Spatial and uniform deposition of cell-laden constructs on 3D printed composite phosphorylated hydrogels for improved osteoblast responses.

Phosphorylated-oligo [poly(ethylene glycol)fumarate] (Pi-OPF) was combined with functionalized clays to facilitate the extrusion 3D printing of Pi-OPF. Acrylated montmorillonite (Ac-MMT) was synthesized for the covalent crosslinking of MMT with the Pi-OPF. The incorporation of Ac-MMT was observed to improve the rheological properties of Pi-OPF, enabling a high-fidelity extrusion printing. A well-dispersed exfoliated MMT phase was observed within the polymer matrix after the crosslinking. This leveraged improved mechanical properties of the Pi-OPF hydrogels evident through the compressive analysis. Additionally, a unique bioink combining chitosan methacrylate (ChiMA) and gelatin was developed with a primary goal of depositing the cells on the 3D printed Pi-OPF scaffolds for uniform cell distribution and for facilitating a spatial interaction between cells and Ac-MMT particles. This bioink was shown to support the encapsulation and proliferation of the printed pre-osteoblasts by the live/dead cell assay results. This excellent cell responses were unaltered when the cell laden was deposited on 3D printed Pi-OPF scaffolds. Furthermore, the spatial interaction between cells and Ac-MMT elicited improved osteoblast responses indicated by the spreading of encapsulated cells and higher intracellular alkaline phosphatase (ALP) expression. Taken together, the results of this study present the combinatorial application of 3D printing and bioprinting to achieve desirable biological responses through the interaction between cells and biomaterials.