Fundamentals of Hydrogels I-Mechanical Characterization

Hydrogels of natural and synthetic origin have become very popular due to their unique position through their biological, physicochemical, and mechanical properties. While macroscale mechanical properties are important for bulk performance, micro/nanoscale properties have roles at a cellular level. Cell phenotype is associated with the mechanical properties of the environment surrounding the cells such as stiffness and viscoelasticity. Cells sense their environment and the mechanical properties of the environment at multiscale. They respond and affect the mechanical characteristics for instance via altering their morphology, differentiation status, matrix synthesis, and proliferation rate. Thus, it is of critical interest to characterize thoroughly the mechanical properties of hydrogels at the macroscale, microscale, and nanoscale, using a range of methods in an accurate and reproducible manner when hydrogels are aimed to be used as cell delivery matrices and in tissue engineering applications. In this chapter, we discuss the essential biomechanical terms and provide an overview of the related works on the mechanical characterization of hydrogels in a multiscale manner including but not limited to dynamic mechanic analysis, dynamic shear oscillation, compression testing, suture retention test, and nanoindentation. With the advances in mechanobiology, we believe that in the near future the clinical translation of mechanobiology will accelerate.