Tough Photo-Cross-Linked PCL-Hydroxyapatite Composites for Bone Tissue Engineering

Acrylate-based photo-cross-linked poly(s-caprolactone) (PCL) tends to show low elongation and strength. Incorporation of osteo-inductive hydroxyapatite (HAp) further enhances this effect, which limits its applicability in bone tissue engineering. To overcome this, the thiol-ene click reaction is introduced for the first time in order to photo-cross-link PCL composites with 0, 10, 20, and 30 wt % HAp nanoparticles. It is demonstrated that the elongation at break and ultimate stren increase 10-and 2-fold, respectively, when the photopolymerization mechanism is shifted from a radical chain-growth (i.e., acrylate cross-linking) toward a radical step-growth polymerization (i.e., thiol-ene cross-linking). Additionally, it is illustrated that osteoblasts can attach to and proliferate on the surface of the photo-cross-linked PCL-HAp composites. Finally, the incorporation of HAp nanopartides is shown to reduce the ALP activity of osteoblasts. Overall, thiol-ene cross-linked PCL-HAp composites can be considered as promising potential materials for bone tissue engineering.

Automated summary

In this study, the thiol-ene click reaction was introduced for the first time to improve the elongation and strength of PCL composites by photo-cross-linking them with HAp nanoparticles. The results showed that the thiol-ene cross-linking mechanism significantly increased the elongation and strength of the composites. Furthermore, osteoblasts were able to attach and proliferate on the surface of the photo-cross-linked PCL-HAp composites.