Modifications of nonwoven polyethylene terephthalate fibrous matrices via NaOH hydrolysis: Effects on pore size, fiber diameter, cell seeding and proliferation

2009 ◽  
Vol 44 (9) ◽  
pp. 992-998 ◽  
Author(s):  
Robin Ng ◽  
Xudong Zhang ◽  
Ning Liu ◽  
Shang-Tian Yang
Keyword(s):  
Pore Size ◽  
Polyethylene Terephthalate ◽  
Fiber Diameter ◽  
Cell Seeding ◽  
Fibrous Matrices

The Effects of Processing Parameter on Melt-Blown Filtration Materials

2013 ◽  
Vol 650 ◽  
pp. 78-84 ◽  
Author(s):  
Qing Yan Xu ◽  
Yin Min Wang
Keyword(s):  
Pore Size ◽  
Air Temperature ◽  
Surface Density ◽  
Fiber Diameter ◽  
Air Permeability ◽  
Structure And Properties ◽  
Breaking Force ◽  
Processing Parameter ◽  
Nonwoven Fabrics ◽  
Web Structure

The preparation of melt-blown filtration materials was studied in this paper. The effects of collection distance, screw speed, air temperature on web structure and properties were discussed, and moreover, fiber diameter, thickness, surface density, pore size, air permeability and breaking force of PP nonwoven fabrics were characterized in this paper.

Role of Scaffold Architecture and Mechanical Properties of Electrospun Scaffolds in Cell Seeding

2009 ◽  
Vol 1239 ◽  
Author(s):  
Nandula D. Wanasekara ◽  
Ming Chen ◽  
Vijaya B Chalivendra ◽  
Sankha Bhowmick
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Fiber Diameter ◽  
Young's Modulus ◽  
Electrospun Fiber ◽  
Cell Movement ◽  
Cell Seeding ◽  
3T3 Fibroblasts ◽  
Spun Fiber ◽  
Lower Depth

AbstractSeeding a layer of cells at specific depths within scaffolds is an important optimization parameter for bi-layer skin models. The work presented investigated the effect of fiber diameter and its mechanical property on the depth of cell seeding for electro-spun fiber scaffold. Polycaprolactone (PCL) is used to generate scaffolds that are submicron (400nm) to micron (1100nm) using electro-spinning. 3T3 fibroblasts were seeded on the electro-spun fiber scaffold mat of 50-70 microns thickness in this study. In order to investigate the effect of fiber diameter on cell migration, first, the electrospun fiber scaffold was studied for variation of mechanical properties as a function of fiber diameters. Atomic force microscopy (AFM) was used to investigate the Young’s modulus (E) values as a function of fiber diameter. It was identified that as the fiber diameter increases, the Young’s modulus values decreases considerably from 1.1GPa to 200MPa. The variation in E is correlated with cell seeding depth as a function of vacuum pressure. A higher E value led to a lower depth of cell seeding (closer to the surface) indicating that nanofibrous scaffolds offer larger resistance to cell movement compared to microfibrous scaffolds.

Effect of Needle Diameter on Scaffold Morphology and Strength in E-Jetted Polycaprolactone Scaffolds

2017 ◽  
Author(s):  
Aishwarya Bhargav ◽  
Vinicius Rosa ◽  
Lu Wen Feng ◽  
Jerry Y. H. Fuh
Keyword(s):  
Pore Size ◽  
Mechanical Characteristics ◽  
Bone Cells ◽  
Fiber Diameter ◽  
Biomedical Application ◽  
Study Groups ◽  
Morphological Properties ◽  
Knowledge Database ◽  
Fiber Dimensions ◽  
Needle Diameter

