MgO Nanocomposites as Antibacterial Biomaterials for Orthopedic Tissue Engineering

Regeneration of complex orthopedic tissues (such as ligament, bone, and the tendon-to-bone insertion site) is problematic due to a lack of suitable biomaterials with the appropriate chemical and mechanical properties to elicit the formation of tissues with similar structure, organization, and functionality to natural tissues. Additionally, a non-trivial fraction of implanted biomaterials acquire bacterial infections, which can lead to implant failure, secondary surgeries, and the spread of infection to other tissues throughout the body. Magnesium oxide (MgO) is a biocompatible material exhibiting strong antibacterial properties, which has shown promise as a material for orthopedic implants. Furthermore, decreasing the feature size of MgO into the nano-regime has been demonstrated to improve both its antibacterial efficacy as well as its ability to promote bone cell functions. Here, MgO nanoparticles were dispersed within poly (l-lactic acid) polymer films and these nanocomposites were characterized for their mechanical properties, antibacterial properties, and ability to promote ligament and bone tissue formation compared to plain PLLA and hydroxyapatite (HA) nanocomposites. MTS assays indicated that MgO nanoparticles enhanced the adhesion of osteoblasts (bone forming cells) and supported comparable osteoblast proliferation to HA nanocomposites. The addition of a secondary nanoparticle phase to plain PLLA reduced polymer elasticity and increased the material elastic modulus, established via mechanical tensile testing. The elastic modulus of all tested materials lied within the acceptable