Standardization of a Method for Characterizing Low-Concentration Biogels: Elastic Properties of Low-Concentration Agarose Gels

Abstract

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.

High Sensitivity Micro-Elastometry: Applications in Blood Coagulopathy

“…The concentration-dependent elastic modulus of agarose was observed to follow a phenomenological power-law model with a power of 2, similar to previously reported results 1,16 . Thus, we performed a weighted least-squares fit to the texture analyzer data according to E = a 1 ( c−c 0 ) 2 , where c is the agarose concentration.…”

Mechanics of a Fiber Network Within a Non-Fibrillar Matrix: Model and Comparison with Collagen-Agarose Co-gels

“…The model was compared to experimental data at the equilibrium phase of a stress-relaxation test, so a low Poisson’s value of 0.1 was used. 44 In addition, since the model was constructed to represent collagen-agarose co-gels, values for the shear modulus were based on properties of agarose-only gels tested experimentally, 6 which are comparable to those used in other tissue modeling studies. 14,25,29,32 For native tissues, defining these parameters is more difficult because the NFM term, as presently defined, lumps all non-collagenous material together (i.e., there is no single definition of NFM), making tissue-specific definition of these parameters challenging, and the experimental measurement of NFM properties very difficult.…”

“…Since the model represents the mechanical response at equilibrium (after relaxation and drainage of any pressurized interstitial water), ν m was taken to be 0.1. 44 Values for G were specified by extrapolating experimental data for the shear modulus of pure agarose gels 6 to concentration values used in our study such that G = 0, 110 and 720 Pa for NoAg, LoAg, and HiAg, respectively. In this way, the only difference between models representing the three experimental groups was in the specific value used for shear modulus.…”

A Coupled Fiber-Matrix Model Demonstrates Highly Inhomogeneous Microstructural Interactions in Soft Tissues Under Tensile Load

“…As done previously [34], V nfm was set to 0.1. The NFM shear modulus was varied over a range of values ( G = 10, 110, 720 and 4300 Pa) corresponding to 0.05, 0.125, 0.25 and 0.5 % w/v agarose [35] in our experimental collagen-agarose studies [25, 36]. To assess the role of compressibility, a set of simulations with V nfm =0.45 was also evaluated for G =110 Pa.…”