40 research outputs found

    An Injectable Enzymatically Crosslinked and Mechanically Tunable Silk Fibroin/Chondroitin Sulfate Chondro‐Inductive Hydrogel

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    Abstract An injectable hybrid hydrogel is synthesized, comprising silk fibroin (SF) and chondroitin sulfate (CS) through di‐tyrosine formation bond of SF chains. CS and SF are reported with excellent biocompatibility as tissue engineering scaffolds. Nonetheless, the rapid degradation rate of pure CS scaffolds presents a challenge to effectively recreate articular cartilage. As CS is one of the cartilage extracellular matrix (ECM) components, it has the potential to enhance the biological activity of SF‐based hydrogel in terms of cartilage repair. Therefore, altering the CS concentrations (i.e., 0 wt%, 0.25 wt%, 0.5 wt%, 1 wt%, and 2 wt%), which are interpenetrated between SF β‐sheets and chains, can potentially adjust the physical, chemical, and mechanical features of these hybrid hydrogels. The formation of β‐sheets by 30 days of immersion in de‐ionized (DI) water can improve the compression strength of the SF/CS hybrid hydrogels in comparison with the same SF/CS hybrid hydrogels in the dried state. Biological investigation and observation depicts proper cell attachment, proliferation and cell viability for C28/I2 cells. Gene expression of sex‐determining region YBox 9 (SOX9), Collagen II α1, and Aggrecan (AGG) exhibits positive C3H10T1/2 growth and expression of cartilage‐specific genes in the 0.25 wt% and 0.5 wt% SF/CS hydrogels

    Tunable viscoelastic features of aqueous mixtures of thermosensitive ethyl(hydroxyethyl)cellulose and cellulose nanowhiskers

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    Ethyl(hydroxyethyl) cellulose (EHEC) is known to form reversible hydrogels in water at elevated temperatures in the presence of an ionic surfactant. However, the toxicity of common ionic surfactants (like SDS and CTAB) hampers pharmaceutical and biomedical applications of EHEC-based thermogels. Addition of a nature-based material to EHEC solutions - in the form of negatively charged cellulose nanowhiskers (CNWs) - will introduce an internal electrostatic repulsion that could also produce the balanced swelling necessary for forming a stable gel at elevated temperatures (ca. 37 °C). This may therefore be an alternative way of designing low toxicity thermoresponsive hydrogels of high mechanical strength for pharmaceutical and biomedical applications without the use of ionic surfactants. The properties of the temperature-induced gelling systems (EHEC/CNW and EHEC/SDS/CNW) were characterized by rheological methods and rheo-small angle light scattering (rheo-SALS), whereas the structure and morphology of CNWs were examined by transmission electron microscope (TEM) and small angle neutron scattering (SANS). Oscillatory shear results for the EHEC/CNW system showed that the gel temperature (ca. 37 °C) was virtually unaffected by the amount of added CNWs, while the fractal dimension values (2.2–2.3) suggested the evolution of a tighter incipient gel network with increasing level of added CNWs. Furthermore, a threefold increase of the gel strength parameter was observed with increasing concentration of CNWs. For the EHEC/CNW/SDS system, a more open network evolved with increasing amount of CNWs, and for this system, higher values of the gel strength parameter were found. Pronounced shear-thinning, even at very low shear rates, was observed for the EHEC/CNW system at all levels of CNW addition, whereas for the EHEC/CNW/SDS system, Newtonian-like behavior was detected at low shear rates

    A review on nanocomposite hydrogels and their biomedical applications

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    In order to improve the drawbacks related to hydrogels, nanocomposite hydrogels were developed by incorporating different types of nanoparticles or nanostructures in the hydrogel network. This review categorizes nanocomposite hydrogels based on the type of their nanoparticle into four groups of carbon-, polymeric-, inorganic- and metallic-based nanocomposite hydrogels. Each type has specific properties that make them appropriate for a special purpose. This is mainly attributed to the improvement of interactions between nanoparticles and polymeric chains and to the enhancement of desirable properties for target applications. The focus of this paper is on biomedical applications of nanocomposite hydrogels and the most recent approaches made to fulfill their current limitations

    Effects of Neutralization and Crosslinking Agents on the Morphology of Chitosan Electrospun Scaffolds

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    Chitosan, a natural polymer derived from chitin by deacetylation process of chitin, has gained an enormous interest in tissue engineering due to its unique features such as antibacterial activity and wound healing properties. Electrospinning of acidified chitosan solution is one of the most widely-used approaches in fabrication of 3D scaffolds. Although there are some reports addressing morphology tailoring of the chitosan nanofibers through solution electrospinning, there is no comparative report concerning the neutralization and stabilization conditions of chitosan electrospun fibers. Therefore, this article compares the effects of different neutralizing agents such as aqueous solutions of sodium carbonate (Na2CO3) and potassium carbonate (K2CO3), and crosslinking reagents including glutaraldehyde (GA) and genipin on morphology of electrospun chitosan fibers. After neutralization and stabilization processes, Fourier transform infrared spectroscopy (FTIR) was employed to investigate the morphology of fibers. Furthermore, the influence of the aforementioned parameters on stability of fibers was probed using scanning electron microscopy. SEM images illustrated that the scaffold resulting from electrospinning of 4 wt% chitosan solution in a mixture of trifluoroacetic acid (TFA) and dichloromethane (DCM) possessed a well-formed nanofibrous structure. Afterwards, different methods for neutralization and stabilization of the electrospun chitosan nanofiber mats were performed. In this respect, aqueous solutions of both Na2CO3 and K2CO3 salts (1M) were employed as neutralization agents and GA and genipin were used as two different crosslinking agents. Based on SEM analysis, the chitosan fibers, crosslinked with genipin, showed better morphology than a scaffold which was crosslinked with glutaraldehyd

    Novel class of collector in electrospinning device for the fabrication of 3D nanofibrous structure for large defect load-bearing tissue engineering application

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    Adequate porosity, appropriate pore size, and 3D-thick shape are crucial parameters in the design of scaffolds, as they should provide the right space for cell adhesion, spreading, migration, and growth. In this work, a novel design for fabricating a 3D nanostructured scaffold by electrospinning was taken into account. Helical spring-shaped collector was purposely designed and used for electrospinning PCL fibers. Improved morphological properties and more uniform diameter distribution of collected nanofibers on the turns of helical spring-shaped collector are confirmed by SEM analysis. SEM images elaboration showed 3D pores with average diameter of 4 and 5.5 micrometer in x-y plane and z-direction, respectively. Prepared 3D scaffold possessed 99.98% porosity which led to the increased water uptake behavior in PBS at 37°C up to 10 days, and higher degradation rate compared to 2D flat structure. Uniaxial compression test on 3D scaffolds revealed an elastic modulus of 7 MPa and a stiffness of 102 MPa, together with very low hysteresis area and residual strain. In vitro cytocompatibility test with MG-63 osteoblast-like cells using AlamarBlue™ colorimetric assay, indicated a continuous increase in cell viability for the 3D structure over the test duration. SEM observation showed enhanced cells spreading and diffusion into the underneath layers for 3D scaffold. Accelerated calcium deposition in 3D substrate was confirmed by EDX analysis. Obtained morphological, physical, and mechanical properties together with in vitro cytocompatibility results, suggest this novel technique as a proper method for the fabrication of 3D nanofibrous scaffolds for the regeneration of critical-size load bearing defects
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