The Effect of β-TCP/45S5 -Ratio on the In Vitro Degradation of Synthetic Composite Bone Grafts
Virpinen, Miika (2025)
Virpinen, Miika
2025
Materiaalitekniikan DI-ohjelma - Master's Programme in Materials Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Hyväksymispäivämäärä
2025-01-16
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202501161463
https://urn.fi/URN:NBN:fi:tuni-202501161463
Tiivistelmä
Bone tissue has the outstanding ability to self-repair and remodel. However, its regenerative capacity can sometimes be insufficient to repair the defect site, if the defect is critical. In such case, reconstructive surgery is necessary to stabilize the defect site and rebuild the fractured bone. With approximately four million annual operations and the limitations with the current treatment options, the adequate availability of well-performing bone graft substitutes is of utmost importance. Bone tissue engineering tries to answer this growing problem by developing biomaterials, that are able to promote bone regeneration and provide adequate structural support for the regenerating bone tissue.
Bone is a complex tissue, and hence the requirements for optimal bone grafts may differ depending on the bone type and location. Due to the inherent complexity of bone, no material alone has been sufficient in meeting the diverse criteria of the optimal bone graft. However, polymer-matrix composites with ceramic particles provide a promising alternative for the currently used bone grafts. While calcium phosphate ceramics and bioactive glasses (BaG) have been proven to promote bone regeneration, their inherent brittleness and poor handling properties limit their use. In turn, synthetic polymers have superior handling properties but lack bioactivity unlike BaGs.
In this study, biodegradable composite granules of poly(L-lactide-co-ε-caprolactone) (PLCL), β-tricalcium phosphate (β-TCP) and a BaG 45S5 with various β-TCP/45S5 -ratios were manufactured. The main focus of this study was to evaluate the potential of the composite granules for bone applications by performing in vitro testing. The study focused on determining the effect of the β-TCP/45S5 -ratio on the packing properties, in vitro degradation and in vitro bioactivity properties of the composite granules.
This study revealed that the packing properties of the composite granules are independent of the β-TCP/45S5 -ratio. However, the β-TCP/45S5 -ratio significantly affected the in vitro degradation properties of the composites: increased content of 45S5 accelerated the degradation of both the ceramic and the polymer phases of the composite granules. All investigated composite granules were confirmed to be bioactive in vitro with no significant differences in the hydroxyapatite layer formation onto the granule surfaces regardless of the β-TCP/45S5 -ratio. This study introduced novel composite granules that have potential for use in bone tissue engineering applications.
Bone is a complex tissue, and hence the requirements for optimal bone grafts may differ depending on the bone type and location. Due to the inherent complexity of bone, no material alone has been sufficient in meeting the diverse criteria of the optimal bone graft. However, polymer-matrix composites with ceramic particles provide a promising alternative for the currently used bone grafts. While calcium phosphate ceramics and bioactive glasses (BaG) have been proven to promote bone regeneration, their inherent brittleness and poor handling properties limit their use. In turn, synthetic polymers have superior handling properties but lack bioactivity unlike BaGs.
In this study, biodegradable composite granules of poly(L-lactide-co-ε-caprolactone) (PLCL), β-tricalcium phosphate (β-TCP) and a BaG 45S5 with various β-TCP/45S5 -ratios were manufactured. The main focus of this study was to evaluate the potential of the composite granules for bone applications by performing in vitro testing. The study focused on determining the effect of the β-TCP/45S5 -ratio on the packing properties, in vitro degradation and in vitro bioactivity properties of the composite granules.
This study revealed that the packing properties of the composite granules are independent of the β-TCP/45S5 -ratio. However, the β-TCP/45S5 -ratio significantly affected the in vitro degradation properties of the composites: increased content of 45S5 accelerated the degradation of both the ceramic and the polymer phases of the composite granules. All investigated composite granules were confirmed to be bioactive in vitro with no significant differences in the hydroxyapatite layer formation onto the granule surfaces regardless of the β-TCP/45S5 -ratio. This study introduced novel composite granules that have potential for use in bone tissue engineering applications.