Micro-digital light processing of conventional and hollow Gyroid mesoscale hydrogel scaffolds for neural cell cultures

Here, we report a high-resolution micro-digital light processing (μDLP) 3D printing protocol for fabricating soft hydrogel scaffolds featuring mesoscale millimetre-sized gyroid-based architectures tailored for 3D neural cell culture. The developed bioink formulation combines poly(ethylene glycol) diacrylate (PEGDA), as the structural backbone, and gelatin methacryloyl (GelMA), to enhance biocompatibility and promote cell adhesion via arginylglycylaspartic acid (RGD) motifs. By combining lithium phenyl (2,4,6-trimethylbenzoyl) phosphinate (LAP) as photoinitiator, along with tartrazine as photoabsorber, we achieved feature sizes down to 12.4 μm with high printing fidelity, reproducibility, and mechanical stability. The mechanical properties of the resulting hydrogel structures showed a Young's modulus (YM) in the 770 kPa – 2.25 MPa range, depending on the presence of GelMA, thus very relevant for neural cells (brain YM in the kPa range), along with remarkable biocompatibility (≈80 % cell viability) and good cell adhesion (≈55 % cell coverage). Two scaffold geometries based on triply periodic minimal surface gyroids were developed: a fully porous structure for culturing dissociated neuroepithelial stem cells and a hollow variant designed to host pre-formed neural organoids. Both scaffold types enabled strong cell adhesion and organoid sprouting, thereby demonstrating their suitability for advanced 3D culture systems. The results highlight the potential of μDLP-fabricated hydrogel meso-scale architectures as a platform for neuromechanobiology studies and tissue-mimetic engineering.