Cryo‐3D Printing of Hierarchically Porous Polyhydroxymethylene Scaffolds for Hard Tissue Regeneration. Issue 1 (12th November 2020)

• Record Type: Journal Article
• Authors: Stolz, Benjamin; Mader, Markus; Volk, Lukas; Steinberg, Thorsten; Mülhaupt, Rolf
• Is Part Of: Macromolecular materials and engineering. Volume 306:Issue 1(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-11-12
• Subjects: 3D printing -- polyhydroxymethylene -- regenerative medicine -- scaffolds -- tissue engineering; Plastics -- Periodicals; Polymers -- Periodicals; Polymerization -- Periodicals; 547.705
• DOI: 10.1002/mame.202000541
• Languages: English
• ISSNs: 1438-7492

Abstract

Abstract: High molecular weight polyhydroxymethylene (PHM) has a repeat unit identical to that of low molecular weight sugar alcohols and exhibits carbohydrate‐like properties. Herein, cryogenic extrusion‐based 3D printing is combined with a phase separation in water to fabricate hierarchically porous PHM scaffolds containing interconnected macro‐, micro‐, and nanopores. As PHM is infusible and insoluble in common solvents, its precursor polyvinylene carbonate (PVCA) dissolved in dimethylsulfoxide (DMSO) is used to 3D print hierarchically porous PVCA scaffolds that are converted into PHM by hydrolysis without impairing the pore architectures. Similar to low‐temperature deposition manufacturing, the PVCA/DMSO freezes on a build platform at −78 °C. However, instead of removing the frozen solvent by sublimation, the frozen scaffold is immersed in water to recover DMSO and to effect phase separation by precipitation. However, the computer‐guided printhead pathway controls macropore formation phase separation of frozen PVCA/DMSO upon contact with water accounts for simultaneous micro‐ and nanopore formation. Contrary to 3D printing of PVCA/DMSO at ambient temperature, this cryo‐3D printing process does not require shear thinning additives and affords significantly improved build precision with macropore sizes variable between 200 and 1500 µm. Cryo‐3D‐printed PHM scaffolds are biocompatible and promote osteoblast proliferation. Abstract : Cryogenic extrusion‐based 3D printing of polyvinylene carbonate solutions followed by hydrolysis fabricates hierarchically porous polyhydroxymethylene scaffolds with interconnected macro‐, micro‐, and nanopores. While the printhead pathway governs macropore formation, phase separation by polymer precipitation in water accounts for the formation of interconnected micro‐ and nanopores. The scaffold purification is essential to achieve biocompatibility and osteoblast proliferation.