scholarly journals Chitosan Woven Meshes: Influence of Threads Configuration on Mechanical, Morphological, and Physiological Properties

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 47
Author(s):  
Henrique Nunes da Silva ◽  
Milena Costa da Silva ◽  
Flavia Suzany Ferreira dos Santos ◽  
José Alberto Campos da Silva Júnior ◽  
Rossemberg Cardoso Barbosa ◽  
...  
Keyword(s):  
Sodium Hydroxide Solution ◽  
Tensile Tests ◽  
Coagulation Bath ◽  
Wet Spinning ◽  
Physiological Properties ◽  
Potential Applications ◽  
Spinning Process ◽  
The Individual ◽  
Typical Skin

This study aimed to develop meshes from the weaving of mono- and multifilament wet-spun chitosan (CS), for possible biomedical applications. In the wet-spinning process, CS solution (4% w/v) was extruded in a coagulation bath containing 70% sodium hydroxide solution (0.5 M), and 30% methanol was used. The multifilament thread was prepared by twisted of two and three monofilaments. CS threads obtained were characterized by tensile tests and scanning electron microscopy (SEM). Moreover, it was verified from the morphological tests that threads preserve the characteristics of the individual filaments and present typical “skin-core” microstructure obtained by wet spinning. CS woven meshes obtained were evaluated by optical microscopy (OM), tensile test, swelling degree, and in vitro enzymatic biodegradation. Mechanical properties, biodegradation rate, and amount of fluid absorbed of CS woven meshes were influenced by thread configuration. Hydrated CS meshes showed a larger elastic zone than the dry state. Therefore, CS woven meshes were obtained with modular properties from thread configuration used in weaving, suggesting potential applications in the biomedical field, like dressings, controlled drug delivery systems, or mechanical support.

Effect of coagulation bath parameters on the morphology and absorption behavior of a skin–core filament based on biomedical polyurethane and native silk fibroin microparticles

2019 ◽  
Vol 90 (3-4) ◽  
pp. 460-468 ◽  
Author(s):  
Yan Zhuang ◽  
Han Wang ◽  
Linfeng Wang ◽  
Changjun Liu ◽  
Yuan Xu ◽  
...  
Keyword(s):  
Drug Release ◽  
Water Absorption ◽  
Silk Fibroin ◽  
Controlled Drug Release ◽  
Coagulation Bath ◽  
Wet Spinning ◽  
Electron Microscopy Analysis ◽  
Potential Applications ◽  
Spinning Process ◽  
Biomedical Polyurethane

This study investigates the effect of the constituents and temperature of a coagulation bath on the morphology and water absorption behavior of a skin–core filament, which has potential application in the field of controlled drug release, based on biomedical polyurethane (BPU) and native silk fibroin microparticles (NSFPs). BPU solution and BPU/NSFP blend solution were extruded from the cortex and core channel of a coaxial double injector into a coagulation bath with different constituents and at different temperatures to form filaments. Scanning electron microscopy analysis of the skin–core filament prepared by wet-spinning revealed that the addition of ethanol decreased the exchange speed between the solvent and non-solvent and led to the formation of micropores on the surface. Meanwhile, the interface between the cortex and core became pronounced and the water absorption capability of the filament decreased with increasing ethanol concentration in the coagulation bath. The high temperature of the coagulation bath also improved the exchange speed between the solvent and non-solvent; however, its effect on the morphology of the filament was weak. Thus, a skin–core filament with different morphologies and water absorption behaviors was fabricated by controlling the constituents and temperature of the coagulation bath during the wet-spinning process. This skin–core filament has potential applications in controlled drug release.

Fabrication of the Colored PMIA Fibers by Wet Spinning: Effect of Spinning Parameters on the Coagulation Process

2014 ◽  
Vol 9 (1) ◽  
pp. 155892501400900
Author(s):  
Liqi Liu ◽  
Lei Chen ◽  
Zuming Hu ◽  
Junrong Yu ◽  
Jing-Zhu ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Aromatic Polyamide ◽  
Stretch Ratio ◽  
Coagulation Bath ◽  
Wet Spinning ◽  
Ultrasonic Oscillation ◽  
Coagulation Process ◽  
Polyamide Fiber ◽  
Spinning Process ◽  
Oscillation Method

