AccScience Publishing / IJB / Online First / DOI: 10.36922/IJB025320319
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RESEARCH ARTICLE

Suspended 3D printing of polycaprolactone/ hydroxyapatite composites for the fabrication of complex bone scaffolds

Juhyun Kang1† ,  Masoud Shirzad2† ,  Priya Ranganathan2 ,  Dageon Oh2 ,  Sudip Mondal3 ,  Junghwan Oh1, 2,4 ,  Hae Gyun Lim1, 2, 4 ,  Mahdi Bodaghi5* ,  Seung Yun Nam1, 2, 4*
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1 Department of Biomedical Engineering, Pukyong National University, Busan, Republic of Korea
2 Industry 4.0 Convergence Bionics Engineering, Pukyong National University, Busan, Republic of Korea
3 Digital Healthcare Research Center, Institute of Information Technology and Convergence, Pukyong National University, Busan, Republic of Korea
4 Major of Biomedical Engineering, Division of Smart Healthcare, College of Information Technology and Convergence, Pukyong National University, Busan, Republic of Korea
5 Department of Engineering, School of Science and Technology, Nottingham Trent University, Nottingham, UK
†These authors contributed equally to this work.
IJB, 025320319 https://doi.org/10.36922/IJB025320319
Received: 8 August 2025 | Accepted: 1 September 2025 | Published online: 2 September 2025
© 2025 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/ )
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Abstract

Extrusion-based three-dimensional (3D) printing has been rapidly advancing as a key technique for fabricating tissue-engineering scaffolds. However, printing complex structures with appropriate mechanical strength and biocompatibility remains a challenge. Suspended 3D printing is an emerging fabrication strategy that enables the generation of tissues or organs within a support medium that provides a stable printing environment without the need for additional support structures. This study presents a novel strategy for fabricating intricate scaffolds using suspended 3D printing of bioinks incorporating dissolved polycaprolactone (dPCL) and hydroxyapatite (HA). The optimized dPCL/HA bioink demonstrated up to an 85% reduction in print errors compared to conventional methods, significantly enhancing 3D printability. Moreover, mechanical assessments revealed a compressive Young’s modulus approximately 50 MPa higher in dPCL/HA scaffolds compared to dPCL scaffolds. Furthermore, dPCL/HA scaffolds outperformed both PCL and dPCL scaffolds in cell proliferation tests. Complex 3D shapes, including helices, saddles, multi-curvature structures, hollow hemispheres, and zygomatic bones, were successfully fabricated, demonstrating the ability to mimic natural and intricate anatomical structures of the human body. These approaches pave the way for 3D printing patient-specific and structurally robust bone constructs with enhanced mechanical and biological properties.

Graphical abstract
Keywords
Bone tissue engineering
Biomimetic scaffolds
Composites
Extrusion-based three-dimensional printing
Suspended three-dimensional printing
Funding
This research was supported by a National Research Foundation of Korea grant (NRF-2021R1I1A3040459) funded by the Ministry of Education, Republic of Korea, and by a Korea Health Technology R&D Project grant through the Korea Health Industry Development Institute, funded by the Ministry of Health and Welfare, Republic of Korea (HI22C1323).
Conflict of interest
Seung Yun Nam serves as the Editorial Board Member of the journal, but did not in any way involve in the editorial and peer-review process conducted for this paper, directly or indirectly. Other authors declare they have no competing interests.
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International Journal of Bioprinting, Electronic ISSN: 2424-8002 Print ISSN: 2424-7723, Published by AccScience Publishing
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