title: Viscoelastic behaviour of hydrogel-based composites for tissue engineering under mechanical load.
abstract: Along with biocompatibility, bioinductivity and appropriate biodegradation, mechanical properties are also of crucial importance for tissue engineering scaffolds. Hydrogels, such as gellan gum (GG), are usually soft materials, which may benefit from the incorporation of inorganic particles, e.g. bioactive glass, not only due to the acquired bioactivity, but also due to improved mechanical properties. They exhibit complex viscoelastic properties, which can be evaluated in various ways. In this work, to reliably evaluate the effect of the bioactive glass (BAG) addition on viscoelastic properties of the composite hydrogel, we employed and compared the three most commonly used techniques, analyzing their advantages and limitations: monotonic uniaxial unconfined compression, small amplitude oscillatory shear (SAOS) rheology and dynamic mechanical analysis (DMA). Creep and small amplitude dynamic strain-controlled tests in DMA are suggested as the best ways for the characterization of mechanical properties of hydrogel composites, whereas the SAOS rheology is more useful for studying the hydrogel's processing kinetics, as it does not induce volumetric changes even at very high strains. Overall, the results confirmed a beneficial effect of BAG (nano)particles on the elastic modulus of the GG-BAG composite hydrogel. The Young's modulus of 6.6 ± 0.8 kPa for the GG hydrogel increased by two orders of magnitude after the addition of 2 wt.% BAG particles (500-800 kPa).
authors.affiliation: Department for Nanostructured Materials, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia. Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000 Ljubljana, Slovenia.
authors.forename: Rok
authors.initials: R
authors.lastname: Kocen
authors.forename: Michael
authors.initials: M
authors.lastname: Gasik
authors.forename: Ana
authors.initials: A
authors.lastname: Gantar
authors.forename: Saša
authors.initials: S
authors.lastname: Novak
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D001696:Biomechanical Phenomena; D019245:Compressive Strength; D055119:Elastic Modulus; D004548:Elasticity; D005898:Glass / Q000737:chemistry; D020100:Hydrogels; D008422:Materials Testing; D011135:Polysaccharides, Bacterial / Q000737:chemistry; D012212:Rheology; D033081:Shear Strength; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry*; D014783:Viscosity
chemical_list: D001672:Biocompatible Materials; D020100:Hydrogels; D011135:Polysaccharides, Bacterial; C048288:gellan gum