Standardization of a method for characterizing low-concentration biogels: elastic properties of low-concentration agarose gels.

Low-concentration biogels, which provide an extracellular matrix for cells in vitro, are involved in a number of important cell biological phenomena, such as cell motility and cell differentiation. In order to characterize soft tissues, which collapse under their own weight, we developed and standardized a new experimental device that enabled us to analyze the mechanical properties of floating biogels with low concentrations, i.e., with values ranging from 2 g/L to 5 g/L. In order to validate this approach, the mechanical responses of free floating agarose gel samples submitted to compression as well as stretching tests were quantified. The values of the Young's moduli, measured in the range of 1000 to 10,000 Pa, are compared to the values obtained from other experimental techniques. Our results showed indeed that the values we obtained with our device closely match those obtained independently by performing compression tests on an Instron device. Thus, the floating gel technique is a useful tool first to characterize and then to model soft tissues that are used in biological science to study the interaction between cell and extracellular matrix.