Advanced bioresin development for 3D printing of hydrogel-based soft tissues with applications in regenerative medicine

The synergy of hydrogel processing and 3D printing technologies has paved the way for the development of advanced tissue engineering scaffolds. Hydrogels constitute a promising class of materials for the creation of scaffolds due to their permeable environment, suitable for encapsulation, as well as their tunable chemical and mechanical properties [1]. 3D printing, on the other hand, has immersed as a novel manufacturing technology that allows the creation of three dimensional constructs with pre-determined architecture. Current advancements haveenabledalsotheprintingofbiomaterialsincorporatingcellsandsupporting components creating complex structures that can mimic living tissue characteristics with high accuracy [2]. Stereolithography and particularly, the Digital Light Processing (DLP) technology appears as one of the most auspicious printing techniques for the fast creation of mechanically stable hollow structures. However, the difficulty in developing hydrogel bioinks, which could be used for the fabrication of high resolution complicated architectures with structural integrity, remains a challenge. In the present study, efforts were focused on finding the components that could be used for the creation of an optimal bioink suitable for DLP printing. After deciding on the most promising components, the bioink’s optimization in terms of printing resolution was performed taking under consideration the fundamental principles of stereolithography. To achieve this goal, the working curves and all the key parameters, which define a photopolymer’s behavior were studied. After the optimization of the resolution, the prospective bioinks were characterized in terms of their crosslinking efficiency and mechanical properties. Consequently, complex porous scaffolds were fabricated from the selected bioinks and mechanically tested. Finally, the encapsulation of cells into the bioinks, as well as, the seeding method were performed for the creation of cell-laden scaffolds, which were also studied through the performance of cell viability and proliferation tests