Gellan Fluid Gel as a Versatile Support Bath Material for Fluid Extrusion Bioprinting

Biomedical applications of three-dimensional (3D) printing demand complex hydrogel-based constructs laden with living cells. Advanced support materials facilitate the fabrication of such constructs. This work demonstrates the versatility and utility of a gellan fluid gel as a support bath material for fabricating freeform 3D hydrogel constructs from a variety of materials. Notably, the gellan fluid gel support bath can supply sensitive biological cross-linking agents such as enzymes to printed fluid hydrogel precursors for mild covalent hydrogel cross-linking. This mild fabrication approach is suitable for fabricating cell-laden gelatin-based constructs in which mammalian cells can form intercellular contacts within hours of fabrication; cellular activity is observed over several days within printed constructs. In addition, gellan is compatible with a wide range of ionic and thermal conditions, which makes it a suitable support material for ionically cross-linked structures generated by printing alginate-based ink formulations as well as thermosensitive hydrogel constructs formed from gelatin. Ultraviolet irradiation of printed structures within the support bath is also demonstrated for photoinitiated cross-linking of acrylated ink materials. Furthermore, gellan support material performance in terms of printed filament stability and residual support material on constructs is found to be comparable and superior, respectively, to previously reported support materials.