Case study: Reinforcement of 45S5 bioglass robocast scaffolds by HA/PCL nanocomposite coatings

Tetracalcium phosphate/polycaprolactone composite scaffold: Mechanical reinforcement, biodegradability regulation and bioactivity induction

Polycaprolactone (PCL) is considered a potential biomaterial due to its good biocompatibility, but its slow degradability and insufficient mechanical properties limit its wide application in bone tissue engineering. Tetracalcium phosphate's (TTCP) good degradability and inherent high stiffness are expected to compensate for the aforementioned defects of PCL and endow it with good biological activity. This goal of this study was to obtain bioactive PCL composite scaffolds with tuneable degradation properties and good mechanical strength via selective laser sintering technology (SLS). Composite porous scaffolds with TTCP contents of 0%, 5%, 10%, 15%, 20%, and 25% were prepared, and the experimental results showed that the addition of TTCP significantly improved the mechanical properties of the scaffold. Notably, the tensile strength of the composite scaffold with 20% TTCP content reached 15.2 MPa, which was 2.9 times that of pure PCL, and the best flexural strength was found in the scaffold with 15% TTCP content (4.7 MPa). More importantly, the introduced TTCP not only achieved the effective pH regulation of the soaking solution and the promotion of biodegradation, but also provided the scaffold with good bioactivity and biocompatibility.

Additive Manufacturing of Polymer/Bioactive Glass Scaffolds for Regenerative Medicine: A Review

Tissue engineering (TE) is a branch of regenerative medicine with enormous potential to regenerate damaged tissues using synthetic grafts such as scaffolds. Polymers and bioactive glasses (BGs) are popular materials for scaffold production because of their tunable properties and ability to interact with the body for effective tissue regeneration. Due to their composition and amorphous structure, BGs possess a significant affinity with the recipient's tissue. Additive manufacturing (AM), a method that allows the creation of complex shapes and internal structures, is a promising approach for scaffold production. However, despite the promising results obtained so far, several challenges remain in the field of TE. One critical area for improvement is tailoring the mechanical properties of scaffolds to meet specific tissue requirements. In addition, achieving improved cell viability and controlled degradation of scaffolds is necessary to ensure successful tissue regeneration. This review provides a critical summary of the potential and limitations of polymer/BG scaffold production via AM covering extrusion-, lithography-, and laser-based 3D-printing techniques. The review highlights the importance of addressing the current challenges in TE to develop effective and reliable strategies for tissue regeneration.

Complications arising from clinical application of composite polycaprolactone/bioactive glass ceramic implants for craniofacial reconstruction: A prospective study

This study aimed to demonstrate the in vitro performance of a novel polymer-ceramic composite incorporating polycaprolactone (PCL) and bioactive glass (BGS-7), and investigate its clinical outcomes in craniofacial reconstruction. After preparation of the material, the biochemical properties of the composite PCL/BGS-7 implant were tested to evaluate apatite formation in simulated body fluid (SBF). Changes in the implant surface after soaking in the SBF were determined using field-emission scanning electron microscopy. For clinical application of the implant, patients with craniofacial defects were prospectively enrolled to receive three-dimensional (3D)-printed PCL/BGS-7 implants. Clinical outcomes were investigated by reviewing postoperative complications, including wound problems, allergic responses, hematoma, seroma, implant displacement, and bone union. The accuracy of reconstruction was assessed by measuring the surface error between the reconstructed and mirrored models. Upon exposure of the PCL/BGS-7 implant to SBF, apatite particles were actively developed on the surface of the PCL/BGS-7 sample, showing favorable bone-binding capacity. Regarding the clinical application, seven patients with craniofacial defects were included. The clinical outcome was favorable in terms of complications, except in one patient, who presented with delayed wound healing due to previous irradiation. The patients showed improvements in symmetry, with a significant change in mean ± SD surface error between preoperative (5 ± 3 mm) and postoperative (1.5 ± 0.65 mm) status (p = 0.018). Wthin the limitations of the study it seems that the PCL/BGS-7 implants might be a relevant option for repairing craniofacial bone defects, owing to its favorable bone-binding property and clinical safety, with few complications.

Nanocomposite scaffolds composed of Apacite (apatite-calcite) nanostructures, poly (ε-caprolactone) and poly (2-hydroxyethylmethacrylate): The effect of nanostructures on physico-mechanical properties and osteogenic differentiation of human bone marrow mesenchymal stem cells in vitro

Nanocomposite scaffolds were fabricated from poly (ε-caprolactone) (PCL), Poly (2-hydroxyethylmethacrylate) (PHEMA), and Apacite (Apatite-calcite) nanostructures (15 and 25 wt%). The nanoscale structure, physical and chemical properties, mechanical properties, hydrophilic behavior, degradability and osteogenic properties of the fabricated scaffolds were evaluated. The results showed that the mechanical strength, degradation, wetting ability, and mechanical strength of PCL-PHEMA scaffolds significantly increases upon inclusion of Apacite nanoparticles up to 25 wt%. Accordingly, the best mechanical values (E ~ 7.109 MPa and σ ~ 0.414 MPa) and highest degradability (32% within 96 h) were recorded for PCL-PHEMA scaffolds containing 25 wt% of Apacite. Furthermore, highest porosity and roughness were observed in the PCL-PHEMA/25% Apacite as a result of the Apacite nanoparticles inclusion. There was no cytotoxicity recorded for the fabricated scaffolds based on the results obtained from MTT assay and acridine orange staining. Alkaline phosphatase activity, calcium content quantification, Van Kossa staining, FESEM and real time PCR tests confirmed the biomineralization, and the differentiation potential of the nanocomposite scaffolds. Overall, the 3D structure, optimum porosity and balanced dissolution rate of PCL-PHEMA/25% Apacite providing a balanced microenvironment resulted in improved cell adhesion, cell behavior, and replication, as well as osteogenic induction of human bone-marrow-derived mesenchymal stem cells (hBM-MSCs).

Reinforcing 13-93 bioglass scaffolds fabricated by robocasting and pressureless spark plasma sintering with graphene oxide

13-93 bioglass (BG) scaffolds reinforced with graphene oxide (GO) were fabricated by robocasting (direct-ink-writing) technique. Composite scaffolds with 0-4 vol% content of GO platelets were printed, and then consolidated by pressureless spark plasma sintering at 650 °C. It was found that, despite hampering densification of the bioglass, the addition of GO platelets up to a certain content enhanced the mechanical performance of the 13-93 bioglass scaffolds in terms of strength and, especially, toughness. Best performance was obtained for 2 vol.% GO, which increased strain energy density (toughness) of the scaffolds by ∼894%, and their compressive strength by ∼26%. At higher contents, agglomeration of the nanoplatelets and increased porosity significantly reduced the mechanical enhancement obtained. Implications of the results on the fabrication of novel bioglass scaffolds that may find use in load-bearing bone tissue engineering applications are discussed.