Optimizing biomaterial inks: A study on the printability of Carboxymethyl cellulose-Laponite nanocomposite hydrogels and dental pulp stem cells bioprinting

Abstract

Tissue engineering approaches require biocompatible materials with precise pre-designed geometry, shape fidelity, and promote cellular functions. Addressing these requirements, our study focused on developing an optimized bioink formulation using carboxymethyl cellulose (CMC) and Laponite hydrogels tailored for extrusion-based three-dimensional bioprinting. To this, we investigated the rheological properties and filament behavior before and during printing. As Laponite concentration increased in CMC solutions, it improved shear-thinning behavior, viscosity, and storage modulus, resulting in well-defined filament characteristics with lower diffusion rates, excellent shape fidelity, and robust printability. Thus, we achieved a suitable biomaterial ink formulation with concentrations of 1 wt% of CMC and 4 wt% of Laponite (1C4L). Subsequently, a statistical analysis guided us to select the optimal parameters for large-scale construct printing: a nozzle speed of 5 mm/s, a print distance of 0.41 mm, and an extrusion multiplier of 1.35. After that, we enhanced the structural integrity of printed hydrogels through ionic crosslinking with calcium chloride (CaCl₂) and citric acid (CA), revealing higher-strength hydrogels at higher concentrations of CaCl₂. Finally, we have confirmed the groundbreaking potential of our bioink by integrating dental pulp mesenchymal stem cells (DPSC) into the 1C4L ink. Our bioprinted constructs showed optimized swelling, non-toxic effects, and retained excellent shape fidelity, crucial for creating anatomically accurate tissues. Our findings provide crucial insights linking the rheological analysis, the bioprinting process, and the biological properties of hydrogels, paving the way for their use for tissue engineering and other biomedical applications.