Pre-Crosslinked Hybrid Hydrogels for 3D Bio-Printing Process: Rheological Analysis

Bioprinting for regenerative medicine has been gaining a lot of popularity in today’s world. Despite being one of the rigorously studied fields, there are still several challenges yet to be solved. Geometric fidelity and mechanical complexities stand as roadblocks when it comes to the printability of the customized scaffolds. Exploring the rheological properties of the compositions helps us understand the physical and mechanical properties of the biomaterials which are closely tied to the printability of the filament and eventually, geometric fidelity of the scaffolds. To ensure the structural integrity of the scaffolds, viscosity enhancers such as Carboxymethyl Cellulose (CMC) and crosslinkers like CaCl2 and CaSO4 were used. These crosslinkers can be used before (pre-crosslinking) and after (post-crosslinking) the extrusion of considered compositions to investigate and compare the outcome. To do this, mixtures of Carboxymethyl Cellulose (CMC, viscosity enhancer), Alginate, and CaCl2 and CaSO4 (crosslinkers) were prepared at various concentrations maintaining minimum solid content (≤ 8%). Each composition was subjected to a set of rheological tests like Flow curve for shear thinning behavior, three-point thixotropic for recovery rate, amplitude test for gelation point, and frequency tests. This research thoroughly investigates compositions when they are introduced to crosslinkers and viscosity enhancers which can be crucial for 3D printing world.