Mechanical Characterization of Extracellular Matrix Hydrogels: Comparison of Properties Measured by Rheometer and Texture Analyzer

Abstract

Taraka Sai Pavan Grandhi, Noreen Zaman, Alamelu Banda, Varsha Dhamankar , Cathy Chu, Emily Perotta, Irina Kadiyala

Extracellular matrix (ECM) hydrogels have shown remarkable benefit as new materials for regenerative medicine for multiple applications. However, for ECM-based materials to be used in vivo, they must possess appropriate mechanical properties to enable handling during storage and administration, as well as properties to induce the needed biological responses. The experiments carried out in this study allowed deeper understanding of the physical characteristics of gels towards their use in a clinical setting and subsequent commercialization. Using rheometer and texture analyzer, we expanded the previously reported mechanical characterization of ECM gels and here we present data on the new tests such as constant shear at different temperatures; cross-over temperature/gel point; cohesivity, adhesivity and hardness; fitting to Burger’s model; and strain-stiffening. We compared the mechanical properties of ECM hydrogels to collagen hydrogels, the latter were used as an internal control. Mechanical properties of ECM hydrogels were measured during different stages of hydrogel formation (pre-gel, gelation and formed hydrogel). Overall, gel complex modulus measured using rheometer correlated with hardness measured using texture analyzer across measured hydrogel concentrations, indicating that the measurements done with rheometer and texture analyzer were complementary to each other. In addition, two model drugs with poor solubility and similar molecular weight, but differing in charge were incorporated into the UBM ECM hydrogel to study the rheological behavior of the drug-hydrogel composites. The presence and properties of the drugs were found to have a moderate effect on hydrogel mechanical properties depending on the charge of the drug.

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