Swelling Ratio Test Research Articles

The Influence of Astaxanthin on the Proliferation of Adipose-derived Mesenchymal Stem Cells in Gelatin-Methacryloyl (GelMA) Hydrogels.

Recently, astaxanthin, a red lipophilic pigment belonging to the xanthophyllic family of carotenoids, has shown the feasibility of its uses in tissue engineering and regenerative medicine, due to its excellent antioxidant activities and its abilities to enhance the self-renewal potency of stem cells. In this study, we demonstrate the influence of astaxanthin on the proliferation of adipose-derived mesenchymal stem cells in tissue-engineered constructs. The tissue engineered scaffolds were fabricated using photopolymerizable gelatin methacryloyl (GelMA) with different concentrations of astaxanthin. The effects of astaxanthin on cellular proliferation in two-dimensional environments were assessed using alamar blue assay and reverse transcription polymerase chain reaction (RT-PCR). Then, rheological properties, chemical structures and the water absorption of the fabricated astaxanthin-incorporated GelMA hydrogels were characterized using NMR analysis, rheological analysis and a swelling ratio test. Finally, the influence in three-dimensional environments of astaxanthin-incorporated GelMA hydrogels on the proliferative potentials of adipose-derived stem cells was assessed using alamar blue assay and the confocal imaging with Live/dead staining. The experimental results of the study indicate that an addition of astaxanthin promises to induce stem cell potency via proliferation, and that it can be a useful tool for a three-dimensional culture system and various tissue engineering applications.

Development of nanofibrous collagen-grafted poly (vinyl alcohol)/gelatin/alginate scaffolds as potential skin substitute.

The main objective of this work is to fabricate a nanofibrous scaffold to regenerate skin tissue. A scaffold composed of poly (vinyl alcohol)/gelatin/alginate was prepared using electrospinning method. To improve scaffold biocompatibility and wound healing properties, collagen, extracted from rat tail, was grafted on as-prepared nanofibers. The prepared scaffolds were characterized by SEM, FTIR, swelling ratio test, and water vapor transmission rate (WVTR) measurement. Cytotoxicity of the scaffolds against human fibroblasts and L929 (NCBI C161) cells were tested using direct and indirect methods, respectively. Fibroblast cell adhesion and proliferation on the scaffold were also investigated. Results of morphological studies showed that beadless nanofibers with 229 nm diameter were prepared. ATR-FTIR spectra of collagen grafted nanofiber mats confirmed presence of the collagen on their surface. Collagen grafted nanofibers showed higher swelling ratio than nanofibers without collagen graft. Collagen grafting decreased VWTR. Collagen grafting decreased both tensile strength and Young's modulus of the nanofibrous scaffolds while increased their elongation at break. MTT results showed that both scaffolds are biocompatible with higher cell viability for nanofibers with collagen grafting. Fibroblast cell culture on the scaffolds demonstrated that both of scaffolds have good cell viability and proliferation while collagen grafted scaffold showed better results.

Fabrication of Cellulose Nanocrystal/Chitosan Hydrogel for Controlled Drug Release.

In this work, a novel nanocomposite hydrogel based on cellulose nanocrystal (CNC) and chitosan (CS) was fabricated and applied as a carrier for the controlled delivery of theophylline. CNC was firstly periodate-oxidized to obtain dialdehyde nanocellulose (DACNC). Then, chitosan was crosslinked using DACNC as both the matrix and crosslinker in different weight ratios, to fabricate CNC/CS composites. The prepared composites were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), zeta potential measurement and swelling ratio tests. FT-IR results confirmed the successful reaction between the free amino groups on chitosan and the aldehyde groups on DACNC. With the increase of chitosan percentage in the hydrogel, the isoelectric point was shifted towards an alkaline pH, which was probably caused by the higher content of free amino groups. The swelling ratio of the composite also increased, which may have been due to the decrease of crosslinking density. Because the swelling ratio of the drug-loaded hydrogels differed under varied pH values, the cumulative drug release percentage of the composite hydrogel was achieved to approximately 85% and 23% in the gastric (pH 1.5) and intestinal (pH 7.4) fluids, respectively. Therefore, CNC/CS hydrogel has application potential as a theophylline carrier.