Electro-hydrodynamic Jetting or E-Jetting is a process in which a polymer, dissolved in a solvent and extruded through a needle onto a substrate. A potential difference is applied between the needle and the substrate to facilitate the homogeneous extrusion of the fiber. This process is used to fabricate two dimensional scaffolds with porous mesh surfaces which act as a template for cell growth. As cells are very minute and are required to attach to the surface of the scaffold, it is essential to for the scaffold to have an adequate pore size that allows for nutrient transfer while preventing the penetration of cells through the scaffold. The fiber dimensions of the scaffold may be modified by varying the diameter of the needle through which the fiber is extruded. The change in fiber diameter subsequently results in the change in the bulk mechanical characteristics of the scaffold. It also causes a change in the net porosity of the scaffold. This paper aims to study the effect of the needle diameter on the bulk mechanical properties of the scaffold such as Young’s modulus, Tensile strength and Breaking Strength as well as morphological properties (porosity and pore size) of the Scaffolds are dependent on the cell type, as each type of cell has a different set of requirements depending on the functionality. Bone cells are smaller than soft tissue cells, hence a common scaffold design may not be suit either of the applications. Thus, a one size fits all approach is not suitable for the scaffold [9]. As seen in Figure 1, the Red Blood Cells are a fraction of the size of the fibroblasts and bone marrow stem cells [20–22]. Similarly, the stiffness of the cells is also different. Electro Hydrodynamic Jetting (E-jetting) is a process that is used to fabricate such 2D scaffolds by extruding a polymer solution through a needle and forming a fiber by applying a scaffold. For this study, twelve scaffolds belonging to three study groups were synthesized using e-jetting. By studying the effect of needle diameter on scaffold morphology and strength, we aim to develop a co-relation between the scaffold parameters, which will ultimately help in the creation of a knowledge database. The purpose of creating this database is to choose a select needle for a selected biomedical application.

scholarly journals Full cell infiltration and thick tissue formation in vivo in tailored electrospun scaffolds

2020 ◽  
Author(s):  
Jip Zonderland ◽  
Silvia Rezzola ◽  
David Gomes ◽  
Sandra Camarero Espinosa ◽  
Ana Henriques Ferreira Lourenço ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Fiber Diameter ◽  
Cell Infiltration ◽  
Tissue Formation ◽  
Cell Seeding ◽  
Subcutaneous Implantation ◽  
Electrospun Scaffolds ◽  
Limited Depth

AbstractElectrospun (ESP) scaffolds are a promising type of tissue engineering constructs for large defects with limited depth. To form new functional tissue, the scaffolds need to be infiltrated with cells, which will deposit extracellular matrix. However, due to dense fiber packing and small pores, cell and tissue infiltration of ESP scaffolds is limited. Here, we combine two established methods, increasing fiber diameter and co-spinning sacrificial fibers, to create a porous ESP scaffold that allows robust tissue infiltration. Full cell infiltration across 2 mm thick scaffolds is seen 3 weeks after subcutaneous implantation in rats. After 6 weeks, the ESP scaffolds are almost fully filled with de novo tissue. Cell infiltration and tissue formation in vivo in this thickness has not been previously achieved. In addition, we propose a novel method for in vitro cell seeding to improve cell infiltration and a model to study 3D migration through a fibrous mesh. This easy approach to facilitate cell infiltration further improves previous efforts and could greatly aid tissue engineering approaches utilizing ESP scaffolds.Statement of significanceElectrospinning creates highly porous scaffolds with nano- to micrometer sized fibers and are a promising candidate for a variety of tissue engineering applications. However, smaller fibers also create small pores which are difficult for cells to penetrate, restricting cells to the top layers of the scaffolds. Here, we have improved the cell infiltration by optimizing fiber diameter and by co-spinning a sacrificial polymer. We developed novel culture technique that can be used to improve cell seeding and to study cytokine driven 3D migration through fibrous meshes. After subcutaneous implantation, infiltration of tissue and cells was observed up to throughout up to 2 mm thick scaffolds. This depth of infiltration in vivo had not yet been reported for electrospun scaffolds. The scaffolds we present here can be used for in vitro studies of migration, and for tissue engineering in defects with a large surface area and limited depth.

Near-Field Electrospinning and Characterization of Biodegradable Small Diameter Vascular Grafts

2021 ◽  
Author(s):  
◽  
William King, III ◽  
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Pore Size ◽  
Vascular Graft ◽  
Fiber Diameter ◽  
Vascular Grafts ◽  
Small Diameter ◽  
Pore Sizes ◽  
Small Diameter Vascular Grafts

