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John J. Lannutti - One of the best experts on this subject based on the ideXlab platform.
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Effect of Electrospun Fiber Mat Thickness and Support Method on Cell Morphology
'MDPI AG', 2019Co-Authors: Mark A. Calhoun, John J. Lannutti, Sadiyah Sabah Chowdhury, Mark Tyler Nelson, Rebecca B. Dupaix, Jessica O WinterAbstract:Electrospun Fiber mats (EFMs) are highly versatile biomaterials used in a myriad of biomedical applications. Whereas some facets of EFMs are well studied and can be highly tuned (e.g., pore size, Fiber diameter, etc.), other features are under characterized. For example, although substrate mechanics have been explored by several groups, most studies rely on Young’s modulus alone as a characterization variable. The influence of Fiber mat thickness and the effect of supports are variables that are often not considered when evaluating cell-mechanical response. To assay the role of these features in EFM scaffold design and to improve understanding of scaffold mechanical properties, we designed EFM scaffolds with varying thickness (50–200 µm) and supporting methodologies. EFM scaffolds were comprised of polycaprolactone and were either Electrospun directly onto a support, suspended across an annulus (3 or 10 mm inner diameter), or “tension-released„ and then suspended across an annulus. Then, single cell spreading (i.e., Feret diameter) was measured in the presence of these different features. Cells were sensitive to EFM thickness and suspended gap diameter. Overall, cell spreading was greatest for 50 µm thick EFMs suspended over a 3 mm gap, which was the smallest thickness and gap investigated. These results are counterintuitive to conventional understanding in mechanobiology, which suggests that stiffer materials, such as thicker, supported EFMs, should elicit greater cell polarization. Additional experiments with 50 µm thick EFMs on polystyrene and polydimethylsiloxane (PDMS) supports demonstrated that cells can “feel„ the support underlying the EFM if it is rigid, similar to previous results in hydrogels. These results also suggest that EFM curvature may play a role in cell response, separate from Young’s modulus, possibly because of internal tension generated. These parameters are not often considered in EFM design and could improve scaffold performance and ultimately patient outcomes
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hydrogel Electrospun Fiber composite materials for hydrophilic protein release
Journal of Controlled Release, 2012Co-Authors: Ning Han, John J. Lannutti, Jed Johnson, Jessica O WinterAbstract:Although hydrogels are widely used in controlled-release systems, obtaining extended, uniform drug release with little initial burst has been challenging. However, recently researchers have shown that combining hydrogels with another drug delivery material can dramatically improve release kinetics. Here we describe a novel hydrogel-based composite material that exhibits stable, near-linear, sustained release of a model hydrophilic protein (e.g., bovine albumin serum, BSA) for over two months with a significant reduction in initial burst release (7% vs. 20%). The composite is comprised of poly(e-caprolactone) (PCL) Electrospun Fiber mats coupled with poly(ethylene glycol)-poly(e-caprolactone) diacrylate (PEGPCL) hydrogels through photo-polymerization. It is believed that the additional diffusion barrier provided by hydrophobic Electrospun Fiber mats reduces hydrogel swelling and water penetration rates and increases the diffusion path length, resulting in delayed, more uniform drug release. Further, released proteins remain bioactive as demonstrated by PC12 cell neurite extension in response to released nerve growth factor (NGF). The use of Electrospun Fiber mats to modulate hydrogel drug release provides a new method to control release kinetics of hydrophilic proteins, reducing burst release and extending the release duration.
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improved cellular infiltration in Electrospun Fiber via engineered porosity
Tissue Engineering, 2007Co-Authors: Yan Huang, Sudha Agarwal, John J. LannuttiAbstract:Small pore sizes inherent to Electrospun matrices can hinder efficient cellular ingrowth. To facilitate infiltration while retaining its extracellular matrix-like character, electrospinning was combined with salt leaching to produce a scaffold having deliberate, engineered delaminations. We made elegant use of a specific randomizing component of the electrospinning process, the Taylor Cone and the falling Fiber beneath it, to produce a uniform, well-spread distribution of salt particles. After 3 weeks of culture, up to 4 mm of cellular infiltration was observed, along with cellular coverage of up to 70% within the delaminations. To our knowledge, this represents the first observation of extensive cellular infiltration of Electrospun matrices. Infiltration appears to be driven primarily by localized proliferation rather than coordinated cellular locomotion. Cells also moved from the salt-generated porosity into the surrounding Electrospun Fiber matrix. Given that the details of salt deposition (amount, siz...
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improved cellular infiltration in Electrospun Fiber via engineered porosity
Tissue Engineering, 2007Co-Authors: Yan Huang, Sudha Agarwal, John J. LannuttiAbstract:Small pore sizes inherent to Electrospun matrices can hinder efficient cellular ingrowth. To facilitate infiltration while retaining its extracellular matrix-like character, electrospinning was com...
