排序方式: 共有129条查询结果,搜索用时 15 毫秒
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Svetlana V. Shilova Grigory M. Mirgaleev Ksenia A. Romanova Yury G. Galyametdinov 《Biopolymers》2023,114(10):e23555
This work reports synthesis of pH-responsive alginate/chitosan hydrogel spheres with the average diameter of 2.0 ± 0.05 mm, which contain cefotaxime that is an antibiotic of the cefalosporine group. The spheres provided the cefotaxime encapsulation efficiency of 95 ± 1%. An in vitro release of cefotaxime from the spheres in the media that simulate human biological fluids in peroral delivery conditions was found to be a pH-dependent process. The analysis of cefotaxime release kinetics by the Korsmeyer–Peppas model revealed a non-Fickian mechanism of its diffusion, which may be related to intermolecular interactions occurring between the antibiotic and chitosan. Conductometry, UV spectroscopy, and IR spectroscopy were used to study complexation of chitosan with cefotaxime in aqueous media with varied pH, characterize the composition of the complexes, and calculate their stability constants. The composition of the cefotaxime–chitosan complexes was found to correspond to the 1.0:4.0 and 1.0:2.0 molar ratios of the components at pH 2.0 and 5.6, respectively. Quantum chemical modeling was used to evaluate energy characteristics of chitosan–cefotaxime complexation considering the influence of a solvent. 相似文献
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Shivanjali Joshi-Barr Jerome V. Karpiak Yogesh Ner Jessica H. Wen Adam J. Engler Adah Almutairi 《Journal of visualized experiments : JoVE》2013,(72)
Complex tissue culture matrices, in which types and concentrations of biological stimuli (e.g. growth factors, inhibitors, or small molecules) or matrix structure (e.g. composition, concentration, or stiffness of the matrix) vary over space, would enable a wide range of investigations concerning how these variables affect cell differentiation, migration, and other phenomena. The major challenge in creating layered matrices is maintaining the structural integrity of layer interfaces without diffusion of individual components from each layer1. Current methodologies to achieve this include photopatterning2-3, lithography4, sequential functionalization5, freeze drying6, microfluidics7, or centrifugation8, many of which require sophisticated instrumentation and technical skills. Others rely on sequential attachment of individual layers, which may lead to delamination of layers9. DGMP overcomes these issues by using an inert density modifier such as iodixanol to create layers of varying densities10. Since the density modifier can be mixed with any prepolymer or bioactive molecule, DGMP allows each scaffold layer to be customized. Simply varying the concentration of the density modifier prevents mixing of adjacent layers while they remain aqueous. Subsequent single step polymerization gives rise to a structurally continuous multilayered scaffold, in which each layer has distinct chemical and mechanical properties. The density modifier can be easily removed with sufficient rinsing without perturbation of the individual layers or their components. This technique is therefore well suited for creating hydrogels of various sizes, shapes, and materials.A protocol for fabricating a 2D-polyethylene glycol (PEG) gel, in which alternating layers incorporate RGDS-350, is outlined below. We use PEG because it is biocompatible and inert. RGDS, a cell adhesion peptide11, is used to demonstrate spatial restriction of a biological cue, and the conjugation of a fluorophore (Alexa Fluor 350) enables us to visually distinguish various layers. This procedure can be adapted for other materials (e.g. collagen, hyaluronan, etc.) and can be extended to fabricate 3D gels with some modifications10. 相似文献
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Stéphanie M. C. Bruekers Maarten Jaspers José M. A. Hendriks Nicholas A. Kurniawan Gijsje H. Koenderink Paul H. J. Kouwer 《Cell Adhesion & Migration》2016,10(5):495-504
ABSTRACTThe mechanical and structural properties of the extracellular matrix (ECM) play an important role in regulating cell fate. The natural ECM has a complex fibrillar structure and shows nonlinear mechanical properties, which are both difficult to mimic synthetically. Therefore, systematically testing the influence of ECM properties on cellular behavior is very challenging. In this work we show two different approaches to tune the fibrillar structure and mechanical properties of fibrin hydrogels. Addition of extra thrombin before gelation increases the protein density within the fibrin fibers without significantly altering the mechanical properties of the resulting hydrogel. On the other hand, by forming a composite hydrogel with a synthetic biomimetic polyisocyanide network the protein density within the fibrin fibers decreases, and the mechanics of the composite material can be tuned by the PIC/fibrin mass ratio. The effect of the changes in gel structure and mechanics on cellular behavior are investigated, by studying human mesenchymal stem cell (hMSC) spreading and differentiation on these gels. We find that the trends observed in cell spreading and differentiation cannot be explained by the bulk mechanics of the gels, but correlate to the density of the fibrin fibers the gels are composed of. These findings strongly suggest that the microscopic properties of individual fibers in fibrous networks play an essential role in determining cell behavior. 相似文献
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Polysaccharides comprise an important class of natural polymers; they are abundant, diverse, polyfunctional, typically benign, and are biodegradable. Using polysaccharides to design in situ forming hydrogels is an attractive and important field of study since many polysaccharide-based hydrogels exhibit desirable characteristics including self-healing, responsiveness to environmental stimuli, and injectability. These characteristics are particularly useful for biomedical applications. This review will discuss recent discoveries in polysaccharide-based in situ forming hydrogels, including network architecture designs, curing mechanisms, physical and chemical properties, and potential applications. 相似文献
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Marina Kurbasic Ana M. Garcia Simone Viada Silvia Marchesan 《Journal of peptide science》2022,28(1):e3304
Self-assembling short peptides have attracted great interest as enzyme mimics, especially if the catalytic activity resides solely in the supramolecular structure so that it can be switched on/off as needed by controlling assembly/disassembly. Among the various enzyme classes, hydrolases find wide application in biomaterials, and their mimetics often contain His residues, in addition to either divalent cations or other amino acids to mimic the catalytic site. This work reports two self-assembling tetrapeptides based on the Ser-His motif for catalysis and the Phe-Phe motif to drive amyloid structure formation. Both peptides form thermoreversible hydrogels in phosphate buffer at neutral pH that display a mild esterase-like activity, as demonstrated on the hydrolysis of 4-nitrophenyl acetate as a model substrate, although presence of Ser did not enhance catalytic activity. The systems are characterised by circular dichroism, transmission electron microscopy, oscillatory rheology and Thioflavin T fluorescence as an amyloid stain, to provide further insights that may assist the future design of improved supramolecular catalysts. 相似文献