Continuous Fabrication of Temperature-Responsive Hydrogel Fibers with Bilayer Structure by Microfluidic Spinning

Temperature-responsive hydrogel fibers with bilayer structure were prepared by a microfluidic spinning device with a Y-shaped connector. The bilayer hydrogel fibers include two layer with different chemical composition. One layer is the ionic crosslinking hydrogel of calcium alginate (CA) and the other layer is temperature-responsive hydrogel which is semi-interpenetrating polymer networks (semi-IPN) of linear poly (N-isopropylacrylamide) (PNIPAM) and CA. The bilayer hydrogel fibers were evaluated by morphology observation, tensile stress measurement, temperature-responsive actuation test and equilibrium swelling ratio test. The results show that the prepared hydrogel fibers have obvious double layer structure with different porous structures. The bilayer hydrogel fibers can bend in water at 50 °C and the bending rate is influenced by the diameter of the fiber. Moreover, the diameter of the hydrogel fibers can be controlled by changing the flow rates of spinning fluids.

Preparation of anion exchange membrane with branch polyethyleneimine as main skeleton component

A series of anion exchange membranes (AEMs) consisting of polyvinyl alcohol/branched polyethyleneimine (PVA/BPEI) were simply prepared by casting method using glutaraldehyde (GA) as crosslinking agent, then quaternized with benzyl chloride and alkalized in KOH solution. Subsequently, the comparative analysis was performed to select the optimal ratio of PVA to BPEI and crosslinking degree of AEMs. The structure and properties of AEMs were verified by FT-IR, XRD, TGA, mechanical analysis, water uptake test, swelling ratio test, ion exchange capacity (IEC) test, ionic conductivity measurement, and alkaline/oxidative stability test. The results showed that the maximum value of ionic conductivity was 86.0 mS/cm at 80 °C with IEC value of 2.35 meq/g. Moreover, the AEM had excellent chemical stability, as the ionic conductivity decreased by <15% in 1 M KOH at 80 °C for 7 days. These results indicated that polyethyleneimine is a promising raw material for the preparation of alkaline anion-exchange membranes used in fuel cell.

Experimental Study of Expansive Soil Improved by Ionic Soil Stabilizer

Based on expansive soil of Anyang district of Henan improved by Ionic Soil Stabilizer, expansive soil is tested in the free swelling ratio test and Shrinkage test. The results show that after mixing the ISS into expansive soil, free swelling ratio of expansive soil decreases, and performance of expansive soil is significantly weakened. When the ISS with the water volume ratio of 1: 250, a free expansion to minimize the expansive soil. And the ISS than without after adding ISS, expansive soils line shrinkage and shrinkage limit significantly reduced, indicating that the weak soil particles adsorbed on the surface of the part of bound water has been replaced with off the coupling strength between soil particles to strengthen, soil shrinkage deformation smaller.

In situ Biomimetic Mineralization and Characterization of Carbon Nanotubes/chitosan Composite Microspheres†

Carbon nanotubes / chitosan( CNTs / CS) composite microspheres were prepared by emulsification and cross-linking method. Nano-hydroxyapatite crystals were biomimetically formed on the surface of the composite microspheres. The influence of CNTs on the mineralization of the microspheres was investigated. The morphologies,structurs and stability properties of the microspheres before and after mineralization were studied through scanning electronic microscopy( SEM),X-ray diffraction( XRD),swelling ratio and water content tests. The results show that the formation ability of the nano-hydroxyapatite on the CNTs / CS microspheres is significantly higher than that on pure CS microspheres. And the mineralized CNTs / CS microspheres exhibit better structure stability. After culturing with MG63 cells for 7 d,the proliferation of cells cultured with mineralized CNTs / CS microspheres shows significant difference from that of the cells cultured with mineralized CS microspheres.