The poly (m-phenylene isophthalamide) (PMIA) fiber, which can be prepared by wet spinning, is a kind of aromatic polyamide fiber. The spinning parameters could influence the performance and structure of the colored PMIA fiber such as the diffusion coefficient and coagulation bath. In this study, the PMIA spinning solutions doped with Color Inde purple 120 were first commixed in a pressurizer and then spun into a coagulation bath under a pressure about 0.3 MPa. In the coagulation bath, the pure or dope-dyed PMIA fibers were prepared by wet spinning at 323 K, and then the as-spun fibers were extracted by an ultrasonic oscillation method. The effects of jet stretch ratio, temperature, and concentration of the coagulation bath on the ratio of diffusion coefficient of solvent to coagulator were analyzed during the spinning process of dope-dyed PMIA fibers. The properties and structures of the colored PMIA fibers were characterized by SEM. Finally the most optimized spinning technology of the dope-dyed PMIA fiber was obtained and the dope-dyed PMIA fibers were successfully fabricated through wet spinning.

scholarly journals Temperature Effect of Water Coagulation Bath on Chitin Fiber Prepared through Wet-Spinning Process

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1909
Author(s):  
Khoa Dang Nguyen
Keyword(s):  
Phase Inversion ◽  
Room Temperature ◽  
Biomedical Application ◽  
Coagulation Bath ◽  
Wet Spinning ◽  
Crab Shell ◽  
Shell Waste ◽  
Different Temperatures ◽  
Spinning Process ◽  
Crab Shell Waste

Chitin was chemically extracted from crab shell waste and dissolved in N,N-dimethyl acetamine/5% lithium chloride (DMAc/5% LiCl) at room temperature to obtain 1% and 2% concentrations of chitin solution. Chitin fibers were prepared by phase inversion at different temperatures of water coagulation bath at 5, 20, and 60 °C. The deconvolution of FTIR spectra indicated that the area portion of the intermolecular hydrogen bonding NH…OC increased at 60 °C due to the higher density of the chitin segment in the fiber. As a result, scanning electron microscope (SEM) measurement suggests that a denser structure of the chitin fiber was observed when the temperature of the coagulation bath increased. In addition, the resultant chitin fibers generated better mechanical properties relative to the amount of chitin concentration and temperature. At 2% of chitin solution, the tensile strength significantly increased from 80 to 182 MPa for the fiber obtained at temperatures of 5 and 60 °C of the water coagulation bath, respectively. Meanwhile, the water content in the fiber significantly decreased from 1101% to 335%. This green synthesis route has high potential for the fabrication of the fiber as future material of interest for biomedical application.

Research on the multi-scale microstructure of polyacrylonitrile precursors prepared by a dry-jet wet spinning process

2018 ◽  
Vol 31 (6) ◽  
pp. 662-670 ◽  
Author(s):  
Meiling Chen ◽  
Chengguo Wang ◽  
Quan Gao ◽  
Yanxiang Wang ◽  
Min Jing ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Performance ◽  
Nitrogen Adsorption ◽  
Coagulation Bath ◽  
Wet Spinning ◽  
Carbon Fibres ◽  
Cross Sectional ◽  
Multi Scale ◽  
Transmission Electron ◽  
Spinning Process

An understanding of the properties of polyacrylonitrile (PAN) precursors is an essential precondition for manufacturing high-performance carbon fibres, and the structure of the precursors has a direct and profound effect on the performance of carbon fibres. In this study, PAN precursors, formed in a multistage coagulation bath, were spun by a dry-jet wet spinning process, and the multi-scale microstructure and morphology of the precursors were investigated by separating the fibrils from the precursors. Scanning electron microscopy and high-resolution transmission electron microscopy were employed to examine the surface morphology, cross-sectional morphology and microstructure of the precursors. X-ray diffraction was used to characterize the crystal structure. The micropore sizes of the precursors were determined with nitrogen adsorption experiments; the adsorption increased after ultrasonic etching and decreased with an increase in the treated concentration. All the results demonstrated that the PAN precursors had a multi-scale microstructure, the precursors consisted of fibrils with diameters of 80–200 nm and the fibrils consisted of some microfibrils with diameters of 20–40 nm, including the periodic tissues with thicknesses of 16–30 nm perpendicular to the fibre axis.

scholarly journals Strategies to Modulate the Redifferentiation of Chondrocytes

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiaoshen Hu ◽  
Weiyang Zhang ◽  
Xiang Li ◽  
Dongling Zhong ◽  
Yuxi Li ◽  
...  
Keyword(s):  
Cartilage Tissue ◽  
Self Healing ◽  
Human Cartilage ◽  
Physiological Properties ◽  
Potential Applications ◽  
Cell Sources ◽  
Cartilage Injuries ◽  
Extracellular Environment ◽  
Positive Results

