NCs also showed good swelling capacity owing to porous structures and were permeable to aqueous solutions. Silvercontaining sIPN NCs allowed sustained silver release and showed antimicrobial activity against two common types of pathogens—Staphylococcus aureus and Pseudomonas aeruginosa. Incorporation of dendrimers into the gelatin nanofibers through covalent conjugation not only expands drug loading capacity of nanofiber constructs but provides tremendous flexibility for developing multifunctional electrospun dressing materials. PMID:24127747

Production and cross-sectional characterization of aligned co-electrospun hollow microfibrous bulk assemblies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Feng-Lei; The School of Materials, The University of Manchester, Manchester M13 9PL; CRUK-EPSRC Cancer Imaging Centre in Cambridge and Manchester

2015-11-15

The development of co-electrospun (co-ES) hollow microfibrous assemblies of an appreciable thickness is critical for many practical applications, including filtration membranes and tissue-mimicking scaffolds. In this study, thick uniaxially aligned hollow microfibrous assemblies forming fiber bundles and strips were prepared by co-ES of polycaprolactone (PCL) and polyethylene oxide (PEO) as shell and core materials, respectively. Hollow microfiber bundles were deposited on a fixed rotating disc, which resulted in non-controllable cross-sectional shapes on a macroscopic scale. In comparison, fiber strips were produced with tuneable thickness and width by additionally employing an x–y translation stage in co-ES. Scanning electron microscopy (SEM) imagesmore » of cross-sections of fiber assemblies were analyzed to investigate the effects of production time (from 0.5 h to 12 h), core flow rate (from 0.8 mL/h to 2.0 mL/h) and/or translation speed (from 0.2 mm/s to 5 mm/s) on the pores and porosity. We observed significant changes in pore size and shape with core flow rate but the influence of production time varied; five strips produced under the same conditions had reasonably good size and porosity reproducibility; pore sizes didn't vary significantly from strip bottom to surface, although the porosity gradually decreased and then returned to the initial level. - Highlights: • Hollow microfibrous assemblies based on co-electrospinning are demonstrated. • The thickness and width of co-electrospun strips were controllable. • Cross-sections of fibres had non-normally distributed pore sizes and shapes. • Cross-sections were significantly influenced by production time and flow rate. • Co-electrospun strips had reasonably good reproducible cross-sections.« less

Electrospun nanofibrous scaffolds of segmented polyurethanes based on PEG, PLLA and PTMC blocks: Physico-chemical properties and morphology.

PubMed

Trinca, Rafael Bergamo; Abraham, Gustavo A; Felisberti, Maria Isabel

2015-11-01

Biocompatible polymeric scaffolds are crucial for successful tissue engineering. Biomedical segmented polyurethanes (SPUs) are an important and versatile class of polymers characterized by a broad spectrum of compositions, molecular architectures, properties and applications. Although SPUs are versatile materials that can be designed by different routes to cover a wide range of properties, they have been infrequently used for the preparation of electrospun nanofibrous scaffolds. This study reports the preparation of new electrospun polyurethane scaffolds. The segmented polyurethanes were synthesized using low molar masses macrodyols (poly(ethylene glycol), poly(l-lactide) and poly(trimethylene carbonate)) and 1,6-hexane diisocyanate and 1,4-butanodiol as isocyanate and chain extensor, respectively. Different electrospinning parameters such as solution properties and processing conditions were evaluated to achieve smooth, uniform bead-free fibers. Electrospun micro/nanofibrous structures with mean fiber diameters ranging from 600nm to 770nm were obtained by varying the processing conditions. They were characterized in terms of thermal and dynamical mechanical properties, swelling degree and morphology. The elastomeric polyurethane scaffolds exhibit interesting properties that could be appropriate as biomimetic matrices for soft tissue engineering applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Fabrication and characterization of electrospun cellulose/nano-hydroxyapatite nanofibers for bone tissue engineering.

PubMed

Ao, Chenghong; Niu, Yan; Zhang, Ximu; He, Xu; Zhang, Wei; Lu, Canhui

2017-04-01

Nanofibrous scaffolds from cotton cellulose and nano-hydroxyapatite (nano-HA) were electrospun for bone tissue engineering. The solution properties of cellulose/nano-HA spinning dopes and their associated electrospinnability were characterized. Morphological, thermal and mechanical properties of the electrospun cellulose/nano-HA nanocomposite nanofibers (ECHNN) were measured and the biocompatibility of ECHNN with human dental follicle cells (HDFCs) was evaluated. Scanning electron microscope (SEM) images indicated that the average diameter of ECHNN increased with a higher nano-HA loading and the fiber diameter distributions were well within the range of natural ECM (extra cellular matrix) fibers (50-500nm). The ECHNN exhibited extraordinary mechanical properties with a tensile strength and a Young's modulus up to 70.6MPa and 3.12GPa respectively. Moreover, it was discovered that the thermostability of the ECHNN could be enhanced with the incorporation of nano-HA. Cell culture experiments demonstrated that the ECHNN scaffolds were quite biocompatible for HDFCs attachment and proliferation, suggesting their great potentials as scaffold materials in bone tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrospun microfiber membranes embedded with drug-loaded clay nanotubes for sustained antimicrobial protection.

PubMed

Xue, Jiajia; Niu, Yuzhao; Gong, Min; Shi, Rui; Chen, Dafu; Zhang, Liqun; Lvov, Yuri

2015-02-24

Guided tissue regeneration/guided bone regeneration membranes with sustained drug delivery were developed by electrospinning drug-loaded halloysite clay nanotubes doped into poly(caprolactone)/gelatin microfibers. Use of 20 wt % nanotube content in fiber membranes allowed for 25 wt % metronidazole drug loading in the membrane. Nanotubes with a diameter of 50 nm and a length of 600 nm were aligned within the 400 nm diameter electrospun fibers, resulting in membranes with doubling of tensile strength along the collector rotating direction. The halloysite-doped membranes acted as barriers against cell ingrows and have good biocompatibility. The metronidazole-loaded halloysite nanotubes incorporated in the microfibers allowed for extended release of the drugs over 20 days, compared to 4 days when directly admixed into the microfibers. The sustained release of metronidazole from the membranes prevented the colonization of anaerobic Fusobacteria, while eukaryotic cells could still adhere to and proliferate on the drug-loaded composite membranes. This indicates the potential of halloysite clay nanotubes as drug containers that can be incorporated into electrospun membranes for clinical applications.

Charge transport in the electrospun nanofiber composite membrane's three-dimensional fibrous structure

NASA Astrophysics Data System (ADS)

DeGostin, Matthew B.; Peracchio, Aldo A.; Myles, Timothy D.; Cassenti, Brice N.; Chiu, Wilson K. S.

2016-03-01

In this paper, a Fiber Network (FN) ion transport model is developed to simulate the three-dimensional fibrous microstructural morphology that results from the electrospinning membrane fabrication process. This model is able to approximate fiber layering within a membrane as well as membrane swelling due to water uptake. The discrete random fiber networks representing membranes are converted to resistor networks and solved for current flow and ionic conductivity. Model predictions are validated by comparison with experimental conductivity data from electrospun anion exchange membranes (AEM) and proton exchange membranes (PEM) for fuel cells as well as existing theories. The model is capable of predicting in-plane and thru-plane conductivity and takes into account detailed membrane characteristics, such as volume fraction, fiber diameter, fiber conductivity, and membrane layering, and as such may be used as a tool for advanced electrode design.

Optimization of protein cross-linking in bicomponent electrospun scaffolds for therapeutic use

NASA Astrophysics Data System (ADS)

Papa, Antonio; Guarino, Vincenzo; Cirillo, Valentina; Oliviero, Olimpia; Ambrosio, Luigi

2015-12-01

Bio-instructive electrospun scaffolds based on the combination of synthetic polymers, such as PCL or PLLA, and natural polymers (e.g., collagen) have been extensively investigated as temporary extracellular matrix (ECM) analogues able to support cell proliferation and stem cell differentiation for the regeneration of several tissues. The growing use of natural polymers as carrier of bioactive molecules is introducing new ideas for the design of polymeric drug delivery systems based on electrospun fibers with improved bioavailability, therapeutic efficacy and programmed drug release. In particular, the release mechanism is driven by the use of water soluble proteins (i.e., collagen, gelatin) which fully degrade in in vitro microenvironment, thus delivering the active principles. However, these protein are generally rapidly digested by enzymes (i.e., collagenase) produced by many different cell types, both in vivo and in vitro with significant drawbacks in tissue engineering and controlled drug delivery. Here, we aim at investigating different chemical strategies to improve the in vitro stability and mechanical strength of scaffolds against enzymatic degradation, by modifying the biodegradation rates of proteins embedded in bicomponent fibers. By comparing scaffolds treated by different cross-linking agents (i.e., GC, EDC, BDDGE), we have provided an extensive morphological/chemical/physical characterization via SEM and TGA to identify the best conditions to control drug release via protein degradation from bicomponent fibers without compromising in vitro cell response.

bFGF-containing electrospun gelatin scaffolds with controlled nano-architectural features for directed angiogenesis

PubMed Central

Montero, Ramon B.; Vial, Ximena; Nguyen, Dat Tat; Farhand, Sepehr; Reardon, Mark; Pham, Si M.; Tsechpenakis, Gavriil; Andreopoulos, Fotios M.

2011-01-01

Current therapeutic angiogenesis strategies are focused on the development of biologically responsive scaffolds that can deliver multiple angiogenic cytokines and/or cells in ischemic regions. Herein, we report on a novel electrospinning approach to fabricate cytokine-containing nanofibrous scaffolds with tunable architecture to promote angiogenesis. Fiber diameter and uniformity were controlled by varying the concentration of the polymeric (i.e. gelatin) solution, the feed rate, needle to collector distance, and electric field potential between the collector plate and injection needle. Scaffold fiber orientation (random vs. aligned) was achieved by alternating the polarity of two parallel electrodes placed on the collector plate thus dictating fiber deposition patterns. Basic fibroblast growth factor (bFGF) was physically immobilized within the gelatin scaffolds at variable concentrations and human umbilical vein endothelial cells (HUVEC) were seeded on the top of the scaffolds. Cell proliferation and migration was assessed as a function of growth factor loading and scaffold architecture. HUVECs successfully adhered onto gelatin B scaffolds and cell proliferation was directly proportional to the loading concentrations of the growth factor (0–100 bFGF ng/mL). Fiber orientation had a pronounced effect on cell morphology and orientation. Cells were spread along the fibers of the electrospun scaffolds with the aligned orientation and developed a spindle-like morphology parallel to the scaffold's fibers. In contrast, cells seeded onto the scaffolds with random fiber orientation, did not demonstrate any directionality and appeared to have a rounder shape. Capillary formation (i.e. sprouts length and number of sprouts per bead), assessed in a 3-D in vitro angiogenesis assay, was a function of bFGF loading concentration (0 ng, 50 ng and 100 ng per scaffold) for both types of electrospun scaffolds (i.e. with aligned or random fiber orientation). PMID:22200610

All-fiber pyroelectric nanogenerator

NASA Astrophysics Data System (ADS)

Ghosh, Sujoy Kumar; Xie, Mengying; Bowen, Christopher Rhys; Mandal, Dipankar

2018-04-01

An all-fiber pyroelectric nanogenerator (PyNG) is fabricated where both the active pyroelectric component and the electrodes were composed of fiber. The pyroelectric component was made with randomly organized electrospun PVDF nano-fibers possessing ferroelectric β- and γ-phases. The PyNG possess higher level of sensitivity which can detect very low level of temperature fluctuation, as, low as, 2 K. In addition, the thermal energy harvesting ability of the PyNG under several temperature variations and cycling frequencies paves the way for next generation thermal sensor and self-powered flexible micro-electronics.

Albumin fiber scaffolds for engineering functional cardiac tissues.

PubMed

Fleischer, Sharon; Shapira, Assaf; Regev, Omri; Nseir, Nora; Zussman, Eyal; Dvir, Tal

2014-06-01

In recent years attempts to engineer contracting cardiac patches were focused on recapitulation of the myocardium extracellular microenvironment. We report here on our work, where for the first time, a three-dimensional cardiac patch was fabricated from albumin fibers. We hypothesized that since albumin fibers' mechanical properties resemble those of cardiac tissue extracellular matrix (ECM) and their biochemical character enables their use as protein carriers, they can support the assembly of cardiac tissues capable of generating strong contraction forces. Here, we have fabricated aligned and randomly oriented electrospun albumin fibers and investigated their structure, mechanical properties, and chemical nature. Our measurements showed that the scaffolds have improved elasticity as compared to synthetic electrospun PCL fibers, and that they are capable of adsorbing serum proteins, such as laminin leading to strong cell-matrix interactions. Moreover, due to the functional groups on their backbone, the fibers can be chemically modified with essential biomolecules. When seeded with rat neonatal cardiac cells the engineered scaffolds induced the assembly of aligned cardiac tissues with high aspect ratio cardiomyocytes and massive actinin striation. Compared to synthetic fibrous scaffolds, cardiac cells cultured within aligned or randomly oriented scaffolds formed functional tissues, exhibiting significantly improved function already on Day 3, including higher beating rate (P = 0.0002 and P < 0.0001, respectively), and higher contraction amplitude (P = 0.009 and P = 0.003, respectively). Collectively, our results suggest that albumin electrospun scaffolds can play a key role in contributing to the ex vivo formation of a contracting cardiac muscle tissue. © 2014 Wiley Periodicals, Inc.

All-textile flexible supercapacitors using electrospun poly(3,4-ethylenedioxythiophene) nanofibers

NASA Astrophysics Data System (ADS)

Laforgue, Alexis

Poly(3,4-ethylenedioxythiophene) (PEDOT) nanofibers were obtained by the combination of electrospinning and vapor-phase polymerization. The fibers had diameters around 350 nm, and were soldered at most intersections, providing a strong dimensional stability to the mats. The nanofiber mats demonstrated very high conductivity (60 ± 10 S cm -1, the highest value reported so far for polymer nanofibers) as well as improved electrochemical properties, due to the ultraporous nature of the electrospun mats. The mats were incorporated into all-textile flexible supercapacitors, using carbon cloths as the current collectors and electrospun polyacrylonitrile (PAN) nanofibrous membranes as the separator. The textile layers were stacked and embedded in a solid electrolyte containing an ionic liquid and PVDF-co-HFP as the host polymer. The resulting supercapacitors were totally flexible and demonstrated interesting and stable performances in ambient conditions.

Effect of Processing Parameters on the Morphology of PVDF Electrospun Nanofiber

NASA Astrophysics Data System (ADS)

Zulfikar, M. A.; Afrianingsih, I.; Nasir, M.; Alni, A.

2018-03-01

Electrospinning is a process that produces continuous polymer fibers with diameters in the submicron range through the action of an external electric field imposed on a polymer solution or melt. Because of the tiny diameter in several hundreds of nanometers and the high porosity, electrospun membranes show potential applications in extensive areas such as filtration systems, biomedical tissue templates, drug delivery membranes, and so on. In the electrospinning process, some parameters such as polymer concentration, feeding rate of the polymer solution, additives, humidity, viscosity, surface tension, applied voltage, and nozzle-to ground collector distance will affect the fiber diameter and morphology. In this work, we have evaluated the effects of two processing parameters including the flow rate of the polymer solution and nozzle-to ground collector distance, on the morphology of the fibers formed. The solutions used in the electrospinning experiments were prepared using Poly(vinylidene fluoride) (PVDF). This material was dissolved in N,N-dimethylformamide (DMF) to make solutions with concentrations of 20 wt%. These solutions was electrospun using a 5 mL plastic syringe with an 8 gauge stainless needle at an applied voltage of 20.0 kV, a flow rate of 0.02-0.04 mL/min and nozzle-to ground collector distance of 12 and 15 cm. Electrospinning of PVDF polymer solution was performed in horizontal alignment having a grounded aluminum foil which serves as a collector. The nanofibers obtained were characterized by polarizing optical microscope. We find that the low flow rate of the polymer solution and nozzle-to ground collector distance are strongly correlated with the formation of bead defects in the fibers.

Development of electrospun bone-mimetic matrices for bone regenerative applications

NASA Astrophysics Data System (ADS)

Phipps, Matthew Christopher

Although bone has a dramatic capacity for regeneration, certain injuries and procedures present defects that are unable to heal properly, requiring surgical intervention to induce and support osteoregeneration. Our research group has hypothesized that the development of a biodegradable material that mimics the natural composition and architecture of bone extracellular matrix has the potential to provide therapeutic benefit to these patients. Utilizing a process known as electrospinning, our lab has developed a bone-mimetic matrix (BMM) consisting of composite nanofibers of the mechanically sta-ble polymer polycaprolactone (PCL), and the natural bone matrix molecules type-I colla-gen and hydroxyapatite nanocrystals (HA). We herein show that BMMs supported great-er adhesion, proliferation, and integrin activation of mesenchymal stem cells (MSCs), the multipotent bone-progenitor cells within bone marrow and the periosteum, in comparison to electrospun PCL alone. These cellular responses, which are essential early steps in the process of bone regeneration, highlight the benefits of presenting cells with natural bone molecules. Subsequently, evaluation of new bone formation in a rat cortical tibia defect showed that BMMs are highly osteoconductive. However, these studies also revealed the inability of endogenous cells to migrate within electrospun matrices due to the inherently small pore sizes. To address this limitation, which will negatively impact the rate of scaf-fold-to-bone turnover and inhibit vascularization, sacrificial fibers were added to the ma-trix. The removal of these fibers after fabrication resulted in BMMs with larger pores, leading to increased infiltration of MSCs and endogenous bone cells. Lastly, we evaluat-ed the potential of our matrices to stimulate the recruitment of MSCs, a vital step in bone healing, through the sustained delivery of platelet derived growth factor-BB (PDGF-BB). BMMs were found to adsorb and subsequently release greater

21 CFR 177.1640 - Polystyrene and rubber-modified polystyrene.

Code of Federal Regulations, 2011 CFR

2011-04-01

... polystyrene and rubber-modified polystyrene used in food-packaging adhesives complying with § 175.105 of this... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Polystyrene and rubber-modified polystyrene. 177.1640 Section 177.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN...

21 CFR 177.1640 - Polystyrene and rubber-modified polystyrene.

Code of Federal Regulations, 2010 CFR

2010-04-01

... polystyrene and rubber-modified polystyrene used in food-packaging adhesives complying with § 175.105 of this... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polystyrene and rubber-modified polystyrene. 177.1640 Section 177.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN...

21 CFR 177.1640 - Polystyrene and rubber-modified polystyrene.

Code of Federal Regulations, 2013 CFR

2013-04-01

... polystyrene and rubber-modified polystyrene used in food-packaging adhesives complying with § 175.105 of this... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Polystyrene and rubber-modified polystyrene. 177.1640 Section 177.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN...

21 CFR 177.1640 - Polystyrene and rubber-modified polystyrene.

Code of Federal Regulations, 2012 CFR

2012-04-01

... polystyrene and rubber-modified polystyrene used in food-packaging adhesives complying with § 175.105 of this... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Polystyrene and rubber-modified polystyrene. 177.1640 Section 177.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN...

Evaluation of Electrospun Nanofiber-Anchored Silicone for the Degenerative Intervertebral Disc

PubMed Central

Riahanizad, S.

2017-01-01

The nucleus pulposus (NP) substitution by polymeric gel is one of the promising techniques for the repair of the degenerative intervertebral disc (IVD). Silicone gel is one of the potential candidates for a NP replacement material. Electrospun fiber anchorage to silicone disc, referred as ENAS disc, may not only improve the biomechanical performances of the gel but it can also improve restoration capability of the gel, which is unknown. This study successfully produced a novel process to anchor any size and shape of NP gel with electrospun fiber mesh. Viscoelastic properties of silicone and ENAS disc were measured using standard experimental techniques and compared with the native tissue properties. Ex vivo mechanical tests were conducted on ENAS disc-implanted rabbit tails to the compare the mechanical stability between intact and ENAS implanted spines. This study found that viscoelastic properties of ENAS disc are higher than silicone disc and comparable to the viscoelastic properties of human NP. The ex vivo studies found that the ENAS disc restore the mechanical functionality of rabbit tail spine, after discectomy of native NP and replacing the NP by ENAS disc. Therefore, the PCL ENF mesh anchoring technique to a NP implant can have clinical potential. PMID:29181144

Comparison of Adsorption/Desorption of Volatile Organic Compounds (VOCs) on Electrospun Nanofibers with Tenax TA for Potential Application in Sampling

PubMed Central

Chu, Lanling; Deng, Siwei; Zhao, Renshan; Deng, Jianjun; Kang, Xuejun

2016-01-01

The objective of this study was to compare the adsorption/desorption of target compounds on homemade electrospun nanofibers, polystyrene (PS) nanofibers, acrylic resin (AR) nanofibers and PS-AR composite nanofibers with Tenax TA. Ten volatile organic compounds (VOCs) were analyzed by preconcentration onto different sorbents followed by desorption (thermal and solvent orderly) and analysis by capillary gas chromatography. In comparison to Tenax TA, the electrospun nanofibers displayed a significant advantage in desorption efficiency and adsorption selectivity. Stability studies were conducted as a comparative experiment between PS-AR nanofibers and Tenax TA using toluene as the model compound. No stability problems were observed upon storage of toluene on both PS-AR nanofibers and Tenax TA over 60 hours period when maintained in an ultra-freezer (−80°C). The nanofibers provided slightly better stability for the adsorbed analytes than Tenax TA under other storage conditions. In addition, the nanofibers also provided slightly better precision than Tenax TA. The quantitative adsorption of PS-AR nanofibers exhibited a good linearity, as evidenced by the 0.988–0.999 range of regression coefficients (R). These results suggest that for VOCs sampling the electrospun nanofibers can be a potential ideal adsorbent. PMID:27776140

Effects of fiber/matrix interactions on the interfacial deformation micromechanics of cellulose-fiber/polymer composites

NASA Astrophysics Data System (ADS)

Tze, William Tai-Yin

The overall objective of this dissertation was to gain an understanding of the relationship between interfacial chemistry and the micromechanics of the cellulose-fiber/polymer composites. Regenerated cellulose (lyocell) fibers were treated with amine-, phenylamine-, phenyl-, and octadecyl-silanes, and also styrene-maleic anhydride copolymer. Inverse gas chromatography was conducted to evaluate the modified surfaces and to examine the adsorption behavior of ethylbenzene, a model compound for polystyrene, onto the fibers. Micro-composites were formed by depositing micro-droplets of polystyrene onto single fibers. The fiber was subjected to a tensile strain, and Raman spectroscopy was employed to determine the point-to-point variation of the strain- and stress-sensitive 895 cm-1 band of cellulose along the embedded region. Inverse gas chromatography studies reveal that the Ia-b values, calculated by matching the Lewis acid parameter ( KA) and basic parameter (KB) between polystyrene and different fibers, were closely correlated to the acid-base adsorption enthalpies of ethylbenzene onto the corresponding fibers. Hence, Ia-b was subsequently used as a convenient indicator for fiber/matrix acid-base interaction. The Raman micro-spectroscopic studies demonstrate that the interfacial tensile strain and stress are highest at the edge of the droplet, and these values decline from the edge region to the middle region of the embedment. The maximum of these local strains corresponds to a strain-control fracture of the matrix polymer. The minimum of the local tensile stress corresponds to the extent of fiber-to-matrix load transfer. The slope of the tensile stress profile allows for an estimation of the maximum interfacial shear stress, which is indicative of fiber/polymer (practical) adhesion. As such, a novel micro-Raman tensile technique was established for evaluating the ductile-fiber/brittle-polymer system in this study. The micro-Raman tensile technique provided maximum

Optimization of protein cross-linking in bicomponent electrospun scaffolds for therapeutic use

DOE Office of Scientific and Technical Information (OSTI.GOV)

Papa, Antonio; IMAST SCaRL, Piazza Bovio 22, 80133 Naples; Guarino, Vincenzo, E-mail: vincenzo.guarino@cnr.it

Bio-instructive electrospun scaffolds based on the combination of synthetic polymers, such as PCL or PLLA, and natural polymers (e.g., collagen) have been extensively investigated as temporary extracellular matrix (ECM) analogues able to support cell proliferation and stem cell differentiation for the regeneration of several tissues. The growing use of natural polymers as carrier of bioactive molecules is introducing new ideas for the design of polymeric drug delivery systems based on electrospun fibers with improved bioavailability, therapeutic efficacy and programmed drug release. In particular, the release mechanism is driven by the use of water soluble proteins (i.e., collagen, gelatin) which fullymore » degrade in in vitro microenvironment, thus delivering the active principles. However, these protein are generally rapidly digested by enzymes (i.e., collagenase) produced by many different cell types, both in vivo and in vitro with significant drawbacks in tissue engineering and controlled drug delivery. Here, we aim at investigating different chemical strategies to improve the in vitro stability and mechanical strength of scaffolds against enzymatic degradation, by modifying the biodegradation rates of proteins embedded in bicomponent fibers. By comparing scaffolds treated by different cross-linking agents (i.e., GC, EDC, BDDGE), we have provided an extensive morphological/chemical/physical characterization via SEM and TGA to identify the best conditions to control drug release via protein degradation from bicomponent fibers without compromising in vitro cell response.« less

Thermal conductivity of electrospun polyethylene nanofibers.

PubMed

Ma, Jian; Zhang, Qian; Mayo, Anthony; Ni, Zhonghua; Yi, Hong; Chen, Yunfei; Mu, Richard; Bellan, Leon M; Li, Deyu

2015-10-28

We report on the structure-thermal transport property relation of individual polyethylene nanofibers fabricated by electrospinning with different deposition parameters. Measurement results show that the nanofiber thermal conductivity depends on the electric field used in the electrospinning process, with a general trend of higher thermal conductivity for fibers prepared with stronger electric field. Nanofibers produced at a 45 kV electrospinning voltage and a 150 mm needle-collector distance could have a thermal conductivity of up to 9.3 W m(-1) K(-1), over 20 times higher than the typical bulk value. Micro-Raman characterization suggests that the enhanced thermal conductivity is due to the highly oriented polymer chains and enhanced crystallinity in the electrospun nanofibers.

Electrospun TiO₂ nanofibers decorated Ti substrate for biomedical application.

PubMed

Dumitriu, Cristina; Stoian, Andrei Bogdan; Titorencu, Irina; Pruna, Vasile; Jinga, Victor V; Latonen, Rose-Marie; Bobacka, Johan; Demetrescu, Ioana

2014-12-01

Various TiO2 nanofibers on Ti surface have been fabricated via electrospinning and calcination. Due to different elaboration conditions the electrospun fibers have different surface feature morphologies, characterized by scanning electronic microscopy, surface roughness, and contact angle measurements. The results have indicated that the average sample diameters are between 32 and 44 nm, roughness between 61 and 416 nm, and all samples are hydrophilic. As biological evaluation, cell culture with MG63 cell line originally derived from a human osteosarcoma was performed and correlation between nanofibers elaboration, properties and cell response was established. The cell adherence and growth are more evident on Ti samples with more aligned fibers, higher roughness and strong hydrophilic character and such fibers have been elaborated with a high speed rotating cylinder collector, confirming the idea that nanostructure elaboration conditions guide the cells' growth. Copyright © 2014 Elsevier B.V. All rights reserved.

Metal Oxide Nanoparticles in Electrospun Polymers and Their Fate in Aqueous Waste Streams

NASA Astrophysics Data System (ADS)

Hoogesteijn von Reitzenstein, Natalia

Nanotechnology is becoming increasingly present in our environment. Engineered nanoparticles (ENPs), defined as objects that measure less than 100 nanometers in at least one dimension, are being integrated into commercial products because of their small size, increased surface area, and quantum effects. These special properties have made ENPs antimicrobial agents in clothing and plastics, among other applications in industries such as pharmaceuticals, renewable energy, and prosthetics. This thesis incorporates investigations into both application of nanoparticles into polymers as well as implications of nanoparticle release into the environment. First, the integration of ENPs into polymer fibers via electrospinning was explored. Electrospinning uses an external electric field applied to a polymer solution to produce continuous fibers with large surface area and small volume, a quality which makes the fibers ideal for water and air purification purposes. Indium oxide and titanium dioxide nanoparticles were embedded in polyvinylpyrrolidone and polystyrene. Viscosity, critical voltage, and diameter of electrospun fibers were analyzed in order to determine the effects of nanoparticle integration into the polymers. Critical voltage and viscosity of solution increased at 5 wt% ENP concentration. Fiber morphology was not found to change significantly as a direct effect of ENP addition, but as an effect of increased viscosity and surface tension. These results indicate the possibility for seamless integration of ENPs into electrospun polymers. Implications of ENP release were investigated using phase distribution functional assays of nanoscale silver and silver sulfide, as well as photolysis experiments of nanoscale titanium dioxide to quantify hydroxyl radical production. Functional assays are a means of screening the relevant importance of multiple processes in the environmental fate and transport of ENPs. Four functional assays---water-soil, water-octanol, water

Development of Electrospun Nanomaterials and their Applications in Separation Science

NASA Astrophysics Data System (ADS)

Newsome, Toni Elwell

In separations, efficiency is inversely related to the diameter of the sorbent particles of the stationary phase. Thus, materials research in separation science has primarily been directed towards reducing the diameter of the sorbent particle used in the stationary phase. In this dissertation, innovative methods designed for the fabrication and application of electrospun sorbent nanomaterials for separation science are described. Electrospinning is a facile, cost-effective technique that relies on repulsive electrostatic forces to produce nanofibers from a viscoelastic solution. Here, electrospinning is used to generate polymer, carbon, and silica-based nanofibers which are employed as sorbent nanomaterials in extractions and separations. Electrospun carbon nanofibers have proven to be ideal extractive phases for solid-phase microextraction (SPME) when coupled to gas chromatography (GC) for headspace sampling of volatile analytes. Herein, these carbon nanofibers were employed in the direct extraction of nonvolatile analytes and coupled to liquid chromatography (LC) for the first time. The high surface area of the coatings led to enhanced extraction efficiencies; they offered a 3-33 fold increase in efficiency relative to a commercial SPME phase. Carbon nanofibers proved to be stable when immersed in liquids common to LC demonstrating the enhanced stability of these coatings in SPME coupled to LC relative to conventional SPME fibers. The enhanced chemical and mechanical stability of the carbon SPME coatings considerably expanded the range of compounds applicable to SPME and extended the lifetimes of the fibers. Electrospun nanofibers have also proven to be ideal stationary phases in ultra-thin layer chromatography (UTLC). Nanofibers provide faster separations and enhanced separation efficiencies compared to commercial particle-based stationary phases in a relatively short distance. Here, the electrospun-UTLC technology was extended for the first time to nanofibers

Cell-matrix mechanical interaction in electrospun polymeric scaffolds for tissue engineering: Implications for scaffold design and performance.

PubMed

Kennedy, Kelsey M; Bhaw-Luximon, Archana; Jhurry, Dhanjay

2017-03-01

Engineered scaffolds produced by electrospinning of biodegradable polymers offer a 3D, nanofibrous environment with controllable structural, chemical, and mechanical properties that mimic the extracellular matrix of native tissues and have shown promise for a number of tissue engineering applications. The microscale mechanical interactions between cells and electrospun matrices drive cell behaviors including migration and differentiation that are critical to promote tissue regeneration. Recent developments in understanding these mechanical interactions in electrospun environments are reviewed, with emphasis on how fiber geometry and polymer structure impact on the local mechanical properties of scaffolds, how altering the micromechanics cues cell behaviors, and how, in turn, cellular and extrinsic forces exerted on the matrix mechanically remodel an electrospun scaffold throughout tissue development. Techniques used to measure and visualize these mechanical interactions are described. We provide a critical outlook on technological gaps that must be overcome to advance the ability to design, assess, and manipulate the mechanical environment in electrospun scaffolds toward constructs that may be successfully applied in tissue engineering and regenerative medicine. Tissue engineering requires design of scaffolds that interact with cells to promote tissue development. Electrospinning is a promising technique for fabricating fibrous, biomimetic scaffolds. Effects of electrospun matrix microstructure and biochemical properties on cell behavior have been extensively reviewed previously; here, we consider cell-matrix interaction from a mechanical perspective. Micromechanical properties as a driver of cell behavior has been well established in planar substrates, but more recently, many studies have provided new insights into mechanical interaction in fibrillar, electrospun environments. This review provides readers with an overview of how electrospun scaffold mechanics and

Electrospun meshes possessing region-wise differences in fiber orientation, diameter, chemistry and mechanical properties for engineering bone-ligament-bone tissues.

PubMed

Samavedi, Satyavrata; Vaidya, Prasad; Gaddam, Prudhvidhar; Whittington, Abby R; Goldstein, Aaron S

2014-12-01

Although bone-patellar tendon-bone (B-PT-B) autografts are the gold standard for repair of anterior cruciate ligament ruptures, they suffer from drawbacks such as donor site morbidity and limited supply. Engineered tissues modeled after B-PT-B autografts are promising alternatives because they have the potential to regenerate connective tissue and facilitate osseointegration. Towards the long-term goal of regenerating ligaments and their bony insertions, the objective of this study was to construct 2D meshes and 3D cylindrical composite scaffolds - possessing simultaneous region-wise differences in fiber orientation, diameter, chemistry and mechanical properties - by electrospinning two different polymers from off-set spinnerets. Using a dual drum collector, 2D meshes consisting of an aligned polycaprolactone (PCL) fiber region, randomly oriented poly(lactide-co-glycolide) (PLGA) fiber region and a transition region (comprised of both PCL and PLGA fibers) were prepared, and region-wise differences were confirmed by microscopy and tensile testing. Bone marrow stromal cells (BMSCs) cultured on these meshes exhibited random orientations and low aspect ratios on the random PLGA regions, and high aspect ratios and alignment on the aligned PCL regions. Next, meshes containing an aligned PCL region flanked by two transition regions and two randomly oriented PLGA regions were prepared and processed into 3D cylindrical composite scaffolds using an interpenetrating photo-crosslinkable polyethylene glycol diacrylate hydrogel to recapitulate the shape of B-PT-B autografts. Tensile testing indicated that cylindrical composites were mechanically robust, and eventually failed due to stress concentration in the aligned PCL region. In summary, this study demonstrates a process to fabricate electrospun meshes possessing region-wise differences in properties that can elicit region-dependent cell responses, and be readily processed into scaffolds with the shape of B-PT-B autografts. �

A new class of boron nitride fibers with tunable properties by combining an electrospinning process and the polymer-derived ceramics route

NASA Astrophysics Data System (ADS)

Salles, Vincent; Bernard, Samuel; Brioude, Arnaud; Cornu, David; Miele, Philippe

2010-02-01

Novel boron nitride (BN) fibers have been developed with diameters ranging from the nano- to microscale by thermal conversion of as-electrospun fibers from polyacrylonitrile and poly[B-(methylamino)borazine] blend solutions. Such a new class of ceramic fibers is seen as potential candidate for thermal management applications and filtration systems in harsh environments.Novel boron nitride (BN) fibers have been developed with diameters ranging from the nano- to microscale by thermal conversion of as-electrospun fibers from polyacrylonitrile and poly[B-(methylamino)borazine] blend solutions. Such a new class of ceramic fibers is seen as potential candidate for thermal management applications and filtration systems in harsh environments. Electronic supplementary information (ESI) available: Experimental details and EDX results. See DOI: 10.1039/b9nr00185a

Enhanced mechanical properties of thermosensitive chitosan hydrogel by silk fibers for cartilage tissue engineering.

PubMed

Mirahmadi, Fereshteh; Tafazzoli-Shadpour, Mohammad; Shokrgozar, Mohammad Ali; Bonakdar, Shahin

2013-12-01

Articular cartilage has limited repair capability following traumatic injuries and current methods of treatment remain inefficient. Reconstructing cartilage provides a new way for cartilage repair and natural polymers are often used as scaffold because of their biocompatibility and biofunctionality. In this study, we added degummed chopped silk fibers and electrospun silk fibers to the thermosensitive chitosan/glycerophosphate hydrogels to reinforce two hydrogel constructs which were used as scaffold for hyaline cartilage regeneration. The gelation temperature and gelation time of hydrogel were analyzed by the rheometer and vial tilting method. Mechanical characterization was measured by uniaxial compression, indentation and dynamic mechanical analysis assay. Chondrocytes were then harvested from the knee joint of the New Zealand white rabbits and cultured in constructs. The cell proliferation, viability, production of glycosaminoglycans and collagen type II were assessed. The results showed that mechanical properties of the hydrogel were significantly enhanced when a hybrid with two layers of electrospun silk fibers was made. The results of GAG and collagen type II in cell-seeded scaffolds indicate support of the chondrogenic phenotype for chondrocytes with a significant increase in degummed silk fiber-hydrogel composite for GAG content and in two-layer electrospun fiber-hydrogel composite for Col II. It was concluded that these two modified scaffolds could be employed for cartilage tissue engineering. © 2013.

Ceria-based electrospun fibers for renewable fuel production via two-step thermal redox cycles for carbon dioxide splitting.

PubMed

Gibbons, William T; Venstrom, Luke J; De Smith, Robert M; Davidson, Jane H; Jackson, Gregory S

2014-07-21

Zirconium-doped ceria (Ce(1-x)Zr(x)O2) was synthesized through a controlled electrospinning process as a promising approach to cost-effective, sinter-resistant material structures for high-temperature, solar-driven thermochemical redox cycles. To approximate a two-step redox cycle for solar fuel production, fibrous Ce(1-x)Zr(x)O2 with relatively low levels of Zr-doping (0 < x < 0.1) were cycled in an infrared-imaging furnace with high-temperature (up to 1500 °C) partial reduction and lower-temperature (∼800 °C) reoxidation via CO2 splitting to produce CO. Increases in Zr content improve reducibility and sintering resistance, and, for x≤ 0.05, do not significantly slow reoxidation kinetics for CO production. Cycle stability of the fibrous Ce(1-x)Zr(x)O2 (with x = 0.025) was assessed for a range of conditions by measuring rates of O2 release during reduction and CO production during reoxidation and by assessing post-cycling fiber crystallite sizes and surface areas. Sintering increases with reduction temperature but occurs primarily along the fiber axes. Even after 108 redox cycles with reduction at 1400 °C and oxidation with CO2 at 800 °C, the fibers maintain their structure with surface areas of ∼0.3 m(2) g(-1), higher than those observed in the literature for other ceria-based structures operating at similarly high temperature conditions. Total CO production and peak production rate stabilize above 3.0 mL g(-1) and 13.0 mL min(-1) g(-1), respectively. The results show the potential for electrospun oxides as sinter-resistant material structures with adequate surface area to support rapid CO2 splitting in solar thermochemical redox cycles.

Coiled fiber scaffolds embedded with gold nanoparticles improve the performance of engineered cardiac tissues

NASA Astrophysics Data System (ADS)

Fleischer, Sharon; Shevach, Michal; Feiner, Ron; Dvir, Tal

2014-07-01

Coiled perimysial fibers within the heart muscle provide it with the ability to contract and relax efficiently. Here, we report on a new nanocomposite scaffold for cardiac tissue engineering, integrating coiled electrospun fibers with gold nanoparticles. Cultivation of cardiac cells within the hybrid scaffolds promoted cell organization into elongated and aligned tissues generating a strong contraction force, high contraction rate and low excitation threshold.Coiled perimysial fibers within the heart muscle provide it with the ability to contract and relax efficiently. Here, we report on a new nanocomposite scaffold for cardiac tissue engineering, integrating coiled electrospun fibers with gold nanoparticles. Cultivation of cardiac cells within the hybrid scaffolds promoted cell organization into elongated and aligned tissues generating a strong contraction force, high contraction rate and low excitation threshold. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00300d

Evaluation of poly(lactic-co-glycolic acid) and poly(dl-lactide-co-ε-caprolactone) electrospun fibers for the treatment of HSV-2 infection.

PubMed

Aniagyei, Stella E; Sims, Lee B; Malik, Danial A; Tyo, Kevin M; Curry, Keegan C; Kim, Woihwan; Hodge, Daniel A; Duan, Jinghua; Steinbach-Rankins, Jill M

2017-03-01

More diverse multipurpose prevention technologies are urgently needed to provide localized, topical pre-exposure prophylaxis against sexually transmitted infections (STIs). In this work, we established the foundation for a multipurpose platform, in the form of polymeric electrospun fibers (EFs), to physicochemically treat herpes simplex virus 2 (HSV-2) infection. To initiate this study, we fabricated different formulations of poly(lactic-co-glycolic acid) (PLGA) and poly(dl-lactide-co-ε-caprolactone) (PLCL) EFs that encapsulate Acyclovir (ACV), to treat HSV-2 infection in vitro. Our goals were to assess the release and efficacy differences provided by these two different biodegradable polymers, and to determine how differing concentrations of ACV affected fiber efficacy against HSV-2 infection and the safety of each platform in vitro. Each formulation of PLGA and PLCL EFs exhibited high encapsulation efficiency of ACV, sustained-delivery of ACV through one month, and in vitro biocompatibility at the highest doses of EFs tested. Additionally, all EF formulations provided complete and efficacious protection against HSV-2 infection in vitro, regardless of the timeframe of collected fiber eluates tested. This work demonstrates the potential for PLGA and PLCL EFs as delivery platforms against HSV-2, and indicates that these delivery vehicles may be expanded upon to provide protection against other sexually transmitted infections. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis and photocatalytic activity of electrospun niobium oxide nanofibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qi, Shishun; Zuo, Ruzhong, E-mail: piezolab@hfut.edu.cn; Liu, Yi

2013-03-15

Graphical abstract: Different morphologies are obtained for the electrospun niobium oxide nanofibers with different phase structures. The nanofibers of the two phase structures present different band gap value and the light absorption. Hexagonal phase nanofibers show better photocatalytic activity compared with the orthorhombic nanofibers. Highlights: ► Niobium oxide nanofibers of two phase structures were fabricated by electrospinning. ► Photocatalytic properties of the niobium oxide nanofibers were first explored. ► Nanofibers of different phase structures showed different photocatalytic activities. ► Reasons for the differences in the photocatalysis were carefully discussed. - Abstract: Niobium oxide (Nb{sub 2}O{sub 5}) nanofibers have been synthesizedmore » by sol–gel based electrospinning technique. Pure hexagonal phase (H-Nb{sub 2}O{sub 5}) and orthorhombic phase (O-Nb{sub 2}O{sub 5}) nanofibers were obtained by thermally annealing the electrospun Nb{sub 2}O{sub 5}/polyvinylpyrrolidone composite fibers in air at 500 °C and 700 °C, respectively. The fibers were characterized using the X-ray diffraction, scanning electron microscopy, specific surface area analyzer and UV–vis diffuse reflectance spectroscopy. Photocatalytic activities of the obtained nanofibers were evaluated depending on the degradation of methyl orange. The results indicate that the heat-treatment temperature, the crystalline structure and the morphology affected the physical and chemical properties of the as-prepared Nb{sub 2}O{sub 5} nanofibers. The H-Nb{sub 2}O{sub 5} nanofibers obtained at lower temperature showed better potential for the application as a promising photocatalyst.« less

The effect of nozzle-exit-channel shape on resultant fiber diameter in melt-electrospinning

NASA Astrophysics Data System (ADS)

Esmaeilirad, Ahmad; Ko, Junghyuk; Rukosuyev, Maxym V.; Lee, Jason K.; Lee, Patrick C.; Jun, Martin B. G.

