Indirect rapid prototyping as an elegant tool for the production of self-supporting low density gelatin scaffolds

Aim: The present work, pursues the production of porous low density (u003c10w/v%) gelatin scaffolds.1 To this end, methacrylated gelatin (gelMOD) was applied as an extracellular matrix mimicking component. Since low concentration gelMOD solutions can’t be processed using conventional rapid prototyping (RP) techniques in the absence of additives, an indirect RP approach was selected using sacrificial PLLA scaffolds. The scaffolds serve a dual role: hydrogel support while crosslinking and design transfer from scaffold to hydrogel.Methods: Gelatin B was modified with methacrylic anhydride to obtain UV-crosslinkable derivatives (DS 60% u0026 DS 97%). Physical gelation properties were assessed via differential scanning calorimetry (DSC). Crosslinking was performed using 2mol% Irgacure 2959 and UVA light (365nm). Mechanical properties during crosslinking were monitored via rheology. Transparent (365nm) PLLA scaffolds were obtained via FDM (Ultimaker). Post curing, the PLLA scaffolds were dissolved using chloroform (15ml, 3days) and washed with acetone and water. The obtained gelatin scaffolds were characterized using SEM, µ-CT, optical microscopy and texturometry. Both 5 and 10w/v% scaffolds were successfully produced. Preliminary biocompatibility tests using fibroblasts were performed.(vital staining, histology)Results: DSC measurements revealed that physical gelation properties of gelMOD depend on degree of methacrylation and concentration. Previous work indicated that physical gelation of 10w/v% solutions is sufficient to produce 3D scaffolds, therefore, the resulting mechanical properties were set as a benchmark in the current study. Rheology indicated that cross-linked 5w/v% gelMOD (DS: 97%) exhibits sufficient mechanical properties (G’u003e1.5kPa) for transfer to 3D. Furthermore, proper transfer of design from scaffold to hydrogel took place, as strut sizes of the final construct matched the pore sizes of the PLLA scaffolds. Moreover, the approach exhibits the additional benefit that selective scaffold dissolution results in inherently sterile constructs. Preliminary biocompatibility studies revealed cell-interactive and biocompatible behavior of the developed constructs. Conclusions: Physico-chemical testing revealed the scaffold properties (mechanical, degradation, swelling) to depend on the applied gelatin concentration and the methacrylamide content. Structural and biological analysis indicated the success of the indirect RP approach.References1Van Hoorick et al. J Mater Sci: Mater Med (2016)