Understanding the rheology of novel guar-gellan gum composite hydrogels (original) (raw)

Rheological and mechanical properties of acellular and cell-laden methacrylated gellan gum hydrogels

Journal of Biomedical Materials Research Part A, 2013

Tissue engineered hydrogels hold great potential as nucleus pulposus substitutes (NP), as they promote intervertebral disc (IVD) regeneration and re-establish its original function. But, the key to their success in future clinical applications greatly depends on its ability to replicate the native 3D micro-environment and circumvent their limitation in terms of mechanical performance. In the present study, we investigated the rheological/mechanical properties of both ionic-(iGG-MA) and photo-crosslinked methacrylated gellan gum (phGG-MA) hydrogels. Steady shear analysis, injectability and confined compression stress-relaxation tests were carried out. The injectability of the reactive solutions employed for the preparation of iGG-MA and phGG-MA hydrogels was first studied, then the zero-strain compressive modulus and permeability of the acellular hydrogels were evaluated. In addition, human intervertebral disc (hIVD) cells encapsulated in both iGG-MA and phGG-MA hydrogels were cultured in vitro, and its mechanical properties also investigated under dynamic mechanical analysis at 37 C and pH 7.4. After 21 days of culturing, hIVD cells were alive (Calcein AM) and the E' of ionic-crosslinked hydrogels and photo-crosslinked was higher than that observed for acellular hydrogels. Our study suggests that methacrylated gellan gum hydrogels present promising mechanical and biological performance as hIVD cells were producing extracellular matrix. V C 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A: 3438-3446, 2013. How to cite this article: Silva-Correia J, Gloria A, Oliveira MB, Mano JF, Oliveira JM, Ambrosio L, Reis RL. 2013. Rheological and mechanical properties of acellular and cell-laden methacrylated gellan gum hydrogels. J Biomed Mater Res

Rheological characterization of biological hydrogels in aqueous state

Journal of Applied Biotechnology Reports, 2020

Introduction: Biological hydrogels provide a conducive extracellular environment for encapsulating and growing cells and play an important role in regulating cell behavior. Mechanical and rheological properties of hydrogels can influence cell function, mechanotransduction and cellular behaviors such as growth, migration, adhesion, self-renewal, differentiation, morphology and fate. Determination of rheological properties of biogels is important for printing tissues by controlling physical properties and developing efficient drug delivery systems. The main purpose of the current study was to determine some important rheological properties of two well-known hydrogels (agarose and gelatin methacryloyl [GelMA]). Materials and Methods: Rheological properties of gel solutions with different concentrations were measured using oscillatory rheometry. Agarose gels of 1% and 2% (w/v) concentration were prepared in 100 mL de-ionized water. The GelMA solutions of 10% and 15% concentrations were ...

Low viscosity hydrogel of guar gum: Preparation and physicochemical characterization

International journal of …, 2005

Guar gum was cross-linked with glutaraldehyde and characterized by GPC, rheology, WADX, SEM and TGA. This guar gum is a galactomannan polysaccharide, that contains small amount of arabinose, glucose and uronic acid, besides galactose and mannose. The polymer has high molar mass, with M¯w, M¯n and M¯v values of 2.0 × 106, 1.2 × 106 and 1.9 × 106 g/mol, respectively. The reticulation follows a slow process and lead to a viscosity increase of 40 times compared with the original gum solution. The final viscosity was similar to that of Hylan G-F 20, a hyaluronate derivative, commercially used in viscosupplementation treatment. The gel contains 95.6% of water and the amount of residual glutaraldehyde is much lower than the LD-50. Porous structure was detected by SEM and thermal stability was improved by the cross-linking. The low viscosity, the small amount of remained glutaraldehyde, and the thermal stability indicates that the guar hydrogel has potential to be applied as biomaterial with specific rheological requirements.

Structural, rheological and dynamics insights of hydroxypropyl guar gel-like systems

Colloids and surfaces. B, Biointerfaces, 2018

A dynamic, rheological, and structural characterization of aqueous gel-like systems containing hydroxypropyl guar gum (HPG), borax and glycerol is presented in this paper. The role of glycerol, which is introduced as a plasticizer in the formulation, is investigated by means of B NMR and H NMR PGSTE measurements in order to clarify its contribution to the gel network formation and its interaction with borax, with whom it forms a complex. The effect of gels components on the rheological behaviour and on the activation energy related to the relaxation process of the system was assessed by means of rheology. The results obtained suggest that the mechanical properties of these gels can be tuned and controlled by modulating the formulation in a wide range of compositions. Moreover, a structural characterisation has been also carried out by means of Small Angle X-ray Scattering (SAXS) to highlight the role of the various components on the mesh size of the network. The structural and mecha...

Guar gum/borax hydrogel: Rheological, low field NMR and release characterizations

2013

Guar gum (GG) and Guar gum/borax (GGb) hydrogels are studied by means of rheology, Low Field Nuclear Magnetic Resonance (LF NMR) and model drug release tests. These three approaches are used to estimate the mesh size (!) of the polymeric network. A comparison with similar Scleroglucan systems is carried out. In the case of GGb, the rheological and Low Field NMR estimations of ! lead to comparable results, while the drug release approach seems to underestimate !. Such discrepancy is attributed to the viscous effect of some polymeric chains that, although bound to the network to one end, can freely fluctuate among meshes. The viscous drag exerted by these chains slows down drug diffusion through the polymeric network. A proof for this hypothesis is given by the case of Scleroglucan gel, where the viscous contribution is not so significant and a good agreement between the rheological and release test approaches was found.