2017-01-01

In recent decades, electrospinning using a molten poly (ε-caprolactone) resin has gained attention for creating fibrous tissue scaffolds. The topography and diameter control of such electrospun microfibers is an important issue for their different applications in tissue engineering. Charge density, initial nozzle-exit-channel cross-sectional area, nozzle to collector distance, viscosity, and processing temperature are the most important input parameters that affect the final electrospun fiber diameters. In this paper we will show that the effect of nozzle-exit-channel shape is as important as the other effective parameters in a resultant fiber diameter. However, to the best of our knowledge, the effect of nozzle-exit-channel shapes on a resultant fiber diameter have not been studied before. Comparing rectangular and circular nozzles with almost the same exit-channel cross-sectional areas in a similar processing condition showed that using a rectangular nozzle resulted in decreasing final fiber diameter up to 50%. Furthermore, the effect of processing temperature on the final fiber topography was investigated.

Fabrication of drug-loaded electrospun aligned fibrous threads for suture applications.

PubMed

He, Chuang-Long; Huang, Zheng-Ming; Han, Xiao-Jian

2009-04-01

In this work, drug-loaded fibers and threads were successfully fabricated by combining electrospinning with aligned fibers collection. Two different electrospinning processes, that is, blend and coaxial electrospinning, to incorporate a model drug tetracycline hydrochloride (TCH) into poly(L-lactic acid) (PLLA) fibers have been used and compared with each other. The resulting composite ultrafine fibers and threads were characterized through scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and tensile testing. It has been shown that average diameters of the fibers made from the same polymer concentration depended on the processing method. The blend TCH/PLLA fibers showed the smallest fiber diameter, whereas neat PLLA fibers and core-shell TCH-PLLA fibers showed a larger proximal average diameter. Higher rotating speed of a wheel collector is helpful for obtaining better-aligned fibers. Both the polymer and the drug in the electrospun fibers have poor crystalline property. In vitro release study indicated that threads made from the core-shell fibers could suppress the initial burst release and provide a sustained drug release useful for the release of growth factor or other therapeutic drugs. On the other hand, the threads from the blend fibers produced a large initial burst release that may be used to prevent bacteria infection. A combination of these results suggests that electrospinning technique provides a novel way to fabricate medical agents-loaded fibrous threads for tissue suturing and tissue regeneration applications. Copyright 2008 Wiley Periodicals, Inc.

High-throughput and selective solid-phase extraction of urinary catecholamines by crown ether-modified resin composite fiber.

PubMed

Chen, LiQin; Wang, Hui; Xu, Zhen; Zhang, QiuYue; Liu, Jia; Shen, Jun; Zhang, WanQi

2018-08-03

In the present study, we developed a simple and high-throughput solid phase extraction (SPE) procedure for selective extraction of catecholamines (CAs) in urine samples. The SPE adsorbents were electrospun composite fibers functionalized with 4-carboxybenzo-18-crown-6 ether modified XAD resin and polystyrene, which were packed into 96-well columns and used for high-throughput selective extraction of CAs in healthy human urine samples. Moreover, the extraction efficiency of packed-fiber SPE (PFSPE) was examined by high performance liquid chromatography coupled with fluorescence detector. The parameters affecting the extraction efficiency and impurity removal efficiency were optimized, and good linearity ranging from 0.5 to 400 ng/mL was obtained with a low limit of detection (LOD, 0.2-0.5 ng/mL) and a good repeatability (2.7%-3.7%, n = 6). The extraction recoveries of three CAs ranged from 70.5% to 119.5%. Furthermore, stable and reliable results obtained by the fluorescence detector were superior to those obtained by the electrochemical detector. Collectively, PFSPE coupled with 96-well columns was a simple, rapid, selective, high-throughput and cost-efficient method, and the proposed method could be applied in clinical chemistry. Copyright © 2018 Elsevier B.V. All rights reserved.

Electrospun Nanofibers Made of Silver Nanoparticles, Cellulose Nanocrystals, and Polyacrylonitrile as Substrates for Surface-Enhanced Raman Scattering

PubMed Central

Ren, Suxia; Dong, Lili; Zhang, Xiuqiang; Lei, Tingzhou; Ehrenhauser, Franz; Song, Kunlin; Li, Meichun; Sun, Xiuxuan; Wu, Qinglin

2017-01-01

Nanofibers with excellent activities in surface-enhanced Raman scattering (SERS) were developed through electrospinning precursor suspensions consisting of polyacrylonitrile (PAN), silver nanoparticles (AgNPs), silicon nanoparticles (SiNPs), and cellulose nanocrystals (CNCs). Rheology of the precursor suspensions, and morphology, thermal properties, chemical structures, and SERS sensitivity of the nanofibers were investigated. The electrospun nanofibers showed uniform diameters with a smooth surface. Hydrofluoric (HF) acid treatment of the PAN/CNC/Ag composite nanofibers (defined as p-PAN/CNC/Ag) led to rougher fiber surfaces with certain pores and increased mean fiber diameters. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results confirmed the existence of AgNPs that were formed during heat and HF acid treatment processes. In addition, thermal stability of the electrospun nanofibers increased due to the incorporation of CNCs and AgNPs. The p-PAN/CNC/Ag nanofibers were used as a SERS substrate to detect p-aminothiophenol (p-ATP) probe molecule. The results show that this substrate exhibited high sensitivity for the p-ATP probe detection. PMID:28772428

Conductive cable fibers with insulating surface prepared by coaxial electrospinning of multiwalled nanotubes and cellulose.

PubMed

Miyauchi, Minoru; Miao, Jianjun; Simmons, Trevor J; Lee, Jong-Won; Doherty, Thomas V; Dordick, Jonathan S; Linhardt, Robert J

2010-09-13

Core-sheath multiwalled carbon nanotube (MWNT)-cellulose fibers of diameters from several hundreds of nanometers to several micrometers were prepared by coaxial electrospinning from a nonvolatile, nonflammable ionic liquid (IL) solvent, 1-methyl-3-methylimidazolium acetate ([EMIM][Ac]). MWNTs were dispersed in IL to form a gel solution. This gel core solution was electrospun surrounded by a sheath solution of cellulose dissolved in the same IL. Electrospun fibers were collected in a coagulation bath containing ethanol-water to remove the IL completely and dried to form core-sheath MWNT-cellulose fibers having a cable structure with a conductive core and insulating sheath. Enzymatic treatment of a portion of a mat of these fibers with cellulase selectively removed the cellulose sheath exposing the MWNT core for connection to an electrode. These MWNT-cellulose fiber mats demonstrated excellent conductivity because of a conductive pathway of bundled MWNTs. Fiber mat conductivity increased with increasing ratio of MWNT in the fibers with a maximum conductivity of 10.7 S/m obtained at 45 wt % MWNT loading.

In vitro evaluation of crosslinked electrospun fish gelatin scaffolds.

PubMed

Gomes, S R; Rodrigues, G; Martins, G G; Henriques, C M R; Silva, J C

2013-04-01

Gelatin from cold water fish skin was electrospun, crosslinked and investigated as a substrate for the adhesion and proliferation of cells. Gelatin was first dissolved in either water or concentrated acetic acid and both solutions were successfully electrospun. Cross-linking was achieved via three different routes: glutaraldehyde vapor, genipin and dehydrothermal treatment. Solution's properties (surface tension, electrical conductivity and viscosity) and scaffold's properties (chemical bonds, weight loss and fiber diameters) were measured. Cellular viability was analyzed culturing 3T3 fibroblasts plated on the scaffolds and grown up to 7 days. The cells were fixed and observed with SEM or stained for DNA and F-actin and observed with confocal microscopy. In all scaffolds, the cells attached and spread with varying degrees. The evaluation of cell viability showed proliferation of cells until confluence in scaffolds crosslinked by glutaraldehyde and genipin; however the rate of growth in genipin crosslinked scaffolds was slow, recovering only by day five. The results using the dehydrothermal treatment were the less satisfactory. Our results show that glutaraldehyde treated fish gelatin is the most suitable substrate, of the three studied, for fibroblast adhesion and proliferation. Copyright © 2012 Elsevier B.V. All rights reserved.

Electrospun poly(ε-caprolactone) matrices containing silver sulfadiazine complexed with β-cyclodextrin as a new pharmaceutical dosage form to wound healing: preliminary physicochemical and biological evaluation.

PubMed

Souza, Sarah Oliveira Lamas; Cotrim, Monique Alvarenga Pinto; Oréfice, Rodrigo Lambert; Carvalho, Suzana Gonçalves; Dutra, Jessyca Aparecida Paes; de Paula Careta, Francisco; Resende, Juliana Alves; Villanova, Janaina Cecília Oliveira

2018-05-10

Cooperation between researchers in the areas of medical, pharmaceutical and materials science has facilitated the development of pharmaceutical dosage forms that elicit therapeutic effects and protective action with a single product. In addition to optimizing pharmacologic action, such dosage forms provide greater patient comfort and increase success and treatment compliance. In the present work, we prepared semipermeable bioactive electrospun fibers for use as wound dressings containing silver sulfadiazine complexed with β-cyclodextrin in a poly(Ɛ-caprolactone) nanofiber matrix aiming to reduce the direct contact between silver and skin and to modulate the drug release. Wound dressings were prepared by electrospinning, and were subjected to ATR-FT-IR and TG/DTG assays to evaluate drug stability. The hydrophilicity of the fibrous nanostructure in water and PBS buffer was studied by goniometry. Electrospun fibers permeability and swelling capacity were assessed, and a dissolution test was performed. In vitro biological tests were realized to investigate the biological compatibility and antimicrobial activity. We obtained flexible matrices that were each approximately 1.0 g in weight. The electrospun fibers were shown to be semipermeable, with water vapor transmission and swelling indexes compatible with the proposed objective. The hydrophilicity was moderate. Matrices containing pure drug modulated drug release adequately during 24 h but presented a high hemolytic index. Complexation promoted a decrease in the hemolytic index and in the drug release but did not negatively impact antimicrobial activity. The drug was released predominantly by diffusion. These results indicate that electrospun PCL matrices containing β-cyclodextrin/silver sulfadiazine inclusion complexes are a promising pharmaceutical dosage form for wound healing.

Influence of electrospun fiber mesh size on hMSC oxygen metabolism in 3D collagen matrices: experimental and theoretical evidences.

PubMed

Guaccio, Angela; Guarino, Vincenzo; Perez, Marco A Alvarez-; Cirillo, Valentina; Netti, Paolo A; Ambrosio, Luigi

2011-08-01

The traditional paradigm of tissue engineering of regenerating in vitro tissue or organs, through the combination of an artificial matrix and a cellular population has progressively changed direction. The most recent concept is the realization of a fully functional biohybrid, where both, the artificial and the biotic phase, concur in the formation of the novel organic matter. In this direction, interest is growing in approaches taking advantage of the control at micro- and nano-scale of cell material interaction based on the realization of elementary tassels of cells and materials which constitute the beginning point for the expansion of 3D more complex structures. Since a spontaneous assembly of all these components is expected, however, it becomes more fundamental than ever to define the features influencing cellular behavior, either they were material functional properties, or material architecture. In this work, it has been investigated the direct effect of electrospun fiber sizes on oxygen metabolism of h-MSC cells, when any other culture parameter was kept constant. To this aim, thin PCL electrospun membranes, with micro- and nano-scale texturing, were layered between two collagen slices up to create a sandwich structure (µC-PCL-C and nC-PCL-C). Cells were seeded on membranes, and the oxygen consumption was determined by a phosphorescence quenching technique. Results indicate a strong effect of the architecture of scaffolds on cell metabolism, also revealed by the increasing of HIF1-α gene expression in nC-PCL-C. These findings offer new insights into the role of materials in specific cell activities, also implying the existence of very interesting criteria for the control of tissue growth through the tuning of scaffold architecture. Copyright © 2011 Wiley Periodicals, Inc.

Electrospun Superhydrophobic Organic/Inorganic Composite Nanofibrous Membranes for Membrane Distillation.

PubMed

Li, Xiong; Yu, Xufeng; Cheng, Cheng; Deng, Li; Wang, Min; Wang, Xuefen

2015-10-07

Electrospun superhydrophobic organic/inorganic composite nanofibrous membranes exhibiting excellent direct contact membrane distillation (DCMD) performance were fabricated by a facile route combining the hydrophobization of silica nanoparticles (SiO2 NPs) and colloid electrospinning of the hydrophobic silica/poly(vinylidene fluoride) (PVDF) matrix. Benefiting from the utilization of SiO2 NPs with three different particle sizes, the electrospun nanofibrous membranes (ENMs) were endowed with three different delicate nanofiber morphologies and fiber diameter distribution, high porosity, and superhydrophobic property, which resulted in excellent waterproofing and breathability. Significantly, structural attributes analyses have indicated the major contributing role of fiber diameter distribution on determining the augment of permeate vapor flux through regulating mean flow pore size (MFP). Meanwhile, the extremely high liquid entry pressure of water (LEPw, 2.40 ± 0.10 bar), robust nanofiber morphology of PVDF immobilized SiO2 NPs, remarkable mechanical properties, thermal stability, and corrosion resistance endowed the as-prepared membranes with prominent desalination capability and stability for long-term MD process. The resultant choreographed PVDF/silica ENMs with optimized MFP presented an outstanding permeate vapor flux of 41.1 kg/(m(2)·h) and stable low permeate conductivity (∼2.45 μs/cm) (3.5 wt % NaCl salt feed; ΔT = 40 °C) over a DCMD test period of 24 h without membrane pores wetting detected. This result was better than those of typical commercial PVDF membranes and PVDF and modified PVDF ENMs reported so far, suggesting them as promising alternatives for MD applications.

Trifunctional Epoxy Resin Composites Modified by Soluble Electrospun Veils: Effect on the Viscoelastic and Morphological Properties

PubMed Central

Ognibene, Giulia; Mannino, Salvatore

2018-01-01

Electrospun veils from copolyethersulfones (coPES) were prepared as soluble interlaminar veils for carbon fiber/epoxy composites. Neat, resin samples were impregnated into coPES veils with unmodified resin, while dry carbon fabrics were covered with electrospun veils and then infused with the unmodified epoxy resin to prepare reinforced laminates. The thermoplastic content varied from 10 wt% to 20 wt%. TGAP epoxy monomer showed improved and fast dissolution for all the temperatures tested. The unreinforced samples were cured first at 180 °C for 2 h and then were post-cured at 220 °C for 3 h. These sample showed a high dependence on the curing cycle. Carbon reinforced samples showed significant differences compared to the neat resin samples in terms of both viscoelastic and morphological properties. PMID:29522444

Electrospun Polyaniline/Polyethylene Oxide Nanofiber Field Effect Transistor

NASA Technical Reports Server (NTRS)

Pinto, N. J.; Johnson, A. T.; MacDiarmid, A. G.; Mueller, C. H.; Theofylaktos, N.; Robinson, D. C.; Miranda, F. A.

2003-01-01

We report on the observation of field effect transistor (FET) behavior in electrospun camphorsulfonic acid doped polyaniline(PANi)/polyethylene oxide(PE0) nanofibers. Saturation channel currents are observed at surprisingly low source/drain voltages. The hole mobility in the depletion regime is 1.4 x 10(exp -4) sq cm/V s while the 1-D charge density (at zero gate bias) is calculated to be approximately 1 hole per 50 two-ring repeat units of polyaniline, consistent with the rather high channel conductivity (approx. 10(exp -3) S/cm). Reducing or eliminating the PEO content in the fiber is expected to enhance device parameters. Electrospinning is thus proposed as a simple method of fabricating 1-D polymer FET's.

Conductive cable fibers with insulating surface prepared by co-axial electrospinning of multi-walled nanotubes and cellulose

PubMed Central

Miyauchi, Minoru; Miao, Jianjun; Simmons, Trevor J.; Lee, Jong-Won; Doherty, Thomas V.; Dordick, Jonathan S.; Linhardt, Robert J.

2010-01-01

A core-sheath of multi-walled carbon nanotube (MWNT)-cellulose fibers of diameters from several hundreds nm to several µm were prepared by co-axial electrospinning from a non-valatile, non-flammable ionic liquid (IL) solvent, 1-methyl-3-methylimidazolium acetate ([EMIM][Ac]). MWNTs were dispersed in IL to form a gel solution. This gel core solution was electrospun surrounded by a sheath solution of cellulose disolved in the same IL. Electrospun fibers were collected in a coagulation bath containing ethanol-water to completely remove the IL and dried to form a core-sheath MWNT-cellulose fibers having a cable structure with a conductive core and insulating sheath. Enzymatic treatment of a portion of a mat of these fibers with cellulase selectively removed the cellulose sheath exposing the MWNT core for connection to an electrode. These MWNT-cellulose fiber mats demonstrated excellent conductivity due to a conductive pathway of bundleled MWNTs. Fiber mat conductivity increased with increasing ratio of MWNT in the fibers with a maximum conductivity of 10.7 S/m obtained at 45 wt% MWNT loading. PMID:20690644

Effects of quaternization on the morphological stability and antibacterial activity of electrospun poly(DMAEMA-co-AMA) nanofibers.

PubMed

Xu, Jing-Wei; Wang, Yao; Yang, Yun-Feng; Ye, Xiang-Yu; Yao, Ke; Ji, Jian; Xu, Zhi-Kang

2015-09-01

Electrospun nanofibers with antibacterial activity are greatly promising for medical treatment and water purification. Herein we report antibacterial nanofibers electrospun from a series of poly(dimethylamino ethyl methacrylate-co-alkyl methacrylates) (poly(DMAEMA-co-AMA)) and to distinguish the effects of free and cross-linked cations derived from quanternization on the antibacterial activity. Poly(DMAEMA-co-AMA)s are simply synthesized by free radical polymerization from commercial monomers. DSC analysis indicates that they have Tg lower than room temperature and thus the electrospun nanofibers adhere to each other and evenly tend to form films, instead of keeping cylinderic shape. Benzyl chloride (BC) and p-xylylene dichloride (XDC) can quaternize DMAEMA units and to generate cations on the nanofiber surface. XPS analysis and colorimetric assay determine the quaternization degree and the surface accessible quaternary amines (N(+)), respectively. It is very promising that this quaternization endows the electrospun nanofibers with both stable morphology and antibacterial activity. The BC-quaternized fibers show better antibacterial behavior against Escherichia coli and Staphylococcus aureus than those of the XDC-quaternized/cross-linked ones, because cross-linking suppresses the chain mobility of cations. Our results confirm that antibacterial nanofibers can be facilely prepared and chain mobility of the formed cations is the necessary prerequisite for their antibacterial activity. Copyright © 2015 Elsevier B.V. All rights reserved.

Photocatalytic Applications of Electrospun TiO2 Nanofibres Embedded with Bimodal Sized and Prismatic Gold Nanoparticles.

PubMed

Gopika, G; Asha, A M; Sivakumar, N; Balakrishnan, A; Nair, S V; Subramanian, K R V

2015-09-01

In this paper, we have synthesized electrospun TiO2 nanofibers embedded with bimodal sized and prismatic gold nanoparticles. The surface plasmons generated in the gold nanoparticles were used to enhance the performance of photocatalysis. The photocatalytic conversion efficiencies of these bimodal sized/prismatic gold nanoparticles when embedded in electrospun TiO2 fibres showed an enhancement of upto 60% over bare fiber systems and also show higher efficiencies than electrospun fibrous systems embedded with unimodal sized gold nanoparticles. Anisotropic bimodal gold nanoparticles show the highest degree of photocatalytic activity. This may be attributed to greater density/concentration of nanoparticles with higher effective surface area and formation of a junction between the smaller and larger nanoparticles. Such a bimodally distributed range of nanoparticles could also lead to greater trapping of charge carriers at the TiO2 conduction band edge and promoting catalytic reactions on account of these trapped charges. This enhanced photocatalytic activity is explained by invoking different operating mechanisms such as improved surface area, greater trapping, coarse plasmon resonance and band effects. Thus, a useful applicability of the gold nanoparticles is shown in the area of photocatalysis.

Utilization of composite membrane polyethyleneglycol-polystyrene-cellulose acetate from pineapple leaf fibers in lowering levels of methyl orange batik waste

NASA Astrophysics Data System (ADS)

Delsy, E. V. Y.; Irmanto; Kazanah, F. N.

2017-02-01

Pineapple leaves are agricultural waste from the pineapple that the fibers can be utilized as raw material in cellulose acetate membranes. First, made pineapple leaf fibers into pulp and then converted into cellulose acetate by acetylation process in four stages consisting of activation, acetylation, hydrolysis and purification. Cellulose acetate then used as the raw material to manufacture composite membrane with addition of polystyrene and poly (ethylene glycol) as porogen. Composite membrane is made using phase inversion method with dichloromethane-acetone as a solvent. The result of FTIR analysis (Fourier transform infra-red) showed that the absorption of the carbonyl group (C=O) is at 1643.10 cm-1 and acetyl group (C-O ) at 1227.01 cm-1, with a molecular weight of 8.05 x 104 g/mol and the contents (rate) of acetyl is 37.31%. PS-PEG-CA composite membrane had also been characterized by measuring the water flux values and its application to decrease methyl orange content (level) in batik waste. The results showed that the water flux value is of 25.62 L/(m2.hour), and the decrease percentage of methyl orange content in batik waste is 71.53%.

Optical CO2 sensing with ionic liquid doped electrospun nanofibers.

PubMed

Aydogdu, Sibel; Ertekin, Kadriye; Suslu, Aslihan; Ozdemir, Mehtap; Celik, Erdal; Cocen, Umit

2011-03-01

The first use of electrospun nanofibrous materials as highly responsive fluorescence quenching-based optical CO(2) sensors is reported. Poly(methyl methacrylate) and ethyl cellulose were used as polymeric materials. Sensing slides were fabricated by electrospinning technique. A fiber-optic bundle was used for the gas detection. CO(2) sensors based on the change in the fluorescence signal intensity of ion pair form of 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS). The sensor slides showed high sensitivities due to the high surface area-to-volume ratio of the nanofibrous membrane structures. The preliminary results of Stern-Volmer analysis show that the sensitivities of electrospun nanofibrous membranes to detect CO(2) are 24 to 120 fold higher than those of the thin film based sensors. The response times of the sensing reagents were short and the signal changes were fully reversible. The stability of ion pair form of HPTS in the employed matrix materials was excellent and when stored in the ambient air of the laboratory there was no significant drift in signal intensity after 7 months. Our stability tests are still in progress. © Springer Science+Business Media, LLC 2010

Recent advances in electrospun nanofibers for wound healing.

PubMed

Chen, Shixuan; Liu, Bing; Carlson, Mark A; Gombart, Adrian F; Reilly, Debra A; Xie, Jingwei

2017-06-01

Electrospun nanofibers represent a novel class of materials that show great potential in many biomedical applications including biosensing, regenerative medicine, tissue engineering, drug delivery and wound healing. In this work, we review recent advances in electrospun nanofibers for wound healing. This article begins with a brief introduction on the wound, and then discusses the unique features of electrospun nanofibers critical for wound healing. It further highlights recent studies that have used electrospun nanofibers for wound healing applications and devices, including sutures, multifunctional dressings, dermal substitutes, engineered epidermis and full-thickness skin regeneration. Finally, we finish with conclusions and future perspective in this field.

Porous Electrospun Fibers Embedding TiO2 for Adsorption and Photocatalytic Degradation of Water Pollutants.

PubMed

Lee, Chang-Gu; Javed, Hassan; Zhang, Danning; Kim, Jae-Hong; Westerhoff, Paul; Li, Qilin; Alvarez, Pedro J J

2018-04-03

Using a bipolymer system consisting of polyvinylpyrrolidone (PVP) and poly(vinylidene fluoride) (PVDF), P25-TiO 2 was immobilized into thin film mats of porous electrospun fibers. Pores were introduced by dissolving sacrificial PVP to increase surface area and enhance access to TiO 2 . The highest photocatalytic activity was achieved using a PVDF:PVP weight ratio of 2:1. Methylene blue (MB) was used to visualize contaminant removal, assess the sorption capacity (5.93 ± 0.23 mg/g) and demonstrate stable removal kinetics ( k MB > 0.045 min -1 ) under UVA irradiation (3.64 × 10 -9 einstein/cm 2 /s) over 10 cycles. Treatment was also accomplished via sequential MB sorption in the dark and subsequent photocatalytic degradation under UVA irradiation, to illustrate that these processes could be uncoupled to overcome limited light penetration. The photocatalytic mat degraded bisphenol A and 17α-ethynylestradiol in secondary wastewater effluent (17 mg TOC/L), and (relative to TiO 2 slurry) immobilization of TiO 2 in the mat mitigated performance inhibition by co-occurring organics that scavenge oxidation capacity. This significantly lowered the electrical energy-per-order of reaction (EEO) needed to remove such endocrine disruptors in the presence of oxidant scavenging/inhibitory organics. Thus, effective TiO 2 immobilization into polymers with affinity toward specific priority pollutants could both increase the efficiency and reduce energy requirements of photocatalytic water treatment.

Highly efficient hybrid energy generator: coupled organic photovoltaic device and randomly oriented electrospun poly(vinylidene fluoride) nanofiber.

PubMed

Park, Boongik; Lee, Kihwan; Park, Jongjin; Kim, Jongmin; Kim, Ohyun

2013-03-01

A hybrid architecture consisting of an inverted organic photovoltaic device and a randomly-oriented electrospun PVDF piezoelectric device was fabricated as a highly-efficient energy generator. It uses the inverted photovoltaic device with coupled electrospun PVDF nanofibers as tandem structure to convert solar and mechanical vibrations energy to electricity simultaneously or individually. The power conversion efficiency of the photovoltaic device was also significantly improved up to 4.72% by optimized processes such as intrinsic ZnO, MoO3 and active layer. A simple electrospinning method with the two electrode technique was adopted to achieve a high voltage of - 300 mV in PVDF piezoelectric fibers. Highly-efficient HEG using voltage adder circuit provides the conceptual possibility of realizing multi-functional energy generator whenever and wherever various energy sources are available.

Enhancing the Stiffness of Electrospun Nanofiber Scaffolds with Controlled Surface Coating and Mineralization

PubMed Central

Liu, Wenying; Yeh, Yi-Chun; Lipner, Justin; Xie, Jingwei; Sung, Hsing-Wen; Thomopoulos, Stavros; Xia, Younan

2011-01-01

A new method was developed to coat hydroxyapatite (HAp) onto electrospun poly(lactic-co-glycolic acid) (PLGA) nanofibers for tendon-to-bone insertion site repair applications. Prior to mineralization, chitosan and heparin were covalently immobilized onto the surface of the fibers to accelerate the nucleation of bone-like HAp crystals. Uniform coatings of HAp were obtained by immersing the nanofiber scaffolds into a modified 10 times concentrated simulated body fluid (m10SBF) for different periods of time. The new method resulted in thicker and denser coatings of mineral on the fibers compared to previously reported methods. Scanning electron microscopy measurements confirmed the formation of nanoscale HAp particles on the fibers. Mechanical property assessment demonstrated higher stiffness with respect to previous coating methods. A combination of the nanoscale fibrous structure and bone-like mineral coating could mimic the structure, composition, and function of mineralized tissues. PMID:21710996

Functional Electrospun Nanofibrous Scaffolds for Biomedical Applications

PubMed Central

Liang, Dehai; Hsiao, Benjamin S.; Chu, Benjamin

2009-01-01

Functional nanofibrous scaffolds produced by electrospinning have great potential in many biomedical applications, such as tissue engineering, wound dressing, enzyme immobilization and drug (gene) delivery. For a specific successful application, the chemical, physical and biological properties of electrospun scaffolds should be adjusted to match the environment by using a combination of multi-component compositions and fabrication techniques where electrospinning has often become a pivotal tool. The property of the nanofibrous scaffold can be further improved with innovative development in electrospinning processes, such as two-component electrospinning and in-situ mixing electrospinning. Post modifications of electrospun membranes also provide effective means to render the electrospun scaffolds with controlled anisotropy and porosity. In this review, we review the materials, techniques and post modification methods to functionalize electrospun nanofibrous scaffolds suitable for biomedical applications. PMID:17884240

The fabrication and electrochemical properties of electrospun nanofibers of a multiwalled carbon nanotube grafted by chitosan

NASA Astrophysics Data System (ADS)

Feng, Wei; Wu, Zigang; Li, Yu; Feng, Yiyu; Yuan, Xiaoyan

2008-03-01

Multiwalled carbon nanotubes (MWCNTs) were grafted by chitosan (CS); the product could disperse well in poly(vinyl alcohol) (PVA) aqueous solution with 2% (v/v) acetic acid solution. Because this product has potential in several biological fields, it was electrospun so as to enlarge the surface area. Raman spectra indicated that the electrospinning process did not severely alter the electron hybridization of carbon atoms within the nanotube framework. Moreover and interestingly, these nanofibers showed a novel sheath-core structure; the outer and inner diameters of these sheath-core nanofibers were about 200 nm and 100 nm, respectively. These nanofibers' electrochemical properties were characterized by detection of hydrogen peroxide and voltammetric responses of potassium ferricyanide. The electrospun fibers' web displayed faster electron transfer kinetics and better electrochemical properties than its cast film, which justified further applications in biological areas.

Porous Aromatic Framework 48/Gel Hybrid Material Coated Solid-Phase Microextraction Fiber for the Determination of the Migration of Styrene from Polystyrene Food Contact Materials.

PubMed

Jin, Yuanyuan; Li, Zhongyue; Yang, Lei; Xu, Jun; Zhao, Le; Li, Zhonghao; Niu, Jiajia

2017-01-17

A novel solid-phase microextraction (SPME) fiber was fabricated by a porous aromatic framework 48 (PAF-48)/gel hybrid material through a sol-gel process. PAF-48 is a porous organic framework (POF) material that was polymerized from 1,3,5-triphenylbenzene. The uniform pore structure, high surface area, continuous conjugate network, and hydrophobicity make PAF-48 expected to have special abilities to absorb and extract styrene as well as some other harmful volatile aromatic compounds (VACs). The PAF-48/gel-coated fiber was explored for the extraction of styrene and six VACs (benzene, toluene, ethylbenzene, and xylenes) from aqueous food simulants followed by gas chromatography (GC) separation. The fiber was found to be very sensitive for the determination of the target molecules with wide linear ranges (0.1-200 or 500 μg·kg -1 ), low limits of detection (LODs, 0.003-0.060 μg·kg -1 ), acceptable precisions (intraday relative standard deviation, RSD < 5.9%, interday RSD < 7.3%), and long lifetime (>200 times). Particularly for styrene, the PAF-48/gel-coated fiber exhibited a much lower LOD (0.006 μg·kg -1 ) compared with most of the reported fibers. Moreover, the PAF-48/gel-coated fiber had a high extraction selectivity for styrene and VACs over alcohols, phenols, aromatic amines, and alkanes and show a molecular sieving effect for the different molecule sizes. Finally, the PAF-48/gel-coated SPME fiber was successfully applied in GC for the determination of the specific migrations of styrene and VACs from polystyrene (PS) plastic food contact materials (FCMs).

Characterization of Electrospun Nanofibrous Scaffolds for Nanobiomedical Applications

NASA Astrophysics Data System (ADS)

Emul, E.; Saglam, S.; Ates, H.; Korkusuz, F.; Saglam, N.

2016-08-01

The electrospinning method is employed in the production of porous fiber scaffolds, and the usage of electrospun scaffolds especially as drug carrier and bone reconstructive material such as implants is promising for future applications in tissue engineering. The number of publications has grown very rapidly in this field through the fabrication of complex scaffolds, novel approaches in nanotechnology, and improvements of imaging methods. Hence, characterization of these materials has also grown significantly important for getting satisfied and accurate results. This advantageous and versatile method is ideal for mimicking bone extracellular matrix, and many biodegradable and biocompatible polymers are preferred in the field of bone reconstruction. In this study, gelatin, gelatin/nanohydroxyapatite (nHAp) and gelatin/PLLA/nHAp scaffolds were fabricated by the electrospinning process. These composite fibers showed clear and continuous morphology according to observation through a scanning electron microscope and their component analyses were also determined by Fourier transform infrared spectrometer analyses. These characterization experiments revealed the great effects of the electrospinning method for biomedical applications and have an especially important role in bone reconstruction and production of implant coating material.

Cellular migration to electrospun poly(lactic acid) fibermats.

PubMed

Fujikura, Kie; Obata, Akiko; Kasuga, Toshihiro

2012-01-01

Nonwoven fabrics prepared via an electrospinning method, so-called electrospun fibermats, are expected to be promising scaffold materials for bone tissue engineering. In the present work, poly(L-lactic acid) (PLLA) fibermats, consisting of fibers with diameters ranging from 1 to 10 μm, were prepared by electrospinning. Mouse osteoblast-like cells (MC3T3-E1) were seeded on the fibermats with various fiber diameters (10, 5 and 2 μm; they are denoted by samples A, B and C, respectively) and cultured in two different directions in order to compare the migration behaviours into the scaffold of the normal condition and the anti-gravity condition. The cells in/on the fibermats were observed by laser confocal microscopy to estimate the cellular migration ability into them. When the MC3T3-E1 cells were cultured in the normal direction, the thickness of their layer increased to approx. 90 μm in the sample A, consisting of 10-μm fibers after 13 days of culture, while that in the sample C, consisting of 2-μm fibers, did not increase. When the MC3T3-E1 cells were cultured in the anti-gravity condition, the thickness of the cell layer in the sample A increased to approx. 60 μm. These results mean that the MC3T3-E1 cells migrated into the inside of sample A in either the normal direction or the anti-gravity one. The cellular proliferation showed no significant difference among the fibermats with three different fiber diameters; MC3T3-E1 cells on the fibermat with 2 μm fiber diameter grew two-dimensionally, while they grew three-dimensionally in the fibermat with 10 μm fiber diameter.

Bioinspired polydopamine sheathed nanofibers for high-efficient in vivo solid-phase microextraction of pharmaceuticals in fish muscle.

PubMed

Xu, Jianqiao; Huang, Shuyao; Wu, Rongben; Jiang, Ruifen; Zhu, Fang; Wang, Jing; Ouyang, Gangfeng

2015-03-17

In this study, electrospun nanofibers were used as solid-phase microextraction (SPME) fiber coatings after substituting the water-soluble sheath of the emulsion electrospun polystyrene (PS)@Plurinic F-127 core-sheath nanofibers with biocompatible and water-stable polydopamine (PDA) and subsequently being appropriately cross-linked with glutaraldehyde (GA) to enhance the strength of the electrospun architecture. The novel custom-made PS@PDA-GA coating was wettable in aqueous solutions and thus exhibited much higher extraction efficiency than the nonsheathed PS nanofiber coating and the thicker polydimethylsiloxane (PDMS) coating. The novel coating also possessed excellent stability (relative standard deviations (RSDs) less than 7.3% for six sampling-desorption cycles), interfiber reproducibility (RSDs less than 14.3%), and antibiofouling ability, which were beneficial for in vivo sampling. The PS@PDA-GA fiber was used to monitor pharmaceuticals in dorsal-epaxial muscle of living fish, and satisfactory sensitivities with the limits of detection in the range of 1.1 (mefenamic acid) to 8.9 (fluoxetine) ng·g(-1) and comparable accuracies to liquid extraction were achieved. In general, this study explored a convenient and effective method to sheath nanofibers for high-efficient in vivo SPME of analytes of interest in semisolid tissues.

Electrospun Polycaprolactone Scaffolds for Small-Diameter Tissue Engineered Blood Vessels

NASA Astrophysics Data System (ADS)

Lee, Carol Hsiu-Yueh

Cardiovascular disease is the leading cause of death in the United States with many patients requiring coronary artery bypass grafting. The current standard is using autografts such as the saphenous vein or intimal mammary artery, however creating a synthetic graft could eliminate this painful and inconvenient procedure. Large diameter grafts have long been established with materials such as DacronRTM and TeflonRTM, however these materials have not proved successful in small-diameter (< 6 mm) grafts where thrombosis and intimal hyperplasia are common in graft failure. With the use of a synthetic biodegradable polymer (polycaprolactone) we utilize our expertise in electrospinning and femtosecond laser ablation to create a novel tri-layered tissue engineered blood vessel containing microchannels. The benefits of creating a tri-layer is to mimic native arteries that contain an endothelium to prevent thrombosis in the inner layer, aligned smooth muscle cells in the middle to control vasodilation and constriction, and a mechanically robust outer layer. The following work evaluates the mechanical properties of such a graft (tensile, fatigue, burst pressure, and suture retention strength), the ability to rapidly align cells in laser ablated microchannels in PCL scaffolds, and the biological integration (co-culture of endothelial and smooth muscle cells) with electrospun PCL scaffolds. The conclusions from this work establish that the electrospun tri-layers provide adequate mechanical strength as a tissue engineered blood vessel, that laser ablated microchannels are able to contain the smooth muscle cells, and that cells are able to adhere to PCL fibers. However, future work includes adjusting microchannel dimensions to properly align smooth muscle cells along with perfect co-cultures of endothelial and smooth muscle cells on the electrospun tri-layer.

Chitosan functionalized poly-ε-caprolactone electrospun fibers and 3D printed scaffolds as antibacterial materials for tissue engineering applications.

PubMed

Tardajos, Myriam G; Cama, Giuseppe; Dash, Mamoni; Misseeuw, Lara; Gheysens, Tom; Gorzelanny, Christian; Coenye, Tom; Dubruel, Peter

2018-07-01

Tissue engineering (TE) approaches often employ polymer-based scaffolds to provide support with a view to the improved regeneration of damaged tissues. The aim of this research was to develop a surface modification method for introducing chitosan as an antibacterial agent in both electrospun membranes and 3D printed poly-ε-caprolactone (PCL) scaffolds. The scaffolds were functionalized by grafting methacrylic acid N-hydroxysuccinimide ester (NHSMA) onto the surface after Ar-plasma/air activation. Subsequently, the newly-introduced NHS groups were used to couple with chitosan of various molecular weights (Mw). High Mw chitosan exhibited a better coverage of the surface as indicated by the higher N% detected by X-ray photoelectron spectroscopy (XPS) and the observations with either scanning electron microscopy (SEM)(for fibers) or Coomassie blue staining (for 3D-printed scaffolds). A lactate dehydrogenase assay (LDH) using L929 fibroblasts demonstrated the cell-adhesion and cell-viability capacity of the modified samples. The antibacterial properties against S. aureus ATCC 6538 and S. epidermidis ET13 revealed a slower bacterial growth rate on the surface of the chitosan modified scaffolds, regardless the chitosan Mw. Copyright © 2018 Elsevier Ltd. All rights reserved.

Creep anomaly in electrospun fibers made of globular proteins

NASA Astrophysics Data System (ADS)

Regev, Omri; Arinstein, Arkadii; Zussman, Eyal

2013-12-01

The anomalous responses of electrospun nanofibers and film fabricated of unfolded bovine serum albumin (BSA) under constant stress (creep) is observed. In contrast to typical creep behavior of viscoelastic materials demonstrating (after immediate elastic response) a time-dependent elongation, in case of low applied stresses (<1 MPa) the immediate elastic response of BSA samples is followed by gradual contraction up to 2%. Under higher stresses (2-6 MPa) the contraction phase changes into elongation; and in case of stresses above 7 MPa only elongation was observed, with no initial contraction. The anomalous creep behavior was not observed when the BSA samples were subjected to additional creep cycles independently on the stress level. The above anomaly, which was not observed before either for viscoelastic solids or for polymers, is related to specific protein features, namely, to the ability to fold. We hypothesize that the phenomenon is caused by folding of BSA macromolecules into dry molten globule states, feasible after cross-linked bonds break up, resulting from the applied external force.

Galactosylated electrospun membranes for hepatocyte sandwich culture.

PubMed

Chien, Hsiu-Wen; Lai, Juin-Yih; Tsai, Wei-Bor

2014-04-01

In this work, we developed a galactocylated electrospun polyurethane membrane for sandwich culture of hepatocyte sandwich culture. The electrospun fibrous membranes were bio-functionalized with galactose molecules by a UV-crosslinked layer-by-layer polyelectrolyte multilayer deposition technique. The galactosylated electrospun membranes were employed as a top support membrane for the sandwich culture of HepG2/C3A cells on a collagen substrate. Our results demonstrate that HepG2/C3A cells covered by the galactosylated PU membranes form multi-cellular aggregates and lead to improved albumin secretion ability compared to the control membranes (unmodified PU or poly(ethylene imine)-modified PU). Our study reveals the potential of galactosylated electrospun membranes in the application of liver tissue engineering and the regeneration of liver-tissue substitutes. Copyright © 2014 Elsevier B.V. All rights reserved.

Damage-Resistant Composites Using Electrospun Nanofibers: A Multiscale Analysis of the Toughening Mechanisms.

PubMed

Daelemans, Lode; van der Heijden, Sam; De Baere, Ives; Rahier, Hubert; Van Paepegem, Wim; De Clerck, Karen

2016-05-11

Today, fiber-reinforced polymer composites are a standard material in applications where a high stiffness and strength are required at minimal weight, such as aerospace structures, ultralight vehicles, or even flywheels for highly efficient power storage systems. Although fiber-reinforced polymer composites show many advantages compared to other materials, delamination between reinforcing plies remains a major problem limiting further breakthrough. Traditional solutions that have been proposed to toughen the interlaminar region between reinforcing plies have already reached their limit or have important disadvantages such as a high cost or the need for adapted production processes. Recently, electrospun nanofibers have been suggested as a more viable interlaminar toughening method. Although the expected benefits are numerous, the research on composite laminates enhanced with electrospun nanofibrous veils is still very limited. The work that has been done so far is almost exclusively focused on interlaminar fracture toughness tests with different kinds of nanofibers, where typically a trial and error approach has been used. A thorough understanding of the micromechanical fracture mechanisms and the parameters to obtain toughened composites has not been reported as of yet, but it is crucial to advance the research and design highly damage-resistant composites. This article provides such insight by analyzing the nanofiber toughening effect on three different levels for several nanofiber types. Only by combining the results from different levels, a thorough understanding can be obtained. These levels correspond to the hierarchical nature of a composite: the laminate, the interlaminar region, and the matrix resin. It is found that each level corresponds to certain mechanisms that result in a toughening effect. The bridging of microcracks by electrospun nanofibers is the main toughening mechanism resulting in damage resistance. Nevertheless, the way in which the

Platinum blue staining of cells grown in electrospun scaffolds.

PubMed

Yusuf, Mohammed; Millas, Ana Luiza G; Estandarte, Ana Katrina C; Bhella, Gurdeep K; McKean, Robert; Bittencourt, Edison; Robinson, Ian K

2014-01-01

Fibroblast cells grown in electrospun polymer scaffolds were stained with platinum blue, a heavy metal stain, and imaged using scanning electron microscopy. Good contrast on the cells was achieved compared with samples that were gold sputter coated. The cell morphology could be clearly observed, and the cells could be distinguished from the scaffold fibers. Here we optimized the required concentration of platinum blue for imaging cells grown in scaffolds and show that a higher concentration causes platinum aggregation. Overall, platinum blue is a useful stain for imaging cells because of its enhanced contrast using scanning electron microscopy (SEM). In the future it would be useful to investigate cell growth and morphology using three-dimensional imaging methods.

