| dc.description.abstract | The rapidly emerging scientific field of bio fabrication holds many promises for the production of small body parts, organelles or even whole organs. Needless to say, how big of an impact this would have on the daily life of millions of patients. But with this scientific field being relatively young, certain discoveries and advancements are still to be made. One of the most promising approaches of the research lies in a process, called volumetric bioprinting. Instead of using layer-by-layer printing, this volume-in-volume 3-Dimensional printing method creates a construct within seconds. During this process a mixture of substances, called a bioink, is crosslinked in a volumetric printing process in a volumetric printer. The only impact on the bioink during the crosslinking is light, making the printing a gentle process and therefore highly suited for the printing with living cells. These bioinks predominantly rely on methacrylate-modified gelatin. However, methacrylate-modified gelatin shows to have certain limitations and doesn’t allow for further modification, which is needed to create tissues of higher complexity. This report focuses on the synthesis, characterization, and modification of a bioink, which is not reliant on methacrylate. The material used is norbornene-modified gelatin, further on called GelNOR. GelNOR allows for a rapid crosslinking process, making it less susceptible to inhibiting mechanisms compared to methacrylate-modified gelatin. Furthermore, GelNOR hydrogels allow to be modified after crosslinking, utilizing its special crosslinking mechanism. This post-printing modification enables the grafting of biological molecules into the hydrogel. Not only is this new to the field of volumetric bioprinting, but it allows for the spatially controlled printing of specialized tissue by grafting growth factors into the hydrogel. This report is a first step of exploring this promising feature of GelNOR. The first part is focused on the synthesis and analysis of this material, where we could successfully synthesize the material with a high degree of functional groups. Subsequently, the volumetric printing properties of GelNOR were assessed in an approach of optimizing the printing conditions. In this part we optimized the printing resolution of GelNOR by alternating the bioinks composition and the conditions during the printing process. The substances added to the bioink slowed down the crosslinking process, making the printing more modifiable. The third part of this report is focused on the grafting of biological molecules into an already crosslinked GelNOR construct. With various experiments this process was not only proven to be feasible, but it was also shown that, by adjusting the printing conditions to graft the biological molecules, it was possible to spatially control the complex 3-Dimensional designs of the grafted structures inside the printed constructs. | |