Water activity characteristics of deep brittle shale from Southwest China

Understanding the effect of water activity on shale is of major importance for the exploration and development of shale gas reservoirs, especially in the drilling and completion processes. Deep brittle shale samples from the lower Silurian Longmaxi Formation located in Southwest China were characterized using X-ray diffraction (XRD), swelling ratio tests, computerized tomography (CT), Field Emission Scanning Electron Microscope (FE-SEM) and uniaxial compressive strength (UCS) tests. Because of the physical characteristics of the samples, the relationship between water activity and swelling ratio could be approximated by the Frenkel–Halsey–Hill (FHH) equation. The relationships between clay minerals, UCS and water activity were investigated. Based on the physical description of the internal structure, the impact of water activity on micro-fractures was also discussed. The results showed that multilayer adsorption was the main contributor to the swelling of the deep brittle shale samples. The swelling ratio of brittle shale samples was described by the water activity of external environment via a logarithmic expression of the FHH equation, with fractal dimensions ranging from 2.71 to 2.75. The mineralogical composition was a controlling factor on water activity, as shown by the positive correlation between water activity and the total content of clay minerals (TCCM), especially the amount of montmorillonite in illite/smectite mixed layer clay. When soaking in a solution with a water activity above the critical water activity, the brittle samples developed micro-fractures because the clay swelled, acting as cementing material in the weakened planes. The environmental water activity was used to evaluate mechanical properties of the hydrated brittle shale. Brittle shale samples with larger water activity had a higher critical water activity. Water activity analysis led to a better understanding of the characteristics of the brittle shale and the performance of the downhole fluid.

Processing Technique and Property Evaluations of Chitosan Dressings

This study uses acetic acid as the solvent to make two different deacetylated chitosans into chitosan solutions (CS1 and CS2). A specified amount of chitosan solutions are evaporated at 55 °C for 30, 60, and 90 minutes, immersed in NaOH-NaHCO3(aq), and then freeze-dried to form six membrane types, CS1-30, CS1-60, CS1-90 ,CS2-30, CS2-60 and CS2-90. Scanning electron microscopic (SEM) observation, a swelling ratio test, and an antibacterial assay are performed to evaluate the influence of differing evaporation times on the CS membranes. The test results show that membrane CS1 types have good properties. In particular, CS1-60 possesses an optimal swelling property and a maximum inhibition zone.

Gelatin- and hydroxyapatite-based cryogels for bone tissue engineering: synthesis, characterization,in vitroandin vivobiocompatibility

The aim of this study was the synthesis and characterization of gelatin- and hydroxyapatite (osteoconductive component of bone)-based cryogels for tissue-engineering applications. Preliminary in vitro and in vivo biocompatibility tests were conducted. Gelatin- and hydroxyapatite-based cryogels of varying concentrations were synthesized using glutaraldehyde as the crosslinking agent. Chemical structure, pore morphology, pore size distribution, mechanical properties, swelling characteristics and degradation profiles of the synthesized cryogels were demonstrated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), mercury porosimetry, a mechanical test device, swelling ratio tests and weight loss measurements, respectively. In vitro cell viability and in vivo biocompatility tests were performed in order to show the performance of the cryogels in the biological environment. Changing the concentrations of gelatin, hydroxyapatite and crosslinker changed the chemical structure, pore size and pore size distribution of the cryogels, which in turn resulted in the ultimate behaviour (mechanical properties, swelling ratio, degradation profile). In vitro cell culture tests showed the viability of the cells. The cryogels did not show any cytotoxic effects on the cells. Clinical outcomes and the gross pathological results demonstrated that there was no necrosis noted in the abdominal and thoracic regions at the end of implantation and the implanted cryogel was found to be non-irritant and non-toxic at 12 weeks of implantation. Copyright © 2013 John Wiley & Sons, Ltd.

