Comparative Effects of ZnO, MgO, and CaO Nanoparticles in 3D‐Printed Chitosan–Agarose Scaffolds on Antibacterial and Osteogenic Outcomes

In the field of orthopedic surgery, large bone defects resulting from trauma, surgical resection, or congenital anomalies present significant challenges. In many cases, treatment necessitates scaffold structures that not only support bone regeneration but also address potential bacterial infections that can impede healing. In this study, we developed 3D bioprinted scaffolds using hydrogel-based biomaterial ink comprising a blend of chitosan (CS) and agarose (AG), each separately fortified with ZnO, MgO, and CaO nanoparticles (NPs). We performed a comprehensive assessment of the inks' printability and wettability, and ascertained their rheological properties. The in vitro degradation of 3D bioprinted scaffolds was analyzed, their antibacterial capabilities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were explored, and the differentiation of bone marrow mesenchymal stem cells (BMSCs) was evaluated. The findings indicated that the hydrogel, CS-AG (CA), composed of 3.5% (w/v) CS and 1.5% (w/v) AG, demonstrated superior printing characteristics. Among the nanoparticles, ZnO proved to be a notable booster of antibacterial activity and facilitated osteogenic differentiation and proliferation of bone marrow stem cells. Conversely, MgO showed similar antibacterial efficacy but was less successful in promoting cell proliferation compared to ZnO and CaO, whereas CaO displayed the weakest antibacterial efficacy. The results identify the ZnO NP-loaded CA biomaterial ink as a viable option for addressing bone abnormalities, enhancing bone repair, and preventing bacterial infection.