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Degradable amorphous scaffolds with enhanced mechanical properties and homogeneous cell distribution produced by a three-dimensional fiber deposition method
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.ORCID iD: 0000-0002-1922-128X
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
Dept. of Clinical Dentistry-Center for Clinical Dental Research, Faculty of Medicine and Dentistry, University of Bergen, Norway.
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2012 (English)In: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, Vol. 100A, no 10, 2739-2749 p.Article in journal (Refereed) Published
Abstract [en]

The mechanical properties of amorphous, degradable, and highly porous poly(lactide-co-caprolactone) structures have been improved by using a 3D fiber deposition (3DF) method. Two designs of 3DF scaffolds, with 45 degrees and 90 degrees layer rotation, were printed and compared with scaffolds produced by a salt-leaching method. The scaffolds had a porosity range from 64% to 82% and a high interconnectivity, measured by micro-computer tomography. The 3DF scaffolds had 89 times higher compressive stiffness and 35 times higher tensile stiffness than the salt-leached scaffolds. There was a distinct decrease in the molecular weight during printing as a consequence of the high temperature. The chain microstructure was, however, not affected; the glass transition temperature and the decomposition temperature were constant. Human OsteoBlast-like cells were cultured in vitro and the cell morphology and distribution were observed by scanning electron microscopy and fluorescence microscopy. The cell distribution on the 3DF scaffolds was more homogeneous than the salt-leached scaffolds, suggesting that 3DF scaffolds are more suitable as porous biomaterials for tissue engineering. These results show that it is possible to design and optimize the properties of amorphous polymer scaffolds. The 3DF method produce amorphous degradable poly(lactide-co-caprolactone) that are strong and particularly suitable for cell proliferation.

Place, publisher, year, edition, pages
2012. Vol. 100A, no 10, 2739-2749 p.
Keyword [en]
3D fiber deposition method, amorphous degradable copolymer, aliphatic polyester, scaffold, cell distribution
National Category
Polymer Technologies
URN: urn:nbn:se:kth:diva-96625DOI: 10.1002/jbm.a.34210ISI: 000307888200023ScopusID: 2-s2.0-84865630684OAI: diva2:531506

QC 20121004

Available from: 2012-06-07 Created: 2012-06-07 Last updated: 2014-09-29Bibliographically approved
In thesis
1. Engineering and Functionalization of Degradable Scaffolds for Medical Implant Applications
Open this publication in new window or tab >>Engineering and Functionalization of Degradable Scaffolds for Medical Implant Applications
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The treatment of bone defects is facing the situation of lacking donations for autotransplantation. As a valid approach, scaffold-based tissue engineering combines the construction of well-defined porous scaffolds with advanced cell culturing technology to guide tissue regeneration. The role for the scaffold is to provide a suitable environment with a sufficient mechanical stiffness, supports for cell attachment, migration, nutrients and metabolite transport and space for cell remodeling and tissue regeneration. The random copolymers poly(L-lactide-co-ɛ-caprolactone) (poly(LLA-co-CL)) and poly(L-lactide-co-1,5-dioxepan-2-one) (poly(LLA-co-DXO)) have been successfully incorporated into 3D porous scaffolds to induce specific interactions with cells and direct osteogenic cell differentiation. In this thesis, these scaffolds have been modified in chemical and physical ways to map and understand requirements for bone regeneration. Scaffold functionalities and properties, such as hydrophilicity, stiffness, size/shape, and reproducibility, were studied. The hydrophilicity was varied by adding 3–20 % (w/w) Tween 80 to poly(LLA-co-CL) and poly(LLA-co-DXO) respectively, which resulted in contact angles from 35° to 15°. With 3 % Tween 80, the resultant mechanical and thermal properties were similar to pristine polymer materials. Tween 80 did not significantly influence cell attachment or proliferation but did stimulate the mRNA expression of osteogenetic markers. The surface functionality and mechanical properties were altered by introducing nanodiamond particles (n-DP) into poly(LLA-co-CL) scaffolds by means of surface physisorption or hybrid blending. Scaffold with n-DP physisorbed showed improved cell attachment, differentiation, and bone reformation. Hybrid n-DP/poly(LLA-co-CL) composites were obtained by direct blending of polylactide modified n-DP (n-DP-PLA) with poly(LLA-coCL). The n-DP-PLA was prepared by sodium hydride-mediated anionic polymerization using n-DP as the initiator. Prepared n-DP-PLA could be dispersed homogenously in organic solvents and blended with poly(LLA-coCL) solution. The n-DP-PLA particles were homogenously distributed in the composite material, which significantly improved mechanical properties. For comparison, the addition of benzoquinone-modified n-DP (n-DP-BQ) did not reinforce poly(LLA-co-CL). This indicated the importance of specific surface grafting, which determined different particle-polymer interactions. For the treatment of critical size defects, a large porous poly(LLA-co-CL) scaffold (12.5 mm diameter × 25 mm thickness) was developed and produced by molding and salt-leaching methods. The large porous scaffolds were evaluated in a scaffold-customized perfusion-based bioreactor system. It was obvious that the scaffold could support improved cell distribution and support the stimulation of human mesenchymal stem cell (hMSC) especially with dynamic flow in a bioreactor. To improve the scaffolding technique, a three-dimensional fiber deposition (3DF) technique was employed to build layer-based scaffolds. Poly(LLA-coCL) scaffolds produced by the 3DF method showed enhanced mechanical properties and a homogeneous distribution of human osteoblasts (hOBs) in the scaffolds. Although poly(LLA-co-CL) was thermally degraded, the degradation did not influence the scaffold mechanical properties. Based on the computerized design, a 3DF scaffold of amorphous copolymer poly(LLAco-CL) provides high-precision control and reproducibility. In summary, the design of porous scaffolds is one of the essential factors in tissue engineering as to mimicking the intrinsic extracellular environment. For bone tissue engineering, an optimized scaffold can maintain a contact angle greater than 35 degrees. Pristine or modified n-DP, introduced as an additive by surface physisorption or direct blending, can improve scaffold mechanical properties and cell response. Various sizes of scaffolds can be easily produced by a mold-mediated salt-leaching method. However, when 100 % reproducibility is required, the 3DF method can be used to create customizable scaffolds.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. 73 p.
TRITA-CHE-Report, ISSN 1654-1081 ; 2014:36
Tissue engineering, nanodiamond, scaffold, bioreactor
National Category
Polymer Technologies
Research subject
Fibre and Polymer Science
urn:nbn:se:kth:diva-152605 (URN)978-91-7595-256-7 (ISBN)
Public defence
2014-10-17, Kollegiesalen, Brinellvägen 8, KTH, Stockholm, 13:44 (English)
EU, FP7, Seventh Framework Programme, Vascubone

QC 20140929

Available from: 2014-09-29 Created: 2014-09-29 Last updated: 2014-09-29Bibliographically approved

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