Effect of chemical crosslinking degree on mechanical properties of bacterial cellulose/poly(vinyl alcohol) composite membranes

Bacterial cellulose/poly(vinyl alcohol) (BC/PVA) composite membranes using BC as the reinforcement and PVA as the matrix material were prepared in supersaturation of sodium chloride and crosslinked with glutaraldehyde, and characterized by attenuated total reflection Fourier-transform infrared spectroscopy, equilibrium swelling ratio tests, and mechanical properties tests. The chemical crosslinking degree of the membranes was determined by titration method, and it could be controlled by crosslinking time. The effects of the chemical crosslinking degree on properties of the BC/PVA composite membranes were investigated. It was demonstrated that chemical crosslinking was formed between BC/PVA and glutaraldehyde. As a result, the chemically crosslinked BC/PVA composite membranes exhibited some promising characteristics, such as appropriate equilibrium swelling ratio, good mechanical strength, and obvious effect of chemical crosslinking degree. Furthermore, the equilibrium swelling ratio and mechanical properties of the BC/PVA composite membranes were obviously affected by the BC content as well.

A casein-polysaccharide hybrid hydrogel cross-linked by transglutaminase for drug delivery

A protein-polysaccharide hydrogel was reported as a biocompatible, biodegradable, and non-toxic material that had biomedical applications such as drug delivery. The hydrogel, composed of 10% casein and 1% konjac glucomannan (KGM), was formed with 0.4 wt% transglutaminase (MTG) as the cross-linker. The physicochemical properties of the protein-polysaccharide hydrogel were investigated by SEM observation, FT-IR analysis, swelling ratio test, and stability test. The results of the stability test proved that the hydrogel with KGM had an obviously improved stability. Its degradation rate also decreased from 100% to less than 60% compared with the hydrogel without KGM at the end of the test. The results of the swelling ratio test demonstrated that the addition of KGM restricted the mobility of the chains, and decreased the swelling ratio of the hydrogel. The results of the FT-IR revealed hydrogen bond interactions during the gelation process upon the addition of KGM. To investigate in vitro release behavior, docetaxel was chosen as a model drug incorporated into the casein/KGM hydrogels. The hydrogel with 1% KGM exhibited a good drug release behavior.

Experimental Study for Swelling Ratio and Pressure of Water Swelling Material as an Impermeable Material

A water swelling material is one of the rubbery impermeable materials which mixed synthetic resin elastomers as a base material, high absorbency polymers, filler and solvents. In this study, swelling characteristics of the water swelling material on the water polluted with COD and BOD, as an impermeable material at coastal waste landfill site, are examined by laboratory swelling ratio test. Furthermore, the factor in which it influences the swelling pressure of water swelling material is clarified by measuring the swelling pressure. As the results, the COD nor the BOD concentrations in the soaked water influence the swelling ratio of the water swelling material. When the thicknesses of water swelling material are 2 and 3mm, the maximum swelling pressure of 0.5 and 0.7MPa that correspond to hydraulic pressure by depth of 50 and 70 m is possessed, respectively.

Prevulcanized Natural Rubber Latex/Modified Lignin Dispersion for Water Vapour Barrier Coatings on Paperboard Packaging

Modified natural rubber latex can be used as paperboard barrier coating in order to replace unrecyclable wax coating material. Natural rubber latex (NRL) was prevucanized in different time interval and the efficiency of crosslinking were determined by swelling ratio test. Prevulcanized natural rubber latex (Pre-VNRL) was blended with modified lignin dispersion to decrease sticking tendency of the coatings. Particle size of lignin dispersion was reduced by Mannish reaction using octylamine which can increase hydrophobility in lignin. Compared with Pre-VNRL coating, a reduction of water vapour transition rate (WVTR) was observed in blendingcoated paper. Such moisture-barrier behaviour is attributable to a good compatibility of the nanosized modified lignin particles with rubber. The blocking (sticking) tendency decreased with the content increase of lignin due to stiffness of lignin.