3D-Printed Polycaprolactone/Alginate-Whitlockite Composite Scaffolds for Bioactive Bone Tissue Engineering

Abstract Despite advances in 3D printing, achieving simultaneous mechanical stability and biological functionality in polymer-based scaffolds remains challenging for bone tissue engineering applications. In this study, 3D-printed scaffolds fabricated from a polycaprolactone/alginate (PCL/Alg) composite reinforced with different amounts of whitlockite (WL) nanoparticles (including 0, 5, 10, 20, and 30 wt %) were designed. Mechanical studies showed that adding 5 wt % WL significantly improved the mechanical properties, with the compressive strength and elastic modulus increasing from about 7 and 12 MPa to 22 and 48 MPa, respectively. However, increasing the WL content beyond this value reduced mechanical performance, likely due to WL particle aggregation and disruption of the PCL/Alg scaffold. Water contact angle analysis showed that the PCL/Alg scaffold incorporated with WL exhibited better hydrophilicity than pure PCL and PCL/Alg, which was mainly attributed to the hydrophilic nature of these compounds. Immersion results indicated that adding WL facilitated apatite deposition, mainly through the release of calcium and magnesium ions. The MTT assay showed that none of the designed scaffolds was toxic to MG-63 cells. Meanwhile, the scaffold containing 5 wt % WL exhibited the highest cell viability and adhesion, whereas higher WL concentrations yielded less favorable cellular responses. Taken together, the results obtained indicate that the PCL/Alg scaffold containing 5% WL provides a balanced combination of mechanical and biological properties, making it a desirable bioactive platform for bone tissue engineering applications.