Seeram Ramakrishna - One of the best experts on this subject based on the ideXlab platform.
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influence of Electrospun Fiber size on the separation efficiency of thin film nanofiltration composite membrane
Journal of Membrane Science, 2012Co-Authors: Subramanian Sundarrajan, Satinderpal Kaur, Dipak Rana, Takeshi Matsuura, Seeram RamakrishnaAbstract:Abstract Currently, Electrospun nanofibrous membrane (ENM) is classified as a microfiltration (MF) membrane, which upon further modification is used for nanofiltration (NF) applications. The objective of this study was to investigate the suitability of ENM for water treatment applications. Different Fiber sizes were obtained by varying the concentration of polyacrylonitrile solution (namely 4, 6, 8 and 10 wt%) to explore the interplay between Electrospun Fiber size and rejected salt ions. When the Fiber size was larger, its ‘bubble-point’ was higher and hence its pure water flux was also higher. In order to transform these MF membrane to NF membrane, an interfacial polymerization technique was used to coat a thin film on the surface of ENM. Separation of 2000 ppm of various salts was conducted on this developed thin film nanofibrous composite (TFNC) membrane. The results indicated that as the Fiber size decreased, the pore-size also decreased, and the separation of salts increased, while at the expense of flux. When the cross-sectional thickness of the Electrospun layer was decreased together with smaller pore-size, it resulted in the increased flux with high salt rejection. In addition, rejection efficiency of these TFNC membranes against PEG 300, PEG 600 and PEG 3400 were also studied.
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fabrication and characterization of a boehmite nanoparticle impregnated Electrospun Fiber membrane for removal of metal ions
Journal of Materials Science, 2008Co-Authors: G Hota, Rajesh B Kumar, Seeram RamakrishnaAbstract:The fabrication of a composite Electrospun Fiber membrane with sorptive characteristics intended for removal of heavy metals was investigated. The Electrospun Fiber membrane was impregnated with nano-boehmite particles. The latter had been selected to increase surface area of the active component. Cd (II) was chosen as the challenge bivalent cation. The sorption capacity of the nano-boehmite was studied as a function of pH and time. Electrospinning was used to prepare the composite submicron Fiber membrane impregnated with boehmite nanoparticles. The later was blended with the polymer to produce a homogenous mixture before electrospinning. Two polymers, the hydrophobic/PCL/and hydrophilic/Nylon-6/, were chosen to serve as the support for the boehmite. The nanoparticles and resulting composite membranes were characterized using SEM, TEM, and XRD techniques. XRD data confirmed the presence of nano-boehmite particles in the nanoFibers membrane. The membranes so prepared were challenged with aqueous solutions of Cd in batch isotherm tests. Atomic absorption spectroscopy results show sorption of Cd (II) by boehmite impregnated electospun membrane was possible and a capacity of 0.20 mg/g was achieved.
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a dynamic liquid support system for continuous Electrospun yarn fabrication
Polymer, 2007Co-Authors: Wee Eong Teo, Renuga Gopal, Ramakrishnan Ramaseshan, K Fujihara, Seeram RamakrishnaAbstract:Electrospinning is known to be a highly versatile process which is able to produce Fibers made out of different compositions with diameter of a few microns down to several nanometers. Current electrospinning technology generally involves the deposition of Fibers onto a solid substrate although in some cases, a liquid coagulation bath is used to collect the Fibers. However, a liquid collector may offer several advantages over a solid substrate. A novel Electrospun Fiber manipulation process through the use of a water vortex is described in this communication where continuous yarn was made from Electrospun Fibers. Preliminary studies on some parameters such as solution feed rate and solution concentration and their impact on fabrication of the yarn and the Fiber morphology were carried out.
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Biomimetic Electrospun nanoFibers for tissue regeneration
Biomedical Materials, 2006Co-Authors: Susan Liao, Bojun Li, Casey K Chan, Zuwei Ma, Seeram RamakrishnaAbstract:NanoFibers exist widely in human tissue with different patterns. Electrospinning nanotechnology has recently gained a new impetus due to the introduction of the concept of biomimetic nanoFibers for tissue regeneration. The advanced electrospinning technique is a promising method to fabricate a controllable continuous nanoFiber scaffold similar to the natural extracellular matrix. Thus, the biomedical field has become a significant possible application field of Electrospun Fibers. Although electrospinning has developed rapidly over the past few years, Electrospun nanoFibers are still at a premature research stage. Further comprehensive and deep studies on Electrospun nanoFibers are essential for promoting their biomedical applications. Current Electrospun Fiber materials include natural polymers, synthetic polymers and inorganic substances. This review briefly describes several typically Electrospun nanoFiber materials or composites that have great potential for tissue regeneration, and describes their fabrication, advantages, drawbacks and future prospects.