Skeletal myotube formation enhanced by electrospun polyurethane carbon nanotube scaffolds

PubMed Central

Sirivisoot, Sirinrath; Harrison, Benjamin S

2011-01-01

Background This study examined the effects of electrically conductive materials made from electrospun single- or multiwalled carbon nanotubes with polyurethane to promote myoblast differentiation into myotubes in the presence and absence of electrical stimulation. Methods and results After electrical stimulation, the number of multinucleated myotubes on the electrospun polyurethane carbon nanotube scaffolds was significantly larger than that on nonconductive electrospun polyurethane scaffolds (5% and 10% w/v polyurethane). In the absence of electrical stimulation, myoblasts also differentiated on the electrospun polyurethane carbon nanotube scaffolds, as evidenced by expression of Myf-5 and myosin heavy chains. The myotube number and length were significantly greater on the electrospun carbon nanotubes with 10% w/v polyurethane than on those with 5% w/v polyurethane. The results suggest that, in the absence of electrical stimulation, skeletal myotube formation is dependent on the morphology of the electrospun scaffolds, while with electrical stimulation it is dependent on the electrical conductivity of the scaffolds. Conclusion This study indicates that electrospun polyurethane carbon nanotubes can be used to modulate skeletal myotube formation with or without application of electrical stimulation. PMID:22072883

21 CFR 177.1640 - Polystyrene and rubber-modified polystyrene.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Polystyrene and rubber-modified polystyrene. 177.1640 Section 177.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and...

Micropatterned stretchable circuit and strain sensor fabricated by lithography on an electrospun nanofiber mat.

PubMed

Park, Minwoo; Im, Jungkyun; Park, Jongjin; Jeong, Unyong

2013-09-11

This paper describes a novel approach for composite nanofiber mats and its application to fabricate a strain sensor. Electrospun poly(4-vinylpyridine) (P4VP) nanofiber mats are micropatterned by a lithographic approach that includes selective oxidation of the nanofibers and removal of unreacted fibers. The P4VP/HAuCl4 complex is converted to P4VP/Au composites by chemical reduction. We investigate the electrical resistivity of the composite mats according to the number of complexation-and-reduction cycles, the thickness of the fiber mats, and the annealing temperatures which control the percolation of the Au nanoparticles in the fiber mats. Nozzle printing of a polymeric solution on the patterned nanofiber mats simply produces an array of strain-sensitive and strain-invariant units. The patterns demonstrate high strain-sensing performance without any mechanical and electrical failure over 200 bending cycles in the strain range of ε<0.17.

Sodium Polystyrene Sulfonate

MedlinePlus

Sodium polystyrene sulfonate is used to treat hyperkalemia (increased amounts of potassium in the body). Sodium polystyrene sulfonate is in a class of medications called potassium-removing agents. It works by ...

Immobilization of Heparan Sulfate on Electrospun Meshes to Support Embryonic Stem Cell Culture and Differentiation*

PubMed Central

Meade, Kate A.; White, Kathryn J.; Pickford, Claire E.; Holley, Rebecca J.; Marson, Andrew; Tillotson, Donna; van Kuppevelt, Toin H.; Whittle, Jason D.; Day, Anthony J.; Merry, Catherine L. R.

2013-01-01

As our understanding of what guides the behavior of multi- and pluripotent stem cells deepens, so too does our ability to utilize certain cues to manipulate their behavior and maximize their therapeutic potential. Engineered, biologically functionalized materials have the capacity to influence stem cell behavior through a powerful combination of biological, mechanical, and topographical cues. Here, we present the development of a novel electrospun scaffold, functionalized with glycosaminoglycans (GAGs) ionically immobilized onto the fiber surface. Bound GAGs retained the ability to interact with GAG-binding molecules and, crucially, presented GAG sulfation motifs fundamental to mediating stem cell behavior. Bound GAG proved to be biologically active, rescuing the neural differentiation capacity of heparan sulfate-deficient mouse embryonic stem cells and functioning in concert with FGF4 to facilitate the formation of extensive neural processes across the scaffold surface. The combination of GAGs with electrospun scaffolds creates a biomaterial with potent applicability for the propagation and effective differentiation of pluripotent stem cells. PMID:23235146

Immobilization of heparan sulfate on electrospun meshes to support embryonic stem cell culture and differentiation.

PubMed

Meade, Kate A; White, Kathryn J; Pickford, Claire E; Holley, Rebecca J; Marson, Andrew; Tillotson, Donna; van Kuppevelt, Toin H; Whittle, Jason D; Day, Anthony J; Merry, Catherine L R

2013-02-22

As our understanding of what guides the behavior of multi- and pluripotent stem cells deepens, so too does our ability to utilize certain cues to manipulate their behavior and maximize their therapeutic potential. Engineered, biologically functionalized materials have the capacity to influence stem cell behavior through a powerful combination of biological, mechanical, and topographical cues. Here, we present the development of a novel electrospun scaffold, functionalized with glycosaminoglycans (GAGs) ionically immobilized onto the fiber surface. Bound GAGs retained the ability to interact with GAG-binding molecules and, crucially, presented GAG sulfation motifs fundamental to mediating stem cell behavior. Bound GAG proved to be biologically active, rescuing the neural differentiation capacity of heparan sulfate-deficient mouse embryonic stem cells and functioning in concert with FGF4 to facilitate the formation of extensive neural processes across the scaffold surface. The combination of GAGs with electrospun scaffolds creates a biomaterial with potent applicability for the propagation and effective differentiation of pluripotent stem cells.

Evaluation of polyacrylonitrile electrospun nano-fibrous mats as leukocyte removal filter media.

PubMed

Pourbaghi, Raha; Zarrebini, Mohammad; Semnani, Dariush; Pourazar, Abbasali; Akbari, Nahid; Shamsfar, Reihaneh

2018-07-01

Removal of leukocytes from blood products is the most effective means for elimination of undesirable side effects and prevention of possible reactions in recipients. Micro-fibrous mats are currently used for removal of leukocytes from blood. In this study, samples of electrospun nano-fibrous mats were produced. The performance of the produced electrospun nano-fibrous mats as means of leukocytes removal from fresh whole blood was both evaluated and compared with that of commercially available micro-fibrous mats. In order to produce the samples, polyacrylonitrile (PAN) nano-fibrous mats were made under different electrospinning conditions. Mean fiber diameter, pore characterization and surface roughness of the PAN nano-fibrous mats were determined using image processing technique. In order to evaluate the surface tension of the fabricated mats, water contact angle was measured. The leukocyte removal performance, erythrocytes recovery percent and hemolysis rate of the nano-fibrous mats were compared. The effectiveness of nano-fibrous mats in removing leukocyte was established using both scanning electron microscope and optical microscope. Results showed that for given weight, the fabricated nano-fibrous mats were not only more efficient but also more cost-effective than their commercial counterparts. Results confirmed that changes in mean fiber diameter, the number of layer and weight of each layer in the absence of any chemical reaction or physical surface modification, the fabricated nano-fibrous mats were able to remove 5-log of leukocytes. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1759-1769, 2018. © 2017 Wiley Periodicals, Inc.

Time-Resolved Study of Nanomorphology and Nanomechanic Change of Early-Stage Mineralized Electrospun Poly(lactic acid) Fiber by Scanning Electron Microscopy, Raman Spectroscopy and Atomic Force Microscopy

PubMed Central

Wang, Mengmeng; Cai, Yin; Zhao, Bo; Zhu, Peizhi

2017-01-01

In this study, scanning electron microscopy (SEM), Raman spectroscopy and high-resolution atomic force microscopy (AFM) were used to reveal the early-stage change of nanomorphology and nanomechanical properties of poly(lactic acid) (PLA) fibers in a time-resolved manner during the mineralization process. Electrospun PLA nanofibers were soaked in simulated body fluid (SBF) for different periods of time (0, 1, 3, 5, 7 and 21 days) at 10 °C, much lower than the conventional 37 °C, to simulate the slow biomineralization process. Time-resolved Raman spectroscopy analysis can confirm that apatites were deposited on PLA nanofibers after 21 days of mineralization. However, there is no significant signal change among several Raman spectra before 21 days. SEM images can reveal the mineral deposit on PLA nanofibers during the process of mineralization. In this work, for the first time, time-resolved AFM was used to monitor early-stage nanomorphology and nanomechanical changes of PLA nanofibers. The Surface Roughness and Young’s Modulus of the PLA nanofiber quantitatively increased with the time of mineralization. The electrospun PLA nanofibers with delicate porous structure could mimic the extracellular matrix (ECM) and serve as a model to study the early-stage mineralization. Tested by the mode of PLA nanofibers, we demonstrated that AFM technique could be developed as a potential diagnostic tool to monitor the early onset of pathologic mineralization of soft tissues. PMID:28817096

Study of Polydiacetylene-Poly (Ethylene Oxide) Electrospun Fibers Used as Biosensors

PubMed Central

Alam, A K M Mashud; Yapor, Janet P.; Reynolds, Melissa M.; Li, Yan Vivian

2016-01-01

Polydiacetylene (PDA) is an attractive conjugated material for use in biosensors due to its unique characteristic of undergoing a blue-to-red color change in response to external stimuli. 10,12-Pentacosadiynoic acid (PCDA) and poly (ethylene oxide) (PEO) were used in this study to develop fiber composites via an electrospinning method at various mass ratios of PEO to PCDA, solution concentrations, and injection speeds. The PEO-PDA fibers in blue phase were obtained via photo-polymerization upon UV-light irritation. High mass ratios of PEO to PCDA, low polymer concentrations of spinning solution, and low injection speeds promoted fine fibers with small diameters and smooth surfaces. The colorimetric transition of the fibers was investigated when the fibers were heated at temperatures ranging from 25 °C to 120 °C. A color switch from blue to red in the fibers was observed when the fibers were heated at temperatures greater than 60 °C. The color transition was more sensitive in the fibers made with a low mass ratio of PEO to PCDA due to high fraction of PDA in the fibers. The large diameter fibers also promoted the color switch due to high reflectance area in the fibers. All of the fibers were analyzed using Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) and compared before and after the color change occurred. The colorimetric transitional mechanism is proposed to occur due to conformational changes in the PDA macromolecules. PMID:28773326

Study of Polydiacetylene-Poly (Ethylene Oxide) Electrospun Fibers Used as Biosensors.

PubMed

Alam, A K M Mashud; Yapor, Janet P; Reynolds, Melissa M; Li, Yan Vivian

2016-03-16

Polydiacetylene (PDA) is an attractive conjugated material for use in biosensors due to its unique characteristic of undergoing a blue-to-red color change in response to external stimuli. 10,12-Pentacosadiynoic acid (PCDA) and poly (ethylene oxide) (PEO) were used in this study to develop fiber composites via an electrospinning method at various mass ratios of PEO to PCDA, solution concentrations, and injection speeds. The PEO-PDA fibers in blue phase were obtained via photo-polymerization upon UV-light irritation. High mass ratios of PEO to PCDA, low polymer concentrations of spinning solution, and low injection speeds promoted fine fibers with small diameters and smooth surfaces. The colorimetric transition of the fibers was investigated when the fibers were heated at temperatures ranging from 25 °C to 120 °C. A color switch from blue to red in the fibers was observed when the fibers were heated at temperatures greater than 60 °C. The color transition was more sensitive in the fibers made with a low mass ratio of PEO to PCDA due to high fraction of PDA in the fibers. The large diameter fibers also promoted the color switch due to high reflectance area in the fibers. All of the fibers were analyzed using Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) and compared before and after the color change occurred. The colorimetric transitional mechanism is proposed to occur due to conformational changes in the PDA macromolecules.

Electro-spun PLA-PEG-yarns for tissue engineering applications.

PubMed

Kruse, Magnus; Greuel, Marc; Kreimendahl, Franziska; Schneiders, Thomas; Bauer, Benedict; Gries, Thomas; Jockenhoevel, Stefan

2018-06-27

Electro-spinning is widely used in tissue-engineered applications mostly in form of non-woven structures. The development of e-spun yarn opens the door for textile fabrics which combine the micro to nanoscale dimension of electro-spun filaments with three-dimensional (3D) drapable textile fabrics. Therefore, the aim of the study was the implementation of a process for electro-spun yarns. Polylactic acid (PLA) and polyethylene glycol (PEG) were spun from chloroform solutions with varying PLA/PEG ratios (100:0, 90:10, 75:25 and 50:50). The yarn samples produced were analyzed regarding their morphology, tensile strength, water uptake and cytocompatibility. It was found that the yarn diameter decreased when the funnel collector rotation was increasd, however, the fiber diameter was not influenced. The tensile strength was also found to be dependent on the PEG content. While samples composed of 100% PLA showed a tensile strength of 2.5±0.7 cN/tex, the tensile strength increased with a decreasing PLA content (PLA 75%/PEG 25%) to 6.2±0.5 cN/tex. The variation of the PEG content also influenced the viscosity of the spinning solutions. The investigation of the cytocompatibility with endothelial cells was conducted for PLA/PEG 90:10 and 75:25 and indicated that the samples are cytocompatible.

Electrospun curcumin-loaded cellulose acetate/polyvinylpyrrolidone fibrous materials with complex architecture and antibacterial activity.

PubMed

Tsekova, Petya B; Spasova, Mariya G; Manolova, Nevena E; Markova, Nadya D; Rashkov, Iliya B

2017-04-01

Novel fibrous materials from cellulose acetate (CA) and polyvinylpyrrolidone (PVP) containing curcumin (Curc) with original design were prepared by one-pot electrospinning or dual spinneret electrospinning. The electrospun materials were characterized by scanning electron microscopy (SEM), fluorescence microscopy, Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), differential scanning calorimetry (DSC), water contact angle measurements, and microbiological tests. It was found that the incorporation of Curc into the CA and PVP solutions resulted in an increase of the solution viscosity and obtaining fibers with larger diameters (ca. 1.5μm) compared to the neat CA (ca. 800nm) and PVP fibers (ca. 500nm). The incorporation of PVP resulted in increased hydrophilicity of the fibers and in faster Curc release. Curc was found in the amorphous state in the Curc-containing fibers and these mats exhibited antibacterial activity against Staphylococcus aureus (S. aureus). The results suggest that, due to their complex architecture, the obtained new antibacterial materials are suitable for wound dressing applications, which necessitate diverse release behaviors of the bioactive compound. Copyright © 2016 Elsevier B.V. All rights reserved.

Electrospun Membranes for Environmental Protection

NASA Astrophysics Data System (ADS)

Manea, L. R.; Bertea, A.; Popa, A.; Bertea, A. P.

2018-06-01

Electrospinning is a much-used process for making nano-sized fibres as a result of its simplicity and versatility and of unique mechanical and thermodynamic properties of the obtained nanofibres. Electrospun membranes, which have a porous structure characterized by high uniformity and porosity, find applications in many membrane processes, ranging from membrane distillation to reverse osmosis. The paper reviews electrospun membranes applications in environmental protection, focusing on water and wastewater treatment and air purification. Recent progress and prospects for future development are highlighted.

Advantages and challenges offered by biofunctional core-shell fiber systems for tissue engineering and drug delivery.

PubMed

Sperling, Laura E; Reis, Karina P; Pranke, Patricia; Wendorff, Joachim H

2016-08-01

Whereas highly porous scaffolds composed of electrospun nanofibers can mimick major features of the extracellular matrix in tissue engineering, they lack the ability to incorporate and release biocompounds (drugs, growth factors) safely in a controlled way. Here, electrospun core-shell fibers (core made from water and aqueous solutions of hydrophilic polymers and the shell from materials with well-defined release mechanisms) offer unique advantages in comparison with those that have helped make porous nanofibrillar scaffolds highly successful in tissue engineering. This review considers the preparation and biofunctionalization of such core-shell fibers as well as applications in various areas, including neural, vascular, cardiac, cartilage and bone tissue engineering, and touches on the topic of clinical trials. Copyright © 2016 Elsevier Ltd. All rights reserved.

The quintuple-shape memory effect in electrospun nanofiber membranes

NASA Astrophysics Data System (ADS)

Zhang, Fenghua; Zhang, Zhichun; Liu, Yanju; Lu, Haibao; Leng, Jinsong

2013-08-01

Shape memory fibrous membranes (SMFMs) are an emerging class of active polymers, which are capable of switching from a temporary shape to their permanent shape upon appropriate stimulation. Quintuple-shape memory membranes based on the thermoplastic polymer Nafion, with a stable fibrous structure, are achieved via electrospinning technology, and possess a broad transition temperature. The recovery of multiple temporary shapes of electrospun membranes can be triggered by heat in a single triple-, quadruple-, quintuple-shape memory cycle, respectively. The fiber morphology and nanometer size provide unprecedented design flexibility for the adjustable morphing effect. SMFMs enable complex deformations at need, having a wide potential application field including smart textiles, artificial intelligence robots, bio-medical engineering, aerospace technologies, etc in the future.

Exploring the effects of electrospinning processing protocols on fiber surface morphology and polymer chain conformation

NASA Astrophysics Data System (ADS)

Stephens, Jean S.

Electrospinning is a fiber formation technique that uses electrostatic forces to create continuous, nanometer diameter fibers. The work presented here focuses on the continuing efforts to build a stronger fundamental understanding of electrospinning by exploring structure/property/process relationships by investigating the effects of process protocols on fiber surface morphology and polymer chain conformation. By varying the processing parameters it has been possible to produce fibers with unique surface features, microtextured/nanoporous fibers and nanowebs. In the microtextured/nanoporous fiber studies, changing the solution concentration, solvent volatility, and relative humidity was found to alter the size, shape, and distribution of pores on the fiber surface. The mechanisms that can explain the pore formation and texturing on the surface of the fibers are phase separation (aggregation into polymer rich and polymer lean regions) and breath figures (evaporative cooling and vapor condensation). Through a judicious choice of the electrospinning processing parameters we have also been able to create "web" like structures of nanofibers (5--25 nm) from collagen, dragline silk analog, nylon, and denatured collagen. Electrostatic repulsion and thin film dewetting are thought to be responsible for the formation of the nanowebs. These unique structures were characterized using FESEM, TEM, OM, and AFM. Raman spectroscopy, initially developed as a "real time" characterization technique to study electrospun fiber formation, has also been used to investigate the effect of electrospinning on the chain conformation of bioinspired polymers. Comparing the spectrum of the bulk material to that of the electrospun material identified conformational changes in nylon 6 and dragline silk analog. The conformational change in nylon 6 (alpha-form to gamma-form) results from the stresses induced on the electrospinning jet during fiber formation, whereas the conformational change in the

Potential of Electrospun Nanofibers for Biomedical and Dental Applications

PubMed Central

Zafar, Muhammad; Najeeb, Shariq; Khurshid, Zohaib; Vazirzadeh, Masoud; Zohaib, Sana; Najeeb, Bilal; Sefat, Farshid

2016-01-01

Electrospinning is a versatile technique that has gained popularity for various biomedical applications in recent years. Electrospinning is being used for fabricating nanofibers for various biomedical and dental applications such as tooth regeneration, wound healing and prevention of dental caries. Electrospun materials have the benefits of unique properties for instance, high surface area to volume ratio, enhanced cellular interactions, protein absorption to facilitate binding sites for cell receptors. Extensive research has been conducted to explore the potential of electrospun nanofibers for repair and regeneration of various dental and oral tissues including dental pulp, dentin, periodontal tissues, oral mucosa and skeletal tissues. However, there are a few limitations of electrospinning hindering the progress of these materials to practical or clinical applications. In terms of biomaterials aspects, the better understanding of controlled fabrication, properties and functioning of electrospun materials is required to overcome the limitations. More in vivo studies are definitely required to evaluate the biocompatibility of electrospun scaffolds. Furthermore, mechanical properties of such scaffolds should be enhanced so that they resist mechanical stresses during tissue regeneration applications. The objective of this article is to review the current progress of electrospun nanofibers for biomedical and dental applications. In addition, various aspects of electrospun materials in relation to potential dental applications have been discussed. PMID:28787871

Interfacial adhesion of carbon fibers

NASA Technical Reports Server (NTRS)

Bascom, Willard D.

1987-01-01

Relative adhesion strengths between AS4, AS1, and XAS carbon fibers and thermoplastic polymers were determined using the embedded single filament test. Polymers studied included polycarbonate, polyphenylene oxide, polyetherimide, polysulfone, polyphenylene oxide blends with polystyrene, and polycarbonate blends with a polycarbonate polysiloxane block copolymer. Fiber surface treatments and sizings improved adhesion somewhat, but adhesion remained well below levels obtained with epoxy matrices. An explanation for the differences between the Hercules and Grafil fibers was sought using X ray photon spectroscopy, wetting, scanning electron microscopy and thermal desorption analysis.

Tendon tissue engineering: Adipose 1 derived stem cell and GDF-5 mediated regeneration using electrospun matrix systems

PubMed Central

James, R; Kumbar, S G; Laurencin, C T; Balian, G; Chhabra, A B

2011-01-01

Tendon tissue engineering with a biomaterial scaffold that mimics the tendon extracellular matrix (ECM) and is biomechanically suitable when combined with readily available autologous cells may provide successful regeneration of defects in tendon. Current repair strategies using suitable autografts and freeze-dried allografts lead to a slow repair process that is sub-optimal and fails to restore function, particularly in difficult clinical situations such as zone II flexor tendon injuries of the hand. We have investigated the effect of GDF-5 on cell proliferation and gene expression by primary rat adipose-derived stromal cells (ADSCs) that were cultured on poly(DL-lactide-co-glycolide) PLAGA fiber scaffold and compared to PLAGA 2D film scaffold. The electrospun scaffold mimics the collagen fiber bundles present in native tendon tissue, and supports the adhesion and proliferation of multipotent ADSCs. Gene expression of scleraxis, the neotendon marker was upregulated 7 – 8 fold at 1 week with GDF-5 treatment when cultured on 3D electrospun scaffold, and was significantly higher at 2 weeks compared to 2D films with or without GDF-5 treatment. Expression of the genes that encode the major tendon ECM protein, collagen type I, was increased by 4 fold starting at 1 week on treatment with 100ng/mL GDF-5, and at all time points the expression was significantly higher compared to 2D films irrespective of GDF-5 treatment. Thus stimulation with GDF-5 can modulate primary ADSCs on PLAGA fiber scaffold to produce a soft, collagenous musculoskeletal tissue that fulfills the need for tendon regeneration. PMID:21436509

Assessing the Increase in Specific Surface Area for Electrospun Fibrous Network due to Pore Induction.

PubMed

Katsogiannis, Konstantinos Alexandros G; Vladisavljević, Goran T; Georgiadou, Stella; Rahmani, Ramin

2016-10-26

The effect of pore induction on increasing electrospun fibrous network specific surface area was investigated in this study. Theoretical models based on the available surface area of the fibrous network and exclusion of the surface area lost due to fiber-to-fiber contacts were developed. The models for calculation of the excluded area are based on Hertzian, Derjaguin-Muller-Toporov (DMT), and Johnson-Kendall-Roberts (JKR) contact models. Overall, the theoretical models correlated the network specific surface area to the material properties including density, surface tension, Young's modulus, Poisson's ratio, as well as network physical properties, such as density and geometrical characteristics including fiber radius, fiber aspect ratio and network thickness. Pore induction proved to increase the network specific surface area up to 52%, compared to the maximum surface area that could be achieved by nonporous fiber network with the same physical properties and geometrical characteristics. The model based on Johnson-Kendall-Roberts contact model describes accurately the fiber-to-fiber contact area under the experimental conditions used for pore generation. The experimental results and the theoretical model based on Johnson-Kendall-Roberts contact model show that the increase in network surface area due to pore induction can reach to up to 58%.

Improved capacitance characteristics of electrospun ACFs by pore size control and vanadium catalyst.

PubMed

Im, Ji Sun; Woo, Sang-Wook; Jung, Min-Jung; Lee, Young-Seak

2008-11-01

Nano-sized carbon fibers were prepared by using electrospinning, and their electrochemical properties were investigated as a possible electrode material for use as an electric double-layer capacitor (EDLC). To improve the electrode capacitance of EDLC, we implemented a three-step optimization. First, metal catalyst was introduced into the carbon fibers due to the excellent conductivity of metal. Vanadium pentoxide was used because it could be converted to vanadium for improved conductivity as the pore structure develops during the carbonization step. Vanadium catalyst was well dispersed in the carbon fibers, improving the capacitance of the electrode. Second, pore-size development was manipulated to obtain small mesopore sizes ranging from 2 to 5 nm. Through chemical activation, carbon fibers with controlled pore sizes were prepared with a high specific surface and pore volume, and their pore structure was investigated by using a BET apparatus. Finally, polyacrylonitrile was used as a carbon precursor to enrich for nitrogen content in the final product because nitrogen is known to improve electrode capacitance. Ultimately, the electrospun activated carbon fibers containing vanadium show improved functionality in charge/discharge, cyclic voltammetry, and specific capacitance compared with other samples because of an optimal combination of vanadium, nitrogen, and fixed pore structures.

From single fiber to macro-level mechanics: A structural finite-element model for elastomeric fibrous biomaterials

PubMed Central

D'Amore, Antonio; Amoroso, Nicholas; Gottardi, Riccardo; Hobson, Christopher; Carruthers, Christopher; Watkins, Simon; Wagner, William R.; Sacks, Michael S.

2014-01-01

In the present work, we demonstrate that the mesoscopic in-plane mechanical behavior of membrane elastomeric scaffolds can be simulated by replication of actual quantified fibrous geometries. Elastomeric electrospun polyurethane (ES-PEUU) scaffolds, with and without particulate inclusions, were utilized. Simulations were developed from experimentally-derived fiber network geometries, based on a range of scaffold isotropic and anisotropic behaviors. These were chosen to evaluate the effects on macro-mechanics based on measurable geometric parameters such as fiber intersections, connectivity, orientation, and diameter. Simulations were conducted with only the fiber material model parameters adjusted to match the macro-level mechanical test data. Fiber model validation was performed at the microscopic level by individual fiber mechanical tests using AFM. Results demonstrated very good agreement to the experimental data, and revealed the formation of extended preferential fiber orientations spanning the entire model space. We speculate that these emergent structures may be responsible for the tissue-like macroscale behaviors observed in electrospun scaffolds. To conclude, the modeling approach has implications for (1) gaining insight on the intricate relationship between fabrication variables, structure, and mechanics to manufacture more functional devices/materials, (2) elucidating the effects of cell or particulate inclusions on global construct mechanics, and (3) fabricating better performing tissue surrogates that could recapitulate native tissue mechanics. PMID:25128869

Tendon tissue engineering: adipose-derived stem cell and GDF-5 mediated regeneration using electrospun matrix systems.

PubMed

James, R; Kumbar, S G; Laurencin, C T; Balian, G; Chhabra, A B

2011-04-01

Tendon tissue engineering with a biomaterial scaffold that mimics the tendon extracellular matrix (ECM) and is biomechanically suitable, and when combined with readily available autologous cells, may provide successful regeneration of defects in tendon. Current repair strategies using suitable autografts and freeze-dried allografts lead to a slow repair process that is sub-optimal and fails to restore function, particularly in difficult clinical situations such as zone II flexor tendon injuries of the hand. We have investigated the effect of GDF-5 on cell proliferation and gene expression by primary rat adipose-derived stem cells (ADSCs) that were cultured on a poly(DL-lactide-co-glycolide) PLAGA fiber scaffold and compared to a PLAGA 2D film scaffold. The electrospun scaffold mimics the collagen fiber bundles present in native tendon tissue, and supports the adhesion and proliferation of multipotent ADSCs. Gene expression of scleraxis, the neotendon marker, was upregulated seven- to eightfold at 1 week with GDF-5 treatment when cultured on a 3D electrospun scaffold, and was significantly higher at 2 weeks compared to 2D films with or without GDF-5 treatment. Expression of the genes that encode the major tendon ECM protein, collagen type I, was increased by fourfold starting at 1 week on treatment with 100 ng mL(-1) GDF-5, and at all time points the expression was significantly higher compared to 2D films irrespective of GDF-5 treatment. Thus stimulation with GDF-5 can modulate primary ADSCs on a PLAGA fiber scaffold to produce a soft, collagenous musculoskeletal tissue that fulfills the need for tendon regeneration.

Comparison of cell behavior on pva/pva-gelatin electrospun nanofibers with random and aligned configuration

NASA Astrophysics Data System (ADS)

Huang, Chen-Yu; Hu, Keng-Hsiang; Wei, Zung-Hang

2016-12-01

Electrospinning technique is able to create nanofibers with specific orientation. Poly(vinyl alcohol) (PVA) have good mechanical stability but poor cell adhesion property due to the low affinity of protein. In this paper, extracellular matrix, gelatin is incorporated into PVA solution to form electrospun PVA-gelatin nanofibers membrane. Both randomly oriented and aligned nanofibers are used to investigate the topography-induced behavior of fibroblasts. Surface morphology of the fibers is studied by optical microscopy and scanning electron microscopy (SEM) coupled with image analysis. Functional group composition in PVA or PVA-gelatin is investigated by Fourier Transform Infrared (FTIR). The morphological changes, surface coverage, viability and proliferation of fibroblasts influenced by PVA and PVA-gelatin nanofibers with randomly orientated or aligned configuration are systematically compared. Fibroblasts growing on PVA-gelatin fibers show significantly larger projected areas as compared with those cultivated on PVA fibers which p-value is smaller than 0.005. Cells on PVA-gelatin aligned fibers stretch out extensively and their intracellular stress fiber pull nucleus to deform. Results suggest that instead of the anisotropic topology within the scaffold trigger the preferential orientation of cells, the adhesion of cell membrane to gelatin have substantial influence on cellular behavior.

Integration of nondegradable polystyrene and degradable gelatin in a core–sheath nanofibrous patch for pelvic reconstruction

PubMed Central

Ge, Liangpeng; Li, Qingtao; Jiang, Junzi; You, Xiaoyan; Liu, Zuohua; Zhong, Wen; Huang, Yong; Xing, Malcolm MQ

2015-01-01

Pelvic organ prolapse (POP) is a serious health issue affecting many adult women. Complications of POP include pelvic pressure, pelvic pain, and problems in emptying their bowels or bladder. Sometimes, POP may even cause urinary outflow obstruction and lead to bladder or kidney infections. Currently, synthetic and naturally derived materials have been chosen for treatment of POP to reduce the high recurrence rates after surgical interventions. However, existing materials for POP treatment cannot meet the clinical requirements in terms of biocompatibility, mechanics, and minimal risk of rejection. Especially, erosion in synthetic polymers and rapid degradation in natural polymers limit their further applications in clinics. To address these concerns, we report a novel POP replacement using core–sheath polystyrene/gelatin electrospun nanofiber mesh. The outside gelatin sheath provides a hydrophilic surface and implantable integrity between host and guest, while the inner PS core offers the necessary mechanical support. The composite mesh shows graft accommodation in pelvic submucosa after implantation in vivo, as shown in hematoxylin–eosin staining and T helper cell phenotype and macrophage phenotype stainings. Qualitative analysis of inducible nitric oxide synthase, arginase, interferon-γ, and interleukin-10 gene expressions also indicates that the implanted composite mesh switches to accommodation mode 2 weeks postimplantation. Thus, these novel core–sheath polystyrene/gelatin nanofibrous membranes are promising in pelvic reconstruction. PMID:25995629

Fabrication of micro/nano optical fiber by mechano-electrospinning

NASA Astrophysics Data System (ADS)

Chen, Qinnan; Wu, Dezhi; Yu, Zhe; Mei, Xuecui; Fang, Ke; Sun, Daoheng

2017-10-01

We study a novel fabrication method of micro/nano optical fiber by mechano-electrospinning (MES) direct-written technology. MES process is able to precisely manipulate the position and diameter of the electro-spun micro/nano fiber by adjusting the mechanical drawing force, which through changing the speed of motion stage (substrate). By adjusting the substrate speed, the nozzle-to-substrate distance and the applied voltage, the poly(methyl methacrylate) (PMMA) micro/nano optical fibers (MNOF) with controlled diameter are obtained and the tapered MNOF are fabricated by continuously changing the substrate speed. The transmission characteristics of PMMA micro/nano fiber is experimentally demonstrated, and a PMMA micro/nano fiber based refractive index sensor is designed. Our works shows the new fabrication method of MNOF by MES has the potential in the field of light mode conversion, optical waveguide coupling, refractive index detection and new micro/nano optical fiber components.

From single fiber to macro-level mechanics: A structural finite-element model for elastomeric fibrous biomaterials.

PubMed

D'Amore, Antonio; Amoroso, Nicholas; Gottardi, Riccardo; Hobson, Christopher; Carruthers, Christopher; Watkins, Simon; Wagner, William R; Sacks, Michael S

2014-11-01

In the present work, we demonstrate that the mesoscopic in-plane mechanical behavior of membrane elastomeric scaffolds can be simulated by replication of actual quantified fibrous geometries. Elastomeric electrospun polyurethane (ES-PEUU) scaffolds, with and without particulate inclusions, were utilized. Simulations were developed from experimentally-derived fiber network geometries, based on a range of scaffold isotropic and anisotropic behaviors. These were chosen to evaluate the effects on macro-mechanics based on measurable geometric parameters such as fiber intersections, connectivity, orientation, and diameter. Simulations were conducted with only the fiber material model parameters adjusted to match the macro-level mechanical test data. Fiber model validation was performed at the microscopic level by individual fiber mechanical tests using AFM. Results demonstrated very good agreement to the experimental data, and revealed the formation of extended preferential fiber orientations spanning the entire model space. We speculate that these emergent structures may be responsible for the tissue-like macroscale behaviors observed in electrospun scaffolds. To conclude, the modeling approach has implications for (1) gaining insight on the intricate relationship between fabrication variables, structure, and mechanics to manufacture more functional devices/materials, (2) elucidating the effects of cell or particulate inclusions on global construct mechanics, and (3) fabricating better performing tissue surrogates that could recapitulate native tissue mechanics. Copyright © 2014 Elsevier Ltd. All rights reserved.

Electrospun Polymer Blend Nanofibers for Tunable Drug Delivery: The Role of Transformative Phase Separation on Controlling the Release Rate.

PubMed

Tipduangta, Pratchaya; Belton, Peter; Fábián, László; Wang, Li Ying; Tang, Huiru; Eddleston, Mark; Qi, Sheng

2016-01-04

Electrospun fibrous materials have a wide range of biomedical applications, many of them involving the use of polymers as matrices for incorporation of therapeutic agents. The use of polymer blends improves the tuneability of the physicochemical and mechanical properties of the drug loaded fibers. This also benefits the development of controlled drug release formulations, for which the release rate can be modified by altering the ratio of the polymers in the blend. However, to realize these benefits, a clear understanding of the phase behavior of the processed polymer blend is essential. This study reports an in depth investigation of the impact of the electrospinning process on the phase separation of a model partially miscible polymer blend, PVP K90 and HPMCAS, in comparison to other conventional solvent evaporation based processes including film casting and spin coating. The nanoscale stretching and ultrafast solvent removal of electrospinning lead to an enhanced apparent miscibility between the polymers, with the same blends showing micronscale phase separation when processed using film casting and spin coating. Nanoscale phase separation in electrospun blend fibers was confirmed in the dry state. Rapid, layered, macroscale phase separation of the two polymers occurred during the wetting of the fibers. This led to a biphasic drug release profile from the fibers, with a burst release from PVP-rich phases and a slower, more continuous release from HPMCAS-rich phases. It was noted that the model drug, paracetamol, had more favorable partitioning into the PVP-rich phase, which is likely to be a result of greater hydrogen bonding between PVP and paracetamol. This led to higher drug contents in the PVP-rich phases than the HPMCAS-rich phases. By alternating the proportions of the PVP and HPMCAS, the drug release rate can be modulated.

Diameter-Dependent Modulus and Melting Behavior in Electrospun Semicrystalline Polymer Fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Y Liu; S Chen; E Zussman

2011-12-31

Confinement of the semicrystalline polymers, poly(ethylene-co-vinyl acetate) (PEVA) and low-density polyethylene (LDPE), produced by electrospinning has been observed to produce fibers with large protrusions, which have not been previously observed in fibers of comparable diameters produced by other methods. SAXS spectra confirmed the crystalline structure and determined that the lamellar spacing was almost unchanged from the bulk. Measurement of the mechanical properties of these fibers, by both shear modulation force microscopy (SMFM) and atomic force acoustic microscopy (AFAM), indicates that the modulii of these fibers increases with decreasing diameter, with the onset at {approx}10 {micro}m, which is an order ofmore » magnitude larger than previously reported. Melting point measurements indicate a decrease of more than 7% in T{sub m}/T{sub 0} (where T{sub m} is the melting point of semicrystalline polymer fibers and T{sub 0} is the melting point of the bulk polymer) for fibers ranging from 4 to 10 {micro}m in diameter. The functional form of the decrease followed a universal curve for PEVA, when scaled with T{sub 0}.« less

Electrospun composite matrices of poly(ε-caprolactone)-montmorillonite made using tenside free Pickering emulsions.

PubMed

Samanta, Archana; Takkar, Sonam; Kulshreshtha, Ritu; Nandan, Bhanu; Srivastava, Rajiv K

2016-12-01

The production of composite electrospun matrices of poly(ε-caprolactone) (PCL) using an emulsifier-free emulsion, made with minimal organic solvent, as precursor is reported. Pickering emulsions of PCL were prepared using modified montmorillonite (MMT) clay as the stabilizer. Hydrophobic tallow group of the modified MMT clay resulted in analogous interaction of clay with oil and aqueous phase and its adsorption at the interface to provide stability to the resultant emulsion. Composite fibrous matrices of PCL and MMT were produced using electrospinning under controlled conditions. The fiber fineness was found to alter with PCL concentration and volume fraction of the aqueous and oil phases. A higher tensile strength and modulus was obtained with inclusion of MMT in PCL electrospun matrix in comparison to a matrix made using neat PCL. The presence of clay in the fibrous matrix did not change the cell proliferation efficiency in comparison to neat PCL matrix. Composite fibrous matrices of PCL/MMT bearing enhanced tensile properties may find applications in areas other than tissue engineering for example food packaging and filtration. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of polystyrene scintillator fiber array and monolithic polystyrene for neutron imaging and radiography.

PubMed

Simpson, R; Cutler, T E; Danly, C R; Espy, M A; Goglio, J H; Hunter, J F; Madden, A C; Mayo, D R; Merrill, F E; Nelson, R O; Swift, A L; Wilde, C H; Zocco, T G

2016-11-01

The neutron imaging diagnostic at the National Ignition Facility has been operating since 2011 generating neutron images of deuterium-tritium (DT) implosions at peak compression. The current design features a scintillating fiber array, which allows for high imaging resolution to discern small-scale structure within the implosion. In recent years, it has become clear that additional neutron imaging systems need to be constructed in order to provide 3D reconstructions of the DT source and these additional views need to be on a shorter line of sight. As a result, there has been increased effort to identify new image collection techniques that improve upon imaging resolution for these next generation neutron imaging systems, such as monolithic deuterated scintillators. This work details measurements performed at the Weapons Neutron Research Facility at Los Alamos National Laboratory that compares the radiographic abilities of the fiber scintillator with a monolithic scintillator, which may be featured in a future short line of sight neutron imaging systems.

Comparison of polystyrene scintillator fiber array and monolithic polystyrene for neutron imaging and radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simpson, R., E-mail: raspberry@lanl.gov; Cutler, T. E.; Danly, C. R.

The neutron imaging diagnostic at the National Ignition Facility has been operating since 2011 generating neutron images of deuterium-tritium (DT) implosions at peak compression. The current design features a scintillating fiber array, which allows for high imaging resolution to discern small-scale structure within the implosion. In recent years, it has become clear that additional neutron imaging systems need to be constructed in order to provide 3D reconstructions of the DT source and these additional views need to be on a shorter line of sight. As a result, there has been increased effort to identify new image collection techniques that improvemore » upon imaging resolution for these next generation neutron imaging systems, such as monolithic deuterated scintillators. This work details measurements performed at the Weapons Neutron Research Facility at Los Alamos National Laboratory that compares the radiographic abilities of the fiber scintillator with a monolithic scintillator, which may be featured in a future short line of sight neutron imaging systems.« less

Comparison of polystyrene scintillator fiber array and monolithic polystyrene for neutron imaging and radiography

NASA Astrophysics Data System (ADS)

Simpson, R.; Cutler, T. E.; Danly, C. R.; Espy, M. A.; Goglio, J. H.; Hunter, J. F.; Madden, A. C.; Mayo, D. R.; Merrill, F. E.; Nelson, R. O.; Swift, A. L.; Wilde, C. H.; Zocco, T. G.

2016-11-01

The neutron imaging diagnostic at the National Ignition Facility has been operating since 2011 generating neutron images of deuterium-tritium (DT) implosions at peak compression. The current design features a scintillating fiber array, which allows for high imaging resolution to discern small-scale structure within the implosion. In recent years, it has become clear that additional neutron imaging systems need to be constructed in order to provide 3D reconstructions of the DT source and these additional views need to be on a shorter line of sight. As a result, there has been increased effort to identify new image collection techniques that improve upon imaging resolution for these next generation neutron imaging systems, such as monolithic deuterated scintillators. This work details measurements performed at the Weapons Neutron Research Facility at Los Alamos National Laboratory that compares the radiographic abilities of the fiber scintillator with a monolithic scintillator, which may be featured in a future short line of sight neutron imaging systems.

Electrospun PCL/Gelatin composite fibrous scaffolds: mechanical properties and cellular responses.

PubMed

Yao, Ruijuan; He, Jing; Meng, Guolong; Jiang, Bo; Wu, Fang

2016-06-01

Electrospinning of hybrid polymer has gained widespread interest by taking advantages of the biological property of the natural polymer and the mechanical property of the synthetic polymer. However, the effect of the blend ratio on the above two properties has been less reported despite the importance to balance these two properties in various tissue engineering applications. To this aim, we investigated the electrospun PCL/Gelatin composite fibrous scaffolds with different blend ratios of 4:1, 2:1, 1:1, 1:2, 1:4, respectively. The morphology of the electrospun samples was observed by SEM and the result showed that the fiber diameter distribution became more uniform with the increase of the gelatin content. The mechanical testing results indicated that the 2:1 PCL/Gelatin sample had both the highest tensile strength of 3.7 MPa and the highest elongation rate of about 90%. Surprisingly, the 2:1 PCL/Gelatin sample also showed the best mesenchymal stem cell responses in terms of attachment, spreading, and cytoskeleton organization. Such correlation might be partly due to the fact that the enhanced mechanical property, an integral part of the physical microenvironment, likely played an important role in regulating the cellular functions. Overall, our results indicated that the PCL/Gelatin sample with the blend ratio of 2:1 was a superior candidate for scaffolds for tissue engineering applications.

Electrospun Nafion®/Polyphenylsulfone Composite Membranes for Regenerative Hydrogen Bromine Fuel Cells.

