Fabrication of three-dimensional calcium alginate hydrogels using sacrificial templates of sugar

Hydrogels are receiving increasing attention in bioapplications. Among hydrogels, calcium alginate (Ca-alginate) hydrogels are widely used for their biocompatibility, low toxicity, low cost, and rapid fabrication by simple mixing of Ca²⁺ and sodium alginate (Na-alginate). For bioapplications using hydrogels, it is necessary to construct designed hydrogel structures. Although several methods have been proposed for fabricating designed hydrogels, a simple and low-cost method is desirable. Therefore, we developed a new method using sacrificial templates of sugar structures to fabricate three-dimensional (3D) designed Ca-alginate hydrogels. In this method, Na-alginate solution is mixed with molten sugar, and the resulting highly viscous material used to mold 3D sugar structures as sacrificial templates. Since sugar constructs are easily handled compared to hydrogels, sugar templates are useful for preparing 3D constructs. Finally, the sugar and Na-alginate structure is immersed in a CaCl₂ solution to simultaneously dissolve the template and form the Ca-alginate hydrogel. The resulting hydrogel takes the shape of the sugar template. By stacking and fusing various sugar structures, such as fibers and blocks, 3D designed Ca-alginate hydrogels can be successfully fabricated. This simple and low-cost method shows excellent potential for application to a variety of bioapplications.