A Versatile In Situ Precipitation Assisted Direct‐Write‐3D Printing Strategy for Skinless Hierarchical Porous Polymeric Scaffolds

Skinless, hierarchical porous 3D polymer scaffolds are of critical importance in tissue engineering, enabling improved cell infiltration, nutrient, metabolite and energy exchange, and biomimetic structures, crucial for regenerative medicine, drug delivery, and advanced material applications. However, it is still a great challenge to construct this kind of material with traditional 3D printing techniques. Herein, a novel simple, and versatile in situ precipitation-assisted direct-write-3D printing strategy for skinless, hierarchical porous 3D scaffolds is reported. Homogenous ink containing molecularly dissolved fructose (soluble porogen molecule) and polymer (whether it is hydrophilic, hydrophobic or amphiphilic) is directly extruded into a nonsolvent bath, where simultaneously solidification of the polymer and in situ precipitation of the porogen molecules both on the exterior surface and inside the separated polymer fibers happen. Subsequently, by simply leaching the in situ formed porogen particles, skinless hierarchical porous polymeric 3D scaffolds can be obtained. It is believed that 3D printing, polymer/macromolecule-based scaffolds, especially the skinless hierarchical porous biomaterials, and the tissue engineering market can benefit tremendously from this simple and versatile approach.