PubMed

Park, Jun Woo; Wycisk, Ryszard; Pintauro, Peter N; Yarlagadda, Venkata; Van Nguyen, Trung

2016-02-29

The regenerative H₂/Br₂-HBr fuel cell, utilizing an oxidant solution of Br₂ in aqueous HBr, shows a number of benefits for grid-scale electricity storage. The membrane-electrode assembly, a key component of a fuel cell, contains a proton-conducting membrane, typically based on the perfluorosulfonic acid (PFSA) ionomer. Unfortunately, the high cost of PFSA membranes and their relatively high bromine crossover are serious drawbacks. Nanofiber composite membranes can overcome these limitations. In this work, composite membranes were prepared from electrospun dual-fiber mats containing Nafion ® PFSA ionomer for facile proton transport and an uncharged polymer, polyphenylsulfone (PPSU), for mechanical reinforcement, and swelling control. After electrospinning, Nafion/PPSU mats were converted into composite membranes by softening the PPSU fibers, through exposure to chloroform vapor, thus filling the voids between ionomer nanofibers. It was demonstrated that the relative membrane selectivity, referenced to Nafion ® 115, increased with increasing PPSU content, e.g., a selectivity of 11 at 25 vol% of Nafion fibers. H₂-Br₂ fuel cell power output with a 65 μm thick membrane containing 55 vol% Nafion fibers was somewhat better than that of a 150 μm Nafion ® 115 reference, but its cost advantage due to a four-fold decrease in PFSA content and a lower bromine species crossover make it an attractive candidate for use in H₂/Br₂-HBr systems.

Preparation and characterization of photocatalytic carbon dots-sensitized electrospun titania nanostructured fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Haopeng; Zhu, Yihua, E-mail: yhzhu@ecust.edu.cn; Cao, Huimin

2013-02-15

Graphical abstract: Display Omitted Highlights: ► The TiO{sub 2}-CDs nanostructured fibers are fabricated by using APS combining the electrospinning TiO{sub 2} nanostructured fibers and CDs. ► The CD can work as a photosensitizer in the degradation of rhodamine B under visible light irradiation. ► The TiO{sub 2}-CDs nanostructured fibers exhibit enhanced photocatalytic efficiency and can be easily handled and recycled. -- Abstract: The carbon dots (CDs) are new functional carbon-aceous materials. Compared to conventional dye molecules and semiconductor quantum dots, CDs are superior in chemical inertness and low toxicity. The TiO{sub 2}-CDs nanostructured fibers were fabricated by combining the electrospinningmore » technique and reflux method. Compared with the pure TiO{sub 2} nanostructured fibers and P25, the TiO{sub 2}-CDs nanostructured fibers exhibited enhanced photocatalytic efficiency of photodegradation of rhodamine B (RhB) under visible light irradiation. The enhanced photocatalytic activity of TiO{sub 2}-CDs nanostructured fibers could be attributed to the presence of CDs embedded in TiO{sub 2} nanostructured fibers. The CD can work as a photosensitizer in the degradation. Furthermore, the TiO{sub 2}-CDs nanostructured fibers could be easily handled and recycled due to their one-dimensional nanostructural property.« less

Electrospun polyvinylpyrrolidone (PVP)/green tea extract composite nanofiber mats and their antioxidant activities

NASA Astrophysics Data System (ADS)

Pusporini, Pusporini; Edikresnha, Dhewa; Sriyanti, Ida; Suciati, Tri; Miftahul Munir, Muhammad; Khairurrijal, Khairurrijal

2018-05-01

Electrospinning was employed to make PVP (polyvinylpyrrolidone)/GTE (green tea extract) composite nanofiber mats. The electrospun PVP nanofiber mat as well as the PVP/GTE nanofiber mats were uniform. The average fiber diameter of PVP/GTE composite nanofiber mat decreased with increasing the GTE weight fraction (or decreasing the PVP weight fraction) in the PVP/GTE solution because the PVP/GTE solution concentration decreased. Then, the broad FTIR peak representing the stretching vibrations of O–H in hydroxyl groups of phenols and the stretching of N–H in amine groups of the GTE paste shifted to higher wavenumbers in the PVP/GTE composite nanofiber mats. These peak shifts implied that PVP and catechins of GTE in the PVP/GTE composite nanofiber mats had intermolecular interactions via hydrogen bonds between carbonyl groups of PVP and hydroxyl groups of catechins in GTE. Lastly, the antioxidant activity of the PVP/GTE composite nanofiber mat increased with reducing the average fiber diameter because the amount of catechins in the composite nanofiber mat increased with the increase of surface area due to the reduction of the average fiber diameter.

Electrospun PVDF fibers and a novel PVDF/CoFe2O4 fibrous composite as nanostructured sorbent materials for oil spill cleanup

NASA Astrophysics Data System (ADS)

Dorneanu, Petronela Pascariu; Cojocaru, Corneliu; Olaru, Niculae; Samoila, Petrisor; Airinei, Anton; Sacarescu, Liviu

2017-12-01

In this work, pure polyvinylidene fluoride (PVDF) and PVDF/cobalt ferrite (CoFe2O4) magnetic fibrous composite were successfully prepared by electrospinning method for oil spill sorption applications. The pure spinel phase of CoFe2O4 and PVDF/CoFe2O4 composites were confirmed by X-ray diffraction analysis (XRD). Electrospun sorbent materials were characterized by scanning and transmission electron microscopy (SEM and TEM) as well as by contact angle measurements. In addition, the composite sorbent (PVDF/CoFe2O4) was characterized by magnetic measurements. It revealed good magnetic properties that are of real interest to facilitate the separation of the oil-loaded sorbent under the external magnetic field. Finally, the produced electrospun sorbents were tested for sorption of oily liquids, such as: decane, dodecane and commercial motor oils. We obtained good oil sorption capacity (between 9.751-23.615 g/g of pure PVDF) and (8.133-18.074 g/g for the magnetic composite) depending on the nature of oil tested. The present electrospun magnetic PVDF/CoFe2O4 fibrous composite could be potentially useful for the efficient removal of oil in water and recovery of sorbent material.

Novel nanoporous sorbent for solid-phase extraction in petroleum fingerprinting

NASA Astrophysics Data System (ADS)

Alayande, S. Oluwagbemiga; Hlengilizwe, Nyoni; Dare, E. Olugbenga; Msagati, Titus A. M.; Akinlabi, A. Kehinde; Aiyedun, P. O.

2016-04-01

Sample preparation is crucial in the analysis of petroleum and its derivatives. In this study, developing affordable sorbent for petroleum fingerprinting analysis using polymer waste such expanded polystyrene was explored. The potential of electrospun expanded polystyrene (EPS) as a sorbent for the solid-phase extraction (SPE) technique was investigated, and its efficiency was compared with commercial cartridges such as alumina, silica and alumina/silica hybrid commercial for petroleum fingerprinting analysis. The chromatograms showed that the packed electrospun EPS fibre demonstrated excellent properties for SPE applications relative to the hybrid cartridges.

A novel electrospun nerve conduit enhanced by carbon nanotubes for peripheral nerve regeneration

NASA Astrophysics Data System (ADS)

Yu, Wenwen; Jiang, Xinquan; Cai, Ming; Zhao, Wen; Ye, Dongxia; Zhou, Yong; Zhu, Chao; Zhang, Xiuli; Lu, Xiaofeng; Zhang, Zhiyuan

2014-04-01

For artificial nerve conduits, great improvements have been achieved in mimicking the structures and components of autologous nerves. However, there are still some problems in conduit construction, especially in terms of mechanical properties, biomimetic surface tomography, electrical conductivity and sustained release of neurotrophic factors or cells. In this study, we designed and fabricated a novel electrospun nerve conduit enhanced by multi-walled carbon nanotubes (MWNTs) on the basis of a collagen/poly(ɛ-caprolactone) (collagen/PCL) fibrous scaffold. Our aim was to provide further knowledge about the mechanical effects and efficacy of MWNTs on nerve conduits as well as the biocompatibility and toxicology of MWNTs when applied in vivo. The results showed that as one component, carboxyl MWNTs could greatly alter the composite scaffold’s hydrophilicity, mechanical properties and degradability. The electrospun fibers enhanced by MWNTs could support Schwann cell adhesion and elongation as a substrate in vitro. In vivo animal studies demonstrated that the MWNT-enhanced collagen/PCL conduit could effectively promote nerve regeneration of sciatic nerve defect in rats and prevent muscle atrophy without invoking body rejection or serious chronic inflammation. All of these results showed that this MWNT-enhanced scaffold possesses good biocompatibility and MWNTs might be excellent candidates as engineered nanocarriers for further neurotrophic factor delivery research.

A novel electrospun nerve conduit enhanced by carbon nanotubes for peripheral nerve regeneration.

PubMed

Yu, Wenwen; Jiang, Xinquan; Cai, Ming; Zhao, Wen; Ye, Dongxia; Zhou, Yong; Zhu, Chao; Zhang, Xiuli; Lu, Xiaofeng; Zhang, Zhiyuan

2014-04-25

For artificial nerve conduits, great improvements have been achieved in mimicking the structures and components of autologous nerves. However, there are still some problems in conduit construction, especially in terms of mechanical properties, biomimetic surface tomography, electrical conductivity and sustained release of neurotrophic factors or cells. In this study, we designed and fabricated a novel electrospun nerve conduit enhanced by multi-walled carbon nanotubes (MWNTs) on the basis of a collagen/poly(ε-caprolactone) (collagen/PCL) fibrous scaffold. Our aim was to provide further knowledge about the mechanical effects and efficacy of MWNTs on nerve conduits as well as the biocompatibility and toxicology of MWNTs when applied in vivo.The results showed that as one component, carboxyl MWNTs could greatly alter the composite scaffold's hydrophilicity, mechanical properties and degradability. The electrospun fibers enhanced by MWNTs could support Schwann cell adhesion and elongation as a substrate in vitro. In vivo animal studies demonstrated that the MWNT-enhanced collagen/PCL conduit could effectively promote nerve regeneration of sciatic nerve defect in rats and prevent muscle atrophy without invoking body rejection or serious chronic inflammation. All of these results showed that this MWNT-enhanced scaffold possesses good biocompatibility and MWNTs might be excellent candidates as engineered nanocarriers for further neurotrophic factor delivery research.

Fiber Optics at the JLab CLAS12 Detector

NASA Astrophysics Data System (ADS)

Kroon, John; Giovanetti, Kevin

2008-10-01

The performance of wavelength shifting fibers, WLS, and method of coupling these fibers to extruded polystyrene scintillators are currently under study at James Madison University. These components are two of the main elements for the PCAL, preshower calorimeter, proposed as part of the 12 GeV upgrade for the CLAS detector at Jefferson Laboratory. The WLS fibers have been prepared, optically coupled to scintillator, and tested in order to determine their overall performance as a method of readout. Methods of coupling fiber to scintillator, a description of the test setup, test methods, PCAL readout performance, and fabrication recommendations will be presented.

Recent Advances in Electrospun Nanofiber Interfaces for Biosensing Devices

PubMed Central

Sapountzi, Eleni; Braiek, Mohamed; Chateaux, Jean-François; Lagarde, Florence

2017-01-01

Electrospinning has emerged as a very powerful method combining efficiency, versatility and low cost to elaborate scalable ordered and complex nanofibrous assemblies from a rich variety of polymers. Electrospun nanofibers have demonstrated high potential for a wide spectrum of applications, including drug delivery, tissue engineering, energy conversion and storage, or physical and chemical sensors. The number of works related to biosensing devices integrating electrospun nanofibers has also increased substantially over the last decade. This review provides an overview of the current research activities and new trends in the field. Retaining the bioreceptor functionality is one of the main challenges associated with the production of nanofiber-based biosensing interfaces. The bioreceptors can be immobilized using various strategies, depending on the physical and chemical characteristics of both bioreceptors and nanofiber scaffolds, and on their interfacial interactions. The production of nanobiocomposites constituted by carbon, metal oxide or polymer electrospun nanofibers integrating bioreceptors and conductive nanomaterials (e.g., carbon nanotubes, metal nanoparticles) has been one of the major trends in the last few years. The use of electrospun nanofibers in ELISA-type bioassays, lab-on-a-chip and paper-based point-of-care devices is also highly promising. After a short and general description of electrospinning process, the different strategies to produce electrospun nanofiber biosensing interfaces are discussed. PMID:28813013

Laminated electrospun nHA/PHB-composite scaffolds mimicking bone extracellular matrix for bone tissue engineering.

PubMed

Chen, Zhuoyue; Song, Yue; Zhang, Jing; Liu, Wei; Cui, Jihong; Li, Hongmin; Chen, Fulin

2017-03-01

Electrospinning is an effective means to generate nano- to micro-scale polymer fibers resembling native extracellular matrix for tissue engineering. However, a major problem of electrospun materials is that limited pore size and porosity may prevent adequate cellular infiltration and tissue ingrowth. In this study, we first prepared thin layers of hydroxyapatite nanoparticle (nHA)/poly-hydroxybutyrate (PHB) via electrospinning. We then laminated the nHA/PHB thin layers to obtain a scaffold for cell seeding and bone tissue engineering. The results demonstrated that the laminated scaffold possessed optimized cell-loading capacity. Bone marrow mesenchymal stem cells (MSCs) exhibited better adherence, proliferation and osteogenic phenotypes on nHA/PHB scaffolds than on PHB scaffolds. Thereafter, we seeded MSCs onto nHA/PHB scaffolds to fabricate bone grafts. Histological observation showed osteoid tissue formation throughout the scaffold, with most of the scaffold absorbed in the specimens 2months after implantation, and blood vessels ingrowth into the graft could be observed in the graft. We concluded that electrospun and laminated nanoscaled biocomposite scaffolds hold great therapeutic potential for bone regeneration. Copyright © 2016 Elsevier B.V. All rights reserved.

Multifunctional hydroxyapatite/Na(Y/Gd)F4:Yb3+,Er3+ composite fibers for drug delivery and dual modal imaging.

PubMed

Liu, Min; Liu, Hui; Sun, Shufen; Li, Xuejiao; Zhou, Yanmin; Hou, Zhiyao; Lin, Jun

2014-02-04

Porous hydroxyapatite (HAp) composite fibers functionalized with up-conversion (UC) luminescent and magnetic Na(Y/Gd)F4:Yb(3+),Er(3+) nanocrystals (NCs) have been fabricated via electrospinning. After transferring hydrophobic oleic acid-capped Na(Y/Gd)F4:Yb(3+),Er(3+) NCs into aqueous solution, these water-dispersible NCs were dispersed into precursor electrospun solution containing CTAB. Na(Y/Gd)F4:Yb(3+),Er(3+)@HAp composite fibers were fabricated by the high temperature treatment of the electrospun Na(Y/Gd)F4:Yb(3+),Er(3+) NCs decorated precursor fibers. The biocompatibility test on MC 3T3-E1 cells using MTT assay shows that the HAp composite fibers have negligible cytotoxity, which reveals the HAp composite fibers could be a drug carrier for drug delivery. Because the contrast brightening is enhanced at increased concentrations of Gd(3+), the HAp composite fibers can serve as T1 magnetic resonance imaging contrast agents. In addition, the composites uptaken by MC 3T3-E1 cells present the UC luminescent emission of Er(3+) under the excitation of a 980 nm near-infrared laser. The above findings reveal Na(Y/Gd)F4:Yb(3+),Er(3+)@HAp composite fibers have potential applications in drug storage/release and magnetic resonance/UC luminescence imaging.

Characterization and antibacterial properties of porous fibers containing silver ions

NASA Astrophysics Data System (ADS)

Sun, Zhaoyang; Fan, Chenxu; Tang, Xiaopeng; Zhao, Jianghui; Song, Yanhua; Shao, Zhongbiao; Xu, Lan

2016-11-01

Materials prepared on the base of bioactive silver compounds have become more and more popular. In the present work, the surface morphology, structure and properties, of electrospun Polylactide Polylactic acid (PLA) porous fibers containing various ratios of silver ions were investigated by a combination of X-ray photoelectron spectroscopy (XPS), universal testing machine, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and et al. The biological activities of the proposed porous fibers were discussed in view of the released silver ions concentration. Antibacterial properties of these porous fibers were studied using two bacterial strains: Escherichia coli (E. coli) and Methicillin-resistant Staphylococcus aureus (MRSA). Results of the antibacterial testing suggested that PLA porous fibers containing silver ions could be used as potent antibacterial wound dressing materials in the biomedical field.

Electrospun mulberry-like hierarchical carbon fiber web for high-performance supercapacitors.

PubMed

Liu, Chao; Liu, Jizi; Wang, Jing; Li, Jiansheng; Luo, Rui; Shen, Jinyou; Sun, Xiuyun; Han, Weiqing; Wang, Lianjun

2018-02-15

In this work, we have fabricated a kind of N-doped hierarchal carbon fiber web by electrospinning hollow mesoporous carbon spheres (HMCSs) into fibrous structure. The as-synthesized carbon fiber web with novel mulberry-like morphology, thus denoted as MC-FW, possesses micro/meso/macroporous porosity, large surface area, high conductivity and multi-level structure, which are highly desired for supercapacitor electrode materials. The electrochemical measurements demonstrate that the designed MC-FW shows high capacitance (298.6 F g -1 ), favorable capacitance retention (71.0%) and long cycle life (97.3% capacitance retention after 5000 cycles). Notably, the capacitance of 298.6 F g -1 for MC-FW is higher than the capacitance reported so far for many hollow carbon spheres and carbon fibers, which may contribute to the synergistic effect between the merits of HMCSs (e.g. micro/meso/macroporous hierarchal structure, large surface area, high pore volume) and advantages of 1D carbon fiber (e.g. large aspect ratio and high conductivity). It is believed that this distinctive carbon fiber web may show promising prospects as advanced energy storage materials and catalyst. Copyright © 2017 Elsevier Inc. All rights reserved.

Microbes encapsulated within crosslinkable polymers

DOEpatents

Chidambaram, Devicharan; Liu, Ying; Rafailovich, Miriam H

2013-02-05

The invention relates to porous films comprising crosslinked electrospun hydrogel fibers. Viable microbes are encapsulated within the crosslinked electrospun hydrogel fibers. The crosslinked electrospun hydrogel fibers are water insoluble and permeable. The invention also relates to methods of making and using such porous films.

Fabrication and characterization of tea polyphenols loaded pullulan-CMC electrospun nanofiber for fruit preservation.

PubMed

Shao, Ping; Niu, Ben; Chen, Hangjun; Sun, Peilong

2018-02-01

Edible packaging films using polymer for food preservation have been developed for a long time. In this study, the effects of different concentrations (0.5%, 1%, 1.5%, w/v) of tea polyphenols incorporated into pullulan-Carboxymethylcellulose sodium (Pul-CMC) solutions on electrospun nanofiber films were evaluated. The fiber size distribution was characterized by scanning electron microscopy. The morphological features of nanofibers were modulated through adjusting process parameters (e.g. concentration of polymer solution, applied voltage and feeding rate). Increasing the applied voltage from 19 to 21kV and the feed rate from 0.36 to 0.6mL/h leads to a reduction in mean fiber diameter. Fruit packaging potential was evaluated using strawberry. The pullulan-CMC-TP nanofibers significantly decreased weight loss and maintained the firmness of the strawberries, and improved the quality of the fruit during storage. The findings demonstrate a facile packaging route to improve food sustainability and reduce waste. Copyright © 2017 Elsevier B.V. All rights reserved.

The effect of controlled release of PDGF-BB from heparin-conjugated electrospun PCL/gelatin scaffolds on cellular bioactivity and infiltration

PubMed Central

Lee, Jongman; Yoo, James J.; Atala, Anthony; Lee, Sang Jin

2013-01-01

Heparin-conjugated electrospun poly(ε-caprolactone) (PCL)/gelatin scaffolds were developed to provide controlled release of platelet-derived growth factor-BB (PDGF-BB) and allow prolonged bioactivity of this molecule. A mixture of PCL and gelatin was electrospun into three different morphologies. Next, heparin molecules were conjugated to the reactive surface of the scaffolds. This heparin-conjugated scaffold allowed the immobilization of PDGF-BB via electrostatic interaction. In vitro PDGF-BB release profiles indicated that passive physical adsorption of PDGF-BB to non-heparinized scaffolds resulted in an initial burst release of PDGF-BB within 5 days, which then leveled off. However, electrostatic interaction between PDGF-BB and the heparin-conjugated scaffolds gave rise to a sustained release of PDGF-BB over the course of 20 days without an initial burst. Moreover, PDGF-BB that was strongly bound to the heparin-conjugated scaffolds enhanced smooth muscle cell (SMC) proliferation. In addition, scaffolds composed of 3.0 µm diameter fibers that were immobilized with PDGF-BB accelerated SMC infiltration into the scaffold when compared to scaffolds composed of smaller diameter fibers or scaffolds that did not release PDGF-BB. We concluded that the combination of the large pore structure in the scaffolds and the heparin-mediated delivery of PDGF-BB provided the most effective cellular interactions through synergistic physical and chemical cues. PMID:22770570

Electrospun nanofibres in agriculture and the food industry: a review.

PubMed

Noruzi, Masumeh

2016-11-01

The interesting characteristics of electrospun nanofibres, such as high surface-to-volume ratio, nanoporosity, and high safety, make them suitable candidates for use in a variety of applications. In the recent decade, electrospun nanofibres have been applied to different potential fields such as filtration, wound dressing, drug delivery, etc. and a significant number of review papers have been published in these fields. However, the use of electrospun nanofibres in agriculture is comparatively novel and is still in its infancy. In this paper, the specific applications of electrospun nanofibres in agriculture and food science, including plant protection using pheromone-loaded nanofibres, plant protection using encapsulation of biocontrol agents, preparation of protective clothes for farm workers, encapsulation of agrochemical materials, deoxyribonucleic acid extraction in agricultural research studies, pre-concentration and measurement of pesticides in crops and environmental samples, preparation of nanobiosensors for pesticide detection, encapsulation of food materials, fabrication of food packaging materials, and filtration of beverage products are reviewed and discussed. This paper may help researchers develop the use of electrospun nanofibres in agriculture and food science to address some serious problems such as the intensive use of pesticides. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Quantitative Analysis of Complex Glioma Cell Migration on Electrospun Polycaprolactone Using Time-Lapse Microscopy

PubMed Central

Johnson, Jed; Nowicki, M. Oskar; Lee, Carol H.; Chiocca, E. Antonio; Viapiano, Mariano S.; Lawler, Sean E.

2009-01-01

Malignant gliomas are the most common tumors originating within the central nervous system and account for over 15,000 deaths annually in the United States. The median survival for glioblastoma, the most common and aggressive of these tumors, is only 14 months. Therapeutic strategies targeting glioma cells migrating away from the tumor core are currently hampered by the difficulty of reproducing migration in the neural parenchyma in vitro. We utilized a tissue engineering approach to develop a physiologically relevant model of glioma cell migration. This revealed that glioma cells display dramatic differences in migration when challenged by random versus aligned electrospun poly-ɛ-caprolactone nanofibers. Cells on aligned fibers migrated at an effective velocity of 4.2 ± 0.39 μm/h compared to 0.8 ± 0.08 μm/h on random fibers, closely matching in vivo models and prior observations of glioma spread in white versus gray matter. Cells on random fibers exhibited extension along multiple fiber axes that prevented net motion; aligned fibers promoted a fusiform morphology better suited to infiltration. Time-lapse microscopy revealed that the motion of individual cells was complex and was influenced by cell cycle and local topography. Glioma stem cell–containing neurospheres seeded on random fibers did not show cell detachment and retained their original shape; on aligned fibers, cells detached and migrated in the fiber direction over a distance sixfold greater than the perpendicular direction. This chemically and physically flexible model allows time-lapse analysis of glioma cell migration while recapitulating in vivo cell morphology, potentially allowing identification of physiological mediators and pharmacological inhibitors of invasion. PMID:19199562

Coaxial Electrospinning and Characterization of Core-Shell Structured Cellulose Nanocrystal Reinforced PMMA/PAN Composite Fibers

PubMed Central

Li, Chao; Li, Qingde; Ni, Xiaohui; Liu, Guoxiang; Cheng, Wanli; Han, Guangping

2017-01-01

A modified coaxial electrospinning process was used to prepare composite nanofibrous mats from a poly(methyl methacrylate) (PMMA) solution with the addition of different cellulose nanocrystals (CNCs) as the sheath fluid and polyacrylonitrile (PAN) solution as the core fluid. This study investigated the conductivity of the as-spun solutions that increased significantly with increasing CNCs addition, which favors forming uniform fibers. This study discussed the effect of different CNCs addition on the morphology, thermal behavior, and the multilevel structure of the coaxial electrospun PMMA + CNCs/PAN composite nanofibers. A morphology analysis of the nanofibrous mats clearly demonstrated that the CNCs facilitated the production of the composite nanofibers with a core-shell structure. The diameter of the composite nanofibers decreased and the uniformity increased with increasing CNCs concentrations in the shell fluid. The composite nanofibrous mats had the maximum thermal decomposition temperature that was substantially higher than electrospun pure PMMA, PAN, as well as the core-shell PMMA/PAN nanocomposite. The BET (Brunauer, Emmett and Teller) formula results showed that the specific surface area of the CNCs reinforced core-shell composite significantly increased with increasing CNCs content. The specific surface area of the composite with 20% CNCs loading rose to 9.62 m2/g from 3.76 m2/g for the control. A dense porous structure was formed on the surface of the electrospun core-shell fibers. PMID:28772933

3D X-Ray Nanotomography of Cells Grown on Electrospun Scaffolds.

PubMed

Bradley, Robert S; Robinson, Ian K; Yusuf, Mohammed

2017-02-01

Here, it is demonstrated that X-ray nanotomography with Zernike phase contrast can be used for 3D imaging of cells grown on electrospun polymer scaffolds. The scaffold fibers and cells are simultaneously imaged, enabling the influence of scaffold architecture on cell location and morphology to be studied. The high resolution enables subcellular details to be revealed. The X-ray imaging conditions were optimized to reduce scan times, making it feasible to scan multiple regions of interest in relatively large samples. An image processing procedure is presented which enables scaffold characteristics and cell location to be quantified. The procedure is demonstrated by comparing the ingrowth of cells after culture for 3 and 6 days. © 2016 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Towards a novel bioelectrocatalytic platform based on “wiring” of pyrroloquinoline quinone-dependent glucose dehydrogenase with an electrospun conductive polymeric fiber architecture

NASA Astrophysics Data System (ADS)

Gladisch, Johannes; Sarauli, David; Schäfer, Daniel; Dietzel, Birgit; Schulz, Burkhard; Lisdat, Fred

2016-01-01

Electrospinning is known as a fabrication technique for electrode architectures that serve as immobilization matrices for biomolecules. The current work demonstrates a novel approach to construct a conductive polymeric platform, capable not only of immobilization, but also of electrical connection of the biomolecule with the electrode. It is produced upon electrospinning from mixtures of three different highly conductive sulfonated polyanilines and polyacrylonitrile on ITO electrodes. The resulting fiber mats are with a well-retained conductivity. After coupling the enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) to polymeric structures and addition of the substrate glucose an efficient bioelectrocatalysis is demonstrated. Depending on the choice of the sulfonated polyanilline mediatorless bioelectrocatalysis starts at low potentials; no large overpotential is needed to drive the reaction. Thus, the electrospun conductive immobilization matrix acts here as a transducing element, representing a promising strategy to use 3D polymeric scaffolds as wiring agents for active enzymes. In addition, the mild and well reproducible fabrication process and the active role of the polymer film in withdrawing electrons from the reduced PQQ-GDH lead to a system with high stability. This could provide access to a larger group of enzymes for bioelectrochemical applications including biosensors and biofuel cells.

Electrospun Nafion ®/Polyphenylsulfone composite membranes for regenerative Hydrogen bromine fuel cells

DOE PAGES

Park, Jun; Wycisk, Ryszard; Pintauro, Peter N.; ...

2016-02-29

Here, the regenerative H 2/Br 2-HBr fuel cell, utilizing an oxidant solution of Br 2 in aqueous HBr, shows a number of benefits for grid-scale electricity storage. The membrane-electrode assembly, a key component of a fuel cell, contains a proton-conducting membrane, typically based on the perfluorosulfonic acid (PFSA) ionomer. Unfortunately, the high cost of PFSA membranes and their relatively high bromine crossover are serious drawbacks. Nanofiber composite membranes can overcome these limitations. In this work, composite membranes were prepared from electrospun dual-fiber mats containing Nafion ® PFSA ionomer for facile proton transport and an uncharged polymer, polyphenylsulfone (PPSU), for mechanicalmore » reinforcement, and swelling control. After electrospinning, Nafion/PPSU mats were converted into composite membranes by softening the PPSU fibers, through exposure to chloroform vapor, thus filling the voids between ionomer nanofibers. It was demonstrated that the relative membrane selectivity, referenced to Nafion ® 115, increased with increasing PPSU content, e.g., a selectivity of 11 at 25 vol% of Nafion fibers. H 2-Br 2 fuel cell power output with a 65 m thick membrane containing 55 vol% Nafion fibers was somewhat better than that of a 150 m Nafion ® 115 reference, but its cost advantage due to a four-fold decrease in PFSA content and a lower bromine species crossover make it an attractive candidate for use in H 2/Br 2-HBr systems.« less

Integration of Multiple Components in Polystyrene-based Microfluidic Devices Part 1: Fabrication and Characterization

PubMed Central

Johnson, Alicia S.; Anderson, Kari B.; Halpin, Stephen T.; Kirkpatrick, Douglas C.; Spence, Dana M.; Martin, R. Scott

2012-01-01

In Part I of a two-part series, we describe a simple, and inexpensive approach to fabricate polystyrene devices that is based upon melting polystyrene (from either a Petri dish or powder form) against PDMS molds or around electrode materials. The ability to incorporate microchannels in polystyrene and integrate the resulting device with standard laboratory equipment such as an optical plate reader for analyte readout and micropipettors for fluid propulsion is first described. A simple approach for sample and reagent delivery to the device channels using a standard, multi-channel micropipette and a PDMS-based injection block is detailed. Integration of the microfluidic device with these off-chip functions (sample delivery and readout) enables high throughput screens and analyses. An approach to fabricate polystyrene-based devices with embedded electrodes is also demonstrated, thereby enabling the integration of microchip electrophoresis with electrochemical detection through the use of a palladium electrode (for a decoupler) and carbon-fiber bundle (for detection). The device was sealed against a PDMS-based microchannel and used for the electrophoretic separation and amperometric detection of dopamine, epinephrine, catechol, and 3,4-dihydroxyphenylacetic acid. Finally, these devices were compared against PDMS-based microchips in terms of their optical transparency and absorption of an anti-platelet drug, clopidogrel. Part I of this series lays the foundation for Part II, where these devices were utilized for various on-chip cellular analysis. PMID:23120747

Protein adsorption on electrospun zinc doped hydroxyapatite containing nylon 6 membrane: kinetics and isotherm.

PubMed

Esfahani, Hamid; Prabhakaran, Molamma P; Salahi, Esmaeil; Tayebifard, Ali; Keyanpour-Rad, Mansour; Rahimipour, Mohamad Reza; Ramakrishna, Seeram

2015-04-01

Surface modification of electrospun polymeric membrane surfaces is a critical step towards the separation process including protein adsorption. In this study, the electrospun Nylon fibers was incorporated with positively charged zinc doped hydroxyapatite (HAp) nanoparticles to study the adsorption of negatively charged proteins, namely bovine serum albumin (BSA). Effects of zinc amount within the atomic structure of HAp (nZH; n=0, 4, 8 At.%) was evaluated on produced scaffolds and consequently protein adsorption. The results showed that the ability of Nylon membrane to adsorb BSA increased with incorporation of nZH nanoparticles within the nylon structure. This phenomenon is appeared to be relate to different electrostatic charge and not to physical characteristic of scaffolds. The incorporated membrane (N-4ZH) by nanoparticles with highest zeta (ξ) potential adsorbed the maximum amount of protein. The adsorption of BSA was best fitted with pseudo-second order kinetic model. The experimental isotherm data were further analyzed by using Langmuir and Freundlich equations. By comparing the correlation coefficients obtained for each linear transformation of isotherm analysis, it was found that the Langmuir equation was the best fit equilibrium model that described the adsorption of BSA on these membranes. Copyright © 2014 Elsevier Inc. All rights reserved.

Ductility of polystyrene waste panel

NASA Astrophysics Data System (ADS)

Sulistyorini, Dewi; Yasin, Iskandar

2018-03-01

Polystyrene waste panel is one of alternative materials that uses polystyrene waste. This experiment is to utilize the polystyrene waste as a non structural panel to be evaluated the ductility. The specimen consisted of cement 250 kg/m3, polystyrene waste was as aggregate, water cement ratio was 0.4 and wire mesh diameter was 0.6 mm with the grid 6 mm × 6 mm placed on the top and bottom of the panels. The polystyrene panels were compressed at 2 MPa. Six specimens had dimension 80 cm length, 30 cm width and the thickness planned were two varieties, they were 0.5 cm and 1 cm. Flexural testing is used to examine load and deflection to measure the ductility. The load and the deflection showed that the maximum load for the specimen with 0.5 cm thickness is 0.4, 0.56 and 0.37. And for 1 cm thickness is 0.4, 0.36, 0.64. It shows that the thickness variation does not give effect on the maximum load. Result showed the average of Displacement Ductility Index of polystyrene waste panels with 0.5 cm thickness was 1.692 and for 1 cm thickness, the average was 4.043. So the average of the panel with 0.5 cm thickness planned is under 1.99 and the panel with 1 cm thickness planned is upper 3, therefore, it is considered imperative for adequate ductility.

Graphite fiber surface treatment to improve impact strength and fracture resistance in subsequent composites

NASA Technical Reports Server (NTRS)

Paul, J. T., Jr.; Buntin, G. A.

1982-01-01

Graphite (or carbon) fiber composite impact strength improvement was attempted by modifying the fiber surface. Elastomeric particles were made into lattices and deposited ionically on surface treated graphite fiber in an attempt to prepare a surface containing discrete rubber particles. With hard, nonelastomeric polystyrene discrete particle coverage was achieved. All the elastomeric containing lattices resulted in elastomer flow and filament agglomeration during drying.

Engineering cholesterol-based fibers for antibody immobilization and cell capture

NASA Astrophysics Data System (ADS)

Cohn, Celine

In 2015, the United States is expected to have nearly 600,000 deaths attributed to cancer. Of these 600,000 deaths, 90% will be a direct result of cancer metastasis, the spread of cancer throughout the body. During cancer metastasis, circulating tumor cells (CTCs) are shed from primary tumors and migrate through bodily fluids, establishing secondary cancer sites. As cancer metastasis is incredibly lethal, there is a growing emphasis on developing "liquid biopsies" that can screen peripheral blood, search for and identify CTCs. One popular method for capturing CTCs is the use of a detection platform with antibodies specifically suited to recognize and capture cancer cells. These antibodies are immobilized onto the platform and can then bind and capture cells of interest. However, current means to immobilize antibodies often leave them with drastically reduced function. The antibodies are left poorly suited for cell capture, resulting in low cell capture efficiencies. This body of work investigates the use of lipid-based fibers to immobilize proteins in a way that retains protein function, ultimately leading to increased cell capture efficiencies. The resulting increased efficiencies are thought to arise from the retained three-dimensional structure of the protein as well as having a complete coating of the material surface with antibodies that are capable of interacting with their antigens. It is possible to electrospin cholesterol-based fibers that are similar in design to the natural cell membrane, providing proteins a more natural setting during immobilization. Such fibers have been produced from cholesterol-based cholesteryl succinyl silane (CSS). These fibers have previously illustrated a keen aptitude for retaining protein function and increasing cell capture. Herein the work focuses on three key concepts. First, a model is developed to understand the immobilization mechanism used by electrospun CSS fibers. The antibody immobilization and cell capturing

Selective Permeating Properties of Butanol and Water through Polystyrene- b-polydimethylsiloxane- b-polystyrene Pervaporation Membranes

NASA Astrophysics Data System (ADS)

Shin, Chaeyoung; Baer, Zachary; Chen, X. Chelsea; Ozcam, A. Evren; Clark, Douglas; Balsara, Nitash

2015-03-01

Polystyrene- b-polydimethylsiloxane- b-polystyrene (SDS) membranes have been studied in butanol-water binary pervaporation experiments and pervaporation experiments integrated with viable fermentation broths. Polydimethylsiloxane has been widely known to be a suitable material for separating organic chemicals from aqueous solutions, and it thus provides a continuous matrix phase in SDS membranes for permeation of small molecules. The polystyrene block provides mechanical stability to maintain the membrane structure in the pervaporation membranes. We take advantage of these features to fabricate a thin and butanol-selective SDS membrane for in situ product removal in fermentation.

Using a slightly tapered optical fiber to attract and transport microparticles.

PubMed

Sheu, Fang-Wen; Wu, Hong-Yu; Chen, Sy-Hann

2010-03-15

We exploit a fiber puller to transform a telecom single-mode optical fiber with a 125 microm diameter into a symmetric and unbroken slightly tapered optical fiber with a 50 microm diameter at the minimum waist. When the laser light is launched into the optical fiber, we can observe that, due to the evanescent wave of the slightly tapered fiber, the nearby polystyrene microparticles with 10 microm diameters will be attracted onto the fiber surface and roll separately in the direction of light propagation. We have also simulated and compared the optical propulsion effects on the microparticles when the laser light is launched into a slightly tapered fiber and a heavily tapered (subwavelength) fiber, respectively.

Cytotoxicity associated with electrospun polyvinyl alcohol.

PubMed

Pathan, Saif G; Fitzgerald, Lisa M; Ali, Syed M; Damrauer, Scott M; Bide, Martin J; Nelson, David W; Ferran, Christiane; Phaneuf, Tina M; Phaneuf, Matthew D

2015-11-01

Polyvinyl alcohol (PVA) is a synthetic, water-soluble polymer, with applications in industries ranging from textiles to biomedical devices. Research on electrospinning of PVA has been targeted toward optimizing or finding novel applications in the biomedical field. However, the effects of electrospinning on PVA biocompatibility have not been thoroughly evaluated. In this study, the cytotoxicity of electrospun PVA (nPVA) which was not crosslinked after electrospinning was assessed. PVA polymers of several molecular weights were dissolved in distilled water and electrospun using the same parameters. Electrospun PVA materials with varying molecular weights were then dissolved in tissue culture medium and directly compared against solutions of nonelectrospun PVA polymer in human coronary artery smooth muscle cells and human coronary artery endothelial cells cultures. All nPVA solutions were cytotoxic at a threshold molar concentration that correlated with the molecular weight of the starting PVA polymer. In contrast, none of the nonelectrospun PVA solutions caused any cytotoxicity, regardless of their concentration in the cell culture. Evaluation of the nPVA material by differential scanning calorimetry confirmed that polymer degradation had occurred after electrospinning. To elucidate the identity of the nPVA component that caused cytotoxicity, nPVA materials were dissolved, fractionated using size exclusion columns, and the different fractions were added to HCASMC and human coronary artery endothelial cells cultures. These studies indicated that the cytotoxic component of the different nPVA solutions were present in the low-molecular-weight fraction. Additionally, the amount of PVA present in the 3-10 kg/mol fraction was approximately sixfold greater than that in the nonelectrospun samples. In conclusion, electrospinning of PVA resulted in small-molecular-weight fractions that were cytotoxic to cells. This result demonstrates that biocompatibility of electrospun

Poly(2-ethyloxazoline) as matrix for highly active electrospun enzymes in organic solvents.

PubMed

Plothe, Ramona; Sittko, Ina; Lanfer, Franziska; Fortmann, Maximilian; Roth, Meike; Kolbach, Vivien; Tiller, Joerg C

2017-01-01

Nanofibers are advantageous carriers for biocatalysts, because they show lower diffusion limitations due to their high surface/volume ratio. Only a few samples are known where enzymes are directly spun into nanofibers, mostly because there are not many suited polymer carriers. In this study, poly(2-ethyloxazoline) (PEtOx) was explored regarding its usefulness to activate various enzymes in organic solvents by directly electrospinning them from aqueous solutions containing the polymer. It was found that the concentration of PEtOx in the spinning solution and also the swellability of the fibers play a great role in the activity of the enzymes in organic solvents. Using electrospun lipase B from Candida antarctica (CaLB) under optimized conditions revealed a higher carrier activity than the commercial Novozyme 435 with 10 times less immobilized protein. The electrospinning of PEtOx/CaLB fibers onto a stirrer is used to realize a biocatalytic stirrer for organic solvents. Biotechnol. Bioeng. 2017;114: 39-45. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Particle levitation and guidance in hollow-core photonic crystal fiber.

PubMed

Benabid, Fetah; Knight, J; Russell, P

2002-10-21

We report the guidance of dry micron-sized dielectric particles in hollow core photonic crystal fiber. The particles were levitated in air and then coupled to the air-core of the fiber using an Argon ion laser beam operating at a wavelength of 514 nm. The diameter of the hollow core of the fiber is 20 m . A laser power of 80 mW was sufficient to levitate a 5 m diameter polystyrene sphere and guide it through a ~150 mm long hollow-core crystal photonic fiber. The speed of the guided particle was measured to be around 1 cm/s.

Electrical properties of a liquid crystal dispersed in an electrospun cellulose acetate network

PubMed Central

Danila, Octavian; Ganea, Constantin Paul

2018-01-01

Electro-optical devices that work in a similar fashion as PDLCs (polymer-dispersed liquid crystals), produced from cellulose acetate (CA) electrospun fibers deposited onto indium tin oxide coated glass and a nematic liquid crystal (E7), were studied. CA and the CA/liquid crystal composite were characterized by multiple investigation techniques, such as polarized optical microscopy, dielectric spectroscopy and impedance measurements. Dielectric constant and electric energy loss were studied as a function of frequency and temperature. The activation energy was evaluated and the relaxation time was obtained by fitting the spectra of the dielectric loss with the Havriliak–Negami functions. To determine the electrical characteristics of the studied samples, impedance measurements results were treated using the Cole–Cole diagram and the three-element equivalent model. PMID:29441261

Electrical properties of a liquid crystal dispersed in an electrospun cellulose acetate network.

PubMed

Maximean, Doina Manaila; Danila, Octavian; Almeida, Pedro L; Ganea, Constantin Paul

2018-01-01

Electro-optical devices that work in a similar fashion as PDLCs (polymer-dispersed liquid crystals), produced from cellulose acetate (CA) electrospun fibers deposited onto indium tin oxide coated glass and a nematic liquid crystal (E7), were studied. CA and the CA/liquid crystal composite were characterized by multiple investigation techniques, such as polarized optical microscopy, dielectric spectroscopy and impedance measurements. Dielectric constant and electric energy loss were studied as a function of frequency and temperature. The activation energy was evaluated and the relaxation time was obtained by fitting the spectra of the dielectric loss with the Havriliak-Negami functions. To determine the electrical characteristics of the studied samples, impedance measurements results were treated using the Cole-Cole diagram and the three-element equivalent model.

Synthesis and Process Optimization of Electrospun PEEK-Sulfonated Nanofibers by Response Surface Methodology.

PubMed

Boaretti, Carlo; Roso, Martina; Lorenzetti, Alessandra; Modesti, Michele

2015-07-07

In this study electrospun nanofibers of partially sulfonated polyether ether ketone have been produced as a preliminary step for a possible development of composite proton exchange membranes for fuel cells. Response surface methodology has been employed for the modelling and optimization of the electrospinning process, using a Box-Behnken design. The investigation, based on a second order polynomial model, has been focused on the analysis of the effect of both process (voltage, tip-to-collector distance, flow rate) and material (sulfonation degree) variables on the mean fiber diameter. The final model has been verified by a series of statistical tests on the residuals and validated by a comparison procedure of samples at different sulfonation degrees, realized according to optimized conditions, for the production of homogeneous thin nanofibers.

