AccScience Publishing / IJB / Online First / DOI: 10.36922/ijb.3805
RESEARCH ARTICLE
Early Access

Direct ink writing of biomimetic hydroxyapatite scaffolds with tailored concave porosity

Laura del-Mazo-Barbara1,2,3 Anna Diez-Escudero1,2,3,4 Irene Lodoso-Torrecilla1,2,3 Morteza Aramesh5,6 Cecilia Persson5,6 Maria-Pau Ginebra1,2,4,6,7*
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1 Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Engineering and Research Centre for Biomedical Engineering, Universitat Politècnica de Catalunya, c/Eduard Maristany 14, 08019 Barcelona, Spain
2 Barcelona Research Centre in Multiscale Science and Engineering, Universitat Politècnica de Catalunya, Barcelona, Spain
3 Institut de Recerca Sant Joan de Déu, Barcelona, Spain
4 Centro de Investigación Biomédica en Red—Bioingeniería, Biomedicina y Nanomedicina (CIBER-BBN)
5 Department of Materials Science and Engineering, Division of Biomedical Engineering, Uppsala University, 751 21 Uppsala, Sweden
6 Additive Manufacturing for the Life Sciences Competence Centre (AM4Life), Uppsala University, 751 21 Uppsala, Sweden
7 Institute for Bioengineering of Catalonia (IBEC), Barcelona Institute of Science and Technology, Barcelona, Spain
Submitted: 31 May 2024 | Accepted: 19 July 2024 | Published: 25 July 2024
(This article belongs to the Special Issue Advanced Biomaterials for 3D Printing and Healthcare Application)
© 2024 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )
Abstract

Direct ink writing is a promising technology for the fabrication of personalized bone grafts, as it enables the customization of their geometrical conformation with high reproducibility and is compatible with the use of self-setting calcium deficient hydroxyapatite inks. However, the scaffolds obtained by DIW consist mostly of convex filaments, which is a limitation since concave surfaces have been shown to promote bone regeneration in vivo. In this work, we explore the use of triply periodic minimal surface (TPMS) designs in DIW of calcium phosphate self-hardening inks as a strategy to obtain scaffolds with controlled concave macropores. The limitations of the printing parameters with high ceramic loaded inks used in DIW enabled achieving only 20% nominal porosities of Gyroid-, Diamond- and Schwarz-based structures. The inherent layered pores from TPMS geometries allowed obtaining concavities typically unattainable via DIW, bearing substantial implications for subsequent osteoinductive capabilities. Although the mechanical properties were lower in the TPMS-based scaffolds than in the orthogonal patterned ones, the blood permeability of the TPMS-based structures was higher. The concave pore architecture enhanced the osteogenic potential of the biomimetic ceramic, increasing SaOs-2 cell adhesion, proliferation, differentiation and mineralisation.  

Keywords
Bone Scaffold
Biomimetic Hydroxyapatite
Direct Ink Writing
Biomorphic Structures
Concavity
Pore Architecture
Funding
This work was supported by the European Research Council (ERC), through grant agreement number 101055053 (BAMBBI), the Spanish Ministry of Science and Innovation through project PID2019-103892RB-I00/AEI/10.13039/501100011033 and the FPU scholarship of LdMB and by AM4Life Competence Centre in Additive Manufacturing for the Life Sciences through Sweden’s Innovation Agency VINNOVA, project number 2019-00029. ADE acknowledges the Spanish Ministry of Universities for support through Maria Zambrano fellowship.
Conflict of interest
The authors declare no conflict of interest.
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International Journal of Bioprinting, Electronic ISSN: 2424-8002 Print ISSN: 2424-7723, Published by AccScience Publishing