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To investigate the role of mechanical constraints in morphogenesis and development, we have developed a pipeline of techniques based on incompressible elastic sensors. These techniques combine the advantages of incompressible liquid droplets, which have been used as precise in situ shear stress sensors, and of elastic compressible beads, which are easier to tune and to use. Droplets of a polydimethylsiloxane mix, made fluorescent through specific covalent binding to a rhodamin dye, are produced by a microfluidics device. The elastomer rigidity after polymerization is adjusted to the tissue rigidity. Its mechanical properties are carefully calibrated in situ, for a sensor embedded in a cell aggregate submitted to uniaxial compression. The local shear stress tensor is retrieved from the sensor shape, accurately reconstructed through an active contour method. In vitro, within cell aggregates, and in vivo, in the prechordal plate of the zebrafish embryo during gastrulation, our pipeline of techniques demonstrates its efficiency to directly measure the three dimensional shear stress repartition within a tissue. [ABSTRACT FROM AUTHOR]

Dura injury can be intractable during neurosurgical operations. Dural sealant is effective for aiding dura repair and diminishing postoperative complications. However, a more optimal dural sealant is still clinically required. On the other hand, spinal cord injury (SCI) is a common comorbidity of the dural injury. Exception for surgical decompression, other clinically approved treatment for SCI is still limited. In this study, an elastic gel consisting of natural polyphenol tannic acid (TA) and pluronic F-127 (PF127) was prepared by a facile strategy. Comparing with traditional fibrin glue, the prepared TA-PF127 gel exhibited much higher bonding strength and sealing effect both in vitro and in vivo , and thus effectively prevented postoperative cerebral spinal fluid leakage. Based on a mice severe SCI model of spinal cord transection, the sealing and antioxidant property of TA-PF127 gel effectively decreased the reactive oxygen species production, inhibited neural cells apoptosis and inflammatory response, promoted glial scar formation and restrained lesion zone, maintained neurons and dramatically promoted neurological function recovery of mice after SCI. Due to the simple and biocompatible components in the gel, TA-PF127 has a promising potential to become a novel dural sealant for simultaneous dura sealing and SCI treatment in clinical neurosurgical operations. Unlabelled Image • An elastic gel consisting of natural polyphenol and pluronic F-127 was prepared. • The gel exhibits high bonding strength and sealing effect both in vitro and in vivo. • The gel has effects of antioxidant, anti-inflammation and anti-apoptosis. • The gel can be used for simultaneous dura sealing and treatment of spinal cord injury. [ABSTRACT FROM AUTHOR]

Surface-deacetylated chitin nanofibers (SDACNFs) reinforced with a sulfobutyl ether β-cyclodextrin (SBE-β-CD) (NFs-CDs) gel were developed to obtain a controlled release carrier of prednisolone (PD) for the treatment of colitis. PD was released slowly from the gel at both pH 1.2 and 6.8. The in vitro slow release of PD from the NFs-CDs gel was reflected in the in vivo absorption of the drug after oral administration to rats. These results suggest that a simple gel composed of a mixture of SDACNFs and SBE-β-CD has the potential for use in the controlled release of PD. We also evaluated the therapeutic effects of the NFs-CDs gel containing PD on dextran sulfate sodium (DSS)-induced colitis model mice. The administration of the NFs-CDs gel at intervals of 3 days from the beginning of the DSS treatment resulted in a significant improvement, not only in colitis symptoms but also histopathological changes in colon tissue. In addition, the therapeutic effects of the NFs-CDs gel on colitis can be attributed to decreased levels of neutrophil infiltration and the development of oxidative stress. These efficacy profiles of the NFs-CDs gel containing PD suggest that it has the potential for use in the treatment of, not only colitis, but also a variety of other disorders associated with inflammation and oxidative injuries. [ABSTRACT FROM AUTHOR]

A freeze-dried gel composed of surface-deacetylated chitin nanofibers (SDACNFs), reinforced with an anionic cyclodextrin, sulfobutyl ether β-cyclodextrin (SBE-β-CD) was evaluated for treating wounds in a rat model, and the results were compared with a SDACNFs gel without SBE-β-CD. The incorporation of prednisolone (PD), a poorly water-soluble drug, in both types of gels and its release from the gels were also compared. In both cases, wound areas were decreased and their effect was higher than that of commercially available wound dressings. The rate of release of PD from the freeze-dried SDACNFs/SBE-β-CD was much faster than that form SDACNFs alone without SBE-β-CD, due to fact that the PD is more soluble in the amorphous SBE-β-CD complex compared to the other preparations. The findings indicate that the freeze-dried SDACNFs/SBE-β-CD gel would be beneficial as a new biomaterial for the treatment of wounds and for preparing homogeneous high-content gels that contain poorly water-soluble drugs. [ABSTRACT FROM AUTHOR]