VOCs Air Pollutant Cleaning with Polyacrylonitrile/Fly Ash Nanocomposite Electrospun Nanofibrous Membranes

NASA Astrophysics Data System (ADS)

Cong Ge, Jun; Wang, Zi Jian; Kim, Min Soo; Choi, Nag Jung

2018-01-01

Volatile organic compounds (VOCs) as an environmental pollution, which have many kinds of chemical structures, and many of them are very toxic. Therefore, controlling and reducing the presence of VOCs has become a hot topic among researchers for many years. In this study, the VOCs adsorption capacity of polyacrylonitrile/fly ash (PAN/FA) nanocomposite electrospun nanofibrous membranes were investigated. The results indicated that the PAN with different contents of FA powder (20%, 40%, 60%, 80%, and 100% compared with PAN by weight) could be spun well by electrospinning. The diameter of the fiber was very fine and its arrangement was irregular. The PAN nanofibrous membrane containing 60 wt% FA powder had the highest VOCs absorption capacity compared with other nanofibrous membranes due to its large specific surface area.

Kinetics and Antioxidant Capacity of Proanthocyanidins Encapsulated in Zein Electrospun Fibers by Cyclic Voltammetry.

PubMed

Wang, Hualin; Hao, Lilan; Niu, Baicheng; Jiang, Suwei; Cheng, Junfeng; Jiang, Shaotong

2016-04-20

The proanthocyanidins encapsulated in zein (zein-PA) fibers was via electrospinning technique. The kinetics and antioxidant capacity of PA from zein fibers was investigated by cyclic voltammetry. Circular dichroism was used to investigate the secondary structure change of zein and its influence on the shape of fibers. The addition of PA caused a significant increase in viscosity and made fibers wider. These hydrogen bonds between zein and PA molecules would favor the α-helix change and decrease the β-folds of zein in electrospinning solutions, leading to a round-shaped tendency of fibers and enhancing the thermal properties slightly. Zein-PA fibers showed high encapsulation efficiency close to 100%, and the encapsulated PA retained its antioxidant capacity in fibers. Zein-PA fibers showed a good controlled release toward PA, and the predominant release of PA from fibers was Fickian diffusion, which could be well described by first-order model and Hixson-Crowell model.

Electrospun Fibro-porous Polyurethane Coatings for Implantable Glucose Biosensors

PubMed Central

Wang, Ning; Burugapalli, Krishna; Song, Wenhui; Halls, Justin; Moussy, Francis; Ray, Asim; Zheng, Yudong

2012-01-01

This study reports methods for coating miniature implantable glucose biosensors with electrospun polyurethane (PU) membranes, their effects on sensor function and efficacy as mass-transport limiting membranes. For electrospinning fibres directly on sensor surface, both static and dynamic collector systems, were designed and tested. Optimum collector configurations were first ascertained by FEA modelling. Both static and dynamic collectors allowed complete covering of sensors, but it was the dynamic collector that produced uniform fibro-porous PU coatings around miniature ellipsoid biosensors. The coatings had random fibre orientation and their uniform thickness increased linearly with increasing electrospinning time. The effects of coatings having an even spread of submicron fibre diameters and sub-100μm thicknesses on glucose biosensor function were investigated. Increasing thickness and fibre diameters caused a statistically insignificant decrease in sensor sensitivity for the tested electrospun coatings. The sensors’ linearity for the glucose detection range of 2 to 30mM remained unaffected. The electrospun coatings also functioned as mass-transport limiting membranes by significantly increasing the linearity, replacing traditional epoxy-PU outer coating. To conclude, electrospun coatings, having controllable fibro-porous structure and thicknesses, on miniature ellipsoid glucose biosensors were demonstrated to have minimal effect on pre-implantation sensitivity and also to have mass-transport limiting ability. PMID:23146433

Investigation of influence of conductivity on the polyaniline fiber mats, produced via electrospinning

NASA Astrophysics Data System (ADS)

Varnaitė-Žuravliova, Sandra; Savest, Natalja; Abraitienė, Aušra; Baltušnikaitė-Guzaitienė, Julija; Krumme, Andres

2018-05-01

Intrinsically conductive polymers are one very attractive material, because of their good electrical, electrochemical and optical properties, and a wide range of applications. The spinnability of Polyaniline (PANI) solutions is generally insufficient for it to be electrospun directly into fibers, but addition of another polymer to the organic solutions or usage of dopant and solvent may improve it. The aim of the research was: to produce nanofibers of the smallest diameter as possible by using conventional electrospinning setup; to investigate the influence of viscosity and electrical conductivity to the spinnability of PANI solutions; to control the electrical conductivity of prepared solutions and electrospun nanofibers by changing concentrations of chemicals used. The results of investigations made with prepared solutions shave showed, that the viscosity increases and the electrical conductivity is tending to decrease with increase of Polyethylenoxide (PEO) concentration in the spinning solution. In order to achieve greater conductivity, the Dimethylformamide (DMF) was added as a dopant. Though the conductivity of solutions was reached high enough, but the loss in viscosity resulted in depriation of greater spinnability of PANI nanofibers. Also it was noticed, that despite the fact that the electrical conductivity of all solutions was different, the electrical conductivity of fiber mats can be divided in two groups: fiber mats without DMF and fiber mats with DMF. The morphological analysis of produced fiber mats have showed, that higher PEO concentration resulted in thicker PANI nanofibers—the diameter varied from 333 nm till 4434 nm. The usage of DMF gave an opportunity to receive almost twice thinner conductive PANI nanofibers with narrower distribution in diameter. Slower flow rate of the electrospinning process resulted in thinner nanofibers as well.

Electrospun polycaprolactone/gelatin composites with enhanced cell-matrix interactions as blood vessel endothelial layer scaffolds.

PubMed

Jiang, Yong-Chao; Jiang, Lin; Huang, An; Wang, Xiao-Feng; Li, Qian; Turng, Lih-Sheng

2017-02-01

During the fabrication of tissue engineering scaffolds and subsequent tissue regeneration, surface bioactivity is vital for cell adhesion, spreading, and proliferation, especially for endothelium dysfunction repair. In this paper, synthetic polymer polycaprolactone (PCL) was blended with natural polymer gelatin at four different weight ratios followed by crosslinking (i.e., 100:0, 70:30, 50:50, 30:70, labeled as PCL-C, P7G3-C, P5G5-C, and P3G7-C) to impart enhanced bioactivity and tunable mechanical properties. The PCL/gelatin blends were first dissolved in 2,2,2-trifluroethanol (TFE) and supplementary acetic acid (1% relative to TFE) solvent, electrospun, and then cross-linked to produce PBS-proof fibrous scaffolds. Scanning electron micrographs (SEM) indicated that fibers of each sample were smooth and homogeneous, with the fiber diameters increasing from 1.01±0.51μm to 1.61±0.46μm as the content of gelatin increased. While thermal resistance and crystallization of the blends were affected by the presence of gelatin, as reflected by differential scanning calorimetry (DSC) results, water contact angle (WCA) tests confirmed that the scaffold surfaces became more hydrophilic. Tensile tests showed that PCL-C and P7G3-C scaffolds had mechanical properties comparable to those of human coronary arteries. As for cytocompatibility, skeleton staining images showed that human mesenchymal stem cells (hMSCs) had more favorable binding sites on PCL/gelatin scaffolds than those on PCL scaffolds. Cell proliferation assays revealed that P7G3-C scaffolds could support the most number of hMSCs. The results of this study demonstrated the enhanced cell-matrix interactions and potential use of electrospun PCL/gelatin scaffolds in the tissue engineering field, especially in wound dressings and endothelium regeneration. Copyright © 2016 Elsevier B.V. All rights reserved.

Electrospun gelatin/sodium bicarbonate and poly(lactide-co-ε-caprolactone)/sodium bicarbonate nanofibers as drug delivery systems.

PubMed

Sang, Qingqing; Williams, Gareth R; Wu, Huanling; Liu, Kailin; Li, Heyu; Zhu, Li-Min

2017-12-01

In this work, we report electrospun nanofibers made of model hydrophobic (poly(lactide-co-ε-caprolactone); PLCL) and hydrophilic (gelatin) polymers. We explored the effect on drug release of the incorporation of sodium bicarbonate (SB) into these fibers, using the potent antibacterial agent ciprofloxacin as a model drug. The fibers prepared are smooth and have relatively uniform diameters lying between ca. 600 and 850nm. The presence of ciprofloxacin in the fibers was confirmed using IR spectroscopy. X-ray diffraction showed the drug to be incorporated into the fibers in the amorphous form. In vitro drug release studies revealed that, as expected, more rapid drug release was seen with gelatin fibers than those made of PLCL, and a greater final release percentage was obtained. The inclusion of SB in the gelatin fibers imparts them with pH sensitivity: gelatin/SB fibers showed faster release at pH5 than pH7.4, while fibers without SB gave the same release profiles at both pHs. The PLCL fibers have no pH sensitivity, even when SB was included, as a result of their hydrophobic structure precluding the ingress of solvent. In vitro cell culture studies showed that all the fibers are able to promote cell proliferation. The ciprofloxacin loaded fibers are effective in inhibiting Escherichia coli and Staphylococcus aureus growth in antibacterial tests. Thus, the gelatin-based fibers can be used as pH-responsive drug delivery systems, with potential applications for instance in the treatment of tumor resection sites. Should these become infected, the pH would drop, resulting in ciprofloxacin being released and the infection halted. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Electrospun nanofibers: Work for medicine?

NASA Astrophysics Data System (ADS)

Liao, Susan; Chan, Casey K.; Ramakrishna, S.

2010-03-01

Attempts have been made to fabricate nanofibrous scaffolds to mimic the chemical composition and structural properties of the extracellular matrix (ECM) for tissue/organ replacement. Nanofiber scaffolds with various patterns have been successfully produced from synthetic and natural polymers through a relatively simple technique of electrospinning. The resulting patterns can mimic some of the diverse tissue-specific orientation and three-dimensional (3D) fibrous structures. Studies on cell-nanofiber interactions, including studies on stem cells, have revealed the importance of nanotopography on cell adhesion, proliferation and differentiation. Furthermore, clinical application of electrospun nanofibers including wound healing, tissue regeneration, drug delivery and stem cell therapy are highly feasible due to the ease and flexibility of fabrication of making nanofiber with this cost-effective method using electrospinning. In this review, we have highlighted the current state of the art and provided future perspectives on electrospun nanofiber in medical applications.

Surface and interfacial properties of carbon fibers

NASA Technical Reports Server (NTRS)

Bascom, Willard D.

1991-01-01

The adhesion strength of AS4 fibers to thermoplastic polymers was determined. The specific polymers were polycarbonate, polyphenylene oxide, polyetherimide, polyphenylene oxide blends with polystyrene, and polycarbonate blends with a polycarbonate-polysiloxan copolymer. Data are also included for polysulfone. It was recognized at the outset that an absolute measure of the fiber matrix adhesion would be difficult. However, it is feasible to determine the fiber bond strengths to the thermoplastics relative to the bond strengths of the same fibers to epoxy polymers. It was anticipated, and in fact realized, that the adhesion of AS4 to the thermoplastic polymers was relatively low. Therefore, further objectives of the study were to identify means of increasing fiber/matrix adhesion and to try to determine why the adhesion of AS4 to thermoplastics is significantly less than to epoxy polymers.

Electrospun Composites of Polycaprolactone and Porous Silicon Nanoparticles for the Tunable Delivery of Small Therapeutic Molecules

PubMed Central

McInnes, Steven J. P.; Macdonald, Thomas J.; Parkin, Ivan P.; Voelcker, Nicolas H.

2018-01-01

This report describes the use of an electrospun composite of poly(ε-caprolactone) (PCL) fibers and porous silicon (pSi) nanoparticles (NPs) as an effective system for the tunable delivery of camptothecin (CPT), a small therapeutic molecule. Both materials are biodegradable, abundant, low-cost, and most importantly, have no known cytotoxic effects. The composites were treated with and without sodium hydroxide (NaOH) to investigate the wettability of the porous network for drug release and cell viability measurements. CPT release and subsequent cell viability was also investigated. We observed that the cell death rate was not only affected by the addition of our CPT carrier, pSi, but also by increasing the rate of dissolution via treatment with NaOH. This is the first example of loading pSi NPs as a therapeutics nanocarrier into electronspun PCL fibers and this system opens up new possibilities for the delivery of molecular therapeutics. PMID:29596352

Packing Products: Polystyrene vs. Cornstarch

ERIC Educational Resources Information Center

Starr, Suzanne

2009-01-01

Packing materials such as polystyrene take thousands of years to decompose, whereas packing peanuts made from cornstarch, which some companies are now using, can serve the same purpose, but dissolve in water. The author illustrates this point to her class one rainy day using the sculptures students made from polystyrene and with the cornstarch…

Double emulsion electrospun nanofibers as a growth factor delivery vehicle for salivary gland regeneration

NASA Astrophysics Data System (ADS)

Foraida, Zahraa I.; Sharikova, Anna; Peerzada, Lubna N.; Khmaladze, Alexander; Larsen, Melinda; Castracane, James

2017-08-01

Sustained delivery of growth factors, proteins, drugs and other biologically active molecules is necessary for tissue engineering applications. Electrospun fibers are attractive tissue engineering scaffolds as they partially mimic the topography of the extracellular matrix (ECM). However, they do not provide continuous nourishment to the tissue. In search of a biomimetic scaffold for salivary gland tissue regeneration, we previously developed a blend nanofiber scaffold composed of the protein elastin and the synthetic polymer polylactic-co-glycolic acid (PLGA). The nanofiber scaffold promoted in vivo-like salivary epithelial cell tissue organization and apicobasal polarization. However, in order to enhance the salivary cell proliferation and biomimetic character of the scaffold, sustained growth factor delivery is needed. The composite nanofiber scaffold was optimized to act as a growth factor delivery system using epidermal growth factor (EGF) as a model protein. The nanofiber/EGF hybrid nanofibers were synthesized by double emulsion electrospinning where EGF is emulsified within a water/oil/water (w/o/w) double emulsion system. Successful incorporation of EGF was confirmed using Raman spectroscopy. EGF release profile was characterized using enzyme-linked immunosorbent assay (ELIZA) of the EGF content. Double emulsion electrospinning resulted in slower release of EGF. We demonstrated the potential of the proposed double emulsion electrospun nanofiber scaffold for the delivery of growth factors and/or drugs for tissue engineering and pharmaceutical applications.

Single and dual fiber nano-tip optical tweezers: trapping and analysis.

PubMed

Decombe, Jean-Baptiste; Huant, Serge; Fick, Jochen

2013-12-16

An original optical tweezers using one or two chemically etched fiber nano-tips is developed. We demonstrate optical trapping of 1 micrometer polystyrene spheres at optical powers down to 2 mW. Harmonic trap potentials were found in the case of dual fiber tweezers by analyzing the trapped particle position fluctuations. The trap stiffness was deduced using three different models. Consistent values of up to 1 fN/nm were found. The stiffness linearly decreases with decreasing light intensity and increasing fiber tip-to-tip distance.

Magnetic graphene oxide-polystyrene and magnetic activated carbon-polystyrene nanocomposites as sorbents for bisphenol A.

NASA Astrophysics Data System (ADS)

Rekos, Kyriazis; Kampouraki, Zoi Christina; Samanidou, Victoria; Deliyanni, Eleni

2016-04-01

Magnetic graphene oxide-polystyrene and magnetic activated carbon-polystyrene nanocomposites as sorbents for bisphenol A. Kyriazis Rekos1, Zoi Christina Kampouraki1, Victoria Samanidou2, Eleni Deliyanni1 1 Laboratory of General and Inorganic Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece 2 Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece The aim of this work was to prepare and characterize novel composites of magnetic activated carbon or magnetic graphene oxide with polystyrene (GO/PSm), through one step simple and effective route. Μagnetite nanoparticles, prepared in the laboratory, were dispersed in the presence of activated carbon (C) or graphene oxide (GO) in a polystyrene (PS) solution in dimethylformamide, at elevated temperature, for the fabrication of the magnetite-Carbon-PS (C-PSm) and magnetite- Graphene Oxide-PS (GO-PSm) hybrid-nanoparticles. For comparison, C-PS and GO-PS composites were also prepared in the same route. The nanocomposites were tested for their sorption ability for an endocrine disruptor, bisphenol A. The effect of solution pH, initial concentration, contact time and temperature were examined. The magnetic graphite oxide-polystyrene presented higher adsorption capacity (100 mg/g) than the non magnetic composites (70 mg/g), as well as than initial graphite oxide (20 mg/g). FTIR, XRD, BET, TGA, VSM and SEM were performed in order to investigate the role of the PS on the better adsorption performance of the mGO-PS nanocomposites. The characterization with these techniques revealed the possible interactions of the surface functional groups of activated carbon and/or graphite oxide with polystyrene that resulted in the better performance of the magnetic nanocomposites for bisphenol A adsorption.

Compliant electrospun silk fibroin tubes for small vessel bypass grafting.

PubMed

Marelli, Benedetto; Alessandrino, Antonio; Farè, Silvia; Freddi, Giuliano; Mantovani, Diego; Tanzi, Maria Cristina

2010-10-01

Processing silk fibroin (SF) by electrospinning offers a very attractive opportunity for producing three-dimensional nanofibrillar matrices in tubular form, which may be useful for a biomimetic approach to small calibre vessel regeneration. Bypass grafting of small calibre vessels, with a diameter less than 6mm, is performed mainly using autografts, like the saphenous vein or internal mammary artery. At present no polymeric grafts made of SF are commercially available, mainly due to inadequate properties (low compliance and lack of endothelium cells). The aim of this work was to electrospin SF into tubular structures (Ø=6mm) for small calibre vessel grafting, characterize the morphological, chemico-physical and mechanical properties of the electrospun SF structures and to validate their potential to interact with cells. The morphological properties of electrospun SF nanofibres were investigated by scanning electron microscopy. Chemico-physical analyses revealed an increase in the crystallinity of the structure of SF nanofibres on methanol treatment. Mechanical tests, i.e. compliance and burst pressure measurements, of the electrospun SF tubes showed that the inner pressure to radial deformation ratio was linear for elongation up to 15% and pressure up to 400 mm Hg. The mean compliance value between 80 and 120 mm Hg was higher than the values reported for both Goretex(R) and Dacron(R) grafts and for bovine heterografts, but still slightly lower than those of saphenous and umbilical vein, which nowadays represent the gold standard for the replacement of small calibre arteries. The electrospun tubes resisted up to 575+/-17 mmHg, which is more than four times the upper physiological pressure of 120 mmHg and more than twice the pathological upper pressures (range 180-220 mmHg). The in vitro tests showed a good cytocompatibility of the electrospun SF tubes. Therefore, the electrospun SF tubes developed within this work represent a suitable candidate for small calibre

Scanning fiber angle-resolved low coherence interferometry

PubMed Central

Zhu, Yizheng; Terry, Neil G.; Wax, Adam

2010-01-01

We present a fiber-optic probe for Fourier-domain angle-resolved low coherence interferometry for the determination of depth-resolved scatterer size. The probe employs a scanning single-mode fiber to collect the angular scattering distribution of the sample, which is analyzed using the Mie theory to obtain the average size of the scatterers. Depth sectioning is achieved with low coherence Mach–Zehnder interferometry. In the sample arm of the interferometer, a fixed fiber illuminates the sample through an imaging lens and a collection fiber samples the backscattered angular distribution by scanning across the Fourier plane image of the sample. We characterize the optical performance of the probe and demonstrate the ability to execute depth-resolved sizing with subwavelength accuracy by using a double-layer phantom containing two sizes of polystyrene microspheres. PMID:19838271

Electrospun nanofibers for neural tissue engineering

NASA Astrophysics Data System (ADS)

Xie, Jingwei; MacEwan, Matthew R.; Schwartz, Andrea G.; Xia, Younan

2010-01-01

Biodegradable nanofibers produced by electrospinning represent a new class of promising scaffolds to support nerve regeneration. We begin with a brief discussion on the electrospinning of nanofibers and methods for controlling the structure, porosity, and alignment of the electrospun nanofibers. The methods include control of the nanoscale morphology and microscale alignment of the nanofibers, as well as the fabrication of macroscale, three-dimensional tubular structures. We then highlight recent studies that utilize electrospun nanofibers to manipulate biological processes relevant to nervous tissue regeneration, including stem cell differentiation, guidance of neurite extension, and peripheral nerve injury treatments. The main objective of this feature article is to provide valuable insights into methods for investigating the mechanisms of neurite growth on novel nanofibrous scaffolds and optimization of the nanofiber scaffolds and conduits for repairing peripheral nerve injuries.

Electrospun nerve guide scaffold of poly(ε-caprolactone)/collagen/nanobioglass: an in vitro study in peripheral nerve tissue engineering.

PubMed

Mohamadi, Forouzan; Ebrahimi-Barough, Somayeh; Reza Nourani, Mohammad; Ali Derakhshan, Mohammad; Goodarzi, Vahabodin; Sadegh Nazockdast, Mohammad; Farokhi, Mehdi; Tajerian, Roksana; Faridi Majidi, Reza; Ai, Jafar

2017-07-01

Among various methods, nerve tissue engineering (NTE) is one of the applicable methods to reconstruct damaged nerve tissues. Electrospinning technique and biomaterials are often considered to fabricate fibrous tissue engineered conduits which have great similarity to the extracellular matrix on fiber structure. Polymer blending is one of the most effective methods for the production of new materials with outstanding features. In this study, conduit structures as main part of the peripheral nerve regeneration based on polymer blend nanocomposites poly(ε-caprolactone)/collagen/nanobioglass (PCL/collagen/NBG) were manufactured by electrospinning technique. Various properties of electrospun mats were investigated by using contact angle, tensile, degradation time, porosity, scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), and wide-angle X-ray scattering (WAXS). The SEM analysis was shown that size range and average pore size of polymer blend nanocomposite nanofibers were about 250-400 nm and 0.7 µm, respectively, with an optimum porosity of 62.5%. The XRD result was shown that synthesized nanoparticles of NBG had amorphous structures. Also, FTIR analysis indicated that good interaction between polymer-polymer macromolecules and polymer particles. The contact angle and tensile tests were indicated that electrospun webs showed good hydrophilicity and toughness properties. According to SEM, MTT assay and DAPI staining technique, the ability to support cell attachment and viability of samples were characterized. In vitro study indicated electrospun collagen/PCL/NBG nanofibrous conduit promoted Human Endometrial Stem cells (hEnSCs) adhesion and proliferation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1960-1972, 2017. © 2017 Wiley Periodicals, Inc.

Synthesis and Process Optimization of Electrospun PEEK-Sulfonated Nanofibers by Response Surface Methodology

PubMed Central

Boaretti, Carlo; Roso, Martina; Lorenzetti, Alessandra; Modesti, Michele

2015-01-01

In this study electrospun nanofibers of partially sulfonated polyether ether ketone have been produced as a preliminary step for a possible development of composite proton exchange membranes for fuel cells. Response surface methodology has been employed for the modelling and optimization of the electrospinning process, using a Box-Behnken design. The investigation, based on a second order polynomial model, has been focused on the analysis of the effect of both process (voltage, tip-to-collector distance, flow rate) and material (sulfonation degree) variables on the mean fiber diameter. The final model has been verified by a series of statistical tests on the residuals and validated by a comparison procedure of samples at different sulfonation degrees, realized according to optimized conditions, for the production of homogeneous thin nanofibers. PMID:28793427

Mechanical properties of single electrospun drug-encapsulated nanofibres

PubMed Central

Chew, Sing Yian; Hufnagel, Todd C; Lim, Chwee Teck; Leong, Kam W

2008-01-01

The mechanical and structural properties of a surface play an important role in determining the morphology of attached cells, and ultimately their cellular functions. As such, mechanical and structural integrity are important design parameters for a tissue scaffold. Electrospun fibrous meshes are widely used in tissue engineering. When in contact with electrospun scaffolds, cells see the individual micro- or nanofibres as their immediate microenvironment. In this study, tensile testing of single electrospun nanofibres composed of poly(ε-caprolactone) (PCL), and its copolymer, poly(caprolactone-co-ethyl ethylene phosphate) (PCLEEP), revealed a size effect in the Young's modulus, E, and tensile strength, σT. Both strength and stiffness increase as the fibre diameter decreases from bulk (∼5 μm) into the nanometre region (200–300 nm). In particular, E and σT of individual PCL nanofibres were at least two-fold and an order of magnitude higher than that of PCL film, respectively. PCL films were observed to have more pronounced crystallographic texture than the nanofibres; however no difference in crystalline fraction, perfection, or texture was detected among the various fibres. When drugs were encapsulated into single PCLEEP fibres, mechanical properties were enhanced with 1–20 wt% of loaded retinoic acid, but weakened by 10–20 wt% of encapsulated bovine serum albumin. This understanding of the effect of size and drug and protein encapsulation on the mechanical properties of electrospun fibres may help in the optimization of tissue scaffold design that combines biochemical and biomechanical cues for tissue regeneration. PMID:19079553

Preparation of uniaxially aligned TiO2 ultrafine fibers by electrospinning.

PubMed

Nien, Yu-Hsun; Tsai, Yan-Sheng; Wang, Jia-Yi; Syu, Shu-Ping

2012-11-01

TiO2 nanofibers are often produced by electrospinning using a collector consisting of two parallel electrodes. In this work, a high speed rotating drum was used as a collector to produce uniaxially aligned TiO2 ultrafine fibers. The apparatus to manufacture uniaxially aligned TiO2 ultrafine fiber consisted of a high-speed roller, a high-voltage power supply, a controllable syringe pump and a syringe. Titanium (IV) isopropoxide and polyvinylpyrrolidone were used as precursor and auxiliary, respectively. Titanium (IV) isopropoxide and polyvinylpyrrolidone were well mixed with other essential reagents to form the polymer solution. The polymer solution was poured into the syringe and pumped at various flow rates. The electrospun ultrafine fibers collected on the roller were heat treated up to 600 degrees C and the uniaxially aligned TiO2 ultrafine fibers were formed and characterized using scanning electron microscope and X-ray diffraction.

Polystyrene Prints

ERIC Educational Resources Information Center

O'Malley, William

1969-01-01

Discussed are the exciting advantages and possibilities of using polystyrene trays found in meat packaging for printmaking. Among them are ease of use, low cost and quick availability of materials, beautiful textural effects. Procedures are explained for various age levels. (BF)

Peptide-modified PELCL electrospun membranes for regulation of vascular endothelial cells.

PubMed

Zhou, Fang; Jia, Xiaoling; Yang, Yang; Yang, Qingmao; Gao, Chao; Zhao, Yunhui; Fan, Yubo; Yuan, Xiaoyan

2016-11-01

The efficiency of biomaterials used in small vascular repair depends greatly on their ability to interact with vascular endothelial cells (VECs). Rapid endothelialization of the vascular grafts is a promising way to prevent thrombosis and intimal hyperplasia. In this work, modification of electrospun membranes of poly(ethylene glycol)-b-poly(l-lactide-co-ε-caprolactone) (PELCL) by three different peptides for regulation of VECs were studied in order to obtain ideal bioactive biomaterials as small diameter vascular grafts. QK (a mimetic peptide to vascular endothelial growth factor), Arg-Glu-Asp-Val (REDV, a specific adhesive peptide to VECs) and Val-Ala-Pro-Gly (VAPG, a specific adhesive peptide to vascular smooth muscle cells) were investigated. Surface properties of the modified membranes and the response of VECs were verified. It was found that protein adsorption and platelet adhesion were effectively suppressed with the introduction of QK, REDV or VAPG peptides on the PELCL electrospun membranes. Both QK- and REDV-modified electrospun membranes could accelerate the proliferation of VECs in the first 9days, and the QK-modified electrospun membrane promoted cell proliferation more significantly than the REDV-modified one. The REDV-modified PELCL membrane was the most favorable for VECs adhesion than QK- and VAPG-modified membranes. It was suggested that QK- or REDV-modified PELCL electrospun membranes may have great potential applications in cardiovascular biomaterials for rapid endothelialization in situ. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation and electrochemical characterization of gel polymer electrolyte based on electrospun polyacrylonitrile nonwoven membranes for lithium batteries

NASA Astrophysics Data System (ADS)

Raghavan, Prasanth; Manuel, James; Zhao, Xiaohui; Kim, Dul-Sun; Ahn, Jou-Hyeon; Nah, Changwoon

Electrospun membranes of polyacrylonitrile are prepared, and the electrospinning parameters are optimized to get fibrous membranes with uniform bead-free morphology. The polymer solution of 16 wt.% in N, N-dimethylformamide at an applied voltage of 20 kV results in the nanofibrous membrane with average fiber diameter of 350 nm and narrow fiber diameter distribution. Gel polymer electrolytes are prepared by activating the nonwoven membranes with different liquid electrolytes. The nanometer level fiber diameter and fully interconnected pore structure of the host polymer membranes facilitate easy penetration of the liquid electrolyte. The gel polymer electrolytes show high electrolyte uptake (>390%) and high ionic conductivity (>2 × 10 -3 S cm -1). The cell fabricated with the gel polymer electrolytes shows good interfacial stability and oxidation stability >4.7 V. Prototype coin cells with gel polymer electrolytes based on a membrane activated with 1 M LiPF 6 in ethylene carbonate/dimethyl carbonate or propylene carbonate are evaluated for discharge capacity and cycle property in Li/LiFePO 4 cells at room temperature. The cells show remarkably good cycle performance with high initial discharge properties and low capacity fade under continuous cycling.

Biofunctionalization of PAMAM-montmorillonite decorated poly (Ɛ-caprolactone)-chitosan electrospun nanofibers for cell adhesion and electrochemical cytosensing.

PubMed

Kirbay, Fatma Ozturk; Yalcinkaya, Esra Evrim; Atik, Gozde; Evren, Gizem; Unal, Betul; Demirkol, Dilek Odaci; Timur, Suna

2018-06-30

The construction and biofunctionalization of the poly (Ɛ-caprolactone) (PCL)-chitosan (CHIT) nanofibrous mats, which included Polyamidoamine (PAMAM) dendrimer modified montmorillonite (Mt), for the cell adhesion and electrochemical cytosensing were accomplished in this report. After the intercalation of the PAMAM generation zero dendrimer into the Mt, PAMAM-Mt decorated PCL-CHIT electrospun nanofibers were formed. The addition of PAMAM caused the decrease of contact angle of PCL-CHIT nanofibers. The covalent immobilization of a tripeptide namely Arginylglycylaspartate (RGD) on both the PCL-CHIT/Mt and PCL-CHIT/PAMAM-Mt surface was carried out. U87-MG and HaCaT (negative control) cell lines were incubated on the PCL-CHIT/Mt/RGD and PCL-CHIT/PAMAM-Mt/RGD. The proliferation studies and imaging of the cells were carried out on these fibers. Finally, electrochemical measurements were performed after each modification step by differential pulse/cyclic voltammetry and electrochemical impedance spectroscopy. U87-MG cells were grown better than HaCaT cells on the PCL-CHIT/PAMAM-Mt/RGD surfaces. To the best of our knowledge, there is no study that developed electrochemical cytosensor using electrospun nanofibers as a cell adhesion platform. Copyright © 2018 Elsevier B.V. All rights reserved.

Liquefied Petroleum Gas Monitoring System Based on Polystyrene Coated Long Period Grating

PubMed Central

Zotti, Aldobenedetto; Palumbo, Giovanna; Zuppolini, Simona; Consales, Marco; Cutolo, Antonello; Borriello, Anna; Zarrelli, Mauro; Iadicicco, Agostino

2018-01-01

In this work, we report the in-field demonstration of a liquefied petroleum gas monitoring system based on optical fiber technology. Long-period grating coated with a thin layer of atactic polystyrene (aPS) was employed as a gas sensor, and an array comprising two different fiber Bragg gratings was set for the monitoring of environmental conditions such as temperature and humidity. A custom package was developed for the sensors, ensuring their suitable installation and operation in harsh conditions. The developed system was installed in a real railway location scenario (i.e., a southern Italian operative railway tunnel), and tests were performed to validate the system performances in operational mode. Daytime normal working operations of the railway line and controlled gas expositions, at very low concentrations, were the searched realistic conditions for an out-of-lab validation of the developed system. Encouraging results were obtained with a precise indication of the gas concentration and external conditioning of the sensor. PMID:29734731

Role of solvent-mediated carbodiimide cross-linking in fabrication of electrospun gelatin nanofibrous membranes as ophthalmic biomaterials.

PubMed

Chou, Shih-Feng; Luo, Li-Jyuan; Lai, Jui-Yang; Ma, David Hui-Kang

2017-02-01

Due to their ability to mimic the structure of extracellular matrix, electrospun gelatin nanofibers are promising cell scaffolding materials for tissue engineering applications. However, the hydrophilic gelatin molecules usually need stabilization before use in aqueous physiological environment. Considering that biomaterials cross-linked via film immersion technique may have a more homogeneous cross-linked structure than vapor phase cross-linking, this work aims to investigate the chemical modification of electrospun gelatin nanofibrous membranes by liquid phase carbodiimide in the presence of ethanol/water co-solvents with varying ethanol concentrations ranging from 80 to 99.5vol%. The results of characterization showed that increasing water content in the binary reaction solvent system increases the extent of cross-linking of gelatin nanofibers, but simultaneously promotes the effect of biopolymer swelling and distortion in fiber mat structure. As compared to non-cross-linked counterparts, carbodiimide treated gelatin nanofibrous mats exhibited better thermal and biological stability where the shrinkage temperature and resistance to enzymatic degradation varied in response to ethanol/water solvent composition-mediated generation of cross-links. Irrespective of their cross-linking density, all studied membrane samples did not induce any responses in ocular epithelial cell cultures derived from cornea, lens, and retina. Unlike many other cross-linking agents and/or methods (e.g., excessive vapor phase cross-linking) that may pose a risk of toxicity, our study demonstrated that these nanofibrous materials are well tolerated by anterior segment tissues. These findings also indicate the safety of using ethanol/water co-solvents for chemical cross-linking of gelatin to engineer nanofibrous materials with negligible biological effects. In summary, the present results suggest the importance of solvent-mediated carbodiimide cross-linking in modulating structure

Electrospun Hydroxyapatite-Containing Chitosan Nanofibers Crosslinked with Genipin for Bone Tissue Engineering

PubMed Central

Frohbergh, Michael E.; Katsman, Anna; Botta, Gregory P.; Lazarovici, Phillip; Schauer, Caroline L.; Wegst, Ulrike G. K.; Lelkes, Peter I.

2012-01-01

Reconstruction of large bone defects remains problematic in orthopedic and craniofacial clinical practice. Autografts are limited in supply and are associated with donor site morbidity while other materials show poor integration with the host’s own bone. This lack of integration is often due to the absence of periosteum, the outer layer of bone that contains osteoprogenitor cells and is critical for the growth and remodeling of bone tissue. In this study we developed a one-step platform to electrospin nanofibrous scaffolds from chitosan, which also contain hydroxyapatite nanoparticles and are crosslinked with genipin. We hypothesized that the resulting composite scaffolds represent a microenvironment that emulates the physical, mineralized structure and mechanical properties of non-weight bearing bone extracellular matrix while promoting osteoblast differentiation and maturation similar to the periosteum. The ultrastructure and physicochemical properties of the scaffolds were studied using scanning electron microscopy and spectroscopic techniques. The average fiber diameters of the electrospun scaffolds were 227±154 nm as spun, and increased to 335±119 nm after crosslinking with genipin. Analysis by X-ray diffraction, Fourier transformed infrared spectroscopy and energy dispersive spectroscopy confirmed the presence of characteristic features of hydroxyapatite in the composite chitosan fibers. The Young’s modulus of the composite fibrous scaffolds was 142±13 MPa, which is similar to that of the natural periosteum. Both pure chitosan scaffolds and composite hydroxyapatite-containing chitosan scaffolds supported adhesion, proliferation and osteogenic differentiation of mouse 7F2 osteoblast-like cells. Expression and enzymatic activity of alkaline phosphatase, an early osteogenic marker, were higher in cells cultured on the composite scaffolds as compared to pure chitosan scaffolds, reaching a significant, 2.4 fold, difference by day 14 (p<0.05). Similarly

Measuring the charge density of a tapered optical fiber using trapped microparticles.

PubMed

Kamitani, Kazuhiko; Muranaka, Takuya; Takashima, Hideaki; Fujiwara, Masazumi; Tanaka, Utako; Takeuchi, Shigeki; Urabe, Shinji

2016-03-07

We report the measurements of charge density of tapered optical fibers using charged particles confined in a linear Paul trap at ambient pressure. A tapered optical fiber is placed across the trap axis at a right angle, and polystyrene microparticles are trapped along the trap axis. The distance between the equilibrium position of a positively charged particle and the tapered fiber is used to estimate the amount of charge per unit length of the fiber without knowing the amount of charge of the trapped particle. The charge per unit length of a tapered fiber with a diameter of 1.6 μm was measured to be 2-1+3×10 -11 C/m.

Biomimetic and bioactive nanofibrous scaffolds from electrospun composite nanofibers

PubMed Central

Zhang, YZ; Su, B; Venugopal, J; Ramakrishna, S; Lim, CT

2007-01-01

Electrospinning is an enabling technology that can architecturally (in terms of geometry, morphology or topography) and biochemically fabricate engineered cellular scaffolds that mimic the native extracellular matrix (ECM). This is especially important and forms one of the essential paradigms in the area of tissue engineering. While biomimesis of the physical dimensions of native ECM’s major constituents (eg, collagen) is no longer a fabrication-related challenge in tissue engineering research, conveying bioactivity to electrospun nanofibrous structures will determine the efficiency of utilizing electrospun nanofibers for regenerating biologically functional tissues. This can certainly be achieved through developing composite nanofibers. This article gives a brief overview on the current development and application status of employing electrospun composite nanofibers for constructing biomimetic and bioactive tissue scaffolds. Considering that composites consist of at least two material components and phases, this review details three different configurations of nanofibrous composite structures by using hybridizing basic binary material systems as example. These are components blended composite nanofiber, core-shell structured composite nanofiber, and nanofibrous mingled structure. PMID:18203429

Gold nanoparticles-decorated electrospun poly(N-vinyl-2-pyrrolidone) nanofibers with tunable size and coverage density for nanomolar detection of single and binary component dyes by surface-enhanced raman spectroscopy

NASA Astrophysics Data System (ADS)

Kurniawan, Alfin; Wang, Meng-Jiy

2017-09-01

The application of the electrospun nanomaterials to surface-enhanced Raman spectroscopy (SERS) is a rapidly evolving field which holds potential for future developments in the generation of portable plasmonic-based detection platforms. In this study, a simple approach to fabricate electrospun poly(N-vinylpyrrolidone) (PVP) mats decorated with gold nanoparticles (AuNPs) by combining electrospinning and calcination was presented. AuNPs were decorated on the fiber mat surface through electrostatic interactions between positively charged aminosilane groups and negatively charged AuNPs. The size and coverage density of AuNPs on the fiber mats could be tuned by varying the calcination temperature. Calcination of AuNPs-decorated PVP fibers at 500 °C-700 °C resulted in the uniform decoration of high density AuNPs with very narrow gaps on every single fiber, which in turn contribute to strong electromagnetic SERS enhancement. The robust free-standing AuNPs-decorated mat which calcined at 500 °C (500/AuNPs-F) exhibited high SERS activity toward cationic (methylene blue, MB) and anionic (methyl orange, MO) dyes in single and binary systems with a detection range from tens of nM to a few hundred μM. The fabricated SERS substrate demonstrated high reproducibility with the spot-to-spot variation in SERS signal intensities was ±10% and ±12% for single and binary dye systems, respectively. The determination of MB and MO in spiked river water and tap water with 500/AuNPs-F substrate gave satisfactory results in terms of the percent spike recoveries (ranging from 92.6%-96.6%) and reproducibility (%RSD values less than 15 for all samples).

Environmental fate and effect of biodegradable electro-spun scaffolds (biomaterial)-a case study.

PubMed

Irizar, A; Amorim, M J B; Fuller, K P; Zeugolis, D I; Scott-Fordsmand, J J

2018-04-30

Poly-ε-caprolactone (PCL) based medical devices are increasingly produced and thus, their presence in the environment is likely to increase. The present study analysed the biodegradation of PCL electro-spun scaffolds (alone) and PCL electro-spun scaffolds coated with human recombinant (hR) collagen and Bovine Achilles tendon (BAT) collagen in sewage sludge and in soil. Additionally, an eco-toxicological test with the model organism Enchytraeus crypticus was performed to assess environmental hazard of the produced materials in soils. The electro-spun scaffolds were exposed to activated sludge and three different soils for various time periods (0-7-14-21-28-56-180 days); subsequently the degradation was determined by weight loss and microscopical analysis. Although no toxicity occurred in terms of Enchytraeus crypticus reproduction, our data indicate that biodegradation was dependent on the coating of the material and exposure condition. Further, only partial PCL decomposition was possible in sewage treatment plants. Collectively, these data indicate that electro-spun PCL scaffolds are transferred to amended soils.

Fibrillar films obtained from sodium soap fibers and polyelectrolyte multilayers.

PubMed

Zawko, Scott A; Schmidt, Christine E

2011-08-01

An objective of tissue engineering is to create synthetic polymer scaffolds with a fibrillar microstructure similar to the extracellular matrix. Here, we present a novel method for creating polymer fibers using the layer-by-layer method and sacrificial templates composed of sodium soap fibers. Soap fibers were prepared from neutralized fatty acids using a sodium chloride crystal dissolution method. Polyelectrolyte multilayers (PEMs) of polystyrene sulfonate and polyallylamine hydrochloride were deposited onto the soap fibers, crosslinked with glutaraldehyde, and then the soap fibers were leached with warm water and ethanol. The morphology of the resulting PEM structures was a dense network of fibers surrounded by a nonfibrillar matrix. Microscopy revealed that the PEM fibers were solid structures, presumably composed of polyelectrolytes complexed with residual fatty acids. These fibrillar PEM films were found to support the attachment of human dermal fibroblasts. Copyright © 2011 Wiley Periodicals, Inc.

Chitin butyrate coated electrospun nylon-6 fibers for biomedical applications

NASA Astrophysics Data System (ADS)

Pant, Hem Raj; Kim, Han Joo; Bhatt, Lok Ranjan; Joshi, Mahesh Kumar; Kim, Eun Kyo; Kim, Jeong In; Abdal-hay, Abdalla; Hui, K. S.; Kim, Cheol Sang

2013-11-01

In this study, we describe the preparation and characterizations of chitin butyrate (CB) coated nylon-6 nanofibers using single-spinneret electrospinning of blends solution. The physicochemical properties of nylon-6 composite fibers with different proportions of CB to nylon-6 were determined using FE-SEM, TEM, FT-IR spectroscopy, and water contact angle measurement. FE-SEM and TEM images revealed that the nylon-6 and CB were immiscible in the as-spun nanofibers, and phase separated nanofiber morphology becomes more pronounced with increasing amounts of CB. The bone formation ability of composite fibers was evaluated by incubating in biomimetic simulated body fluid. In order to assay the cytocompatibility and cell behavior on the composite scaffolds, osteoblast cells were seeded on the matrix. Results suggest that the deposition of CB layer on the surface of nylon-6 could increase its cell compatibility and bone formation ability. Therefore, as-synthesized nanocomposite fibrous mat has great potentiality in hard tissue engineering.