Gregory C Rutledge - One of the best experts on this subject based on the ideXlab platform.
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separation of oil in water emulsions stabilized by different types of surfactants using Electrospun Fiber membranes
Journal of Membrane Science, 2018Co-Authors: Yimin Lin, Gregory C RutledgeAbstract:Abstract The compositions of oil-in-water emulsions encountered in industrial processes or in the environment vary widely in the nature of surfactants that stabilize them. This variety creates challenges for applications of membrane separation. Electrospun Fiber membranes have shown high permeability and improved robustness against fouling in emulsion separation, but the interaction between emulsions and the membrane, and the fouling mechanism, remains unclear. In this paper, Electrospun polyamide membranes were challenged by model emulsions of dodecane stabilized by anionic, cationic, non-ionic and zwitterionic surfactants in both dead-end and cross-flow filtration configurations under constant pressure of 2 psi. The membrane was shown to have high oil rejection (92.7 ± 1.5%), sufficient to meet EPA's regulatory limit, when separating emulsions stabilized by anionic surfactant in cross-flow filtration, while maintaining a steady flux of 44.3 ± 2.6 LMH. Analysis of permeate flux and oil rejection revealed that the types of surfactants influenced the membrane fouling in both dead-end and cross-flow systems, but in different ways. Fouling in dead-end filtration was found to be a function of the electrostatic interactions between the oil droplets and the membrane, while fouling in cross-flow filtration was mainly determined by the hydrophilic/hydrophobic interactions due to the adsorption of surfactants at the interfaces. Blocking filtration models are used to corroborate these findings and illustrate the transition between modes of fouling in dead-end filtration. A de-fouling process was found when separating emulsions stabilized by cationic surfactant in dead-end filtration, which was attributed to coalescence of oil droplets at the membrane surface, based on a kinetic model and direct observation. These results indicate that not only membrane-foulant but foulant-foulant interactions can influence the membrane fouling.
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three dimensional imaging of Electrospun Fiber mats using confocal laser scanning microscopy and digital image analysis
Prof. Rutledge via Erja Kajosalo, 2015Co-Authors: Looh Tchuin Choong, Gregory C RutledgeAbstract:Confocal laser scanning microscopy with fluorescent markers and index matching has been used to collect three-dimensional (3D) digitized images of Electrospun Fiber mats and of a borosilicate glass Fiber material. By embedding the fluorescent dye in either the material component (Fibers) or pore space component (the index-matching fluid), acquisitions of both positive and negative images of the porous fibrous materials are demonstrated. Image analysis techniques are then applied to the 3D reconstructions of the fibrous materials to extract important morphological characteristics such as porosity, specific surface area, distributions of Fiber diameter and of pore diameter, and Fiber orientation distribution; the results are compared with other experimental measurements where available. The topology of the pore space is quantified for an Electrospun mat for the first time using the Euler-Poincare characteristic. Finally, a method is presented for subdividing the pore space into a network of cavities and the gates that interconnect them, by which the network structure of the pore space in these Electrospun mats is determined.
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permeability of Electrospun Fiber mats under hydraulic flow
Journal of Membrane Science, 2014Co-Authors: Looh Tchuin Choong, Zafarullah Khan, Gregory C RutledgeAbstract:Abstract The hydraulic permeabilities of Electrospun Fiber mats are found to be functions of their compressibility. Hydraulic permeabilities of Electrospun mats of bis-phenol A polysulfone (PSU) comprising Fibers of different mean diameters, annealed at temperatures at and above the glass transition of the polymer, were measured for feed water pressures ranging from 5 kPa to 140 kPa. The Electrospun mats experience a decrease of more than 60% in permeability between 5 kPa and 140 kPa, due to the loss of porosity, attributed to flow-induced compression. This behavior is explained using a simple model based on Darcy's law applied to a compressible, porous medium. Happel's equation is used to model the permeability of the Fiber mats, and Toll's equation is used to model their compressibility. The permeation model accurately estimates the changes in solidity, and hence the permeability of the Electrospun mats, over a range of pressure differentials.
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mechanical and transport properties of layer by layer Electrospun composite proton exchange membranes for fuel cell applications
Prof. Rutledge via Erja Kajosalo, 2013Co-Authors: Matthew M. Mannarino, David S Liu, Paula T Hammond, Gregory C RutledgeAbstract: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 p...
