Supporting Information

3D Printed Multi-scale Scaffolds with Ultrafine Fibers

for Providing Excellent Biocompatibility

Qing Gao#1,2, Chaoqi Xie#1,2, Peng Wang#1,2, Mingjun Xie1,2, Haibing Li3, Anyu Sun1, Jianzhong Fu1,2,

Yong He*1,2

(1State Key Laboratory of Fluid Power and Mechatronic Systems, School of Mechanical Engineering, Zhejiang University, Hangzhou

310027, China2Key Laboratory of 3D Printing Process and Equipment of Zhejiang Province, School of Mechanical Engineering, Zhejiang University,

Hangzhou 310027, China3Department of Paediatric Orthopaedics, The Children’s Hospital, Zhejiang University School of Medicine, Hangzhou 310027, China

* Correspondence to: Yong He; e-mail: yongqin@zju.edu.cn# These authors contributed equally to the work)

Figure S1. Three types of thin fiber deposition affected by printing speed and distance. (A) Drooping fibers. (B) Straight fibers. (C) Curving fibers.

Figure S2. Cell viability analysis of BMSCs seeded on the multi-scale scaffolds.

Figure S3. SEM images of cell morphology change on the multi-scale scaffolds.

Figure S4. Comparison of cell morphology change between macro-scale and multi-scale scaffolds.

Figure S5. Cell responses on different fiber diameters. A) BMSCs on homogeneous fibers in X and Y direction. B) BMSCs on thick fibers (≈20μm) in X direction and thin fibers (≈5μm) in Y direction.

Figure S6. Biocompatibility analysis of GelMA by viability assay and cytoskeletal observation of BMSCs encapsulated in GelMA.

Figure S7. Comparison of cell growth between multi-scale scaffold/GelMA structures and pure GelMA structures.

Video S1. Printing process of the multi-scale scaffold.

Video S2. 3D rotation of BMSCs-seeded multi-scale scaffolds showing the cell growth process.

Video S3. 3D rotation of BMSCs-encapsulated scaffold/GelMA structures showing the cell growth process.