Controlled Quenching of Agarose Defines Hydrogels with Tunable Structural, Bulk Mechanical, Surface Nanomechanical And Cell Response in 2d Cultures.

The scaffolding of agarose hydrogel networks depends critically on the rate of cooling (quenching) after heating. Efforts have been made to understand the kinetics and evolution of biopolymer self-assembly upon cooling, but information is lacking on whether quenching might affect the final hydrogel structure and performance. Here, we report a material strategy for the fine modulation of quenching that involves temperature-curing steps of agarose. Combining microscopy techniques, standard and advanced macro/nanomechanical tools, we reveal that agarose accumulates on the surface when the curing temperature is set at 121°C. The inhomogeneity can be mostly recovered when it is reduced to 42°C. This has a drastic effect on the stiffness of the surface, but not on the viscoelasticity, roughness and wettability. When hydrogels are strained at small/large deformations, the curing temperature has no effect on the viscoelastic response of the hydrogel bulk, but does play a role in the onset of non-linear region. Cells cultured on these hydrogels exhibit surface stiffness-sensing that affects cell adhesion, spreading, F-actin fiber tension and maturation of vinculin-rich focal adhesions. Collectively, our results indicate that the temperature curing of agarose is an efficient strategy to produce networks with tunable mechanics and suitable for mechanobiology studies. This article is protected by copyright. All rights reserved.