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Compressibility of Electrospun Fiber mats
Journal of Materials Science, 2013Co-Authors: Looh Tchuin Choong, Matthew M. Mannarino, Sandip Basu, Gregory C RutledgeAbstract:Compressive properties of Electrospun Fiber mats are reported for the first time. Mats of bisphenol-A polysulfone (PSU) and of poly(trimethyl hexamethylene terephthalamide) [PA 6(3)T] were Electrospun and annealed over a range of temperatures spanning the glass transition temperature of each polymer. The data for applied stress versus mat solidity were found to be well-described by a power law of the form \( \sigma_{\text{zz}} = kE\left( {\phi^{n} - \phi_{0}^{n} } \right) \), where \( \sigma_{\text{zz}} \) is the applied stress and ϕ is solidity, in accord with the analysis of Toll (Polym Eng Sci 38(8):1337, 2004). The values of n range from 3.2 to 6 for PSU and from 8.0 to 20 for PA 6(3)T. The lowest values in each case were exhibited by mats annealed near the glass transition temperature of the Fiber material. The values of n are independent of Fiber diameter. The higher values of n are attributed to Fiber slippage via a mechanism analogous to that of work hardening of metals. The values of kE can vary by an order of magnitude and were difficult to determine precisely, due to the nature of the power law and the inhomogeneity of the mats. The compressibility of Electrospun mats in response to an applied stress is sufficiently large that it cannot be neglected in applications where large pressures may be involved, such as filtration or membrane separations. In addition to the initial solidity of the mats, the material compressibility and the operating pressure relevant to the application are important to describe the structure of Electrospun mats quantitatively under conditions of use.
Pitt Supaphol - One of the best experts on this subject based on the ideXlab platform.
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bone scaffolds from Electrospun Fiber mats of poly 3 hydroxybutyrate poly 3 hydroxybutyrate co 3 hydroxyvalerate and their blend
Polymer, 2007Co-Authors: Korakot Sombatmankhong, Neeracha Sanchavanakit, Prasit Pavasant, Pitt SupapholAbstract:Abstract In the present contribution, electrospinning was used to fabricate ultrafine Fiber mats from poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate- co -2-hydroxyvalerate) (PHBV), and their 50/50 w/w blend for potential use as bone scaffolds. Cytotoxicity evaluation of these as-spun Fiber mats with human osteoblasts (SaOS-2) and mouse fibroblasts (L929) indicated biocompatibility of these materials to both types of cells. The potential for use of these Fiber mats as bone scaffolds was further assessed in vitro in terms of the attachment, the proliferation, and the alkaline phosphatase (ALP) activity of SaOS-2 that were seeded or cultured at different times. The cells appeared to adhere well on all types of the fibrous scaffolds after 16 h of cell seeding. During the early stage of the proliferation period (i.e., from ∼24 to 72 h in culture), the viability of the cells increased considerably and appeared to be unchanged with further increase in the time in culture. In comparison with the corresponding solution-cast film scaffolds, all of the fibrous scaffolds exhibited much better support for cell attachment and proliferation. Lastly, among the various fibrous scaffolds investigated, the Electrospun Fiber mat of the 50/50 w/w PHB/PHBV blend showed the highest ALP activity. These results implied a high potential for use of these Electrospun Fiber mats as bone scaffolds.
Yan Huang - One of the best experts on this subject based on the ideXlab platform.
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improved cellular infiltration in Electrospun Fiber via engineered porosity
Tissue Engineering, 2007Co-Authors: Yan Huang, Sudha Agarwal, John J. LannuttiAbstract:Small pore sizes inherent to Electrospun matrices can hinder efficient cellular ingrowth. To facilitate infiltration while retaining its extracellular matrix-like character, electrospinning was combined with salt leaching to produce a scaffold having deliberate, engineered delaminations. We made elegant use of a specific randomizing component of the electrospinning process, the Taylor Cone and the falling Fiber beneath it, to produce a uniform, well-spread distribution of salt particles. After 3 weeks of culture, up to 4 mm of cellular infiltration was observed, along with cellular coverage of up to 70% within the delaminations. To our knowledge, this represents the first observation of extensive cellular infiltration of Electrospun matrices. Infiltration appears to be driven primarily by localized proliferation rather than coordinated cellular locomotion. Cells also moved from the salt-generated porosity into the surrounding Electrospun Fiber matrix. Given that the details of salt deposition (amount, siz...
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improved cellular infiltration in Electrospun Fiber via engineered porosity
Tissue Engineering, 2007Co-Authors: Yan Huang, Sudha Agarwal, John J. LannuttiAbstract:Small pore sizes inherent to Electrospun matrices can hinder efficient cellular ingrowth. To facilitate infiltration while retaining its extracellular matrix-like character, electrospinning was com...