Electrospun strontium titanata nanofibers incorporated with nickel oxide nanoparticles for improved photocatalytic activities

NASA Astrophysics Data System (ADS)

Alharbi, Abdulaziz; Alarifi, Ibrahim M.; Khan, Waseem S.; Asmatulu, Ramazan

2015-03-01

The inexpensive sources of fossil fuels in the world are limited, and will deplete soon because of the huge demand on the energy and growing economies worldwide. Thus, many research activities have been focused on the non-fossil fuel based energy sources, and this will continue next few decades. Water splitting using photocatalysts is one of the major alternative energy technologies to produce hydrogen directly from water using photon energy of the sun. Numerous solid photocatalysts have been used by researchers for water splitting. In the present study, nickel oxide and strontium titanata were chosen as photocatalysts for water splitting. Poly (vinyl pyrrolidone) (PVP) was incorporated with nickel oxide [Ni2O3] (co-catalyst), while poly (vinyl acetate) (PVAc) was mixed with titanium (IV) isopropoxide [C12H28O4Ti] and strontium nitrate [Sr(NO3)2]. Then, two solutions were electrospun using coaxial electrospinning technique to generate nanoscale fibers incorporated with NiOx nanoparticles. The fibers were then heat treated at elevated temperatures for 2hr in order to transform the strontium titanata and nickel oxide into crystalline form for a better photocatalytic efficiency. The morphology of fibers was characterized via scanning electron microscopy (SEM), while the surface hydrophobicity was determined using water contact angle goniometer. The UV-vis spectrophotometer was also used to determine the band gap energy values of the nanofibers. This study may open up new possibilities to convert water into fuel directly using the novel photocatalysts.

Optimization of suture-free laser-assisted vessel repair by solder-doped electrospun poly(ε-caprolactone) scaffold.

PubMed

Pabittei, Dara R; Heger, Michal; Beek, Johan F; van Tuijl, Sjoerd; Simonet, Marc; van der Wal, Allard C; de Mol, Bas A; Balm, Ron

2011-01-01

Poor welding strength constitutes an obstacle in the clinical employment of laser-assisted vascular repair (LAVR) and anastomosis. We therefore investigated the feasibility of using electrospun poly(ε-caprolactone) (PCL) scaffold as reinforcement material in LAVR of medium-sized vessels. In vitro solder-doped scaffold LAVR (ssLAVR) was performed on porcine carotid arteries or abdominal aortas using a 670-nm diode laser, a solder composed of 50% bovine serum albumin and 0.5% methylene blue, and electrospun PCL scaffolds. The correlation between leaking point pressures (LPPs) and arterial diameter, the extent of thermal damage, structural and mechanical alterations of the scaffold following ssLAVR, and the weak point were investigated. A strong negative correlation existed between LPP and vessel diameter, albeit LPP (484±111 mmHg) remained well above pathophysiological pressures. Histological analysis revealed that thermal damage extended into the medial layer with a well-preserved internal elastic lamina and endothelial cells. Laser irradiation of PCL fibers and coagulation of solder material resulted in a strong and stiff scaffold. The weak point of the ssLAVR modality was predominantly characterized by cohesive failure. In conclusion, ssLAVR produced supraphysiological LPPs and limited tissue damage. Despite heat-induced structural/mechanical alterations of the scaffold, PCL is a suitable polymer for weld reinforcement in medium-sized vessel ssLAVR.

Optimization of Suture-Free Laser-Assisted Vessel Repair by Solder-Doped Electrospun Poly(ε-caprolactone) Scaffold

PubMed Central

Pabittei, Dara R.; Heger, Michal; Beek, Johan F.; van Tuijl, Sjoerd; Simonet, Marc; van der Wal, Allard C.; de Mol, Bas A.

2010-01-01

Poor welding strength constitutes an obstacle in the clinical employment of laser-assisted vascular repair (LAVR) and anastomosis. We therefore investigated the feasibility of using electrospun poly(ε-caprolactone) (PCL) scaffold as reinforcement material in LAVR of medium-sized vessels. In vitro solder-doped scaffold LAVR (ssLAVR) was performed on porcine carotid arteries or abdominal aortas using a 670-nm diode laser, a solder composed of 50% bovine serum albumin and 0.5% methylene blue, and electrospun PCL scaffolds. The correlation between leaking point pressures (LPPs) and arterial diameter, the extent of thermal damage, structural and mechanical alterations of the scaffold following ssLAVR, and the weak point were investigated. A strong negative correlation existed between LPP and vessel diameter, albeit LPP (484 ± 111 mmHg) remained well above pathophysiological pressures. Histological analysis revealed that thermal damage extended into the medial layer with a well-preserved internal elastic lamina and endothelial cells. Laser irradiation of PCL fibers and coagulation of solder material resulted in a strong and stiff scaffold. The weak point of the ssLAVR modality was predominantly characterized by cohesive failure. In conclusion, ssLAVR produced supraphysiological LPPs and limited tissue damage. Despite heat-induced structural/mechanical alterations of the scaffold, PCL is a suitable polymer for weld reinforcement in medium-sized vessel ssLAVR. PMID:20835847

Polymer surfaces structured with random or aligned electrospun nanofibers to promote the adhesion of blood platelets.

PubMed

Wan, Ling-Shu; Xu, Zhi-Kang

2009-04-01

Fibrous membranes (nonwoven meshes) prepared via electrospinning technique have great potential in tissue engineering. This work is the first study on the behaviors of blood platelets at the nanostructured surface generated by electrospinning. Poly[acrylonitrile-co-(N-vinyl-2-pyrrolidone)] (PANCNVP) that shows excellent antiplatelet adhesion ability was directly electrospun onto its dense membrane surface. Polyacrylonitrile (PAN) samples were used as controls. The depth as well as the density of the nanofibers can be easily controlled. The results showed that the PANCNVP dense membrane certainly suppressed the activation and adhesion of platelets. However, whether the nanofibers and underlying membranes were composed of PAN or PANCNVP, the nanostructured surfaces promoted the activation, adhesion, and orientation of platelets. It was also found that, if the space between fibers was too large or the depth of fibers was too small, the nanostructured surface did not change the property of antiplatelet adhesion of PANCNVP. The promotion of activation and adhesion of platelets was obviously due to the presence of nanofibers, which induced the changes of surface topography and charge. Copyright 2008 Wiley Periodicals, Inc.

Fabrication, characterization and biomedical application of two-nozzle electrospun polycaprolactone/zein-calcium lactate composite nonwoven mat.

PubMed

Liao, Nina; Joshi, Mahesh Kumar; Tiwari, Arjun Prasad; Park, Chan-Hee; Kim, Cheol Sang

2016-07-01

The objective of the current work is to incorporate calcium lactate (CL) into polycaprolactone (PCL)/zein composite micro/nanofibrous scaffolds via electrospinning to engineer bone tissue. In this study, a composite micro/nano fibrous scaffold was fabricated using a single two-nozzle electrospinning system to combine indicative nanofibers from a blended solution of zein-CL and micro-sized fibers from a PCL solution. Incorporation of the CL into the PCL/zein fibers were shown to improve the wettability, tensile strength and biological activity of the composite mats. Moreover, the composite mats have a high efficiency to nucleate calcium phosphate from simulated body fluid (SBF) solution. An in vitro cell culture with osteoblast cells demonstrated that the electrospun composite mats possessed improved biological properties, including a better cell adhesion, spread and proliferation. This study has demonstrated that the PCL/zein-CL composite provides a simple platform to fabricate a new biomimetic scaffold for bone tissue engineering, which can recapitulate both the morphology of extracellular matrix and composition of the bone. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electrospun formulations of bevacizumab for sustained release in the eye.

PubMed

Angkawinitwong, Ukrit; Awwad, Sahar; Khaw, Peng T; Brocchini, Steve; Williams, Gareth R

2017-12-01

Medicines based on vascular endothelial growth factor (VEGF) neutralising antibodies such as bevacizumab have revolutionized the treatment of age related macular degeneration (AMD), a common blinding disease, and have great potential in preventing scarring after surgery or accelerating the healing of corneal injuries. However, at present frequent invasive injections are required to deliver these antibodies. Such administration is uncomfortable for patients and expensive for health service providers. Much effort is thus focused on developing dosage forms that can be administered less frequently. Here we use electrospinning to prepare a solid form of bevacizumab designed for prolonged release while maintaining antibody stability. Electrospun fibers were prepared with bevacizumab encapsulated in the core, surrounded by a poly-ε-caprolactone sheath. The fibers were generated using aqueous bevacizumab solutions buffered at two different pH values: 6.2 (the pH of the commercial product; F beva ) and 8.3 (the isoelectric point of bevacizumab; F bevaP ). The fibers had smooth and cylindrical morphologies, with diameters of ca. 500nm. Both sets of bevacizumab loaded fibers gave sustained release profiles in an in vitro model of the subconjunctival space of the eye. F beva displayed first order kinetics with t 1/2 of 11.4±4.4 days, while F bevaP comprises a zero-order reservoir type release system with t 1/2 of 52.9±14.8 days. Both SDS-PAGE and surface plasmon resonance demonstrate that the bevacizumab in F bevaP did not undergo degradation during fiber fabrication or release. In contrast, the antibody released from F beva had degraded, and failed to bind to VEGF. Our results demonstrate that pH control is crucial to maintain antibody stability during the fabrication of core/shell fibers and ensure release of functional protein. Bevacizumab is a potent protein drug which is highly effective in the treatment of degenerative conditions in the eye. To be effective, frequent

Evaluation of gallic acid loaded zein sub-micron electrospun fibre mats as novel active packaging materials.

PubMed

Neo, Yun Ping; Swift, Simon; Ray, Sudip; Gizdavic-Nikolaidis, Marija; Jin, Jianyong; Perera, Conrad O

2013-12-01

The applicability of gallic acid loaded zein (Ze-GA) electrospun fibre mats towards potential active food packaging material was evaluated. The surface chemistry of the electrospun fibre mats was determined using X-ray photon spectroscopy (XPS). The electrospun fibre mats showed low water activity and whitish colour. Thermogravimetric analysis (TGA) and Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy revealed the stability of the fibre mats over time. The Ze-GA fibre mats displayed similar rapid release profiles, with Ze-GA 20% exhibiting the fastest release rate in water as compared to the others. Gallic acid diffuses from the electrospun fibres in a Fickian diffusion manner and the data obtained exhibited a better fit to Higuchi model. L929 fibroblast cells were cultured on the electrospun fibres to demonstrate the absence of cytotoxicity. Overall, the Ze-GA fibre mats demonstrated antibacterial activity and properties consistent with those considered desirable for active packaging material in the food industry. Copyright © 2013 Elsevier Ltd. All rights reserved.

An Investigation on bilayer structures of electrospun polyacrylonitrile nanofibrous membrane and cellulose membrane used as filtration media for apple juice clarification

NASA Astrophysics Data System (ADS)

Sawitri, Asti; Miftahul Munir, Muhammad; Edikresnha, Dhewa; Sandi, Ahzab; Fauzi, Ahmad; Rajak, Abdul; Natalia, Dessy; Khairurrijal, Khairurrijal

2018-05-01

Nanofibrous membrane has a potential to use in filtration technology with electrospinning as one of the techniques used in synthesizing nanofibers. Polyacrylonitrile (PAN) nanofibrous membranes with various fibers diameters were electrospun by varying its precursor solution concentration. The average fibers diameters of the PAN nanofibrous membranes obtained from the precursor solution concentrations of 6, 9, 12, and 14 wt% were 341, 534, 1274, and 2107 nm, respectively. Filtration media for apple juice clarification were bilayer-structured membranes made of PAN nanofibrous membranes on commercial cellulose microfibrous membranes. It has been shown that the reduction of apple juice color or turbidity performed by the cellulose microfibrous membrane was well enhanced by the presence of the PAN nanofibrous membrane in the bilayer-structured membrane. In addition, the apple-juice color and turbidity reductions increased with decreasing the average fibers diameter of the PAN nanofibrous membrane. Furthermore, the PAN nanofibrous membrane also helped the cellulose microfibrous membrane in the bilayer-structured membrane enhance the reductions of total phenols, protein, and glucose of the apple juice.

Hollow polycaprolactone composite fibers for controlled magnetic responsive antifungal drug release.

PubMed

Wang, Baolin; Zheng, Hongxia; Chang, Ming-Wei; Ahmad, Zeeshan; Li, Jing-Song

2016-09-01

Hollow magnetic fibers for trigger based drug release were synthesized using one-step co-axial electrospinning (COX-ES). This was achieved by encapsulating the antifungal active 'ketoconazole' (KCZ) and iron oxide (Fe3O4) nanoparticles (NPs) in composite form within the core shell polymeric matrix material (polycaprolactone, PCL) during the COX-ES process. Dimethyl silicone oil was used as the inner core (liquid) of co-flowing solutions, which subsequently perfused out of the two-phase electrospun microstructures to form hollow fibers. Resulting drug-loaded magnetic hollow fibers were characterized using optical microscopy, scanning electron microscopy and Fourier Transform Infra-Red. The tensile strength and magnetization properties of composite fibers were also assessed. KCZ drug concentration in electrospinning solutions strongly influenced resulting fiber morphology, drug loading efficiency and release. Expedited drug release during a slow-sustained phase was demonstrated through the application of an auxiliary magnetic field. Variations in tensile strength (∼1.3-6.3MPa) were due to composite fiber components compromising polymer chain integrity. In-vitro cell studies (using human cervical carcinoma cell lines) demonstrated fiber biocompatibility. The present study demonstrates the potential application of magnetic hollow fibers for controlled treatment of fungal infections and antimicrobial indications. Copyright © 2016 Elsevier B.V. All rights reserved.

Incorporation of T4 bacteriophage in electrospun fibres.

PubMed

Korehei, R; Kadla, J

2013-05-01

Antibacterial food packaging materials, such as bacteriophage-activated electrospun fibrous mats, may address concerns triggered by waves of bacterial food contamination. To address this, we investigated several efficient methods for incorporating T4 bacteriophage into electrospun fibrous mats. The incorporation of T4 bacteriophage using simple suspension electrospinning led to more than five orders of magnitude decrease in bacteriophage activity. To better maintain bacteriophage viability, emulsion electrospinning was developed where the T4 bacteriophage was pre-encapsulated in an alginate reservoir via an emulsification process and subsequently electrospun into fibres. This resulted in an increase in bacteriophage viability, but there was still two orders of magnitude drop in activity. Using a coaxial electrospinning process, full bacteriophage activity could be maintained. In this process, a core/shell fibre structure was formed with the T4 bacteriophage being directly incorporated into the fibre core. The core/shell fibre encapsulated bacteriophage exhibited full bacteriophage viability after storing for several weeks at +4°C. Coaxial electrospinning was shown to be capable of encapsulating bacteriophages with high loading capacity, high viability and long storage time. These results are significant in the context of controlling and preventing bacterial infections in perishable foods during storage. © 2013 The Society for Applied Microbiology.

Polycaprolactone electrospun mesh conjugated with an MSC affinity peptide for MSC homing in vivo.

PubMed

Shao, Zhenxing; Zhang, Xin; Pi, Yanbin; Wang, Xiaokun; Jia, Zhuqing; Zhu, Jingxian; Dai, Linghui; Chen, Wenqing; Yin, Ling; Chen, Haifeng; Zhou, Chunyan; Ao, Yingfang

2012-04-01

Mesenchymal stem cell (MSC) is a promising cell source candidate in tissue engineering (TE) and regenerative medicine. However, the inability to target MSCs in tissues of interest with high efficiency and engraftment has become a significant barrier for MSC-based therapies. The mobilization and transfer of MSCs to defective/damaged sites in tissues or organs in vivo with high efficacy and efficiency has been a major concern. In the present study, we identified a peptide sequence (E7) with seven amino acids through phage display technology, which has a high specific affinity to bone marrow-derived MSCs. Subsequent analysis suggested that the peptide could efficiently interact specifically with MSCs without any species specificity. Thereafter, E7 was covalently conjugated onto polycaprolactone (PCL) electrospun meshes to construct an "MSC-homing device" for the recruitment of MSCs both in vitro and in vivo. The E7-conjugated PCL electrospun meshes were implanted into a cartilage defect site of rat knee joints, combined with a microfracture procedure to mobilize the endogenous MSCs. After 7 d of implantation, immunofluorescence staining showed that the cells grown into the E7-conjugated PCL electrospun meshes yielded a high positive rate for specific MSC surface markers (CD44, CD90, and CD105) compared with those in arginine-glycine-aspartic acid (RGD)-conjugated PCL electrospun meshes (63.67% vs. 3.03%; 59.37% vs. 2.98%; and 61.45% vs. 3.82%, respectively). Furthermore, the percentage of CD68 positive cells in the E7-conjugated PCL electrospun meshes was much lower than that in the RGD-conjugated PCL electrospun meshes (5.57% vs. 53.43%). This result indicates that E7-conjugated PCL electrospun meshes absorb much less inflammatory cells in vivo than RGD-conjugated PCL electrospun meshes. The results of the present study suggest that the identified E7 peptide sequence has a high specific affinity to MSCs. Covalently conjugating this peptide on the synthetic PCL mesh

Continuing differentiation of human mesenchymal stem cells and induced chondrogenic and osteogenic lineages in electrospun PLGA nanofiber scaffold

PubMed Central

Xin, Xuejun; Hussain, Mohammad; Mao, Jeremy J.

2010-01-01

Nanofibers have recently gained substantial interest for potential applications in tissue engineering. The objective of this study was to determine whether electrospun nanofibers accommodate the viability, growth, and differentiation of human mesenchymal stem cells (hMSCs) as well as their osteogenic (hMSC-Ob) and chondrogenic (hMSC-Ch) derivatives. Poly(D,L-lactide-co-glycolide) (PLGA) beads with a PLA:PGA ratio of 85:15 were electrospun into non-woven fibers with an average diameter of 760±210 nm. The average Young’s modulus of electrospun PLGA nanofibers was 42±26 kPa, per nanoindentation with atomic force microscopy (AFM). Human MSCs were seeded 1–4 weeks at a density of 2×106 cells/mL in PLGA nanofiber sheets. After 2 week culture on PLGA nanofiber scaffold, hMSCs remained as precursors upon immunoblotting with hKL12 antibody. SEM taken up to 7 days after cell seeding revealed that hMSCs, hMSC-Ob and hMSC-Ch apparently attached to PLGA nanofibers. The overwhelming majority of hMSCs was viable and proliferating in PLGA nanofiber scaffolds up to the tested 14 days, as assayed live/dead tests, DNA assay and BrdU. In a separate experiment, hMSCs seeded in PLGA nanofiber scaffolds were differentiated into chodrogenic and osteogenic cells. Histological assays revealed that hMSCs continuously differentiated into chondrogenic cells and osteogenic cells after 2 week incubation in PLGA nanofibers. Taken together, these data represent an original investigation of continuous differentiation of hMSCs into chondrogenic and osteogenic cells in PLGA nanofiber scaffold. Consistent with previous work, these findings also suggest that nanofibers may serve as accommodative milieu for not only hMSCs, but also as a 3D carrier vehicle for lineage specific cells. PMID:17010425

Synergetic effect of topological cue and periodic mechanical tension-stress on osteogenic differentiation of rat bone mesenchymal stem cells.

PubMed

Liu, Yao; Yang, Guang; Ji, Huanzhong; Xiang, Tao; Luo, En; Zhou, Shaobing

2017-06-01

Mesenchymal stem cells (MSCs) are able to self-renew and differentiate into tissues of mesenchymal origin, making them to be significant for cell-based therapies, such as metabolic bone diseases and bone repair. Regulating the differentiation of MSCs is significant for bone regeneration. Electrospun fibers mimicking natural extracellular matrix (ECM), is an effective artificial ECM to regulate the behaviors and fates of MSCs. The aligned electrospun fibers can modulate polar cell pattern of bone mesenchymal stem cells, which leads to more obvious osteogenic differentiation. Apart from the topographic effect of electrospun fibers, mechanical cues can also intervene the cell behaviors. In this study, the osteogenic differentiation of rat bone mesenchymal stem cells was evaluated, which were cultured on aligned/random electrospun fiber mats materials under mechanical tension intervention. Scanning electron microscope and immune-fluorescent staining were used to directly observe the polarity changing of cellular morphology and cytoskeleton. The results proved that aligned electrospun fibers could be more conducive to promote osteogenic differentiation of rat bone mesenchymal stem cells and this promotion of osteogenic differentiation was enhanced by tension intervention. These results were correlated to the quantitative real-time PCR assay. In general, culturing rat bone mesenchymal stem cells on electrospun fibers under the intervention of mechanical tension is an effective way to mimic a more real cellular microenvironment. Copyright © 2017 Elsevier B.V. All rights reserved.

Development and application of biomimetic electrospun nanofibers in total joint replacement

NASA Astrophysics Data System (ADS)

Song, Wei

Failure of osseointegration (direct anchorage of an implant by bone formation at the bone-implant surface) and implant infection (such as that caused by Staphylococcus aureus, S. aureus) are the two main causes of implant failure and loosening. There is a critical need for orthopedic implants that promote rapid osseointegration and prevent bacterial colonization, particularly when placed in bone compromised by disease or physiology of the patients. A better understanding of the key factors that influence cell fate decisions at the bone-implant interface is required. Our study is to develop a class of "bone-like" nanofibers (NFs) that promote osseointegration while preventing bacterial colonization and subsequent infections. This research goal is supported by our preliminary data on the preparation of coaxial electrospun NFs composed of polycaprolactone (PCL) and polyvinyl alcohol (PVA) polymers arranged in a core-sheath shape. The PCL/PVA NFs are biocompatible and biodegradable with appropriate fiber diameter, pore size and mechanical strength, leading to enhanced cell adhesion, proliferation and differentiation of osteoblast precursor cells. The objective is to develop functionalized "bone-like" PCL/PVA NFs matrix embedded with antibiotics (doxycycline (Doxy), bactericidal and anti-osteoclastic) on prosthesis surface. Through a rat tibia implantation model, the Doxy incorporated coaxial NFs has demonstrated excellent in promoting osseointegration and bacteria inhibitory efficacy. NFs coatings significantly enhanced the bonding between implant and bone remodeling within 8 weeks. The SA-induced osteomyelitis was prevented by the sustained release of Doxy from NFs. The capability of embedding numerous bio-components including proteins, growth factors, drugs, etc. enables NFs an effective solution to overcome the current challenged issue in Total joint replacement. In summary, we proposed PCL/PVA electrospun nanofibers as promising biomaterials that can be applied on

Vitamin-loaded electrospun cellulose acetate nanofiber mats as transdermal and dermal therapeutic agents of vitamin A acid and vitamin E.

PubMed

Taepaiboon, Pattama; Rungsardthong, Uracha; Supaphol, Pitt

2007-09-01

The present contribution reports the use of mats of electrospun cellulose acetate (CA; acetyl content=39.8%; Mw=30,000 Da) nanofibers as carriers for delivery of the model vitamins, all-trans retinoic acid or vitamin A acid (Retin-A) and alpha-tocopherol or vitamin E (Vit-E). The amounts of Vit-E and Retin-A loaded in the base CA solution [17% w/v in 2:1 v/v acetone/N,N-dimethylacetamide (DMAc)] were 5 and 0.5 wt% (based on the weight of CA), respectively. Cross-sectionally round and smooth fibers were obtained. The average diameters of these fibers ranged between 247 and 265 nm. The total immersion of the vitamin-loaded as-spun CA fiber mats in the acetate buffer solutions containing either 0.5 vol % Tween 80 or 0.5 vol % Tween 80 and 10 vol % methanol was used to arrive at the cumulative release of the vitamins from the fiber mat samples. The same was also conducted on the vitamin-loaded solution-cast CA films for comparison. In most cases, the vitamin-loaded as-spun fiber mats exhibited a gradual and monotonous increase in the cumulative release of the vitamins over the test periods (i.e., 24 h for Vit-E-loaded samples and 6 h for Retin-A-loaded ones), while the corresponding as-cast films exhibited a burst release of the vitamins.

Uptake and effects of microplastic textile fibers on freshwater crustacean Daphnia magna.

PubMed

Jemec, Anita; Horvat, Petra; Kunej, Urban; Bele, Marjan; Kržan, Andrej

2016-12-01

Microplastic fibers (MP) from textile weathering and washing are increasingly being recognized as environmental pollutants. The majority of studies on the bioavailability and effects of microplastic focused on small polystyrene spherical plastic particles, while less data are available for fibers and for other materials besides polystyrene. We investigated the ingestion and effects of ground polyethylene terephthalate (PET) textile microfibers (length range: 62-1400 μm, width 31-528 μm, thickness 1-21.5 μm) on the freshwater zooplankton crustacean Daphnia magna after a 48 h exposure and subsequent 24 h of recovery in MP free medium and algae. The majority of ingested fibers by D. magna were around 300 μm, but also some very large twisted MP fibers around 1400 μm were found inside the gut. Exposure to these fibers results in increased mortality of daphnids after 48 h only in the case where daphnids were not pre-fed with algae prior to experiment, but no effect was found when daphnids were fed before the experiments. Regardless of the feeding regime, daphnids were not able to recover from MP exposure after additional 24 h incubation period in a MP free medium with algae. The uptake and effects of PET textile MP on D. magna are presented here for the first time. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electrospinning of gelatin with tunable fiber morphology from round to flat/ribbon.

PubMed

Topuz, Fuat; Uyar, Tamer

2017-11-01

The electrospinning of gelatin with tunable fiber morphology from round to flat/ribbon was shown, and the detailed studies were conducted to correlate the fiber morphology with electrospinning process parameters and gelatin concentration in electrospinning solution. Particularly, variations in the applied voltage and the concentration of gelatin led to the transition of fiber shape from round to flat/ribbon. The formation of flat-shaped fibers was attributed to rapid evaporation of the solvent (formic acid) from the fiber matrix with increasing the applied voltage and gelatin concentration. On the other hand, round fibers were due to the steady evaporation of formic acid throughout the cross-section of fibers. WAXS analysis revealed that the loss of triple-helical crystalline structure in gelatin after the electrospinning process. The gelatin fibers were cross-linked through treatment with toluene 2,4-diisocyanate (TDI) in a mixed solution of acetone and pyridine, and XPS confirmed the cross-linking of the fibers over an increased carbon content on the elemental composition of the fiber surface due to the incorporated TDI moieties. Overall, this study focuses on morphological tuning of gelatin electrospun fibers towards a flat/ribbon-like structure by variation of electrospinning parameters and polymer concentration, and thus, the proposed concept can be adapted towards flattened/ribbon-like fibers of other protein-based systems by electrospinning. Copyright © 2017 Elsevier B.V. All rights reserved.

Layer-by-layer assembly of MXene and carbon nanotubes on electrospun polymer films for flexible energy storage.

PubMed

Zhou, Zehang; Panatdasirisuk, Weerapha; Mathis, Tyler S; Anasori, Babak; Lu, Canhui; Zhang, Xinxing; Liao, Zhiwei; Gogotsi, Yury; Yang, Shu

2018-03-29

Free-standing, highly flexible and foldable supercapacitor electrodes were fabricated through the spray-coating assisted layer-by-layer assembly of Ti3C2Tx (MXene) nanoflakes together with multi-walled carbon nanotubes (MWCNTs) on electrospun polycaprolactone (PCL) fiber networks. The open structure of the PCL network and the use of MWCNTs as spacers not only limit the restacking of Ti3C2Tx flakes but also increase the accessible surface of the active materials, facilitating fast diffusion of electrolyte ions within the electrode. Composite electrodes have areal capacitance (30-50 mF cm-2) comparable to other templated electrodes reported in the literature, but showed significantly improved rate performance (14-16% capacitance retention at a scan rate of 100 V s-1). Furthermore, the composite electrodes are flexible and foldable, demonstrating good tolerance against repeated mechanical deformation, including twisting and folding. Therefore, these tens of micron thick fiber electrodes will be attractive for applications in energy storage, electroanalytical chemistry, brain electrodes, electrocatalysis and other fields, where flexible freestanding electrodes with an open and accessible surface are highly desired.

Preparation and characterization of electrospun alginate/PLA nanofibers as tissue engineering material by emulsion eletrospinning.

PubMed

Xu, Weihong; Shen, Renzhe; Yan, Yurong; Gao, Jie

2017-01-01

Scaffolds made by biomaterials offer favorite environment for cell grow and show a wide potential application in tissue engineering. Novel biocompatibility materials polylatic acid (PLA) nanofiber membranes with favorable biocompatibility and good mechanical strength could serve as an innovative tissue engineering scaffold. Sodium alginate (SA) could be used in biomedical areas because of its anti-bacterial property, hydrophilicity and biocompatibility. In this article, we chose PLA as continuous phase and SA as dispersion phase to prepare a W/O emulsion and then electrospun it to get a SA/PLA composite nanofiber membranes. The CLSM images illustrated that the existence of SA was located on the surface of composite fibers and the FTIR results confirmed the result. A calcium ion replacement step was used as an after-treatment for SA/PLA nanofiber membranes in order to anchor the alginic ion in a form of gelated calcium alginate (CA). The single fiber tensile test shows a good mechanical property of CA/PLA nanofiber membranes, and the nanofiber membranes are beneficial for cell proliferation and differentiation owing to MTT array as well as Alizarin red S (ARS) staining test. Copyright © 2016 Elsevier Ltd. All rights reserved.

Discovery of the beta-form crystal structure in electrospun nanofibers of bio-based poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] and its implication on properties

NASA Astrophysics Data System (ADS)

Gong, Liang

Bacterially produced poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] (PHBHx) is a new type of bioplastic which not only inherits the excellent biodegradability and biocompatibility of its parent homopolymer, polyhydroxybutyrate (PHB), but also overcomes PHB’s brittleness and stiffness with the incorporation of 3-hydroxyhexanoate (Hx) comonomer units with medium-chain-length (mcl) side chains. The tough and ductile PHBHx, with a much lower crystallinity and melting temperature, is well-suited for many practical applications. Efforts have been made to broaden the application range of PHBHx by introducing the beta-form crystalline structure, where the molecular chains adopt a planar zig-zag conformation. However, it is extremely difficult to produce this beta-form in PHBHx due to its much lower crystallinity and much more flexible molecular chains. In this study, we report an approach using the technique of electrospinning. The strain-induced metastable β-form crystalline structure was successfully introduced in PHBHx by collecting the macroscopically aligned electrospun PHBHx nanofibers across the air gap on a piece of aluminum foil and on the tapered edge of a high-speed rotary disk. The presence of the β-form crystal structure in electrospun fiber mats was confirmed by wide-angle X-ray diffraction (WAXD) and Fourier transform infrared spectroscopy (FTIR), with molecular orientation of the polymer chains along the fiber axis revealed by polarized FTIR. Selected area electron diffraction (SAED) and AFM-IR were utilized to investigate the morphological and structural details of individual PHBHx nanofibers. The results demonstrated a coexistence of the thermodynamically stable α-form crystalline structure, where molecular chains adopt a left-handed 21 helical conformation, and the β-form in single fibers. The molecular orientation level and the relative amounts of the two crystalline polymorphs were found to be highly dependent on fiber collection methods

In vitro evaluation of electrospun chitosan mats crosslinked with genipin as guided tissue regeneration barrier membranes

NASA Astrophysics Data System (ADS)

Norowski, Peter Andrew, Jr.

Guided tissue regeneration (GTR) is a surgical technique commonly used to exclude bacteria and soft tissues from bone graft sites in oral/maxillofacial bone graft sites by using a barrier membrane to maintain the graft contour and space. Current clinical barrier membrane materials based on expanded polytetrafluoroethylene (ePTFE) and bovine type 1 collagen are non-ideal and experience a number of disadvantages including membrane exposure, bacterial colonization/biofilm formation and premature degradation, all of which result in increased surgical intervention and poor bone regeneration. These materials do not actively participate in tissue regeneration, however bioactive materials, such as chitosan, may provide advantages such as the ability to stimulate wound healing and de novo bone formation. Our hypothesis is that electrospun chitosan GTR membranes will support cell attachment and growth but prevent cell infiltration/penetration of membrane, demonstrate in vitro degradation predictive of 4--6 month in vivo functionality, and will deliver antibiotics locally to prevent/inhibit periopathogenic complications. To test this hypothesis a series of chitosan membranes were electrospun, in the presence or absence of genipin, a natural crosslinking agent, at concentrations of 5 and 10 mM. These membranes were characterized by scanning electron microscopy, tensile testing, suture pullout testing, Fourier transform infrared spectroscopy, X-ray diffraction, and gel permeation chromatography, and in vitro biodegradation for diameter/morphology of fibers, membrane strengths, degree of crosslinking, crystallinity, molecular weight, and degradation kinetics, respectively. Cytocompability of membranes was evaluated in osteoblastic, fibroblastic and monocyte cultures. The activity of minocycline loaded and released from the membranes was determined in zone of inhibition tests using P. gingivalis microbe. The results demonstrated that genipin crosslinking extended the in vitro

Electrospun PBLG/PLA nanofiber membrane for constructing in vitro 3D model of melanoma.

PubMed

Wang, Yaping; Qian, Junmin; Liu, Ting; Xu, Weijun; Zhao, Na; Suo, Aili

2017-07-01

Though much progress in utilizing tissue engineering technology to investigate tumor development in vitro has been made, the effective management of human melanoma is still a challenge in clinic due to lack of suitable 3D culture systems. In this study, we prepared a poly(γ-benzyl-l-glutamate)/poly(lactic acid) (PBLG/PLA) nanofiber membrane by electrospinning and demonstrated its suitability as a matrix for 3D culture of melanoma cells in vitro. The electrospun PBLG/PLA nanofiber membrane displayed a smooth and uniform fibrous morphology and had a desirable water contact angle of 79.3±0.6°. The average diameter of PBLG/PLA nanofibers was 320.3±95.1nm that was less than that (516.2±163.3nm) of pure PLA nanofibers. The addition of PBLG into PLA decreased the cold crystallization peak of PLA fibers from 93 to 75°C. The in vitro biocompatibility of PBLG/PLA nanofiber membrane was evaluated with B16F10 cells using PLA nanofiber membrane as control. It was found that, compared to PLA nanofiber membrane, PBLG/PLA nanofiber membrane could better support cell viability and proliferation, as indicated by MTT assay and live-dead staining. SEM results revealed that PBLG/PLA rather than PLA nanofiber membrane promoted the generation of tumoroid-like structures. These findings clearly demonstrated that the electrospun PBLG/PLA nanofiber membrane could mimick the extracellular matrix of melanoma microenvironment and be a promising platform for 3D cell culture. Copyright © 2017 Elsevier B.V. All rights reserved.

Calcium phosphate deposition rate, structure and osteoconductivity on electrospun poly(l-lactic acid) matrix using electrodeposition or simulated body fluid incubation

PubMed Central

He, Chuanglong; Jin, Xiaobing; Ma, Peter X.

2013-01-01

Mineralized nanofibrous scaffolds have been proposed as promising scaffolds for bone regeneration due to their ability to mimic both nanoscale architecture and chemical composition of natural bone extracellular matrix (ECM). In this study, a novel electrodeposition method was compared with an extensively explored simulated body fluid (SBF) incubation method in terms of the deposition rate, chemical composition, and morphology of calcium phosphate formed on electrospun fibrous thin matrices with a fiber diameter in the range from about 200 nm to about 1400 nm prepared using 6, 8, 10 and 12 wt% poly(l-lactic acid) (PLLA) solutions in a mixture of dichloromethane and acetone (2:1 in volume). The effects of the surface modification using the two mineralization techniques on osteoblastic cell (MC3T3-E1) proliferation and differentiation were also examined. It was found that electrodeposition was two to three orders of magnitude faster than the SBF method in mineralizing the fibrous matrices, reducing the mineralization time from about two weeks to an hour to achieve the same amounts of mineralization. The mineralization rate also varied with the fiber diameter but in opposite directions between the two mineralization methods. As a general trend, the increase of fiber diameter resulted in a faster mineralization rate for the electrodeposition method but a slower mineralization rate for the SBF incubation method. Using the electrodeposition method, one can control the chemical composition and morphology of the calcium phosphate by varying the electric deposition potential and electrolyte temperature to tune the mixture of dicalcium phosphate dihydrate (DCPD) and hydroxy apatite (HAp). Using the SBF method, one can only obtain a low crystallinity HAp. The mineralized electrospun PLLA fibrous matrices from either method similarly facilitate the proliferation and osteogenic differentiation of preosteoblastic MC3T3-E1 cells as compared to neat PLLA matrices. Therefore, the

Simultaneous Delivery of Highly Diverse Bioactive Compounds from Blend Electrospun Fibers for Skin Wound Healing.

PubMed

Peh, Priscilla; Lim, Natalie Sheng Jie; Blocki, Anna; Chee, Stella Min Ling; Park, Heyjin Chris; Liao, Susan; Chan, Casey; Raghunath, Michael

2015-07-15

Blend emulsion electrospinning is widely perceived to destroy the bioactivity of proteins, and a blend emulsion of water-soluble and nonsoluble molecules is believed to be thermodynamically unstable to electrospin smoothly. Here we demonstrate a method to retain the bioactivity of disparate fragile biomolecules when electrospun. Using bovine serum albumin as a carrier protein; water-soluble vitamin C, fat soluble vitamin D3, steroid hormone hydrocortisone, peptide hormone insulin, thyroid hormone triiodothyronine (T3), and peptide epidermal growth factor (EGF) were simultaneously blend-spun into PLGA-collagen nanofibers. Upon release, vitamin C maintained the ability to facilitate Type I collagen secretion by fibroblasts, EGF stimulated skin fibroblast proliferation, and insulin potentiated adipogenic differentiation. Transgenic cell reporter assays confirmed the bioactivity of vitamin D3, T3, and hydrocortisone. These factors concertedly increased keratinocyte and fibroblast proliferation while maintaining keratinocyte basal state. This method presents an elegant solution to simultaneously deliver disparate bioactive biomolecules for wound healing applications.

Trapping and propelling microparticles at long range by using an entirely stripped and slightly tapered no-core optical fiber.

PubMed

Sheu, Fang-Wen; Huang, Yen-Si

2013-02-28

A stripped no-core optical fiber with a 125 µm diameter was transformed into a symmetric and unbroken optical fiber that tapers slightly to a 45-µm-diameter waist. The laser light can be easily launched into the no-core optical fiber. The enhanced evanescent wave of the slightly tapered no-core optical fiber can attract nearby 5-µm-diameter polystyrene microparticles onto the surface of the tapered multimode optical fiber within fast flowing fluid and propel the trapped particles in the direction of the light propagation to longer delivery range than is possible using a slightly tapered telecom single-mode optical fiber.

Effect of a room-temperature ionic liquid on the structure and properties of electrospun poly(vinylidene fluoride) nanofibers.

PubMed

Xing, Chenyang; Guan, Jipeng; Li, Yongjin; Li, Jingye

2014-03-26

Novel anti-static nanofibers based on blends of poly(vinylidene fluoride) (PVDF) and a room-temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], were fabricated using an electrospinning approach. The effects of the RTIL on the morphology, crystal structure, and physical properties of the PVDF nanofibers were investigated. Incorporation of RTIL leads to an increase in the mean fiber diameter and the rough fiber surface of the PVDF/RTIL composite nanofibers compared with the neat PVDF nanofibers. The PVDF in the PVDF/RTIL nanofibers exhibits an extremely high content (almost 100%) of β crystals, in contrast to the dominance of PVDF γ crystals in bulk melt-blended PVDF/RTIL blends. Nonwoven fabrics produced from the electrospun PVDF/RTIL composite nanofibers show better stretchability and higher electrical conductivity than those made from neat PVDF without RTIL, and are thus excellent antielectrostatic fibrous materials. In addition, RTIL greatly improved the hydrophobicity of the PVDF fibers, enabling them to effectively separate a mixture of tetrachloromethane (CCl4) and water. The extremely high β content, excellent antielectrostatic properties, better stretchability, and hydrophobicity of the present PVDF/RTIL nanofibers make them a promising candidate for micro- and nanoscale electronic device applications.

New poly(ester urea) derived from L-leucine: electrospun scaffolds loaded with antibacterial drugs and enzymes.

PubMed

Díaz, Angélica; del Valle, Luis J; Tugushi, David; Katsarava, Ramaz; Puiggalí, Jordi

2015-01-01

Electrospun scaffolds from an amino acid containing poly(ester urea) (PEU) were developed as promising materials in the biomedical field and specifically in tissue engineering applications. The selected poly(ester urea) was obtained with a high yield and molecular weight by reaction of phosgene with a bis(α-aminoacyl)-α,ω-diol-diester monomer. The polymer having L-leucine, 1,6-hexanediol and carbonic acid units had a semicrystalline character and relatively high glass transition and melting temperatures. Furthermore it was highly soluble in most organic solvents, an interesting feature that facilitated the electrospinning process and the effective incorporation of drugs with bactericidal activity (e.g. biguanide derivatives such as clorhexidine and polyhexamethylenebiguanide) and enzymes (e.g. α-chymotrypsin) that accelerated the degradation process. Continuous micro/nanofibers were obtained under a wide range of processing conditions, being diameters of electrospun fibers dependent on the drug and solvent used. Poly(ester urea) samples were degradable in media containing lipases and proteinases but the degradation rate was highly dependent on the surface area, being specifically greater for scaffolds with respect to films. The high hydrophobicity of new scaffolds had repercussions on enzymatic degradability since different weight loss rates were found depending on how samples were exposed to the medium (e.g. forced or non-forced immersion). New scaffolds were biocompatible, as demonstrated by adhesion and proliferation assays performed with fibroblast and epithelial cells. Copyright © 2014 Elsevier B.V. All rights reserved.

Fabrication and Biocompatibility of Electrospun Silk Biocomposites

PubMed Central

Wei, Kai; Kim, Byoung-Suhk; Kim, Ick-Soo

2011-01-01

Silk fibroin has attracted great interest in tissue engineering because of its outstanding biocompatibility, biodegradability and minimal inflammatory reaction. In this study, two kinds of biocomposites based on regenerated silk fibroin are fabricated by electrospinning and post-treatment processes, respectively. Firstly, regenerated silk fibroin/tetramethoxysilane (TMOS) hybrid nanofibers with high hydrophilicity are prepared, which is superior for fibroblast attachment. The electrospinning process causes adjacent fibers to ‘weld’ at contact points, which can be proved by scanning electron microscope (SEM). The water contact angle of silk/tetramethoxysilane (TMOS) composites shows a sharper decrease than pure regenerated silk fibroin nanofiber, which has a great effect on the early stage of cell attachment behavior. Secondly, a novel tissue engineering scaffold material based on electrospun silk fibroin/nano-hydroxyapatite (nHA) biocomposites is prepared by means of an effective calcium and phosphate (Ca–P) alternate soaking method. nHA is successfully produced on regenerated silk fibroin nanofiber within several min without any pre-treatments. The osteoblastic activities of this novel nanofibrous biocomposites are also investigated by employing osteoblastic-like MC3T3-E1 cell line. The cell functionality such as alkaline phosphatase (ALP) activity is ameliorated on mineralized silk nanofibers. All these results indicate that this silk/nHA biocomposite scaffold material may be a promising biomaterial for bone tissue engineering. PMID:24957869

Modeling the permeability of multiaxial electrospun poly(ε-caprolactone)-gelatin hybrid fibers for controlled doxycycline release.

