Evaluating the 3D printability of ADA-GEL based bioinks
3D printing of biocompatible materials in combination with encapsulated cells has become an important approach for the replication of customized tissues in terms of healing or the replacement of damaged human tissues and cartilage. Sodium alginate can be used as a favorable material due to its comparatively low cost, tunable properties and similarity to the extracellular matrix. In order to overcome its poor cell attachment it can be oxidized to alginate di-aldehyde (ADA) and crosslinked afterwards with RGD-containing ligands like e.g. gelatin (ADA-GEL). Not only cell proliferation but also the printability of hydrogels, which is defined by shape fidelity and printing resolution, is a crucial factor in the design of application-specific bioinks.
The aim of this work was to characterize and benchmark the printability of ADA-GEL based composite bioinks with different incorporated inorganic fillers. The printing resolution was evaluated under the effect of gelation time and material composition. Strand homogeneity changed with increasing laying time after deposition of the hydrogel. Moreover, the pore geometry was analyzed by printing different infill patterns with the same bioinks. It could be observed that printing resolution and accuracy depend on material´s as well as printing parameters that have to be critically analyzed for every hydrogel bioink. Hence, this work reveals a simple methodological and systematic approach to facilitate the comparison between newly developed biomaterials for 3D printing.