The microemulsion phase behavior and physicochemical properties of surfactant-water-alcohol-oil systems are the pioneer laboratory study as a function of alcohol, water content and temperature to develop an experimental investigation for a better understanding of the microstructure of a single phase microemulsion and its stability under reservoir condition during hydraulic fracturing to recover the residual trapped oil. Viscosified surfactants are used as an efficient proppant conducting medium in hydraulic fracturing applications. The physicochemical properties of microemulsions are very helpful for characterization of microemulsions to justify their abilities and screening of surfactants. In the study, two branched alcohols, 2-methyl butan-2-ol, 3-methyl butan-1-ol selected as the cosurfactant in the proposed microemulsion system and their effect in tailoring the viscosity of microemulsions were studied. Microemulsion regions elucidated from Winsor's pseudophase model of an oleate surfactant show a signatory distribution pattern of components between different domains with non-polar and asymmetric geometry of cosurfactant directs macromolecular alignments; their alignment contributes to a viscous microemulsions (gel) regime. The effect of surfactant and alkali, and the experimental temperature on the rheological properties of the lamellar mesophase were investigated. Phase transit regions and exact microemulsion and viscous microemulsion magnitudes were elucidated with the help of conductivity and viscosity studies of the ternary system as a function of the aqueous fraction and were in good agreement with Winsor's pseudophase model. Dynamic and steady shear rheological studies showed that the gel is viscoelastic in nature, sustain viscosity and elastic modulus values appropriate for proppant suspension under high shear conditions. The proppant suspension and thermal behavior of ideal gel composition was found to be suitable for Coal Bed Methane and soft rock, clay reservoir stimulation. [ABSTRACT FROM AUTHOR]

Highlight: [•] Film and membrane properties are influenced by the solvent used in their preparation. [•] A non-solvent addition to cellulose acetate (CA) solutions causes chain agglomeration. [•] A three-dimensional elastic gel behavior is observed in some particular CA solutions. [•] CA agglomerates cause changes in the film microstructure and rigidity. [ABSTRACT FROM AUTHOR]

Abstract: Chemical modifications of galactomannans are applied to improve and/or modify their solubility, rheological and functional properties, but have limited specificity and are often difficult to control. Enzymatic reactions, catalyzed under mild process conditions, such as depolymerization, debranching and oxidation, represent a viable and eco-friendly alternative. In this study, we describe oxidation of guar galactomannan primary hydroxyl groups by a fungal laccase using the stable radical TEMPO as mediator. Four fungal laccases were investigated from: Trametes versicolor, Myceliophthora thermophila, Thielavia arenaria, Cerrena unicolor. The laccase from T. versicolor was found to efficiently oxidize TEMPO and to be free of mannanase side activity. Oxidation of galactomannan with this enzyme plus TEMPO brought about a ten-fold increase in viscosity of a guar galactomannan solution and altered its rheological profile, by converting a viscous polysaccharide solution into an elastic gel. This structural modification is presumably due to formation of inter-chain hemiacetalic bonds between newly generated carbonyl groups and free OH groups, yielding a cross-linked gel. These findings could be of practical importance, considering that polysaccharides with high viscosity, gelling and elastic properties can find interesting and novel applications as thickeners, viscosifiers and emulsion stabilizers in several industrial applications such as: personal care, oil operations, paper coating, paints, construction and mining. [Copyright &y& Elsevier]

Blood compatibility of a novel elastic gelatin gel (e-gel) from salmon collagen was evaluated. After a 10-min incubation of the e-gel with rat whole blood, there was a macroscopically small thrombus formation on the e-gel. Microscopic observation revealed that few platelets had adhered to the e-gel. Furthermore, the platelet adhesion rate was markedly lower on the e-gel compared to collagen-coated and fibrinogen-coated surfaces. Comparable results were obtained with re-crosslinked e-gel. In conclusion, the e-gel demonstrated good blood compatibility. [Copyright &y& Elsevier]

To recover the filtered residues on a gel layer in a column, the method using the elasticity of the gel layer and flowing water in a cross-flow manner is proposed. Polymerized spherical gel (40 μm) was packed in a column to a set height of 0.7 cm. The suspensions of graphene oxide at various sizes and shapes were injected on the top of the gel layer and then water was flowed at a flow rate of 1000 mL·h−1 until 0.10 MPa. By releasing the applied pressure, the elastic gel layer rose up, and the filtered graphene oxide also rose above the layer. This rise of the gel layer is due to the difference of pressure between the gel layer, including the filtered graphene oxide, and the open bottom of the column, using the flow of water. The cross flow of water through the column carried away the larger-sized filtered graphene oxide floating above the gel layer. The elasticity of the gel layer and cross flow through the column has the potential to recover the filtered particles. [ABSTRACT FROM AUTHOR]