fig3

Figure 3. The preparation methods of biomaterials with hierarchical structures. (A) Schematic diagram of the preparation of a porous scaffold by electrospinning^[45]. Copyright 2022, Acta Materialia Inc. Published by Elsevier Ltd. (B) The micro morphologies of 3D biomimetic electrospinning scaffolds^[45]. Copyright 2022, Acta Materialia Inc. Published by Elsevier Ltd. (C) Preparation and application diagram of hierarchical chitosan scaffolds by freeze drying^[58]. Copyright 2021, Wiley-VCH GmbH. (D) Schematic diagram of the manufacturing process of micro gel with core-shell structures and 3D printing scaffolds with micro gel loading cells^[62]. Copyright 2021, Elsevier Ltd.