Zein/ZnO-Modified 3D-Printed PCL/Sphene Scaffolds with Improved Bacterial Inhibition and Osteoblast Activity for Bone Regeneration Applications

3D printing offers a significant advantage in creating bioengineering scaffolds for patient-specific treatments of bony defects. In this study, a 3D-printed polycaprolactone (PCL)/sphene (SP, CaTiSiO5) scaffold coated with zein/ZnO was fabricated to provide a suitable environment for bone regeneration. SP nanoparticles were synthesized using a mechanochemical method and characterized by SEM-EDS, FTIR, and XRD. 0–30 wt % of prepared SP nanoparticles was used to fabricate 3D-printed PCL-based scaffolds. Incorporation of SP into PCL scaffolds (up to 20 wt %) significantly increased compressive strength (from 37.5 to 65.2 MPa) and modulus (from 0.33 to 0.63 MPa). In vitro bioactivity evaluation in simulated body fluid demonstrated the apatite formation ability of PCL/SP scaffolds, as confirmed by SEM-EDS analysis. Compared to PCL/SP, the zein/ZnO-modified scaffold showed increased surface hydrophilicity and significantly higher values of bactericidal potency against S. aureus and E. coli. Additionally, MTT assay, cell attachment, and alkaline phosphatase activity revealed that zein and ZnO coexistence on PCL/SP scaffolds resulted in significantly higher cell proliferation, improved cell adhesion, and enhanced osteogenic differentiation of MG-63 cells compared to unmodified samples. Overall, zein/ZnO-modified 3D-printed PCL/SP nanocomposite scaffolds with desirable physicochemical, mechanical, and biological characteristics can serve as superior platforms for bone regeneration applications.