Because of the low self-healing capacity of articular cartilage, cartilage injuries and degenerations triggered by various diseases are almost irreversible. Previous studies have suggested that human chondrocytes cultured in vitro tend to dedifferentiate during the cell-amplification phase and lose the physiological properties and functions of the cartilage itself, which is currently a critical limitation in the cultivation of cartilage for tissue engineering. Recently, numerous studies have focused on the modulation of chondrocyte redifferentiation. Researchers discovered the effect of various conditions (extracellular environment, cell sources, growth factors and redifferentiation inducers, and gene silencing and overexpression) on the redifferentiation of chondrocytes during the in vitro expansion of cells, and obtained cartilage tissue cultured in vitro that exhibited physiological characteristics and functions that were similar to those of human cartilage tissue. Encouragingly, several studies reported positive results regarding the modulation of the redifferentiation of chondrocytes in specific conditions. Here, the various factors and conditions that modulate the redifferentiation of chondrocytes, as well as their limitations and potential applications and challenges are reviewed. We expect to inspire research in the field of cartilage repair toward the future treatment of arthropathy.

Towards a New Approach to Cross-Cultural Distinctiveness and Typicality of Human Faces: The Cross-Group Typicality/Distinctiveness Metric

2018 ◽  
Author(s):  
Karel Kleisner ◽  
Šimon Pokorný ◽  
Selahattin Adil Saribay
Keyword(s):  
Cross Cultural ◽  
Facial Appearance ◽  
Alternative Measure ◽  
Home Culture ◽  
Facial Stimuli ◽  
The Two Cultures ◽  
Potential Applications ◽  
The Individual ◽  
Human Faces ◽  
Ingroup Outgroup

In present research, we took advantage of geometric morphometrics to propose a data-driven method for estimating the individual degree of facial typicality/distinctiveness for cross-cultural (and other cross-group) comparisons. Looking like a stranger in one’s home culture may be somewhat stressful. The same facial appearance, however, might become advantageous within an outgroup population. To address this fit between facial appearance and cultural setting, we propose a simple measure of distinctiveness/typicality based on position of an individual along the axis connecting the facial averages of two populations under comparison. The more distant a face is from its ingroup population mean towards the outgroup mean the more distinct it is (vis-à-vis the ingroup) and the more it resembles the outgroup standards. We compared this new measure with an alternative measure based on distance from outgroup mean. The new measure showed stronger association with rated facial distinctiveness than distance from outgroup mean. Subsequently, we manipulated facial stimuli to reflect different levels of ingroup-outgroup distinctiveness and tested them in one of the target cultures. Perceivers were able to successfully distinguish outgroup from ingroup faces in a two-alternative forced-choice task. There was also some evidence that this task was harder when the two faces were closer along the axis connecting the facial averages from the two cultures. Future directions and potential applications of our proposed approach are discussed.

scholarly journals A Novel Pseudomonas geniculata AGE Family Epimerase/Isomerase and Its Application in d-Mannose Synthesis

Foods ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1809
Author(s):  
Zhanzhi Liu ◽  
Ying Li ◽  
Jing Wu ◽  
Sheng Chen
Keyword(s):  
3D Structure ◽  
Three Dimensional ◽  
Optimal Temperature ◽  
Reaction Conditions ◽  
Enzymatic Production ◽  
Physiological Properties ◽  
Potential Applications ◽  
Kinetics Of ◽  
Optimal Reaction ◽  
Gene Age

d-mannose has exhibited excellent physiological properties in the food, pharmaceutical, and feed industries. Therefore, emerging attention has been applied to enzymatic production of d-mannose due to its advantage over chemical synthesis. The gene age of N-acetyl-d-glucosamine 2-epimerase family epimerase/isomerase (AGEase) derived from Pseudomonas geniculata was amplified, and the recombinant P. geniculata AGEase was characterized. The optimal temperature and pH of P. geniculata AGEase were 60 °C and 7.5, respectively. The Km, kcat, and kcat/Km of P. geniculata AGEase for d-mannose were 49.2 ± 8.5 mM, 476.3 ± 4.0 s−1, and 9.7 ± 0.5 s−1·mM−1, respectively. The recombinant P. geniculata AGEase was classified into the YihS enzyme subfamily in the AGE enzyme family by analyzing its substrate specificity and active center of the three-dimensional (3D) structure. Further studies on the kinetics of different substrates showed that the P. geniculata AGEase belongs to the d-mannose isomerase of the YihS enzyme. The P. geniculata AGEase catalyzed the synthesis of d-mannose with d-fructose as a substrate, and the conversion rate was as high as 39.3% with the d-mannose yield of 78.6 g·L−1 under optimal reaction conditions of 200 g·L−1d-fructose and 2.5 U·mL−1P. geniculata AGEase. This novel P. geniculata AGEase has potential applications in the industrial production of d-mannose.

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