Rheological profiling of a hydrogel drug delivery vehicle

2015

Rheology refers to the study of flow and deformation of materials. Rotational and oscillation experiments are most important methods for rheological profiling of polymers. The objective of the present study was to unveil the rheological profile of Carbopol 940 hydrogel, at a concentration of 1%w/w, by subjecting to flow, frequency sweep, creep recovery and thixotropy measurements. From the flow curve measurements it was observed that shear rate has influence on viscosity and shear stress. Carbopol hydrogel behaved as a viscoplastic or yield stress fluid. Higher values for loss modulus than storage modulus from frequency sweep experiments indicated that elastic component is less is prevailing in the hydrogel than the elastic component. Complex viscosity was found to decrease on increasing frequency and thus a pseudoplastic behaviour of hydrogel was confirmed. From the creep recovery plot it was inferred that the hydrogel sample behaves as viscous material at the applied stress. The h...

Relationship between Structure and Rheology of Hydrogels for Various Applications

Gels

Hydrogels have gained a lot of attention with their widespread use in different industrial applications. The versatility in the synthesis and the nature of the precursor reactants allow for a varying range of hydrogels with different mechanical and rheological properties. Understanding of the rheological behavior and the relationship between the chemical structure and the resulting properties is crucial, and is the focus of this review. Specifically, we include detailed discussion on the correlation between the rheological characteristics of hydrogels and their possible applications. Different rheological tests such as time, temperature and frequency sweep, among others, are described and the results of those tests are reported. The most prevalent applications of hydrogels are also discussed.

Rheological Study of Binary Gels with Carbopol UltrezTM 10 and Hyaluronic Acid

Chemical and Pharmaceutical Bulletin, 2007

Many products containing natural, semi-synthetic and synthetic polymers are used in the pharmaceutical industry as agents for gelling, thickening, stabilizing and modification of viscosity. The polymer materials used to develop pharmaceutical vehicles of topical application must have the appropriate physical, chemical and mechanical properties. Generally, commercialized synthetic polymers comply with these requirements and they are widely used as bases for topical application, but they are not sufficiently biocompatible. The properties of these materials can be improved by combining biological macromolecules such as collagen, elastin and glycosaminoglycans. 1,2) Many semi-solid pharmaceutical vehicles include more than one polymer in the formulation in order to obtain the appropriate properties for topical application. The properties of most of these systems correspond to those of the individual polymers. However, in some cases, the characteristics of the compound systems are superior to those of each of the separate components or they are even qualitatively different. Specifically, the combination of certain synthetic and natural polymers can lead to significant synergistic effects as a result of interaction between the different polymer chains and the formation of mixed bonding areas. 3,4) Mixtures of two or more polymers can show complex properties that depend on the total polymer concentration, the relative proportion of each of the components, the characteristics of the dissolution medium and the temperature. The causes of this non-additive behavior are directly related to the efficiency of the interactions observed among the polymer molecules and to the balance of interaction between the molecules in the same polymer and in different polymers, which depend on the primary and secondary structures in the chains. 5,6) This behavior leads to a wide variety of structural conditions and to the nonlinearity of the macroscopic properties observed in certain compound systems. In fact, the combination of two polymers can produce gels characterized by a higher degree of rigidity than is calculated using a linear combination of rigidity values for gels formed by each of the individual polymers. Many polymers show this non-additive behavior, which is called synergy. 7-9) The combination of specific synthetic and natural polymers can create significant synergistic effects as a result of interaction between different polymeric chains and the formation of mixed bonding areas. 10) Synthetic polymers are widely used in pharmaceutical and biomedical applications. However, mixtures of synthetic and natural polymers are increasingly used as a complementary alternative in these areas. Characterization of these mixtures reveals the existence of synergistic effects that can be used to optimize drug delivery. The advantage of these systems is that the kinetics of drug release from the matrix can be adjusted by varying the composition of the components. 11) However, some types of restructuring observed in some compound polymer systems cause a nonlinear decrease in the resulting properties, that is, negative synergy. 1) This study examines the rheological behavior of binary hydroalcoholic gels made with the synthetic polymer Carbopol ® Ultrez TM 10-U10-and the natural polymer Hyaluronic Acid-HA-. Each of the two components has

Rheological studies of concentrated guar gum

Rheologica Acta, 2003

Polymers and surfactants are essential ingredients of the printing paste. Polysaccharides are used commercially to thicken, suspend or stabilise aqueous systems. Also they are used to produce gels and to act as flocculates, binders, lubricants, to serve as modifiers of film properties, and have a function as adjusters of rheological parameters. Surfactants, on the other hand, perform numerous functions acting as dispersants, wetting agents, emulsifiers and antifoaming agents. The rheological properties of polysaccharide thickeners (guar gums with different substitution levels and different producers) at different concentrations and temperatures and, second, the effects produced by the addition of nonionic surfactants (polyoxyethylene stearyl alcohols with different numbers of EO groups) have been studied under linear and nonlinear shear conditions. Experimental data have been correlated with the different models: flow curves with the Cross, Carreau and Meter-Bird model, and mechanical spectra with the generalized Maxwell model and Friedrich-Braun model. The surface tensions of aqueous systems containing polysaccharide and/or surfactants have been determined over extended concentration ranges in order to detect the CMC conditions and to provide a better understanding about the polysaccharide-surfactant interactions.