scholarly journals Role of Electrospinning Parameters on Poly(Lactic-co-Glycolic Acid) and Poly(Caprolactone-co-Glycolic acid) Membranes

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 695
Author(s):  
María Herrero-Herrero ◽  
José Antonio Gómez-Tejedor ◽  
Ana Vallés-Lluch
Keyword(s):  
Glycolic Acid ◽  
Fiber Diameter ◽  
Polymer Concentration ◽  
Molar Fraction ◽  
Amorphous Structure ◽  
Starting Solution ◽  
Acid Ratio ◽  
Lower Dielectric Constant ◽  
Poly Caprolactone

Poly(lactic-co-glycolic acid) (PLGA) and poly(caprolactone-co-glycolic acid) (PCLGA) solutions were electrospun into membranes with tailored fiber diameter of 1.8 μm. This particular fiber diameter was tuned depending on the used co-polymer by adjusting the electrospinning parameters that mainly influence the fiber diameter. The greatest setting of the fiber diameter was achieved by varying the polymer solution parameters (polymer concentration, solvents and solvents ratio). PLGA was adequately electrospun with 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), whereas PCLGA required a polar solvent (such as chloroform) with a lower dielectric constant. Moreover, due to the amorphous morphology of PCLGA, pyridine as salt had to be added to the starting solution to increase its conductivity and make it electrospinnable. Indeed, the electrospinning of this co-polymer presents notable difficulties due to its amorphous structure. Interestingly, PCLGA, having a higher glycolic acid molar fraction than commonly electrospun co-polymers (caprolactone:glycolic acid ratio of 45:55 instead of 90:10), could be successfully electrospun, which has not been reported to date. To an accurate setting of fiber diameter, the voltage and the distance from needle to collector were varied. Finally, the study of the surface tension, conductivity and viscosity of the polymer solutions allowed to correlate these particular characteristics of the solutions with the electrospinning variables so that prior knowledge of them enables predicting the required processing conditions.

scholarly journals IKBKB siRNA-Encapsulated Poly (Lactic-co-Glycolic Acid) Nanoparticles Diminish Neuropathic Pain by Inhibiting Microglial Activation

2021 ◽  
Vol 22 (11) ◽  
pp. 5657
Author(s):  
Seounghun Lee ◽  
Hyo-Jung Shin ◽  
Chan Noh ◽  
Song-I Kim ◽  
Young-Kwon Ko ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Microglial Activation ◽  
Glycolic Acid ◽  
Nuclear Factor Kappa B ◽  
Decisive Role ◽  
Plga Nanoparticles ◽  
Spinal Nerve ◽  
Nuclear Factor ◽  
Interfering Rna

Activation of nuclear factor-kappa B (NF-κB) in microglia plays a decisive role in the progress of neuropathic pain, and the inhibitor of kappa B (IκB) is a protein that blocks the activation of NF-κB and is degraded by the inhibitor of NF-κB kinase subunit beta (IKBKB). The role of IKBKB is to break down IκB, which blocks the activity of NF-kB. Therefore, it prevents the activity of NK-kB. This study investigated whether neuropathic pain can be reduced in spinal nerve ligation (SNL) rats by reducing the activity of microglia by delivering IKBKB small interfering RNA (siRNA)-encapsulated poly (lactic-co-glycolic acid) (PLGA) nanoparticles. PLGA nanoparticles, as a carrier for the delivery of IKBKB genes silencer, were used because they have shown potential to enhance microglial targeting. SNL rats were injected with IKBKB siRNA-encapsulated PLGA nanoparticles intrathecally for behavioral tests on pain response. IKBKB siRNA was delivered for suppressing the expression of IKBKB. In rats injected with IKBKB siRNA-encapsulated PLGA nanoparticles, allodynia caused by mechanical stimulation was reduced, and the secretion of pro-inflammatory mediators due to NF-κB was reduced. Delivering IKBKB siRNA through PLGA nanoparticles can effectively control the inflammatory response and is worth studying as a treatment for neuropathic pain.

scholarly journals Optimization of Electrospun Poly(caprolactone) Fiber Diameter for Vascular Scaffolds to Maximize Smooth Muscle Cell Infiltration and Phenotype Modulation

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 643 ◽  
Author(s):  
Dae Geun Han ◽  
Chi Bum Ahn ◽  
Ji-Hyun Lee ◽  
Yongsung Hwang ◽  
Joo Hyun Kim ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cell ◽  
Muscle Cell ◽  
Fiber Diameter ◽  
Electrospun Fiber ◽  
Electrospun Nanofibers ◽  
Macrophage Infiltration ◽  
Vsmc Proliferation ◽  
Vascular Scaffolds ◽  
Poly Caprolactone

Due to the morphological resemblance between the electrospun nanofibers and extracellular matrix (ECM), electrospun fibers have been widely used to fabricate scaffolds for tissue regeneration. Relationships between scaffold morphologies and cells are cell type dependent. In this study, we sought to determine an optimum electrospun fiber diameter for human vascular smooth muscle cell (VSMC) regeneration in vascular scaffolds. Scaffolds were produced using poly(caprolactone) (PCL) electrospun fiber diameters of 0.5, 0.7, 1, 2, 2.5, 5, 7 or 10 μm, and VSMC survivals, proliferations, infiltrations, and phenotypes were recorded after culturing cells on these scaffolds for one, four, seven, or 10 days. VSMC phenotypes and macrophage infiltrations into scaffolds were evaluated by implanting scaffolds subcutaneously in a mouse for seven, 14, or 28 days. We found that human VSMC survival was not dependent on the electrospun fiber diameter. In summary, increasing fiber diameter reduced VSMC proliferation, increased VSMC infiltration and increased macrophage infiltration and activation. Our results indicate that electrospun PCL fiber diameters of 7 or 10 µm are optimum in terms of VSMC infiltration and macrophage infiltration and activation, albeit at the expense of VSMC proliferation.

