Year: 2023
Type: dissertation
Abstract: Three-dimensional printing of biological materials is enabling the development of emerging applications of tissue engineering constructs for regenerative and personalized medicine, and engineered tissue models of disease and diagnosis. Hydrogel-based bioinks for extrusion bioprinting are widely applied; however, the development of a new bioink faces the challenge of complying with all printability requirements, as well as having suitable physicochemical properties to provide cells with a biocompatible microenvironment during and after the printing process. Low shear flow and high shape retention are two key properties for dispensing bioinks. This study introduces the synthesis and characterization of tyra-mine-grafted hyaluronic acid (HA) and gelatin (Gel) bioinks, with a horseradish peroxidase/hydrogen peroxide enzymatic crosslinking system to trigger in-demand layer-by-layer gelation over an extruded pattern with an additional drop deposition printhead. HA-based inks (1-4% solutions) and their mixtures with Gel (HA-Gel proportion 80/20 v/v) showed a shear-thinning behavior to be extruded properly. Higher concentrations of polymer yielded an improved construct quality. HA-Gel bioinks were printed together with hepatocarcinoma (HepG2) cells using two sizes of nozzle gauge (20G and 22G). Cell viability was not impacted by the different nozzle size applied, whereas polymer concentration showed a significant effect. In this regard, HA-Gel 4% had a ± 90% post-printing viability, and HA-Gel 5% was reduced by half to ± 45%. Moreover, the assessment of the miscibility of the two bioinks (HA-based and HA-Gel 80/20) provided us with an insight into how much gap shall be considered between contiguous structures to be independent while in contact with each other. For HA-Gel mixtures, a gap of at least 3-4 times the filament width needs to be considered during the design. These bioinks have shown the capability to be extruded, as good quality 3D cell-laden constructs with a biocompatible printing and gelation system, and have the potential to be applied for more complex co-culture models.
Author: DÍAZ JORDÁ, TERESA
Institution: Universidade Nova de Lisboa
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W6989600836