PubMed

Khalf, Abdurizzagh; Madihally, Sundararajan V

2017-07-01

Recent advances in electrospinning allow the formation of multiple layers of micro and nanosize fibers to regulate drug/therapeutic agent release. Although there has been significant progress in fiber formation techniques and drug loading, fundamental models providing insights into controlling individual permeabilities is lacking. In this regard, we first explored forming coaxial hybrid fibers from hydrophobic poly(ε-caprolactone) (PCL) and hydrophilic gelatin (GT) in three different configurations, and the release of hydrophilic doxycycline (Dox) at 37°C over five days. Triaxial fibers were also formed with a GT layer between PCL/GT layers. Fibers were analyzed for fiber thickness, matrix porosity and thickness, surface morphologies, internal structures, stability in hydrated condition, viability and attachment of human adipocyte stem cells (hASC). Formed fibers were 10-30μm in diameter. hASC were viable, and showed attachment. Various release profiles were obtained from these fibers based on the combination of the core and shell polymers over five days. Using fiber characteristics and release profiles from each configuration, we obtained the overall permeability using Fick's first law and then individual layer permeability using resistance in series model. Calculated overall permeability showed dependency on fiber thickness and partition coefficient of the drug in the region where it was loaded. Our modeling approach helps in optimizing the electrospinning process, drug loading, and polymer solution configuration in regulating controlled release of a drug. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrochromic properties of polyaniline-coated fiber webs for tissue engineering applications.

PubMed

Beregoi, Mihaela; Busuioc, Cristina; Evanghelidis, Alexandru; Matei, Elena; Iordache, Florin; Radu, Mihaela; Dinischiotu, Anca; Enculescu, Ionut

2016-08-30

By combining the electrospinning method advantages (high surface-to-volume ratio, controlled morphology, varied composition and flexibility for the resulting structures) with the electrical activity of polyaniline, a new core-shell-type material with potential applications in the field of artificial muscles was synthesized. Thus, a poly(methylmethacrylate) solution was electrospun in optimized conditions to obtain randomly oriented polymer fiber webs. Further, a gold layer was sputtered on their surface in order to make them conductive and improve the mechanical properties. The metalized fiber webs were then covered with a PANI layer by in situ electrochemical polymerization starting from aniline and using sulphuric acid as oxidizing agent. By applying a small voltage on PANI-coated fiber webs in the presence of an electrolyte, the oxidation state of PANI changes, which is followed by the device color modification. The morphological, electrical and biological properties of the resulting multilayered material were also investigated. Copyright © 2015 Elsevier B.V. All rights reserved.

Electrospun Polymer Nanofibers Decorated with Noble Metal Nanoparticles for Chemical Sensing.

PubMed

Chen, Chen; Tang, Yongan; Vlahovic, Branislav; Yan, Fei

2017-12-01

The integration of different noble metal nanostructures, which exhibit desirable plasmonic and/or electrocatalytic properties, with electrospun polymer nanofibers, which display unique mechanical and thermodynamic properties, yields novel hybrid nanoscale systems of synergistic properties and functions. This review summarizes recent advances on how to incorporate noble metal nanoparticles into electrospun polymer nanofibers and illustrates how such integration paves the way towards chemical sensing applications with improved sensitivity, stability, flexibility, compatibility, and selectivity. It is expected that further development of this field will eventually make a wide impact on many areas of research.

Biodegradable electrospun nanofibers coated with platelet-rich plasma for cell adhesion and proliferation

PubMed Central

Díaz-Gómez, Luis; Alvarez-Lorenzo, Carmen; Concheiro, Angel; Silva, Maite; Dominguez, Fernando; Sheikh, Faheem A.; Cantu, Travis; Desai, Raj; Garcia, Vanessa L.; Macossay, Javier

2014-01-01

Biodegradable electrospun poly(ε-caprolactone) (PCL) scaffolds were coated with platelet-rich plasma (PRP) to improve cell adhesion and proliferation. PRP was obtained from human buffy coat, and tested on human adipose-derived mesenchymal stem cells (MSC) to confirm cell proliferation and cytocompatibility. Then, PRP was adsorbed on the PCL scaffolds via lyophilization, which resulted in uniform sponge-like coating of 2.85 (s.d. 0.14) mg/mg. The scaffolds were evaluated regarding mechanical properties (Young’s modulus, tensile stress and tensile strain), sustained release of total protein and growth factors (PDGF-BB, TGF-β1 and VEGF), and hemocompatibility. MSC seeded on the PRP-PCL nanofibers showed an increased adhesion and proliferation compared to pristine PCL fibers. Moreover, the adsorbed PRP enabled angiogenesis features observed as neovascularization in a chicken chorioallantoic membrane (CAM) model. Overall, these results suggest that PRP-PCL scaffolds hold promise for tissue regeneration applications. PMID:24857481

Culture on electrospun polyurethane scaffolds decreases atrial natriuretic peptide expression by cardiomyocytes in vitro.

PubMed

Rockwood, Danielle N; Akins, Robert E; Parrag, Ian C; Woodhouse, Kimberly A; Rabolt, John F

2008-12-01

The function of the mammalian heart depends on the functional alignment of cardiomyocytes, and controlling cell alignment is an important consideration in biomaterial design for cardiac tissue engineering and research. The physical cues that guide functional cell alignment in vitro and the impact of substrate-imposed alignment on cell phenotype, however, are only partially understood. In this report, primary cardiac ventricular cells were grown on electrospun, biodegradable polyurethane (ES-PU) with either aligned or unaligned microfibers. ES-PU scaffolds supported high-density cultures and cell subpopulations remained intact over two weeks in culture. ES-PU cultures contained electrically-coupled cardiomyocytes with connexin-43 localized to points of cell:cell contact. Multi-cellular organization correlated with microfiber orientation and aligned materials yielded highly oriented cardiomyocyte groupings. Atrial natriuretic peptide, a molecular marker that shows decreasing expression during ventricular cell maturation, was significantly lower in cultures grown on ES-PU scaffolds than in those grown on tissue culture polystyrene. Cells grown on aligned ES-PU had significantly lower steady state levels of ANP and constitutively released less ANP over time indicating that scaffold-imposed cell organization resulted in a shift in cell phenotype to a more mature state. We conclude that the physical organization of microfibers in ES-PU scaffolds impacts both multi-cellular architecture and cardiac cell phenotype in vitro.

Lipase polystyrene giant amphiphiles.

PubMed

Velonia, Kelly; Rowan, Alan E; Nolte, Roeland J M

2002-04-24

A new type of giant amphiphilic molecule has been synthesized by covalently connecting a lipase enzyme headgroup to a maleimide-functionalized polystyrene tail (40 repeat units). The resulting biohybrid forms catalytic micellar rods in water.

Advances in skin regeneration: application of electrospun scaffolds.

PubMed

Norouzi, Mohammad; Boroujeni, Samaneh Moghadasi; Omidvarkordshouli, Noushin; Soleimani, Masoud

2015-06-03

The paucity of cellular and molecular signals essential for normal wound healing makes severe dermatological ulcers stubborn to heal. The novel strategies of skin regenerative treatments are focused on the development of biologically responsive scaffolds accompanied by cells and multiple biomolecules resembling structural and biochemical cues of the natural extracellular matrix (ECM). Electrospun nanofibrous scaffolds provide similar architecture to the ECM leading to enhancement of cell adhesion, proliferation, migration and neo tissue formation. This Review surveys the application of biocompatible natural, synthetic and composite polymers to fabricate electrospun scaffolds as skin substitutes and wound dressings. Furthermore, the application of biomolecules and therapeutic agents in the nanofibrous scaffolds viz growth factors, genes, antibiotics, silver nanoparticles, and natural medicines with the aim of ameliorating cellular behavior, wound healing, and skin regeneration are discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Trapping and Propelling Microparticles at Long Range by Using an Entirely Stripped and Slightly Tapered No-Core Optical Fiber

PubMed Central

Sheu, Fang-Wen; Huang, Yen-Si

2013-01-01

A stripped no-core optical fiber with a 125 μm diameter was transformed into a symmetric and unbroken optical fiber that tapers slightly to a 45-μm-diameter waist. The laser light can be easily launched into the no-core optical fiber. The enhanced evanescent wave of the slightly tapered no-core optical fiber can attract nearby 5-μm-diameter polystyrene microparticles onto the surface of the tapered multimode optical fiber within fast flowing fluid and propel the trapped particles in the direction of the light propagation to longer delivery range than is possible using a slightly tapered telecom single-mode optical fiber. PMID:23449118

A new biodegradable sisal fiber-starch packing composite with nest structure.

PubMed

Xie, Qi; Li, Fangyi; Li, Jianfeng; Wang, Liming; Li, Yanle; Zhang, Chuanwei; Xu, Jie; Chen, Shuai

2018-06-01

A new completely biodegradable sisal fiber-starch packing composite was proposed. The effects of fiber content and alkaline treatment on the cushioning property of the composites were studied from energy absorption efficiency, cellular microstructure and compatibility between fiber and starch. With increasing fiber content, the nest structure of composites becomes dense first and then loosens, resulting in initial enhancement and subsequent weakening of the cushioning property of the composites. The composite with 4:13 mass ratio of fiber and thermoplastic starch (TPS) exhibit the optimal cushioning property. Alkaline treatment increases the compatibility between sisal fiber and TPS, promotes the formation of dense nest structure, thereby enhances the cushioning property of the composites. After biodegradability tests for 28 days, the weight loss of the composites was 62.36%. It's found that the composites are a promising replacement for expandable polystyrene (EPS) as packing material, especially under large compression load (0.7-6 MPa). Copyright © 2018 Elsevier Ltd. All rights reserved.

Electrospraying of microfluidic encapsulated cells for the fabrication of cell-laden electrospun hybrid tissue constructs.

PubMed

Weidenbacher, L; Abrishamkar, A; Rottmar, M; Guex, A G; Maniura-Weber, K; deMello, A J; Ferguson, S J; Rossi, R M; Fortunato, G

2017-12-01

The fabrication of functional 3D tissues is a major goal in tissue engineering. While electrospinning is a promising technique to manufacture a structure mimicking the extracellular matrix, cell infiltration into electrospun scaffolds remains challenging. The robust and in situ delivery of cells into such biomimetic scaffolds would potentially enable the design of tissue engineered constructs with spatial control over cellular distribution but often solvents employed in the spinning process are problematic due to their high cytotoxicity. Herein, microfluidic cell encapsulation is used to establish a temporary protection vehicle for the in situ delivery of cells for the development of a fibrous, cell-laden hybrid biograft. Therefore a layer-by-layer process is used by alternating fiber electrospinning and cell spraying procedures. Both encapsulation and subsequent electrospraying of capsules has no negative effect on the viability and myogenic differentiation of murine myoblast cells. Propidium iodide positive stained cells were analyzed to quantify the amount of dead cells and the presence of myosin heavy chain positive cells after the processes was shown. Furthermore, encapsulation successfully protects cells from cytotoxic solvents (such as dimethylformamide) during in situ delivery of the cells into electrospun poly(vinylidene fluoride-co-hexafluoropropylene) scaffolds. The resulting cell-populated biografts demonstrate the clear potential of this approach in the creation of viable tissue engineering constructs. Infiltration of cells and their controlled spatial distribution within fibrous electrospun membranes is a challenging task but allows for the development of functional highly organized 3D hybrid tissues. Combining polymer electrospinning and cell electrospraying in a layer-by-layer approach is expected to overcome current limitations of reduced cell infiltration after traditional static seeding. However, organic solvents, used during the electrospinning

Electro-Responsive Behaviour Multi-Wall Nanotubes/Gelatin Composites and Cross-Linked Gelatin Electrospun Mats

DTIC Science & Technology

2008-02-11

sample , could explain large swelling in blend samples which might enhance ions diffusion and lead to an increase of bending. 21 References [1...1 Final Report on Electro-responsive behaviour multi-wall nanotubes/gelatin composites and cross-linked gelatin electrospun mats...12-10-2007 4. TITLE AND SUBTITLE Electro-responsive behaviour multi-wall nanotubes/gelatin composites and cross-linked gelatin electrospun mats

Enhanced piezoresponse of highly aligned electrospun poly(vinylidene fluoride) nanofibers

NASA Astrophysics Data System (ADS)

Kang, Sung Bum; Won, Sang Hyuk; Im, Min Ji; Kim, Chan Ul; Park, Won Il; Baik, Jeong Min; Choi, Kyoung Jin

2017-09-01

Well-ordered nanostructure arrays with controlled densities can potentially improve material properties; however, their fabrication typically involves the use of complicated processing techniques. In this work, we demonstrate a uniaxial alignment procedure for fabricating poly(vinylidene fluoride) (PVDF) electrospun nanofibers (NFs) by introducing collectors with additional steps. The mechanism of the observed NF alignment, which occurs due to the concentration of lateral electric field lines around collector steps, has been elucidated via finite-difference time-domain simulations. The membranes composed of well-aligned PVDF NFs are characterized by a higher content of the PVDF β-phase, as compared to those manufactured from randomly orientated fibers. The piezoelectric energy harvester, which was fabricated by transferring well-aligned PVDF NFs onto flexible substrates with Ag electrodes attached to both sides, exhibited a 2-fold increase in the output voltage and a 3-fold increase in the output current as compared to the corresponding values obtained for the device manufactured from randomly oriented NFs. The enhanced piezoresponse observed for the aligned PVDF NFs is due to their higher β-phase content, denser structure, smaller effective radius of curvature during bending, greater applied strain, and higher fraction of contributing NFs.

Glass transition behavior of polystyrene/silica nanocomposites.

NASA Astrophysics Data System (ADS)

Xie, Yuping; Sen, Sudeepto; Kumar, Sanat; Bansal, Amitabh

2006-03-01

The change in thermomechanical properties of nano-filled polymers is of considerable scientific and technological interest. The interaction between the nanofillers and the matrix polymer controls the nanocomposite properties. We will present the results from recent and ongoing DSC experiments on polystyrene/silica nanocomposites. Polystyrene of different molecular weights (and from different sources) and silica nanoparticles 10-15 nm in diameter (both as received from Nissan and surface modified by grafted or physisorbed polystyrene) are being used to process the nanocomposites. We are studying trends in the glass transition behavior by changing the matrix molecular weights and the silica weight fractions. Recent data indicate that the glass transition temperature can both decrease and increase depending on the polymer-nanofiller combination as well as the thermal treatment of the nanocomposites prior to the DSC runs.

Smart Electrospun Nanofibers for Controlled Drug Release: Recent Advances and New Perspectives

PubMed Central

Weng, Lin; Xie, Jingwei

2017-01-01

In biological systems, chemical molecules or ions often release upon certain conditions, at a specific location, and over a desired period of time. Electrospun nanofibers that undergo alterations in the physicochemical characteristics corresponding to environmental changes have gained considerable interest for various applications. Inspired by biological systems, therapeutic molecules have been integrated with these smart electrospun nanofibers, presenting activation-modulated or feedback-regulated control of drug release. Compared to other materials like smart hydrogels, environment-responsive nanofiber-based drug delivery systems are relatively new but possess incomparable advantages due to their greater permeability, which allows shorter response time and more precise control over the release rate. In this article, we review the mechanisms of various environmental parameters functioning as stimuli to tailor the release rates of smart electrospun nanofibers. We also illustrate several typical examples in specific applications. We conclude this article with a discussion on perspectives and future possibilities in this field. PMID:25732665

Smart electrospun nanofibers for controlled drug release: recent advances and new perspectives.

PubMed

Weng, Lin; Xie, Jingwei

2015-01-01

In biological systems, chemical molecules or ions often release upon certain conditions, at a specific location, and over a desired period of time. Electrospun nanofibers that undergo alterations in the physicochemical characteristics corresponding to environmental changes have gained considerable interest for various applications. Inspired by biological systems, therapeutic molecules have been integrated with these smart electrospun nanofibers, presenting activation-modulated or feedback-regulated control of drug release. Compared to other materials like smart hydrogels, environment-responsive nanofiber-based drug delivery systems are relatively new but possess incomparable advantages due to their greater permeability, which allows shorter response time and more precise control over the release rate. In this article, we review the mechanisms of various environmental parameters functioning as stimuli to tailor the release rates of smart electrospun nanofibers. We also illustrate several typical examples in specific applications. We conclude this article with a discussion on perspectives and future possibilities in this field.

Direct piezoelectric responses of soft composite fiber mats

NASA Astrophysics Data System (ADS)

Varga, M.; Morvan, J.; Diorio, N.; Buyuktanir, E.; Harden, J.; West, J. L.; Jákli, A.

2013-04-01

Recently soft fiber mats electrospun from solutions of Barium Titanate (BT) ferroelectric ceramics particles and polylactic acid (PLA) were found to have large (d33 ˜ 1 nm/V) converse piezoelectric signals offering a myriad of applications ranging from active implants to smart textiles. Here, we report direct piezoelectric measurements (electric signals due to mechanical stress) of the BT/PLA composite fiber mats at several BT concentrations. A homemade testing apparatus provided AC stresses in the 50 Hz-1.5 kHz-frequency range. The piezoelectric constant d33 ˜ 0.5 nC/N and the compression modulus Y ˜ 104-105 Pa found are in agreement with the prior converse piezoelectric and compressibility measurements. Importantly, the direct piezoelectric signal is large enough to power a small LCD by simple finger tapping of a 0.15 mm thick 2-cm2 area mat. We propose using these mats in active Braille cells and in liquid crystal writing tablets.

Engineering ear-shaped cartilage using electrospun fibrous membranes of gelatin/polycaprolactone.

PubMed

Xue, Jixin; Feng, Bei; Zheng, Rui; Lu, Yang; Zhou, Guangdong; Liu, Wei; Cao, Yilin; Zhang, Yanzhong; Zhang, Wen Jie

2013-04-01

Tissue engineering approach continuously requires for emerging strategies to improve the efficacy in repairing and regeneration of tissue defects. Previously, we developed a sandwich model strategy for cartilage engineering, using the combination of acellular cartilage sheets (ACSs) and chondrocytes. However, the process for the preparation of ACSs is complicated, and it is also difficult to obtain large ACSs. The aim of this study was to engineer cartilage with precise three-dimensional (3-D) structures by applying electrospun fibrous membranes of gelatin/polycaprolactone (GT/PCL). We first prepared the electrospun GT/PCL membranes into rounded shape, and then seeded chondrocytes in the sandwich model. After in vitro and in vivo cultivation, the newly formed cartilage-like tissues were harvested. Macroscopic observations and histological analysis confirmed that the engineering of cartilage using the electrospun GT/PCL membranes was feasible. An ear-shaped cartilage was then constructed in the sandwich model, with the help of an ear-shaped titanium alloy mold. After 2 weeks of culture in vitro and 6 weeks of subcutaneous incubation in vivo, the ear-shaped cartilage largely maintained their original shape, with a shape similarity up to 91.41% of the titanium mold. In addition, the engineered cartilage showed good elasticity and impressive mechanical strength. These results demonstrated that the engineering of 3-D cartilage in a sandwich model using electrospun fibrous membranes was a facile and effective approach, which has the potential to be applied for the engineering of other tissues with complicated 3-D structures. Copyright © 2012 Elsevier Ltd. All rights reserved.

Electrospinning of ceramic nanofibers

NASA Astrophysics Data System (ADS)

Eick, Benjamin M.

Silicon Carbide (SiC) nanofibers of diameters as low as 20 nm are fabricated. The fibers were produced through the electrostatic spinning of the preceramic poly(carbomethylsilane) with pyrolysis to ceramic. A new technique was used where the preceramic was blended with polystyrene (PS) and, subsequent to electrospinning, was exposed to UV to crosslink the PS and prevent fibers flowing during pyrolysis. Electrospun SiC fibers were characterized by FTIR, TGA-DTA, SEM, TEM, XRD, and SAED. Fibers were shown to be polycrystalline and nanograined with alpha-SiC 15R polytype being dominant, where commercial fiber production methods form beta-SiC 3C. Pyrolysis of the bulk polymer blend to SiC produced alpha-SiC 15R as the dominant polytype with larger grains showing that electrospinning nanofibers affects resultant crystallinity. Fibers produced were shown to have a core-shell structure of an oxide scale that was variable by pyrolysis conditions. Metal oxide powders (chromium oxide, cobalt oxide, iron oxide, silicon oxide, tantalum oxide, titanium oxide, tungsten oxide, vanadium oxide, and zirconium oxide), were converted to metal carbide powders and metal nitride powders by the process of carbothermal reduction (CTR). Synthetic pitch was explored as an alternative to graphite which is a common carbon source for CTR. It was shown via characterization with XRD that pitch performs as well and in some cases better than graphite and is therefore a viable alternative in CTR. Conversion of metal oxide powders with pitch led to conversion of sol-gel based metal oxide nanofibers produced by electrospinning. Pitch was soluble in the solutions xv that were electrospun allowing for intimate contact between the sol-gel and the carbon source for CTR. This method became a two step processing method to produce metal carbide and nitride nanofibers: first electrospin sol-gel based metal oxide nanofibers and subsequently pyrolize them in the manner of CTR to transform them. Results indicate

The impact of the molecular weight of dextran on formation of whey protein isolate (WPI)-dextran conjugates in fibers produced by needleless electrospinning after annealing.

PubMed

Turan, Deniz; Gibis, Monika; Gunes, Gurbuz; Baier, Stefan K; Weiss, Jochen

2018-04-25

The conjugation reaction of electrospun fibers of a mixture of whey protein isolate (WPI) and dextran using different molecular weights (40, 70, and 100 kDa) and mixing ratios was studied. This study includes the electrospinnability of a mixture of WPI and dextran, and the conjugation reaction between them via the initial stage of the Maillard reaction. The WPI-dextran fibers were characterized using optical and transmission electron microscopy. The covalent attachment of dextran to WPI was confirmed using sodium-dodecyl-sulfate-polyacrylamide gel-electrophoresis with protein and glycoprotein staining. Both 70 and 100 kDa of dextran and WPI at mixing ratios of 2 : 1 and 3 : 1 in phosphate buffer (30 mM, pH 6.5) were electrospun using needleless electrospinning. The solution concentration of the mixture was 50 wt% (33.3/37.5 wt% for dextran/16.5/12.5 wt% for WPI). The optimal conjugation conditions chosen from the experiments were a mixture of dextran (70 kDa)-WPI at 3 : 1 (75% relative humidity, 60 °C, 48 h).

Electrospinning of PVC with natural rubber

NASA Astrophysics Data System (ADS)

Othman, Muhammad Hariz; Mohamed, Mahathir; Abdullah, Ibrahim

2013-11-01

Polyvinyl chloride (PVC) was mixed with natural rubbers which are liquid natural rubber (LNR), liquid epoxidised natural rubber (LENR) and liquid epoxidised natural rubber acrylate (LENRA) for a preparation of a fine non-woven fiber's mat. PVC and each natural rubbers(PVC:LENR, PVC:LNR and PVC:LENRA) were mixed based on ratio of 70:30. Electrospinning method was used to prepare the fiber. The results show that the spinnable concentration of PVC/ natural rubber/THF solution is 16 wt%. The morphology, diameter, structure and degradation temperature of electrospun fibers were investigated by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). SEM photos showed that the morphology and diameter of the fibers were mainly affected by the addition of natural rubber. TGA results suggested that PVC electrospun fiber has higher degradation temperature than those electrospun fibers that contain natural rubber.

E-Spun Composite Fibers of Collagen and Dragline Silk Protein: Fiber Mechanics, Biocompatibility, and Application in Stem Cell Differentiation

PubMed Central

2015-01-01

Biocomposite matrices with high mechanical strength, high stability, and the ability to direct matrix-specific stem cell differentiation are essential for the reconstruction of lesioned tissues in tissue engineering and cell therapeutics. Toward this end, we used the electrospinning technique to fabricate well-aligned composite fibers from collagen and spider dragline silk protein, obtained from the milk of transgenic goats, mimicking the native extracellular matrix (ECM) on a similar scale. Collagen and the dragline silk proteins were found to mix homogeneously at all ratios in the electrospun (E-spun) fibers. As a result, the ultimate tensile strength and elasticity of the fibers increased monotonically with silk percentage, whereas the stretchability was slightly reduced. Strikingly, we found that the incorporation of silk proteins to collagen dramatically increased the matrix stability against excessive fiber swelling and shape deformation in cell culture medium. When human decidua parietalis placental stem cells (hdpPSCs) were seeded on the collagen–silk matrices, the matrices were found to support cell proliferation at a similar rate as that of the pure collagen matrix, but they provided cell adhesion with reduced strengths and induced cell polarization at varied levels. Matrices containing 15 and 30 wt % silk in collagen (CS15, CS30) were found to induce a level of neural differentiation comparable to that of pure collagen. In particular, CS15 matrix induced the highest extent of cell polarization and promoted the development of extended 1D neural filaments strictly in-line with the aligned fibers. Taking the increased mechanical strength and fiber stability into consideration, CS15 and CS30 E-spun fibers offer better alternatives to pure collagen fibers as scaffolds that can be potentially utilized in neural tissue repair and the development of future nanobiodevices. PMID:25405355

Fabrication and characterization of electrospun gelatin nanofibers crosslinked with oxidized phenolic compounds.

PubMed

Tavassoli-Kafrani, Elham; Goli, Sayed Amir Hossein; Fathi, Milad

2017-10-01

In this study, the ability of oxidized phenolic compounds of tannic, gallic, ferulic and caffeic acids to crosslink gelatin (G) was investigated. The electrospun crosslinked gelatin nanofibers were assessed in terms of gelatin solution properties, fiber morphology, thermal properties, FTIR spectra, XRD pattern and antioxidant activity. Tannic acid showed the most crosslinking activity towards gelatin (13.3 vs 7.44, 4.65, and 3.45% for caffeic, gallic and ferulic, respectively). Crosslinking enhanced roughly electrical conductivity of gelatin solution while the surface tension and viscosity reduced. According to scanning electron microscopy (SEM) results, the fibrous structure of crosslinked gelatin nanofibers didn't change while their diameter increased to the highest value of 280nm for gelatin-tannic. Gelatin-gallic sample showed the highest total phenolic content (86.3mg gallic acid equivalent/g) and antioxidant activity (86.5%). Surprisingly, from differential scanning calorimetry (DSC) curves, it was found that crosslinking led to the reduction of thermal stability of gelatin nanofibers. Copyright © 2017 Elsevier B.V. All rights reserved.

Facile modification of electrospun fibrous structures with antifouling zwitterionic hydrogels.

PubMed

Xu, Tong; Yang, Jing; Zhang, Jiamin; Zhu, Yingnan; Li, Qingsi; Pan, Chao; Zhang, Lei

2017-12-28

Electrospinning technology can easily produce different shaped fibrous structures, making them highly valuable to various biomedical applications. However, surface contamination of biomolecules, cells, or blood has emerged as a significant challenge to the success of electrospun devices, especially artificial blood vessels, catheters and wound dressings etc. Many efforts have been made to resist the surface non-specific biomolecules or cells adsorption, but most of them require complex pre-treatment processes, hard-to-remove metal catalysts or rigorous reaction conditions. In addition, the stability of antifouling coatings, especially in complex conditions, is still a major concern. In this work, inspired by the interpenetrating polymer network and reinforced concrete structure, an efficient and facile strategy for modifying hydrophobic electrospun meshes and tubes with antifouling zwitterionic hydrogels has been introduced. The resulting products could efficiently resist the adhesion of proteins, cells, or even fresh whole blood. Meanwhile, they could maintain the shapes and mechanical strength of the original electrospun structures. Furthermore, the hydrogel structures could retain stable in a physiological condition for at least 3 months. This paper provided a general antifouling and hydrophilicity surface modification strategy for various fibrous structures, and could be of great value for many biomedical applications where antifouling properties are critical.

Protein valves prepared by click reaction grafting of poly(N-isopropylacrylamide) to electrospun poly(vinyl chloride) fibrous membranes

NASA Astrophysics Data System (ADS)

Guo, Jian-Wei; Lin, Zhen-Yu; Chang, Chi-Jung; Lu, Chien-Hsing; Chen, Jem-Kun

2018-05-01

In this study, poly(vinyl chloride) (PVC) was electrospun into fibrous membranes and then reacted with NaN3 to generate azido-terminated PVC fibrous membranes. A propargyl-terminated poly(N-isopropylacrylamide) (PNIPAAm) was also synthesized and then grafted, through click reactions, onto the azido-terminated PVC fiber surface. Protrusion-, scale-, and joint-like structures of the PNIPAAm grafts on the PVC fibers were formed upon increasing the molecular weight of the PNIPAAm grafts. The PNIPAAm-grafted PVC fibrous mats exhibited completely wetted surfaces at 25 °C because of their high roughness. The static water contact angle of the PNIPAAm-grafted PVC fibrous mats reached 140° when the temperature was increased to 45 °C. This thermoresponsive behavior was significantly greater than that of the PNIPAAm grafted on a flat surface. Temperature-responsive membranes were constructed having a pore size of 1.38 μm and applied as protein valves to block and release an antibody (fluorescein-conjugated AffiniPure goat anti-rabbit IgG). At 25 °C, the collection efficiency remained at 94% for antibody concentrations up to 60 ng/L. As the temperature increased to 45 °C, the collection efficiency decreased abruptly, to 4%, when the antibody concentration was greater than 20 ng/L. Accordingly, this system of PNIPAAm-grafted PVC fibers functioned as a protein valve allowing the capture and concentration of proteins.

Electrospun composite nanofiber fabrics containing uniformly dispersed antimicrobial agents as an innovative type of polymeric materials with superior antimicrobial efficacy.

PubMed

Sun, Xinbo; Zhang, Lifeng; Cao, Zhengbing; Deng, Ying; Liu, Li; Fong, Hao; Sun, Yuyu

2010-04-01

Herein we report that electrospun composite nanofiber fabrics containing uniformly dispersed antimicrobial agents and having large surface-to-mass ratios are an innovative type of antimicrobial polymeric materials with durable, nonleachable, and biocompatible characteristics, and more importantly, superior antimicrobial efficacy. Specifically, electrospun cellulose acetate (CA) nanofiber fabrics containing an N-halamine antimicrobial agent of bis(N-chloro-2,2,6,6-tetramethyl-4-piperidinyl) sebacate (Cl-BTMP) were prepared and evaluated; the results of antimicrobial efficacy indicated that the electrospun composite nanofiber fabrics substantially outperformed the control samples that were solution-cast films containing identical amounts of CA and Cl-BTMP. Additionally, the results of trypan blue assay test suggested that the electrospun composite nanofiber fabrics also had excellent mammal cell viability. The developed electrospun composite nanofiber fabrics with superior antimicrobial efficacy are expected to find vital applications in biomedical, hygienic, and many other fields.

Investigation of local ferroelectric and piezoelectric effects on mats of electrospun poly(vinylidene fluoride) (PVDF) fibers

NASA Astrophysics Data System (ADS)

Durgaprasad, P.; Hemalatha, J.

2018-04-01

Poly(vinylidene fluoride) (PVDF) fiber mat was synthesized by using electrospinning technique by using DMF/Acetone as mixed solvent. Structural and functional group studies were studied by using X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy respectively. The morphology of the fiber mat was investigated by using scanning electron microscopy (SEM) which revealed the formation of uniform fibers with an average diameter of 500nm. The local ferroelectric, piezo electric properties and also the domain switching of the fiber mats were investigated by Dynamic Contact Electrostatic Force Microscopy (DC-EFM) studies. The peizoelectric/ferroelectric response was recorded and analyzed.

Preparation and characterization of kefiran electrospun nanofibers.

PubMed

Esnaashari, Seyedeh Sara; Rezaei, Sasan; Mirzaei, Esmaeil; Afshari, Hamed; Rezayat, Seyed Mahdi; Faridi-Majidi, Reza

2014-09-01

In this study, we report the first successful production of kefiran nanofibers through electrospinning process using distilled water as solvent. For this purpose, kefiran was extracted from cultured kefir grains, and homogenous kefiran solutions with different concentrations were prepared and then electrospun to obtain uniform nanofibers. The effect of main process parameters, including applied voltage, tip-to-collector distance, and feeding rate, on diameter and morphology of produced nanofibers, was studied. Scanning electron microscopy (SEM) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy were used to characterize electrospun mats. Rheological behavior of the kefiran solution was evaluated via a cone and plate rheometer too. The results exhibited that diameter of kefiran nanofibers increased with increasing polymer concentration, applied voltage, and polymer feeding rate, while tip-to-collector distance did not have significant effect on nanofiber diameter. ATR-FTIR spectra showed that kefiran has maintained its molecular structure during electrospinning process. Flow curves also demonstrated shear thinning behavior for kefiran solutions. Copyright © 2014 Elsevier B.V. All rights reserved.

A minitablet formulation made from electrospun nanofibers.

PubMed

Poller, Bettina; Strachan, Clare; Broadbent, Roland; Walker, Greg F

2017-05-01

The purpose of this study was to evaluate electrospun drug loaded nanofibers as a new matrix for minitablets. Prednisone, a poorly water-soluble drug, was loaded into povidone (polyvinylpyrrolidone, PVP) nanofibers using the process of electrospinning. The drug-loaded nanofiber mat was compressed into minitablets with a 2mm diameter and a height of 2.63±0.04mm. SEM analysis of the minitablet identified a nano-web structure with a nanofiber diameter in the range of 400-500nm. The minitablets met the requirements of the US Pharmacopeia with respect to content uniformity and friability. DSC and XRPD analysis of the minitablet indicated that the drug-polymer mixture was a one-phase amorphous system. XRPD analysis of the drug loaded nanofiber mat after 10-months of storage at ambient temperature showed no evidence of recrystallization of the drug. Solubility and dissolution properties of the drug formulated into a nanofiber mat and minitablet were evaluated. These results show that electrospun nanofibers may provide a useful matrix for the further development of minitablets. Copyright © 2017 Elsevier B.V. All rights reserved.

Mechanical properties and cellular response of novel electrospun nanofibers for ligament tissue engineering: Effects of orientation and geometry.

PubMed

Pauly, Hannah M; Kelly, Daniel J; Popat, Ketul C; Trujillo, Nathan A; Dunne, Nicholas J; McCarthy, Helen O; Haut Donahue, Tammy L

2016-08-01

Electrospun nanofibers are a promising material for ligamentous tissue engineering, however weak mechanical properties of fibers to date have limited their clinical usage. The goal of this work was to modify electrospun nanofibers to create a robust structure that mimics the complex hierarchy of native tendons and ligaments. The scaffolds that were fabricated in this study consisted of either random or aligned nanofibers in flat sheets or rolled nanofiber bundles that mimic the size scale of fascicle units in primarily tensile load bearing soft musculoskeletal tissues. Altering nanofiber orientation and geometry significantly affected mechanical properties; most notably aligned nanofiber sheets had the greatest modulus; 125% higher than that of random nanofiber sheets; and 45% higher than aligned nanofiber bundles. Modifying aligned nanofiber sheets to form aligned nanofiber bundles also resulted in approximately 107% higher yield stresses and 140% higher yield strains. The mechanical properties of aligned nanofiber bundles were in the range of the mechanical properties of the native ACL: modulus=158±32MPa, yield stress=57±23MPa and yield strain=0.38±0.08. Adipose derived stem cells cultured on all surfaces remained viable and proliferated extensively over a 7 day culture period and cells elongated on nanofiber bundles. The results of the study suggest that aligned nanofiber bundles may be useful for ligament and tendon tissue engineering based on their mechanical properties and ability to support cell adhesion, proliferation, and elongation. Copyright © 2016 Elsevier Ltd. All rights reserved.

In vitro evaluation of electrospun PLGA/PLLA/PDLLA blend fibers loaded with naringin for guided bone regeneration.

PubMed

Guo, Zhenzhao; Wu, Shuai; Li, Hong; Li, Qiyan; Wu, Gang; Zhou, Changren

2018-03-30

The present study was to evaluate fiber mesh loaded with naringin via electrospinning to guide bone regeneration in vitro. The naringin-loaded fiber mesh was prepared via elctrospinning of PLGA, PLLA, PDLLA blending solution with naringin. SEM showed that naringin decreased the fiber's diameter according to the concentration of naringin. After 20 days' degradation in PBS, the drug-loaded fiber meshes still kept their stability with about 10% decrease in tensile strength. In vitro release experiments showed a sustained and steady naringin releasing profile with little initial burst releasing. Compared to the mats without naringin, the fiber mats loaded with naringin showed the most pronounced enhancement of cell growth when MC3T3-E1 cells were cultured on the fiber mats. The blend fiber loaded with naringin has optimized physical properties and sustained release profile in vitro. The study presents a promising fibrous mesh material for guided bone regeneration therapy.

The effectiveness of the biodegradation of raw and processed polystyrene by mealworms

NASA Astrophysics Data System (ADS)

Leluk, Karol; Hanus-Lorenz, Beata; Rybak, Justyna; Bożek, Magdalena

2017-11-01

In our studies biodegradation of four variants of polystyrene was performed. We tested: raw material (PS), processed polystyrene (PSr), building insulation material (EPS) and food packaging boxes (PSp). Materials were characterized by means melt flow ratio (MFR), shore hardness and gloss. The biochemical assessment of macromolecules (proteins, lipids and sugars) in the mealworms organisms fed with tested forms of polystyrene allowed us to set how efficient and beneficial the biodegradation of types of polystyrene is. We also evaluated the variability of bacterial community in larval guts by the use of denaturing gradient gel electrophoresis (DGGE) on the bacterial DNA of 16S rRNA genes amplified in polymerase chain reaction (PCR). The results suggest that EPS and PSp polystyrene are the most digestible for T. molitor larvae. The metabolic degradation of polystyrene is probably strictly connected with the changes in biodiversity of gut bacteria.

Field efficacy of expanded polystyrene and shredded waste polystyrene beads for mosquito control in artificial pools and field trials, Islamic Republic of Iran.

PubMed

Soltani, A; Vatandoost, H; Jabbari, H; Mesdaghinia, A R; Mahvi, A H; Younesian, M; Hanafi-Bojd, A A; Bozorgzadeh, S

2012-10-01

Concerns about traditional chemical pesticides has led to increasing research into novel mosquito control methods. This study compared the effectiveness of 2 different types of polystyrene beads for control of mosquito larvae in south-east Islamic Republic of Iran. Simulated field trials were done in artificial pools and field trials were carried out in 2 villages in an indigenous malaria area using WHO-recommended methods. Application of expanded polystyrene beads or shredded, waste polystyrene chips to pool surfaces produced a significant difference between pre-treatment and post-treatment density of mosquitoes (86% and 78% reduction respectively 2 weeks after treatment). There was no significant difference between the efficacy of the 2 types of material. The use of polystyrene beads as a component of integrated vector management with other supportive measures could assist in the control of mosquito-borne diseases in the Islamic Republic of Iran and neighbouring countries.

Electrospun Nanofiber Scaffolds and Their Hydrogel Composites for the Engineering and Regeneration of Soft Tissues.

PubMed

Manoukian, Ohan S; Matta, Rita; Letendre, Justin; Collins, Paige; Mazzocca, Augustus D; Kumbar, Sangamesh G

2017-01-01

Electrospinning has emerged as a simple, elegant, and scalable technique that can be used to fabricate polymeric nanofibers. Pure polymers as well as blends and composites of both natural and synthetic ones have been successfully electrospun into nanofiber matrices for many biomedical applications. Tissue-engineered medical implants, such as polymeric nanofiber scaffolds, are potential alternatives to autografts and allografts, which are short in supply and carry risks of disease transmission. These scaffolds have been used to engineer various soft tissues, including connective tissues, such as skin, ligament, and tendon, as well as nonconnective ones, such as vascular, muscle, and neural tissue. Electrospun nanofiber matrices show morphological similarities to the natural extracellular matrix (ECM), characterized by ultrafine continuous fibers, high surface-to-volume ratios, high porosities, and variable pore-size distributions. The physiochemical properties of nanofiber matrices can be controlled by manipulating electrospinning parameters so that they meet the requirements of a specific application.Nanostructured implants show improved biological performance over bulk materials in aspects of cellular infiltration and in vivo integration, taking advantage of unique quantum, physical, and atomic properties. Furthermore, the topographies of such scaffolds has been shown to dictate cellular attachment, migration, proliferation, and differentiation, which are critical in engineering complex functional tissues with improved biocompatibility and functional performance. This chapter discusses the use of the electrospinning technique in the fabrication of polymer nanofiber scaffolds utilized for the regeneration of soft tissues. Selected scaffolds will be seeded with human mesenchymal stem cells (hMSCs), imaged using scanning electron and confocal microscopy, and then evaluated for their mechanical properties as well as their abilities to promote cell adhesion

The role of nanostructured mesoporous silicon in discriminating in vitro calcification for electrospun composite tissue engineering scaffolds

NASA Astrophysics Data System (ADS)

Fan, Dongmei; Akkaraju, Giridhar R.; Couch, Ernest F.; CanhamCurrent Address, Intrinsiq Materials Ltd, Geraldine Road, Malvern Wr14 3SZ Uk, Leigh T.; Coffer, Jeffery L.

2011-02-01

The impact of mesoporous silicon (PSi) particles-embedded either on the surface, or totally encapsulated within electrospun poly (ε-caprolactone) (PCL) fibers-on its properties as a tissue engineering scaffold is assessed. Our findings suggest that the resorbable porous silicon component can sensitively accelerate the necessary calcification process in such composites. Calcium phosphate deposition on the scaffolds was measured via in vitro calcification assays both at acellular and cellular levels. Extensive attachment of fibroblasts, human adult mesenchymal stem cells, and mouse stromal cells to the scaffold were observed. Complementary cell differentiation assays and ultrastructural measurements were also carried out; the levels of alkaline phosphatase expression, a specific biomarker for mesenchymal stem cell differentiation, show that the scaffolds have the ability to mediate such processes, and that the location of the Si plays a key role in levels of expression.

Graphene-doped electrospun nanofiber membrane electrodes and proton exchange membrane fuel cell performance

NASA Astrophysics Data System (ADS)

Wei, Meng; Jiang, Min; Liu, Xiaobo; Wang, Min; Mu, Shichun

2016-09-01

A rational electrode structure can allow proton exchange membrane (PEM) fuel cells own high performance with a low noble metal loading and an optimal transport pathway for reaction species. In this study, we develop a graphene doped polyacrylonitile (PAN)/polyvinylident fluoride (PVDF) (GPP) electrospun nanofiber electrode with improved electrical conductivity and high porosity, which could enhance the triple reaction boundary and promote gas and water transport throughout the porous electrode. Thus the increased electrochemical active surface area (ECSA) of Pt catalysts and fuel cell performance can be expected. As results, the ECSA of hot-pressed electrospun electrodes with 2 wt% graphene oxide (GO) is up to 84.3 m2/g, which is greatly larger than that of the conventional electrode (59.5 m2/g). Significantly, the GPP nanofiber electrospun electrode with Pt loading of 0.2 mg/cm2 exhibits higher fuel cell voltage output and stability than the conventional electrode.

