Direct ink writing of metal-oxide hydrocolloid systems enables the manufacturing of biologically inspired, hierarchical architectures using environmentally friendly and biocompatible materials. Furthermore, direct ink writing allows for the previously unattainable incorporation of delicate materials, such as proteins and peptides. In this work, we report on the development of solution-based inks designed around food-grade hydrocolloids, such as Xanthan and Guar gum, compatible with direct ink writing. With this advance, the additive manufacturing of biomedical devices, including tissue scaffolds and stents with embedded drugs and proteins, is possible.
Within this system, the hydrocolloids supply a porous matrix and template suitable for the incorporation of organic molecules, while the metal-oxides provide the necessary mechanical properties. It is found that the porosity, pore-size distribution, and viscosity of the inks may be engineered through variation of the hydrocolloid weight percent, as well as through the refinement of the foaming process. Viscosity measurements, dynamic mechanical analysis, and compressive stress-strain analysis are used to characterize the materials’ rheological and mechanical properties. Moreover, close analyses of the printing parameters are used to create processing maps of the inks, identifying those parameters which result in spanning, free standing, and planar structures, all while maintaining the engineered porous microstructures. Ultimately, this work enables the direct ink writing of biologically inspired, hierarchically porous architectures with embedded organic materials for use in biomedical devices.