The ideal “off the shelf” tissue engineering, small-diameter (< 6 mm inner diameter (ID)) vascular graft hinges on designing a template that facilitates transmural ingrowth of capillaries to regenerate an endothelized neointimal surface. Previous traditionally electrospun (TES) approaches to create bioresorbable vascular grafts lack the pore sizes required to facilitate transmural capillary ingrowth required for successful in situ neovascular regeneration. Therefore, the ability to create scaffolds with program-specific architectures independent of fiber diameter via the relatively recent sub-technique of near-field electrospinning (NFES) represents a promising solution to create tissue engineering vascular grafts. These programmed large pore sizes are anticipated to promote in situ regeneration and improve the outcomes as well as the quality of life of patients with arterial disease. In this dissertation, we manufactured via NFES as well as characterized biodegradable polydioxanone (PDO) small-diameter vascular grafts. Chapter 1 introduces the need for off-the-shelf, small-diameter vascular grafts to facilitate in situ regeneration, the process and pore size limitations of TES vascular grafts, and the promising use of NFES to develop precisely tailored PDO vascular grafts. Chapter 2 describes the process of NFES and details the current progress in NFES of biomedical polymers as well as the major limitations that exist in the field. Chapters 3, 4, and 5 contain primary research exploring the creation of an NFES vascular graft scaffold and characterizing the mechanical as well as biological response of these scaffolds. Specifically, in Chapter 3 we demonstrate a NFES apparatus designed around a commercial 3D printer to write PDO microfibers. The processing parameters of air gap, polymer concentration, translational velocity, needle gauge, and applied voltage were characterized for their effects on PDO fiber diameter. The processing parameters of polymer concentration and translational fiber deposition velocity were further characterized for their effects on fiber crystallinity and individual fiber uniformity. The precision of fiber stacking via a 3D printer was qualitatively evaluated to inform the creation of 3D scaffolds to guide the alignment of human gingival fibroblasts. It was found that fiber diameters correlate positively with polymer concentration, applied voltage, and needle gauge and inversely correlate with translational velocity and air gap distance. Individual fiber diameter variability decreases, and crystallinity increases with increasing translational fiber deposition velocity. These data resulted in the creation of tailored PDO 3D scaffolds which guided the alignment of primary human fibroblast cells. Together, these results suggest that NFES of PDO can be scaled to create precise geometries with tailored fiber diameters for vascular graft scaffolds. In Chapter 4, we demonstrated a NFES device to semi-stably write PDO microfibers. The polymer spinneret was programmed to translate in a stacking grid pattern, which resulted in a scaffold with highly aligned grid fibers that were intercalated with low density, random fibers. As a consequence of this random switching process, increasing the grid dimensions resulted in both a lower density of fibers in the center of each grid in the scaffold as well as a lower density of “rebar-like” stacked fibers per unit area. These hybrid architecture scaffolds resulted in tailorable as well as greater surface pore sizes as given by scanning electron micrographs and effective object permeability as indicated by fluorescent microsphere filtration compared to TES scaffolds of the same fiber diameter. Furthermore, these programmable scaffolds resulted in tailorability in the characterized mechanical properties ultimate tensile strength, percent elongation, yield stress, yield elongation, and Young’s modulus independent of fiber diameter compared to the static TES scaffold characterization. Lastly, the innate immune response of neutrophil extracellular traps (NETs) was further attenuated on NFES scaffolds compared to TES scaffolds. These results suggest that this novel NFES scaffold architecture of PDO can be highly tailored as a function of programming for small diameter vascular graft scaffolds. In Chapter 5, we created two types of NFES PDO architectures, as small-diameter vascular graft scaffolds. The first architecture type consisted of a 200 x 200 µm and 500 x 500 µm grid geometry with random fiber infill produced from one set of processing parameters, while the second architecture consisted of aligned fibers written in a 45°/45° and 20°/70° offset from the long axis, both on a 4 mm diameter cylindrical mandrel. These vascular graft scaffolds were characterized for their effective object transit pore size, mechanical properties, and platelet-material interactions compared to TES scaffolds and Gore-Tex® vascular grafts. It was found that effective pore size, given by 9.9 and 97 µm microsphere filtration through the scaffold wall for NFES grafts, was significantly more permeable compared to TES grafts and Gore-Tex® vascular grafts. Furthermore, the characterized mechanical properties of ultimate tensile strength, percent elongation, suture retention, burst pressure, and Young’s modulus were all tailorable for NFES grafts, independent of fiber diameter, compared to TES graft characterization. Lastly, platelet adhesion was attenuated on large pore size NFES grafts compared to the TES grafts which approximated the low level of platelet adhesion measured on Gore-Tex® grafts, with all grafts showing minimal platelet activation given by P-selectin surface expression. Together, these results suggest a highly tailorable process for the creation of the next generation of small-diameter vascular grafts. Lastly, Chapter 6 expounds future considerations for continuing research in NFES technology, NFES for general tissue engineering, and NFES for vascular tissue engineering as well as gives final conclusions. Together, the finding of this dissertation indicated that NFES vascular grafts result in seamless, small diameter tubular scaffolds with programmable pore sizes on the magnitude anticipated to facilitate transmural endothelialization as well as programmable mechanical properties that approximate native values. Thus, this work represents the next step in developing bioinstructive designed scaffolds to facilitate in situ vascular regeneration to improve the outcomes as well as the quality of life of patients with arterial vascular disease.