Blends based on biodegradable poly(caprolactone) with outstanding barrier properties for packaging applications: The role of free volume and interactions

2020 ◽  
Vol 135 ◽  
pp. 109869
Author(s):  
María Ángeles Corres ◽  
Álvaro Mayor ◽  
Ainara Sangroniz ◽  
Javier del Río ◽  
Marian Iriarte ◽  
...  
Keyword(s):  
Free Volume ◽  
Barrier Properties ◽  
Biodegradable Poly ◽  
Poly Caprolactone

scholarly journals Direct-Write Drawing of Carbon Nanotube/Polymer Composite Microfibers

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Scott M. Berry ◽  
Santosh Pabba ◽  
Robert W. Cohn ◽  
Robert S. Keynton
Keyword(s):  
Carbon Nanotube ◽  
Polymer Solutions ◽  
Fiber Diameter ◽  
Axial Strain ◽  
Polymer Concentration ◽  
Strain Rates ◽  
Direct Write ◽  
Composite Fibers ◽  
Capillary Thinning ◽  
Doped Polymer

Carbon-nanotube- (CNT-) doped polymer solutions were drawn into arrays of microfibers using a novel direct-write process. This process utilizes a micromanipulator-controlled syringe loaded with solvated polymer mixed with CNTs to “write” networks of composite fibers with precisely positioned endpoints. The diameters of these composite fibers are correlated to the degree of capillary thinning that occurs prior to the solidification of the directly written CNT-doped solution filament. The fibers had diameters ranging from 7 μm to over 100 μm and possessed conductivities as high as 0.1 Sm−1. Fiber diameter was found to increase with increasing polymer concentration and decreasing fiber length and can be controlled through modulation of these parameters. The presence of CNTs was found not to significantly affect fiber diameter, despite the CNTs significant effect on viscosity, which was previously reported to influence diameter. This discrepancy is likely related to the non-Newtonian effects of CNT/polymer solutions, including an apparent shear thinning at increasing axial strain rates.

Some Considerations on Confined Water: The Thermal Behavior of Transport Properties in Water-Glycerol and Water-Methanol Mixtures

MRS Advances ◽  
2016 ◽  
Vol 1 (26) ◽  
pp. 1891-1902 ◽  
Author(s):  
Francesco Mallamace ◽  
Carmelo Corsaro ◽  
Domenico Mallamace ◽  
Cirino Vasi ◽  
Sebastiano Vasi ◽  
...  
Keyword(s):  
Hydrophobic Interactions ◽  
Molar Fraction ◽  
Relaxation Times ◽  
Confined Water ◽  
Self Diffusion ◽  
Excess Value ◽  
Water Glycerol ◽  
System Properties ◽  
Dynamical Crossover

ABSTRACTWe discuss recent literature data on the relaxation times (the primary tα), viscosity, and self-diffusion in water-glycerol and water-methanol mixtures across a wide temperature range from the stable water phase to the deep supercooled regime (373–147K). In particular, to clarify the role of hydrophilicity interactions (the hydrogen bonds) and hydrophobic interactions we study the mixture in terms of the water molar fraction (XW) with fixed temperatures at 5K steps across the entire composition range, and we find a marked deviation from the ideal thermodynamic behavior of the transport functions. This deviation is strongly T and XW dependent and spans values that range from two orders of magnitude at the highest temperature to more than five in the deeply supercooled regime (more precisely, at ≃200K). We analyze these deviations in terms of how the measured values differ from ideal values and find that the hydrogen-bonding water network dominates system properties up to XW = 0.3. We also examine an Arrhenius plot of the maximum excess value (Δtα(T) vs. 1/T) and find two significant changes due to water: one at the dynamical crossover temperature (TL ≃ 225K, i.e., the locus of the Widom line), and one at T ≃ 315K (the water isothermal compressibility χT minimum).

Electrospinnability of Poly Lactic-co-glycolic Acid (PLGA): the Role of Solvent Type and Solvent Composition

2017 ◽  
Vol 34 (4) ◽  
pp. 738-749 ◽  
Author(s):  
Xiaoli Liu ◽  
Stefania G. Baldursdottir ◽  
Johanna Aho ◽  
Haiyan Qu ◽  
Lars Porskjær Christensen ◽  
...  
Keyword(s):  
Glycolic Acid ◽  
Solvent Composition ◽  
Solvent Type ◽  
Role Of Solvent

Direct Numerical Simulation of Drops in Three Dimensional Viscoelastic Simple Shear Flows

2001 ◽  
Author(s):  
Shriram B. Pillapakkam ◽  
Pushpendra Singh
Keyword(s):  
Numerical Simulation ◽  
Shear Flow ◽  
Direct Numerical Simulation ◽  
Viscoelastic Fluid ◽  
Simple Shear ◽  
Polymer Concentration ◽  
Three Dimensional ◽  
Simple Shear Flow ◽  
Splitting Technique

Abstract A three dimensional finite element scheme for Direct Numerical Simulation (DNS) of viscoelastic two phase flows is implemented. The scheme uses the Level Set Method to track the interface and the Marchuk-Yanenko operator splitting technique to decouple the difficulties associated with the governing equations. Using this numerical scheme, the shape of Newtonian drops in a simple shear flow of viscoelastic fluid and vice versa are analyzed as a function of Capillary number, Deborah number and polymer concentration. The viscoelastic fluid is modeled via the Oldroyd-B model. The role of viscoelastic stresses in deformation of a drop subjected to simple shear flow and its effect on the steady state shape is analyzed. Our results compare favorably with existing experimental data and also help in understanding the role of viscoelastic stresses in drop deformation.

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