Dynamic electro-regulation of the stiffness gradient hydrogels.

Hydrogels are promising biomaterials which provide bionic environments to study the effect of stiffness. A hydrogel with dynamically changeable stiffness can be used to further understand the dynamic biological processes such as embryonic development, tumorigenesis, here we present an electro-regulation method which can dynamically control the stiffness of hydrogels with ionic crosslinks. By applying an electric field and controlling the voltage applied to the hydrogel the mechanical properties of the hydrogel can be changed. The voltage can directly change the stress-relaxation properties of the hydrogel, and after the voltage was applied for hundreds of seconds, a gradient stiffness was generated along the direction of the electric field. The value of gradient stiffness can be regulated by charge. With the increase of charge, the stiffness of the hydrogel near the anode increases, while the stiffness of the hydrogel near the cathode decreases. Experiments show that the electro-regulation method allows dynamic manipulation of the material properties of the hydrogel with ionic crosslinks. Dynamic electro-regulation of hydrogels is a powerful tool that will promote the study of the dynamic microenvironments and lead to a better understanding of the fundamental phenomena of the extracellular matrix.