Просмотр исходного текста страницы Shear-thinningselfhealing-hydrogel-based-on-natural-polymers-with-secondary-photocrosslinking-for-biomedical-applications-s

Sciences, University of Vermont, Burlington, VT 05405, USA. Electronic address: University of Otago, Dunedin 9054, New Zealand.Injectable hydrogel systems are useful in many biomedical applications, including drug or cell delivery carriers and scaffolds. Here, we describe the design and characterization of a shear thinning hydrogel that undergoes a disassembly when shear forces are applied during injection and is self-healing once the shear forces are removed. This hydrogel is based on a cyclodextrin modified alginate, and a methacrylated gelatin which initially forms through a weak guest-host interaction between hydrophobic cyclodextrin cavities and the aromatic residue of gelatin. Methacrylated gelatin possesses photocrosslinkable functionalities which can go through a light-initiated polymerization to create secondary crosslinking sites and further crosslink the matrix.<br /><br /> The shear thinning and self-healing behavior of these gels monitored in low and high strain range, viscosity of the hydrogels components and gelation kinetic were studied. The rheological analyses showed the formation of shear thinning gels which were further stabilized by visible light exposure. The cytotoxicity of the hydrogels towards human mesenchymal stem cells were assessed and the rate of mass loss over a week period was studied.Xylan, Xylooligosaccharides, and Aromatic Structures With Antioxidant Activity Released by Xylanase Treatment of Alkaline-Sulfite-Pretreated Sugarcane Bagasse.Xylanase enzymes are useful to fractionate plant biomass, producing xylan, xylooligosaccharides (XOS), and antioxidant-derived XOS. In a biorefinery, pretreated biomass can be digested with xylanase prior to cellulose saccharification, enhancing the product portfolio in the process. With [http://allinno.com/news/166.html Chemical Properties and Reactions of 6-butyl-n-hydroxynaphthimide trifluoromethanesulfonic acid] , this study highlighted a wide range of new products attainable from alkaline-sulfite-pretreated sugarcane bagasse by treatments with endo-xylanase under controlled conditions.<br /><br /> The developed process provided a crude extract corresponding to 29% (w/w) of pretreated sugarcane bagasse. The crude extract included a relatively polymeric glucuronoarabinoxylan fraction, DP2-DP6 xylooligosaccharides, and aromatic compounds. The enzymatically produced extract was fractionated with increasing ethanol concentrations [up to 90% (v/v)], providing precipitation of varied polymeric xylan fractions (48% (w/w) of the crude extract) with average molar masses ranging from 28&nbsp;kDa to 3&nbsp;kDa. The fraction soluble in 90% ethanol was subjected to adsorption on 4% (w/v) activated charcoal and eluted with an ethanol gradient from 10% to 70% (v/v), thus providing xylooligosaccharides and aromatic fractions. Most of the xylooligosaccharides (74% of the eluted sugars) were washed out in 10%-30% ethanol. DP2 and DP3 structures predominated in the 10% ethanol fraction, while DP5 structures were significantly enriched in the 30% ethanol fraction. Higher ethanol concentrations desorbed xylooligosaccharides associated with higher amounts of aromatic compounds.<br /><br /> Total aromatics, phenolic structures, and p-hydroxycinnamates predominated in the fractions desorbed with 60% and 70% ethanol. The antioxidant activity of produced fractions correlated with their phenolic contents. Compiled results indicate that a wide variety of products can be prepared from pretreated biomass using xylanase-aided extraction procedures. Recovered fractions presented different features and specific application prospects. Beyond polymeric xylan with low lignin contamination, xylooligosaccharides or even lignin-carbohydrate complexes with antioxidant activity can be included in the biorefinery portfolio based on the currently conducted in the absence of any commercial or financial relationships that could Biodegradation of asphaltene and petroleum compounds by a highly potent and Research (ACECR), Shahid Beheshti University, Tehran, Iran.Petroleum, as the major energy source, is indispensable from our lives. Presence of compounds resistant to degradation can pose risks for human health and environment.<br /><br /> Basidiomycetes have been considered as powerful candidates in biodegradation of petroleum compounds via secreting ligninolytic enzymes. In this study a wood-decaying fungus was isolated by significant degradation ability that was identified as Daedaleopsis sp. by morphological and molecular identification methods. According to GC/MS studies, incubation of heavy crude oil with Daedaleopsis sp. resulted in increased amounts of <c24 hydrocarbons and decreased amounts of><br /><br />  <br /><br />  C24 compounds. Degradation of asphaltene, anthracene, and dibenzofuran by the identified fungal strain was determined to evaluate its potential in biodegradation. After 14 days of incubation, Daedaleopsis sp.<br /><br />  <br /><br />  <br /><br />  <br /><br /> <br /><br />  <br /><br />  <br /><br />  <br /><br />  could degrade 93% and 91% of anthracene and dibenzofuran, respectively, in pH 5 and 40 °C in optimized medium, as revealed by GC/FID. Notably, [http://en.wikipedia.org/wiki/Photoacid Photoinitiator] of saturates, aromatics, resins, and asphaltenes showed a reduction of 88% and 38% in asphaletene and aromatic fractions. Laccase, lignin peroxidase, and manganese peroxidase activities were enhanced from 51, 145, 214 U ml-1 in the absence to 121, 231, and 352 U ml-1 in the presence of heavy crude oil, respectively. This is the first report that Daedaleopsis sp. can degrade asphaltene and dibenzofuran.<br /><br />  <br /><br /> <br /><br /> <br /><br /></c24>