Fluorescence-based remote irradiation sensor in liquid-filled hollow-core photonic crystal fiber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeltner, R.; Russell, P. St.J.; Department of Physics, University of Erlangen-Nuremberg, Guenther-Scharowsky-Str. 1, 91058 Erlangen

2016-06-06

We report an irradiation sensor based on a fluorescent “flying particle” that is optically trapped and propelled inside the core of a water-filled hollow-core photonic crystal fiber. When the moving particle passes through an irradiated region, its emitted fluorescence is captured by guided modes of the fiber core and so can be monitored using a filtered photodiode placed at the fiber end. The particle speed and position can be precisely monitored using in-fiber Doppler velocimetry, allowing the irradiation profile to be measured to a spatial resolution of ∼10 μm. The spectral response can be readily adjusted by appropriate choice of particlemore » material. Using dye-doped polystyrene particles, we demonstrate detection of green (532 nm) and ultraviolet (340 nm) light.« less

Electrospun nanofibrous 3D scaffold for bone tissue engineering.

PubMed

Eap, Sandy; Ferrand, Alice; Palomares, Carlos Mendoza; Hébraud, Anne; Stoltz, Jean-François; Mainard, Didier; Schlatter, Guy; Benkirane-Jessel, Nadia

2012-01-01

Tissue engineering aims at developing functional substitutes for damaged tissues by mimicking natural tissues. In particular, tissue engineering for bone regeneration enables healing of some bone diseases. Thus, several methods have been developed in order to produce implantable biomaterial structures that imitate the constitution of bone. Electrospinning is one of these methods. This technique produces nonwoven scaffolds made of nanofibers which size and organization match those of the extracellular matrix. Until now, seldom electrospun scaffolds were produced with thickness exceeding one millimeter. This article introduces a new kind of electrospun membrane called 3D scaffold of thickness easily exceeding one centimeter. The manufacturing involves a solution of poly(ε-caprolactone) in DMF/DCM system. The aim is to establish parameters for electrospinning in order to characterize these 3D scaffolds and, establish whether such scaffolds are potentially interesting for bone regeneration.

Solvent effect on polystyrene surface roughness on top of QCM sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sakti, Setyawan P., E-mail: sakti@ub.ac.id; Rahmawati, Eka; Robiandi, Fadli

2016-03-11

Quartz Crystal Microbalance (QCM) has been used as a basis for many chemical sensors and biosensor. Its sensitivity to mass change which can detect a mass change on its surface down to sub ng/cm2 is one of its interesting aspects. Another interesting feature is its ability to work in liquid environment. However, there are many aspects which influence QCM sensor properties in contact with liquid. One of the aspects is surface roughness of the matrix layer where on top of it a biological sensitive layer will be immobilized. One of matrix layers in the immobilizing biological sensitive layer was polystyrene.more » Polystyrene was coated on the QCM sensor by using the spin coating method. During the coating process, polystyrene was solved using non-polar solvent. It is known that the physical and chemical properties of the solvent affect a transition process from soluble polymer becoming rigid polymer layer. In this work, we show that polystyrene solved in chloroform has a higher surface roughness compare to one solved in toluene, xylene, or tetrahydrofuran. Surface roughness of the polystyrene coating were measured using a non-contact profilometer. However, we also found that there is no difference on the electrical impedance of the QCM sensor coated with polystyrene resulted from differing solvent when the sensor was in contact with air and water. Thus, all of the mentioned solvent can be used to solve the polystyrene as a coating material for QCM sensor without affecting the electrical performance of the sensor, but the choice of the solution can be used as a simple method to control the difference roughness of the polystyrene coating.« less

Solvent effect on polystyrene surface roughness on top of QCM sensor

NASA Astrophysics Data System (ADS)

Sakti, Setyawan P.; Rahmawati, Eka; Robiandi, Fadli

2016-03-01

Quartz Crystal Microbalance (QCM) has been used as a basis for many chemical sensors and biosensor. Its sensitivity to mass change which can detect a mass change on its surface down to sub ng/cm2 is one of its interesting aspects. Another interesting feature is its ability to work in liquid environment. However, there are many aspects which influence QCM sensor properties in contact with liquid. One of the aspects is surface roughness of the matrix layer where on top of it a biological sensitive layer will be immobilized. One of matrix layers in the immobilizing biological sensitive layer was polystyrene. Polystyrene was coated on the QCM sensor by using the spin coating method. During the coating process, polystyrene was solved using non-polar solvent. It is known that the physical and chemical properties of the solvent affect a transition process from soluble polymer becoming rigid polymer layer. In this work, we show that polystyrene solved in chloroform has a higher surface roughness compare to one solved in toluene, xylene, or tetrahydrofuran. Surface roughness of the polystyrene coating were measured using a non-contact profilometer. However, we also found that there is no difference on the electrical impedance of the QCM sensor coated with polystyrene resulted from differing solvent when the sensor was in contact with air and water. Thus, all of the mentioned solvent can be used to solve the polystyrene as a coating material for QCM sensor without affecting the electrical performance of the sensor, but the choice of the solution can be used as a simple method to control the difference roughness of the polystyrene coating.

Microporous polystyrene particles for selective carbon dioxide capture.

PubMed

Kaliva, Maria; Armatas, Gerasimos S; Vamvakaki, Maria

2012-02-07

This study presents the synthesis of microporous polystyrene particles and the potential use of these materials in CO(2) capture for biogas purification. Highly cross-linked polystyrene particles are synthesized by the emulsion copolymerization of styrene (St) and divinylbenzene (DVB) in water. The cross-link density of the polymer is varied by altering the St/DVB molar ratio. The size and the morphology of the particles are characterized by scanning and transmission electron microscopy. Following supercritical point drying with carbon dioxide or lyophilization from benzene, the polystyrene nanoparticles exhibit a significant surface area and permanent microporosity. The dried particles comprising 35 mol % St and 65 mol % DVB possess the largest surface area, ∼205 m(2)/g measured by Brunauer-Emmett-Teller and ∼185 m(2)/g measured by the Dubinin-Radushkevich method, and a total pore volume of 1.10 cm(3)/g. Low pressure measurements suggest that the microporous polystyrene particles exhibit a good separation performance of CO(2) over CH(4), with separation factors in the range of ∼7-13 (268 K, CO(2)/CH(4) = 5/95 gas mixture), which renders them attractive candidates for use in gas separation processes.

Enhancing the Mechanical Properties of Electrospun Nanofiber Mats through Controllable Welding at the Cross Points.

PubMed

Li, Haoxuan; Zhu, Chunlei; Xue, Jiajia; Ke, Qinfei; Xia, Younan

2017-05-01

This communication describes a simple and effective method for welding electrospun nanofibers at the cross points to enhance the mechanical properties of their nonwoven mats. The welding is achieved by placing a nonwoven mat of the nanofibers in a capped vial with the vapor of a proper solvent. For polycaprolactone (PCL) nanofibers, the solvent is dichloromethane (DCM). The welding can be managed in a controllable fashion by simply varying the partial pressure of DCM and/or the exposure time. Relative to the pristine nanofiber mat, the mechanical strength of the welded PCL nanofiber mat can be increased by as much as 200%. Meanwhile, such a treatment does not cause any major structural changes, including morphology, fiber diameter, and pore size. This study provides a generic method for improving the mechanical properties of nonwoven nanofiber mats, holding great potential in various applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tailor-Made Electrospun Multilayer Composite Polymer Electrolytes for High-Performance Lithium Polymer Batteries.

PubMed

Lim, Du-Hyun; Haridas, Anupriya K; Figerez, Stelbin Peter; Raghavan, Prasanth; Matic, Aleksandar; Ahn, Jou-Hyeon

2018-09-01

A novel tailor-made multilayer composite polymer electrolyte, consisting of two outer layers of electrospun polyacrylonitrile (PAN) and one inner layer of poly(vinyl acetate) (PVAc)/poly(methyl methacrylate) (PMMA)/poly(ethylene oxide) (PEO) fibrous membrane, was prepared using continuous electrospinning. These membranes, which are made up of fibers with diameters in the nanometer range, were stacked in layers to produce interconnected pores that result in a high porosity. Gel polymer electrolytes (GPEs) were prepared by entrapping a liquid electrolyte (1 M LiPF6 in ethylene carbonate/dimethyl carbonate) in the membranes. The composite membranes exhibited a high electrolyte uptake of 450-510%, coupled with an improved room temperature ionic conductivity of up to 4.72 mS cm-1 and a high electrochemical stability of 4.6 V versus Li/Li+. Electrochemical investigations of a composite membrane of PAN-PVAc-PAN, with a LiFePO4 cathode synthesized in-house, showed a high initial discharge capacity of 145 mAh g-1, which corresponds to 85% utilization of the active material, and displayed stable cycle performance.

An electrospun nanofiber matrix based on organo-clay for biosensors: PVA/PAMAM-Montmorillonite

NASA Astrophysics Data System (ADS)

Unal, Betul; Yalcinkaya, Esra Evrim; Demirkol, Dilek Odaci; Timur, Suna

2018-06-01

Diagnostic techniques based on biomolecules have huge a potential to be applied in the application in various areas such as food/beverage industries, diseases diagnostics, monitoring of bio-processes and environmental pollutants. Immobilization of biomolecules on a transducer is the key parameter to being able to prepare a highly stable diagnostic tests. Electrospun nanofibers are a good alternative to immobilize biomolecules. Here, electrospun nanofibers based on an organoclay were used to design the first generation amperometric enzyme biosensor. PAMAM G2 dendrimers were used to intercalate montmorillonite clay (Mt) and then the modification of Mt by PAMAM was characterized using FTIR, XRD, TGA and zeta potential measurements. After that nanofibers were prepared by electrospinning Mt and PAMAM-Mt using poly(vinyl) alcohol (PVA) as an auxiliary polymer and the formed PVA/PAMAM-Mt electrospun nanofibers were proved by SEM, TEM and AFM techniques. Finally, pyranose oxidases (PyOx) were immobilized on a glassy carbon electrode surface, which was modified using the PVA/PAMAM-Mt electrospun nanofibers. Amperometric measurements were carried out using buffer solution at -0.7 V under stirring conditions. The linear response for glucose was from 0.005 mM to 0.25 mM using PVA/Mt/PyOx and PVA/PAMAM-Mt/PyOx biosensors. The limit of detection was 0.7 μM glucose with PVA/PAMAM-Mt/PyOx biosensor. To detect glucose in real sample, measurements were carried out using soft drink cola as a substrate instead of glucose.

Microscale synthesis and characterization of polystyrene: NSF-POLYED scholars project

NASA Technical Reports Server (NTRS)

Quaal, Karen S.; Wu, Chang-Ning

1994-01-01

Polystyrene is a familiar polymer with many commercial uses. Its applications range from the clear, high index of refraction, brittle plastic used to form audio cassette and CD cases to the foamed material used in insulated drink cups and packaging material. Polystyrene constitutes 11 percent of the plastics used in packaging with only High Density Polyethylene (HDPE) and Low Density Polyethylene (LDPE) contributing a larger share: so much polystyrene is used today, it is one of six common plastics that manufacturers have assigned an identification code. The code helps recycling efforts. Polystyrene's code is (PS code 6). During the summer and fall of 1992 several new polymeric experiments were developed by the NSF POLYED Scholars for introduction into the chemistry core curriculum. In this presentation, one such project will be discussed. This laboratory project is recommended for a first or second year laboratory course allowing the introduction of polymeric science to undergraduates at the earliest opportunity. The reliability of the experiments which make up this project and the recognition factor of polystyrene, a material we come in contact with everyday, makes the synthesis and characterization of polystyrene a good choice for the introduction of polymerization to undergraduates. This laboratory project appeals to the varied interests of students enrolled in the typical first year chemistry course and becomes an ideal way to introduce polymers to a wide variety of science and engineering students.

Electrospun conductive nanofibrous scaffolds for engineering cardiac tissue and 3D bioactuators.

PubMed

Wang, Ling; Wu, Yaobin; Hu, Tianli; Guo, Baolin; Ma, Peter X

2017-09-01

Mimicking the nanofibrous structure similar to extracellular matrix and conductivity for electrical propagation of native myocardium would be highly beneficial for cardiac tissue engineering and cardiomyocytes-based bioactuators. Herein, we developed conductive nanofibrous sheets with electrical conductivity and nanofibrous structure composed of poly(l-lactic acid) (PLA) blending with polyaniline (PANI) for cardiac tissue engineering and cardiomyocytes-based 3D bioactuators. Incorporating of varying contents of PANI from 0wt% to 3wt% into the PLA polymer, the electrospun nanofibrous sheets showed enhanced conductivity while maintaining the same fiber diameter. These PLA/PANI conductive nanofibrous sheets exhibited good cell viability and promoting effect on differentiation of H9c2 cardiomyoblasts in terms of maturation index and fusion index. Moreover, PLA/PANI nanofibrous sheets enhanced the cell-cell interaction, maturation and spontaneous beating of primary cardiomyocytes. Furthermore, the cardiomyocytes-laden PLA/PANI conductive nanofibrous sheets can form 3D bioactuators with tubular and folding shapes, and spontaneously beat with much higher frequency and displacement than that on cardiomyocytes-laden PLA nanofibrous sheets. Therefore, these PLA/PANI conductive nanofibrous sheets with conductivity and extracellular matrix like nanostructure demonstrated promising potential in cardiac tissue engineering and cardiomyocytes-based 3D bioactuators. Cardiomyocytes-based bioactuators have been paid more attention due to their spontaneous motion by integrating cardiomyocytes into polymer structures, but developing suitable scaffolds for bioactuators remains challenging. Electrospun nanofibrous scaffolds have been widely used in cardiac tissue engineering because they can mimic the extracellular matrix of myocardium. Developing conductive nanofibrous scaffolds by electrospinning would be beneficial for cardiomyocytes-based bioactuators, but such scaffolds have been

Suspended, Shrinkage-Free, Electrospun PLGA Nanofibrous Scaffold for Skin Tissue Engineering.

PubMed

Ru, Changhai; Wang, Feilong; Pang, Ming; Sun, Lining; Chen, Ruihua; Sun, Yu

2015-05-27

Electrospinning is a technique for creating continuous nanofibrous networks that can architecturally be similar to the structure of extracellular matrix (ECM). However, the shrinkage of electrospun mats is unfavorable for the triggering of cell adhesion and further growth. In this work, electrospun PLGA nanofiber assemblies are utilized to create a scaffold. Aided by a polypropylene auxiliary supporter, the scaffold is able to maintain long-term integrity without dimensional shrinkage. This scaffold is also able to suspend in cell culture medium; hence, keratinocyte cells seeded on the scaffold are exposed to air as required in skin tissue engineering. Experiments also show that human skin keratinocytes can proliferate on the scaffold and infiltrate into the scaffold.

Enhanced sensitivity of a microfabricated resonator using a graphene-polystyrene bilayer membrane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yun, Minhyuk; Lee, Eunho; Cho, Kilwon

2014-08-18

A graphene layer was synthesized using chemical vapor deposition methods and a polystyrene solution was spin-cast onto the graphene film. The graphene-polystyrene bilayer membrane was attached between the two tines of a microfabricated quartz tuning fork (QTF). The modulus of the graphene-polystyrene bilayer was measured to be twice that of a pristine polystyrene membrane. Exposure of the membrane-coated QTF to ethanol vapor decreased the resonance frequency of the microresonator. The bilayer membrane-coated QTF produced a frequency change that was three times the change obtained using a polystyrene membrane-coated QTF, with a lower degree of degradation in the Q factor. Themore » limit of detection of the bilayer membrane-coated QTF to ethanol vapor was determined to be 20 ppm.« less

Incorporating Platelet-Rich Plasma into Electrospun Scaffolds for Tissue Engineering Applications

PubMed Central

Wolfe, Patricia S.; Ericksen, Jeffery J.; Simpson, David G.; Bowlin, Gary L.

2011-01-01

Platelet-rich plasma (PRP) therapy has seen a recent spike in clinical interest due to the potential that the highly concentrated platelet solutions hold for stimulating tissue repair and regeneration. The aim of this study was to incorporate PRP into a number of electrospun materials to determine how growth factors are eluted from the structures, and what effect the presence of these factors has on enhancing electrospun scaffold bioactivity. PRP underwent a freeze-thaw-freeze process to lyse platelets, followed by lyophilization to create a powdered preparation rich in growth factors (PRGF), which was subsequently added to the electrospinning process. Release of protein from scaffolds over time was quantified, along with the quantification of human macrophage and adipose-derived stem cell (ADSC) chemotaxis and proliferation. Protein assays demonstrated a sustained release of protein from PRGF-containing scaffolds at up to 35 days in culture. Scaffold bioactivity was enhanced as ADSCs demonstrated increased proliferation in the presence of PRGF, whereas macrophages demonstrated increased chemotaxis to PRGF. In conclusion, the work performed in this study demonstrated that the incorporation of PRGF into electrospun structures has a significant positive influence on the bioactivity of the scaffolds, and may prove beneficial in a number of tissue engineering applications. PMID:21679135

Copper ion sensing with fluorescent electrospun nanofibers.

PubMed

Ongun, Merve Zeyrek; Ertekin, Kadriye; Gocmenturk, Mustafa; Ergun, Yavuz; Suslu, Aslıhan

2012-05-01

In this work, the use of electrospun nanofibrous materials as highly responsive fluorescence quenching-based copper sensitive chemosensor is reported. Poly(methyl methacrylate) and ethyl cellulose were used as polymeric support materials. Sensing slides were fabricated by electrospinning technique. Copper sensors based on the change in the fluorescence signal intensity of fluoroionophore; N'-3-(4-(dimethylamino phenly)allylidene)isonicotinohydrazide. The sensor slides exhibited high sensitivities due to the high surface area of the nanofibrous membrane structures. The preliminary results of Stern-Volmer analysis show that the sensitivities of electrospun nanofibrous membranes to detect Cu(II) ions are 6-20-fold higher than those of the continuous thin films. By this way we obtained linear calibration plots for Cu(II) ions in the concentration range of 10(-12)-10(-5)M. The response times of the sensing slides were less than 1 min. Stability of the employed ionophore in the matrix materials was excellent and when stored in the ambient air of the laboratory there was no significant drift in signal intensity after 6 months. Our stability tests are still in progress. Copyright © 2012 Elsevier B.V. All rights reserved.

Two ply tubular scaffolds comprised of proteins/poliglecaprone/polycaprolactone fibers.

PubMed

Zhang, Xing; Thomas, Vinoy; Vohra, Yogesh K

2010-02-01

Electrospun bi-layer tubular hybrid scaffolds composed of poliglecaprone (PGC), polycaprolactone (PCL), elastin (E), and gelatin (G) were prepared and thereafter crosslinked by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). Scanning electron microscopic (SEM) images revealed a highly porous micro-structure comprising randomly distributed non-woven fibers with the majority of fibers in submicron diameters. The EDC-crosslinking yielded an average crosslinking degree of 40%. Uni-axial tensile test of hydrated scaffolds in both longitudinal and circumferential directions revealed tensile properties, comparable to those of native arteries. The graft (PGC:PCL = 1:3) did not demonstrate significant difference before and after EDC-crosslinking in tensile strength or % strain in either longitudinal or circumferential directions. However, crosslinking increased the Young's modulus of the graft along the longitudinal direction (from 5.84 to 8.67 MPa). On the contrary, the graft (3:1) demonstrated a significant decrease in maximum strain in both directions. Cyto-assay using human umbilical vein endothelial cells (HUVECs) showed excellent cell viability.

Increased NIH 3T3 fibroblast functions on cell culture dishes which mimic the nanometer fibers of natural tissues.

PubMed

Bhardwaj, Garima; Webster, Thomas J

2015-01-01

Traditional flat tissue cell culture dishes have consisted of polystyrene treated with plasma gases for growing, subculturing, and studying cell behavior in vitro. However, increasingly it has been observed that mimicking natural tissue properties (such as chemistry, three-dimensional structure, mechanical properties, etc) in vitro can lead to a better correlation of in vitro to in vivo cellular functions. The following studies compared traditional NIH 3T3 fibroblasts' functions on XanoMatrix scaffolds to standard tissue culture polystyrene. Results found significantly greater fibroblast adhesion and proliferation on XanoMatrix cell culture dishes which mimic the nanoscale geometry of natural tissue fibers with true, tortuous fiber beds creating a robust, consistent, and versatile growth platform. In this manner, this study supports that cell culture dishes which mimic features of natural tissues should be continually studied for a wide range of applications in which mimicking natural cellular functions are important.

Polystyrene/Hyperbranched Polyester Blends and Reactive Polystyrene/Hyperbranched Polyester Blends

DTIC Science & Technology

1999-01-01

interfacial tension between the PE and polystyrene phases. This was brought about by the chemical interaction between the acidic anhydride groups in the...multiple 2,2 dimethylol propionic acid (C5H10O4) chain extenders or repeat units. 11 Core HO \\ HO’ /■ J OH V *OH Pentaerythritol Chain Extender...O 2,2 - Dimethylol propionic acid Figure 11. HBP Building Blocks. These materials were supplied in small quantities with little technical data. The

Human dental pulp stem cell adhesion and detachment in polycaprolactone electrospun scaffolds under direct perfusion

PubMed Central

Paim, A.; Braghirolli, D.I.; Cardozo, N.S.M.; Pranke, P.; Tessaro, I.C.

2018-01-01

Cell adhesion in three-dimensional scaffolds plays a key role in tissue development. However, stem cell behavior in electrospun scaffolds under perfusion is not fully understood. Thus, an investigation was made on the effect of flow rate and shear stress, adhesion time, and seeding density under direct perfusion in polycaprolactone electrospun scaffolds on human dental pulp stem cell detachment. Polycaprolactone scaffolds were electrospun using a solvent mixture of chloroform and methanol. The viable cell number was determined at each tested condition. Cell morphology was analyzed by confocal microscopy after various incubation times for static cell adhesion with a high seeding density. Scanning electron microscopy images were obtained before and after perfusion for the highest flow rate tested. The wall pore shear stress was calculated for all tested flow rates (0.005–3 mL/min). An inversely proportional relationship between adhesion time with cell detachment under perfusion was observed. Lower flow rates and lower seeding densities reduced the drag of cells by shear stress. However, there was an operational limit for the lowest flow rate that can be used without compromising cell viability, indicating that a flow rate of 0.05 mL/min might be more suitable for the tested cell culture in electrospun scaffolds under direct perfusion. PMID:29590258

Physical and Biological Modification of Polycaprolactone Electrospun Nanofiber by Panax Ginseng Extract for Bone Tissue Engineering Application.

PubMed

Pajoumshariati, Seyedramin; Yavari, Seyedeh Kimia; Shokrgozar, Mohammad Ali

2016-05-01

Medicinal plants as a therapeutic agent with osteogenic properties can enhance fracture-healing process. In this study, the osteo-inductive potential of Asian Panax Ginseng root extract within electrospun polycaprolactone (PCL) based nanofibers has been investigated. Scanning electron microscopy images revealed that all nanofibers were highly porous and beadles with average diameter ranging from 250 to 650 nm. The incorporation of ginseng extract improved the physical characteristics (i.e., hydrophilicity) of PCL nanofibers, as well as the mechanical properties. Although ginseng extract increased the degradation rate of pure PCL nanofibers, the porous structure and morphology of fibers did not change significantly after 42 days. It was found that nanofibrous scaffolds containing ginseng extract had higher proliferation (up to ~1.5 fold) compared to the pristine PCL. The qRT-PCR analysis demonstrated the addition of ginseng extract into PCL nanofibers induced significant expression of osteogenic genes (Osteocalcin, Runx-2 and Col-1) in MSCs in a concentration dependent manner. Moreover, higher calcium content, alkaline phosphatase activity and higher mineralization of MSCs were observed compared to the pristine PCL fibers. Our results indicated the promising potential of ginseng extract as an additive to enhance osteo-inductivity, mechanical and physical properties of PCL nanofibers for bone tissue engineering application.

24 CFR 200.947 - Building product standards and certification program for polystyrene foam insulation board.

Code of Federal Regulations, 2011 CFR

2011-04-01

... certification program for polystyrene foam insulation board. 200.947 Section 200.947 Housing and Urban... program for polystyrene foam insulation board. (a) Applicable standards. (1) All polystyrene foam... visit the manufacturer's facility to select a sample of each certified polystyrene foam insulation board...

Calcium Silicate/Chitosan-Coated Electrospun Poly (Lactic Acid) Fibers for Bone Tissue Engineering.

PubMed

Su, Chu-Jung; Tu, Ming-Gene; Wei, Li-Ju; Hsu, Tuan-Ti; Kao, Chia-Tze; Chen, Tsui-Han; Huang, Tsui-Hsien

2017-05-05

Electrospinning technology allows fabrication of nano- or microfibrous fibers with inorganic and organic matrix and it is widely applied in bone tissue engineering as it allows precise control over the shapes and structures of the fibers. Natural bone has an ordered composition of organic fibers with dispersion of inorganic apatite among them. In this study, poly (lactic acid) (PLA) mats were fabricated with electrospinning and coated with chitosan (CH)/calcium silicate (CS) mixer. The microstructure, chemical component, and contact angle of CS/CH-PLA composites were analyzed by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. In vitro, various CS/CH-coated PLA mats increased the formation of hydroxyapatite on the specimens' surface when soaked in cell cultured medium. During culture, several biological characteristics of the human mesenchymal stem cells (hMSCs) cultured on CS/CH-PLA groups were promoted as compared to those on pure PLA mat. Increased secretion levels of Collagen I and fibronectin were observed in calcium silicate-powder content. Furthermore, with comparison to PLA mats without CS/CH, CS10 and CS15 mats markedly enhanced the proliferation of hMSCs and their osteogenesis properties, which was characterized by osteogenic-related gene expression. These results clearly demonstrated that the biodegradable and electroactive CS/CH-PLA composite mats are an ideal and suitable candidate for bone tissue engineering.

CHARACTERIZATION OF THE COMPLETE FIBER NETWORK TOPOLOGY OF PLANAR FIBROUS TISSUES AND SCAFFOLDS

PubMed Central

D'Amore, Antonio; Stella, John A.; Wagner, William R.; Sacks, Michael S.

2010-01-01

Understanding how engineered tissue scaffold architecture affects cell morphology, metabolism, phenotypic expression, as well as predicting material mechanical behavior have recently received increased attention. In the present study, an image-based analysis approach that provides an automated tool to characterize engineered tissue fiber network topology is presented. Micro-architectural features that fully defined fiber network topology were detected and quantified, which include fiber orientation, connectivity, intersection spatial density, and diameter. Algorithm performance was tested using scanning electron microscopy (SEM) images of electrospun poly(ester urethane)urea (ES-PEUU) scaffolds. SEM images of rabbit mesenchymal stem cell (MSC) seeded collagen gel scaffolds and decellularized rat carotid arteries were also analyzed to further evaluate the ability of the algorithm to capture fiber network morphology regardless of scaffold type and the evaluated size scale. The image analysis procedure was validated qualitatively and quantitatively, comparing fiber network topology manually detected by human operators (n=5) with that automatically detected by the algorithm. Correlation values between manual detected and algorithm detected results for the fiber angle distribution and for the fiber connectivity distribution were 0.86 and 0.93 respectively. Algorithm detected fiber intersections and fiber diameter values were comparable (within the mean ± standard deviation) with those detected by human operators. This automated approach identifies and quantifies fiber network morphology as demonstrated for three relevant scaffold types and provides a means to: (1) guarantee objectivity, (2) significantly reduce analysis time, and (3) potentiate broader analysis of scaffold architecture effects on cell behavior and tissue development both in vitro and in vivo. PMID:20398930

Electrospinning of PVC with natural rubber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Othman, Muhammad Hariz; Abdullah, Ibrahim; Mohamed, Mahathir

Polyvinyl chloride (PVC) was mixed with natural rubbers which are liquid natural rubber (LNR), liquid epoxidised natural rubber (LENR) and liquid epoxidised natural rubber acrylate (LENRA) for a preparation of a fine non-woven fiber’s mat. PVC and each natural rubbers(PVC:LENR, PVC:LNR and PVC:LENRA) were mixed based on ratio of 70:30. Electrospinning method was used to prepare the fiber. The results show that the spinnable concentration of PVC/ natural rubber/THF solution is 16 wt%. The morphology, diameter, structure and degradation temperature of electrospun fibers were investigated by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). SEM photos showed that the morphologymore » and diameter of the fibers were mainly affected by the addition of natural rubber. TGA results suggested that PVC electrospun fiber has higher degradation temperature than those electrospun fibers that contain natural rubber.« less

Preliminary investigation of airgap electrospun silk-fibroin-based structures for ligament analogue engineering.

PubMed

Sell, S A; McClure, M J; Ayres, C E; Simpson, D G; Bowlin, G L

2011-01-01

The process of electrospinning has proven to be highly beneficial for use in a number of tissue-engineering applications due to its ease of use, flexibility and tailorable properties. There have been many publications on the creation of aligned fibrous structures created through various forms of electrospinning, most involving the use of a metal target rotating at high speeds. This work focuses on the use of a variation known as airgap electrospinning, which does not use a metal collecting target but rather a pair of grounded electrodes equidistant from the charged polymer solution to create highly aligned 3D structures. This study involved a preliminary investigation and comparison of traditionally and airgap electrospun silk-fibroin-based ligament constructs. Structures were characterized with SEM and alignment FFT, and underwent porosity, permeability, and mechanical anisotropy evaluation. Preliminary cell culture with human dermal fibroblasts was performed to determine the degree of cellular orientation and penetration. Results showed airgap electrospun structures to be anisotropic with significantly increased porosity and cellular penetration compared to their traditionally electrospun counterparts.

Nanosphere Lithography on Fiber: Towards Engineered Lab-On-Fiber SERS Optrodes

PubMed Central

Quero, Giuseppe; Zito, Gianluigi; Cusano, Andrea

2018-01-01

In this paper we report on the engineering of repeatable surface enhanced Raman scattering (SERS) optical fiber sensor devices (optrodes), as realized through nanosphere lithography. The Lab-on-Fiber SERS optrode consists of polystyrene nanospheres in a close-packed arrays configuration covered by a thin film of gold on the optical fiber tip. The SERS surfaces were fabricated by using a nanosphere lithography approach that is already demonstrated as able to produce highly repeatable patterns on the fiber tip. In order to engineer and optimize the SERS probes, we first evaluated and compared the SERS performances in terms of Enhancement Factor (EF) pertaining to different patterns with different nanosphere diameters and gold thicknesses. To this aim, the EF of SERS surfaces with a pitch of 500, 750 and 1000 nm, and gold films of 20, 30 and 40 nm have been retrieved, adopting the SERS signal of a monolayer of biphenyl-4-thiol (BPT) as a reliable benchmark. The analysis allowed us to identify of the most promising SERS platform: for the samples with nanospheres diameter of 500 nm and gold thickness of 30 nm, we measured values of EF of 4 × 105, which is comparable with state-of-the-art SERS EF achievable with highly performing colloidal gold nanoparticles. The reproducibility of the SERS enhancement was thoroughly evaluated. In particular, the SERS intensity revealed intra-sample (i.e., between different spatial regions of a selected substrate) and inter-sample (i.e., between regions of different substrates) repeatability, with a relative standard deviation lower than 9 and 15%, respectively. Finally, in order to determine the most suitable optical fiber probe, in terms of excitation/collection efficiency and Raman background, we selected several commercially available optical fibers and tested them with a BPT solution used as benchmark. A fiber probe with a pure silica core of 200 µm diameter and high numerical aperture (i.e., 0.5) was found to be the most

7 CFR 3201.53 - Expanded polystyrene (EPS) foam recycling products.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 15 2014-01-01 2014-01-01 false Expanded polystyrene (EPS) foam recycling products... FOR FEDERAL PROCUREMENT Designated Items § 3201.53 Expanded polystyrene (EPS) foam recycling products... with this part, will give a procurement preference for qualifying biobased EPS foam recycling products...

7 CFR 3201.53 - Expanded polystyrene (EPS) foam recycling products.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 15 2012-01-01 2012-01-01 false Expanded polystyrene (EPS) foam recycling products... FOR FEDERAL PROCUREMENT Designated Items § 3201.53 Expanded polystyrene (EPS) foam recycling products... with this part, will give a procurement preference for qualifying biobased EPS foam recycling products...

7 CFR 2902.53 - Expanded polystyrene (EPS) foam recycling products.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 15 2011-01-01 2011-01-01 false Expanded polystyrene (EPS) foam recycling products... FEDERAL PROCUREMENT Designated Items § 2902.53 Expanded polystyrene (EPS) foam recycling products. (a..., will give a procurement preference for qualifying biobased EPS foam recycling products. By that date...

7 CFR 3201.53 - Expanded polystyrene (EPS) foam recycling products.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 15 2013-01-01 2013-01-01 false Expanded polystyrene (EPS) foam recycling products... FOR FEDERAL PROCUREMENT Designated Items § 3201.53 Expanded polystyrene (EPS) foam recycling products... with this part, will give a procurement preference for qualifying biobased EPS foam recycling products...

Training High School Students in the Scientific Method via Hands On Projects in a Laboratory Environment

DTIC Science & Technology

2015-02-27

Poly(vinylidene Fluoride with Trifluoroethylene) P(VDF-TrFE) 75:25 Thin Films by Atomic Force Microscope Nanolithography, Scanning, (04 2012): 0...doi: 10.1002/sca.21024 William Serrano, Nicholas J. Pinto. Electrospun Fibers of Poly(Vinylidene Fluoride -Trifluoroethylene)/Poly (3-Hexylthiophene...Nicholas Pinto. Electrospun fibers of poly (vinylidene fluoride -trifluoroethylene)/ poly (3- hexylthiophene) blends from tetrahydrofuran, National

Sensitive Detection of Small Particles in Fluids Using Optical Fiber Tip with Dielectrophoresis

PubMed Central

Tai, Yi-Hsin; Chang, Dao-Ming; Pan, Ming-Yang; Huang, Ding-Wei; Wei, Pei-Kuen

2016-01-01

This work presents using a tapered fiber tip coated with thin metallic film to detect small particles in water with high sensitivity. When an AC voltage applied to the Ti/Al coated fiber tip and indium tin oxide (ITO) substrate, a gradient electric field at the fiber tip induced attractive/repulsive force to suspended small particles due to the frequency-dependent dielectrophoresis (DEP) effect. Such DEP force greatly enhanced the concentration of the small particles near the tip. The increase of the local concentration also increased the scattering of surface plasmon wave near the fiber tip. Combined both DEP effect and scattering optical near-field, we show the detection limit of the concentration for 1.36 μm polystyrene beads can be down to 1 particle/mL. The detection limit of the Escherichia coli (E. coli) bacteria was 20 CFU/mL. The fiber tip sensor takes advantages of ultrasmall volume, label-free and simple detection system. PMID:26927128

Effects of Electrospun Carbon Nanofibers' Interlayers on High-Performance Lithium-Sulfur Batteries.

PubMed

Gao, Tianji; Le, TrungHieu; Yang, Ying; Yu, Zhihao; Huang, Zhenghong; Kang, Feiyu

2017-03-31

Two different interlayers were introduced in lithium-sulfur batteries to improve the cycling stability with sulfur loading as high as 80% of total mass of cathode. Melamine was recommended as a nitrogen-rich (N-rich) amine component to synthesize a modified polyacrylic acid (MPAA). The electrospun MPAA was carbonized into N-rich carbon nanofibers, which were used as cathode interlayers, while carbon nanofibers from PAA without melamine was used as an anode interlayer. At the rate of 0.1 C, the initial discharge capacity with two interlayers was 983 mAh g -1 , and faded down to 651 mAh g -1 after 100 cycles with the coulombic efficiency of 95.4%. At the rate of 1 C, the discharge capacity was kept to 380 mAh g -1 after 600 cycles with a coulombic efficiency of 98.8%. It apparently demonstrated that the cathode interlayer is extremely effective at shutting down the migration of polysulfide ions. The anode interlayer induced the lithium ions to form uniform lithium metal deposits confined on the fiber surface and in the bulk to strengthen the cycling stability of the lithium metal anode.

Effects of Electrospun Carbon Nanofibers’ Interlayers on High-Performance Lithium–Sulfur Batteries

PubMed Central

Gao, Tianji; Le, TrungHieu; Yang, Ying; Yu, Zhihao; Huang, Zhenghong; Kang, Feiyu

2017-01-01

Two different interlayers were introduced in lithium–sulfur batteries to improve the cycling stability with sulfur loading as high as 80% of total mass of cathode. Melamine was recommended as a nitrogen-rich (N-rich) amine component to synthesize a modified polyacrylic acid (MPAA). The electrospun MPAA was carbonized into N-rich carbon nanofibers, which were used as cathode interlayers, while carbon nanofibers from PAA without melamine was used as an anode interlayer. At the rate of 0.1 C, the initial discharge capacity with two interlayers was 983 mAh g−1, and faded down to 651 mAh g−1 after 100 cycles with the coulombic efficiency of 95.4%. At the rate of 1 C, the discharge capacity was kept to 380 mAh g−1 after 600 cycles with a coulombic efficiency of 98.8%. It apparently demonstrated that the cathode interlayer is extremely effective at shutting down the migration of polysulfide ions. The anode interlayer induced the lithium ions to form uniform lithium metal deposits confined on the fiber surface and in the bulk to strengthen the cycling stability of the lithium metal anode. PMID:28772731

Electrospun nanofiber membranes for adsorption of dye molecules from textile wastewater

NASA Astrophysics Data System (ADS)

Akduman, C.; Akçakoca Kumbasar, E. P.; Morsunbul, S.

2017-10-01

The nanofiber membranes prepared by the electrospinning method have unique properties such as high specific surface area and high porosity with fine pores. These properties led electrospun nanofiber membranes to use for the removal of dye molecules from textile wastewater. In this study, a hydrophobic Thermoplastic Polyurethane (TPU) and a hydrophilic Poly (vinyl alcohol) (PVA) were selected for producing electrospun nanofibers and their sorption capacities were investigated. The largest sorption capacity reached to maximum 88.31 mg/g, belong to BTCA cross-linked PVA membranes due to hydrophilic character of PVA. Contrary to expectation, hydrophobic character of TPU was dominant and incorporation of CD to the TPU nanofibers did not affect the sorption of the TPU membranes, and showed very low adsorption capacity (14.48 mg/g).

In vitro feasibility study of the use of a magnetic electrospun chitosan nanofiber composite for hyperthermia treatment of tumor cells.

PubMed

Lin, Ta-Chun; Lin, Feng-Huei; Lin, Jui-Che

2012-07-01

Hyperthermia has been reported to be an effective cancer treatment modality, as tumor cells are more temperature-sensitive than their normal counterparts. Since the ambient temperature can be increased by placing magnetic nanoparticles in an alternating magnetic field it has become of interest to incorporate these magnetic nanoparticles into biodegradable nanofibers for possible endoscopic hyperthermia treatment of malignant tumors. In this preliminary investigation we have explored various characteristics of biodegradable electrospun chitosan nanofibers containing magnetic nanoparticles prepared by different methods. These methods included: (1) E-CHS-Fe(3)O(4), with electrospun chitosan nanofibers directly immersed in a magnetic nanoparticle solution; (2) E-CHS-Fe(2+), with the electrospun chitosan nanofibers initially immersed in Fe(+2)/Fe(+3) solution, followed by chemical co-precipitation of the magnetic nanoparticles. The morphology and crystalline phase of the magnetic electrospun nanofiber matrices were determined by scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, and X-ray diffraction spectroscopy. The magnetic characteristics were measured using a superconducting quantum interference device. The heating properties of these magnetic electrospun nanofiber matrices in an alternating magnetic field were investigated at a frequency of 750 kHz and magnetic intensity of 6.4 kW. In vitro cell incubation experiments indicated that these magnetic electrospun nanofiber matrices are non-cytotoxic and can effectively reduce tumor cell proliferation upon application of a magnetic field. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Developing and physicochemical evaluation of cross-linked electrospun gelatin-glycerol nanofibrous membranes for medical applications

NASA Astrophysics Data System (ADS)

Morsy, Reda; Hosny, Marwa; Reicha, Fikry; Elnimr, Tarek

2017-05-01

This study aims to develop optimal cross-linked electrospun gelatin-glycerol (GEL-GLY) nano-fibrous mats suitable for tissue engineering and wound dressing applications. The optimized procedure involves heating the gelatin and gelatin-glycerol solutions up to 90 °C. The electrospinning process was performed, followed by further cross-linking of electrospun films in a container containing glutaraldehyde (GTA) vapor. The results of X-ray diffraction (XRD), Fourier transformed infrared (FTIR), and Differential thermal analysis (DTA) confirmed that heating gelatin solution up to 90 °C in the presence of glycerol affected the cross-linking efficiency and interactions between GTA molecules and gelatin chains. Scanning Electron Microscope (SEM) analysis showed that GEL-GLY nano-fibrous mats with weight ratios less than or equal (12:3 w/w) exhibited a regular morphology with defect free in addition to increasing the degradation time, cross-linking efficiency, and swelling degree of electrospun gelatin/glycerol.

Electrospun polymeric dressings functionalized with antimicrobial peptides and collagen type I for enhanced wound healing

NASA Astrophysics Data System (ADS)

Felgueiras, H. P.; Amorim, M. T. P.

2017-10-01

Modern wound dressings combine medical textiles with active compounds that stimulate wound healing while protecting against infection. Electrospun wound dressings have been extensively studied and the electrospinning technique recognized as an efficient approach for the production of nanoscale fibrous mats. The unique diverse function and architecture of antimicrobial peptides (AMPs) has attracted considerable attention as a tool for the design of new anti-infective drugs. Functionalizing electrospun wound dressings with these AMPs is nowadays being researched. In the present work, we explore these new systems by highlighting the most important characteristics of electropsun wound dressings, revealing the importance of AMPs to wound healing, and the methods available to functionalize the electrospun mats with these molecules. The combined therapeutic potential of collagen type I and these AMP functionalized dressings will be highlighted as well; the significance of these new strategies for the future of wound healing will be clarified.

Polymer based nanocomposites with nanofibers and exfoliated clay

NASA Technical Reports Server (NTRS)

Meador, Michael A.; Reneker, Darrell H.

2005-01-01

Polymer solutions, containing clay sheets, were electrospun into nanofibers and microfibers that contained clay sheets inside. Controllable removal of polymer by plasma etching from the surface of fibers revealed the arrangement of clay. The shape, flexibility, size distribution and arrangement of clay sheets were observed by transmission and scanning electron microscopy. The clay sheets were partially aligned in big fibers with normal direction of clay sheets perpendicular to fiber axis. Crumpling of clay sheets inside fibers was observed when the fiber diameter was comparable to the lateral size of clay sheets. Single sheets of clay were observed both by catching clay sheets dispersed in water with electrospun nanofiber mats and by the deliberate removal of most of the polymer in the fibers. Thin, flexible gas barrier films, that are reasonably strong, were assembled from clay sheets and polymer nanofibers. Structure of composite films was characterized with scanning electron microscopy. Continuous film of clay sheets were physically attached to the surface of fiber mats. Spincoating film of polymer and clay sheets was reinforced by electrospun fiber scaffold. Certain alignment of clay sheets was observed in the vicinity of fibers.

Conductivity dependence of lithium diffusivity and electrochemical performance for electrospun TiO2 fibers

NASA Astrophysics Data System (ADS)

Qing, Rui; Liu, Li; Bohling, Christian; Sigmund, Wolfgang