Effect of Blend Ratio on Morphology and Swelling Properties of PVA/Chitosan Nanofibers

2017 ◽  
Vol 901 ◽  
pp. 79-84 ◽  
Author(s):  
Nasikhudin ◽  
Intan Puspitasari ◽  
Markus Diantoro ◽  
Ahmad Kusumaatmaja ◽  
Kuwat Triyana
Keyword(s):  
Pore Size ◽  
Smooth Surface ◽  
Fiber Diameter ◽  
High Porosity ◽  
Swelling Properties ◽  
Blend Ratio ◽  
Small Pore Size ◽  
Small Pore ◽  
Electrospinning Method ◽  
Solution Increase

PVA/chitosan nanofibers have been prepared by electrospinning method. A novel nanofibers mat was prepared in a various blend ratio of PVA to chitosan. The structure of PVA/chitosan nanofibers was examined by FTIR and SEM. The results showed that PVA/chitosan nanofibers were successfully formed. The result of FTIR indicates that PVA and chitosan exist in PVA/chitosan Nanofibers. SEM observation showed that the fiber has several hundred nanometers with a smooth surface. It also observed that fibers diameters decreased by increase percentage of chitosan, this occurs because of the conductivity of electrospun solution increase and the viscosity decrease. Reduction of fiber diameter followed by a decrease in pore size, this is a very important property of a membrane having a small pore size with high porosity. PVA/chitosan nanofibers have pH sensitive of swelling properties and better-swelling properties in acid conditions.

Pore Size Manipulation in 3D Printed Cryogels Enables Selective Cell Seeding

2018 ◽  
Vol 3 (4) ◽  
pp. 1700340 ◽  
Author(s):  
Ludovic Serex ◽  
Thomas Braschler ◽  
Aleksandra Filippova ◽  
Ariane Rochat ◽  
Amélie Béduer ◽  
...  
Keyword(s):  
Pore Size ◽  
Cell Seeding ◽  
3D Printed

Study of Microstructure in Polyethylene Terephthalate(PET) Fiber Using SAXS

2011 ◽  
Vol 332-334 ◽  
pp. 1171-1175
Author(s):  
Xiao Yun Li ◽  
Xiu Hong Li ◽  
Yu Zhu Wang ◽  
Jie Wang
Keyword(s):  
Experimental Method ◽  
Polyethylene Terephthalate ◽  
Small Angle ◽  
Lamellar Structure ◽  
Fiber Diameter ◽  
Saxs Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Edge Scattering ◽  
Pet Fibers

An experimental method was developed in this work to study the PET fibers by synchrotron small-angle X-ray scattering (SAXS). Compared with the traditional measurement in air, the new method measured in the glycerin is helpful to eliminate edge scattering arising from the fiber edge. The results showed that intensity from edge scattering is so high as to cover the microstructure information. PET fiber with a diameter of 25 μm was measured by the new experimental method, and a lobed shape can be seen clearly on the meridian which didn't emerge in traditional measurement. The SAXS data were evaluated to extract parameters of lamellar structure and microvoids. In addition, the effect of fiber diameter on edge scattering was also investigated.

scholarly journals Effect of Temperature on the Structure and Filtration Performance of Polypropylene Melt-Blown Nonwovens

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Si Cheng ◽  
Alam S. M. Muhaiminul ◽  
Zhonghua Yue ◽  
Yan Wang ◽  
Yuanxiang Xiao ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Pore Size ◽  
Fiber Diameter ◽  
Temperature Treatment ◽  
Filtration Efficiency ◽  
Effect Of Temperature ◽  
Filtration Performance ◽  
Different Temperatures ◽  
Polypropylene Melt ◽  
Filtration Properties

AbstractBy applying the simultaneous corona-temperature treatment, the effect of electret temperature on the structure and filtration properties of melt-blown nonwovens was investigated. Fiber diameter, pore size, thickness, areal weight, porosity, crystallinity, filtration efficiency, and pressure drop were evaluated. The results demonstrated that some changes occurred in the structure of electret fabrics after treatment under different temperatures. In the range of 20°C~105°C, the filtration efficiency of melt-blown nonwovens has a relationship with the change in crystallinity, and the pressure drop increased because of the change in areal weight and porosity. This work may provide a reference for further improving filtration efficiency of melt-blown nonwovens.

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