Influence des propriétés rhéologiques et des paramètres d’extrusion sur les structures créées par bio-impression 3D

Abstract

Extrusion 3D bioprinting is a rapidly expanding field, for which it is necessary to optimize the materials serving as bio-ink, which are generally hydrogels. The objective of this master's degree is to propose rheological methods making it possible to compare hydrogels with each other and to better predict their behavior during printing. We have studied 3 rheological properties: the capacity of recovery, the yield stress and shear thinning. These properties were observed on 3 hydrogel formulations based on chitosan as well as one formulation based on alginate which is already used for 3D bioprinting and serves as a positive control. First, the effect of extrusion parameters such as flow rate, nozzle movement speed, extrusion diameter and extrusion height on the quality of extruded filaments were analyzed on a formulation. As expected, increasing the amount of material deposited per unit of distance (thus increasing the flow rate or decreasing the speed of movement of the nozzle) increases the width of the deposited filaments. The effect of the deposition height is less obvious, as this parameter must be selected in relation to the others to allow the extrusion of thin, continuous and uniform filaments. Second, the rheological data was measured and a correlation study was attempted with the print results, including print fidelity and filament width. Contrary to the literature, the percentage of recovery is not identified as being a determining parameter. On the other hand, the preextrusion viscosity has a fairly good inversely proportional correlation with the width of the filaments. Alginate gelatin hydrogel has given the best results. On the side of chitosan gels, the lack of reproducibility and the low capacity to withstand several layers of pre-gelled gel affects its potential. The results suggest that studying the rheological properties can help determine the ability of a gel to be used for extrusion bioprinting. Although, the tests must be modified to allow a better analysis of thermosensitive gels such as chitosan and to standardize the results.

Date	17 Aug 2021
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Sophie Lerouge (Supervisor)