Multiscale Structuring of Hydroxyapatite via Two‐Photon Lithography of Nanocomposites

ABSTRACT Hydroxyapatite is widely used in tissue engineering due to its similarity to the mineral in bone. Microstructured hydroxyapatite scaffolds are of interest as they provide mechanical support for cells and guide cell behavior through structural cues. However, current structuring methods are limited to either large structures that lack the smallest features of bone or to nanoscale structuring that is not scalable to larger constructs. In this work, we bridge this gap by using two‐photon lithography of a transparent nanocomposite to fabricate dense and mechanically stable hydroxyapatite microscaffolds. Structures ranging from one centimeter in length to structuring submicron features are achieved, enabling multiscale structuring. Mesenchymal stromal/stem cells that are seeded on hydroxyapatite show high viability, and an examination of cell morphology and osteogenic differentiation demonstrates the impact of high‐resolution scaffolds for cell culture over commercial low‐resolution counterparts. This approach enables efficient fabrication of multiscale hydroxyapatite scaffolds, with great potential for bone tissue engineering.