Crosslinked alginate-xanthan gum blends as effective hydrogels for 3D bioprinting of biological tissues

3D bioprinting has a high potential for directly printing customized tissues and organs for surgical transplantation. However, adequate bioink formulations, in which cells can be combined with proper fluids for bioprinting structures with complex architectures, are still needed. In this work, we have combined alginate and xanthan gum in different proportions, aiming at producing an effective noncytotoxic, shear-thinning, and easily sterilizable hydrogel, crosslinkable by the addition of low amounts of strontium ions, which would lead to stronger structures than those crosslinked with calcium. The results attained show that increases in xanthan gum concentration improve the rheological behavior of the material regarding printability and that heat-sterilized formulations can show adequate rheological performance for bioprinting. Stable and noncytotoxic structures were obtained with a hydrogel consisting of 1% (w/v) alginate and 2.5% (w/v) xanthan gum in alpha-MEM supplemented culture medium crosslinked by immersion in 50 mmol L-1 strontium chloride solution for 10 min postprinting. In conclusion, this new hydrogel formulation, optimized for bioink production, is designed to mimic the extracellular matrix with significant potential to be used for a wide plethora of applications, from the production of simple cellularized structures useful in drug screening and as microtissue models to complex organ bioprinting.