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

Abstract

Acrylate-based photo-cross-linked poly­(ε-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 strength 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 nanoparticles 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.

Introducing photo-crosslinked bio-nanocomposites based on polyvinylidene fluoride/poly(glycerol azelaic acid)-g-glycidyl methacrylate for bone tissue engineering

“…18 It should be noted that the Young's modulus and UTS of PGAG/PVDF and its nanocomposites are within the range of those for the cancellous bone (i.e., 4-300 MPa and 10-20 MPa, respectively). 23 Mechanical properties of tissue-engineered scaffolds are of key importance in determining their efficiency for implantation, since these scaffolds need to endure high in vivo mechanical stresses. Nonetheless, considering a single mechanical parameter, such as modulus or strength, in fabricating scaffolds is insufficient to meet the performance criteria for TE applications.…”

“…Hydroxyapatite is a brittle bioceramic that is abundantly present in human bone and promotes osteogenic differentiation. 23 As a nanofiller, it can improve the hydrophilicity and mechanical properties of biopolyesters, such as PGAz, and promote cell metabolic activity and cell-polymer interactions. 18,20 In a previous work, 24 a PGAz/nHA nanocomposite was prepared.…”

Volumetric Printing of Thiol‐Ene Photo‐Cross‐Linkable Poly(ε‐caprolactone): A Tunable Material Platform Serving Biomedical Applications

“…[16,22] To overcome this limitation, we have recently introduced thiol-ene cross-linking to photo-cross-link PCL which resulted in a 10-fold improvement of the ultimate strength and elongation at break as compared to the state-ofthe-art. [23,24] This effect was attributed to the homogeneous network topology, stemming from the step-growth polymerization mechanism involved. [25] In an attempt to progress toward the outlined ideal scenario, volumetric 3D-printing of tunable and mechanically robust thiolene cross-linked PCL networks is herein introduced.…”

“…[ 16,22 ] To overcome this limitation, we have recently introduced thiol‐ene cross‐linking to photo‐cross‐link PCL which resulted in a 10‐fold improvement of the ultimate strength and elongation at break as compared to the state‐of‐the‐art. [ 23,24 ] This effect was attributed to the homogeneous network topology, stemming from the step‐growth polymerization mechanism involved. [ 25 ]…”

Fabrication and functionality of 3D-printed porous scaffolds composing natural derivatives of duck bones and fish shells and poly(ε-caprolactone)

“…In order to enhance the biomineralization activity and antibacterial property of PCL, natural derivatives of the duck bones and sh shell were introduced into PCL [12] .In terms of biomineralization activity, bioceramic hydroxyapatite (HA) can be added to the PCL, thereby promoting the release and deposition of calcium ions (Ca 2+ ) and phosphate ions by cells from the scaffold. The properties of the composite scaffold thus resemble those of natural bone [13,14]. Cestari et al [15] used PCL and biologically derived HA to make 3D-printed scaffolds, onto which were seeded osteoblasts whose biological activity was then monitored.…”