Nanocomposite Bioinks Based on Agarose and 2D Nanosilicates with Tunable Flow Properties and Bioactivity for 3D Bioprinting

Three-dimensional (3D) bioprinting enables the controlled fabrication of complex constructs for tissue engineering applications and has been actively explored in recent years. However, its progress has been limited by the existing difficulties in the development of bioinks with suitable biocompatibility and mechanical properties and at the same time adaptability to the process. Herein, we describe the engineering of a nanocomposite agarose bioink with tailored properties using 2D nanosilicate additives. The suitability of agarose for 3D bioprinting has been debated due to its bioinert nature and compatibility with extrusion-based bioprinting. Nanosilicates were used to tailor the flow behavior of agarose solutions, and detailed rheological characterization of different bioink formulations was performed to elucidate the effect of nanosilicates on the flow behavior and gelation of agarose bioinks. The proper selection of nanosilicate concentration resulted in extrusion 3D printed structures with high shape fidelity and structural integrity. Moreover, the influence of addition of nanosilicates on the bioactivity of agarose was studied, and nanocomposite bioinks showed significant improvement in metabolic activity of encapsulated cells. The bioactivity of the nanocomposite bioinks was also evaluated through a cell spreading assay; the charged surfaces of nanosilicates resulted in full spreading and elongation of fibroblasts, and the extent of change in morphology of cells was found to be directly correlated with the nanosilicate concentration. Our findings suggested that engineered agarose-nanosilicate bioinks can be exploited as a new generation of hydrogel bioinks for extrusion 3D bioprinting with tunable flow properties and bioactivity.