Gelatin-based photo-crosslinkable hydrogels are promising scaffold materials to serve regenerative medicine. They are widely applicable in additive manufacturing, which allows for the production of various scaffold microarchitectures in line with the anatomical requirements of the organ to be replaced or tissue defect to be treated. Upon their in vivo utilization, the main bottleneck is to monitor cell colonization along with their degradation (rate). In order to enable non-invasive visualization, labeling with MRI-active components like N-(2,2-difluoroethyl)acrylamide (DFEA) provides a promising approach. Herein, we report on the development of a gelatin-methacryloyl-aminoethyl-methacrylate-based biomaterial ink in combination with DFEA, applicable in digital light processing-based additive manufacturing towards bone tissue regeneration. The fabricated hydrogel constructs show excellent shape fidelity in line with the printing resolution, as DFEA acts as a small molecular crosslinker in the system. The constructs exhibit high stiffness (E = 36.9 ± 4.1 kPa, evaluated via oscillatory rheology), suitable to serve bone regeneration and excellent MRI visualization capacity. Moreover, in combination with adipose tissue-derived stem cells (ASCs), the 3D-printed constructs show biocompatibility, and upon 4 weeks of culture, the ASCs express the osteogenic differentiation marker Ca2+.

BIO INX Technologiepark Zwijnaarde 66 9052 Ghent Belgium

Center for Advanced Preclinical Imaging 1st Faculty of Medicine Charles University Salmovská 3 120 00 Prague Czech Republic

Institute of Biophysics and Informatics 1st Faculty of Medicine Charles University Salmovská 1 120 00 Prague Czech Republic

Institute of Organic Chemistry and Biochemistry Czech Academy of Sciences Flemingovo sq 2 160 00 Prague Czech Republic

Polymer Chemistry and Biomaterials Group Center of Macromolecular Chemistry Department of Organic and Macromolecular Chemistry Ghent University Krijgslaan 281 S4 9000 Ghent Belgium

Tissue Technologiepark Zwijnaarde 48 9052 Ghent Belgium

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