Mechanically tunable ion-crosslinked alginate-based gradient hydrogels by electrolysis-electrophoresis method

Abstract

Introducing the gradient structure into ion-crosslinked polysaccharide (ICP) hydrogels is an effective strategy to expand their application scope in biomedicine and smart materials. However, fast gelation between polysaccharide and metal ion makes it difficult to construct/regulate gradient structure. Here, we developed a new method to address the issue by combining electrolysis with electrophoresis. Making use of the gradual generation of copper ions from the Cu anode and continuous migration to the cathode, a Cu²⁺-crosslinked sodium alginate (SA)-based hydrogel was obtained with both crosslinking density gradient and SA distribution gradient. The gradient structure can be conveniently adjusted to achieve excellent mechanical properties and delicate patterning. The electrolysis-electrophoresis method is successfully extended to versatile hydrogels by varying different metal electrodes (Fe or Zn electrodes), or different types of polysaccharides (chitosan or sodium carboxymethyl cellulose). This work opens a new insight for designing gradient ICP hydrogels and provides the potential for bionic applications.

Keywords: Electrolysis; Electrophoresis; Gradient; Hydrogel; Ion-crosslinked.