The effect of selected process parameters on shape fidelity in extrusion-based bioprinting of natural and synthetic hydrogels

Abstract

Recently application of 3D bioprinting to bioengineering has gained interest for the availability of advanced biomaterials with promising properties for regenerative medicine and drug delivery. In particular, extrusion-based bioprinting has the possibility to use a wide range of hydrogels of natural and synthetic origin. One of the most critical weaknesses of bioprinting is the poor post-printing shape fidelity of 3D scaffold possibly due to the porous-viscoelastic nature and swelling behavior of extruded polymers through the printing head. In this work, a quantitative index, termed shape fidelity index, is proposed to evaluate the discrepancy between ideal and real printed scaffolds. Scaffolds were printed with natural polysaccharides, such as alginate and cellulose (Xplore®), and synthetic polymers, such as polyethylene glycol (START®). Four process parameters on 2 levels were selected for the study according to a DOE analysis: inlet pressure, printing speed, temperature and type of biomaterial. 16 experiments were performed with an extrusion-based bioprinter to produce 3D porous scaffolds, the shape and surface areas of which were characterized with optical microscopy and image analysis. Shape fidelity indices were characterized to guide the optimization of the bioprinting process. The proposed approach permits also to determine the process parameter influencing the most the printing outcome and to rank the parameter importance for optimizing the shape fidelity of the bioprinted manufacts with soft biomaterials.