Oxidative stress will cause irreversible damage to osteoblasts associated with bone loss, which has an adverse effect on fracture repair under pathological conditions. The orthopedic implants with antioxidative capability has thus provided an important therapeutic option to ameliorate osteoblast activity and bone mass around implants in osteoporosis.
In a study published in Chemical Engineering Journal, the researchers from Shanghai Institute of Ceramics of the Chinese Academy of Sciences constructed titanium oxide nanotube arrays supported cerium oxide nanoparticles on the surface of titanium implants, which effectively alleviates the damage of oxidative stress to the activity of osteoblasts and solves the osteogenic problem of the implants in osteoporotic animals.
The researchers found that vertically aligned titania nanotube array supported CeNPs (TiNTA-CeNPs), regardless of the pre-dominant Ce oxidation state, retained the cycling capability of Ce4+/Ce3+ in H2O2 containing phosphate-buffered saline (PBS) compared with Ti supported CeNPs.
Phosphate ions in the physiological environment can easily combine with Ce3+ in CeNPs, hindering the reversible cycle between Ce3+ and Ce4+. However, due to the preferentially ligand exchange between Ti3+ and phosphate on the TiNTA surface, the binding of phosphate ions to Ce3+ is limited, thereby retaining the cyclic antioxidant function of TiNTA-CeNPs.
Furthermore, the researchers established a correlation between electronic band structures of Ce-Ti mixed oxides and redox potential of reactive oxygen species (ROS) aided in interpretation of enhanced redox cycling capability and enzyme-like activities.
The matching degree between the energy of surface defective state (ESDS) and the potential of the redox couple in the catalytic reaction of superoxide dismutase (SOD) and catalase (CAT) can significantly affect the enzyme-like activity of the material. Accordingly, Ce3+-rich TiNTA-CeNP1 and Ce4+-rich TiNTA-CeNP2 in PBS exhibited more sustained superoxide dismutase and catalase mimetic response, respectively.
To demonstrate in vivo osteoprotective effect, the researchers established a rat model of oxidative stress-related osteoporosis. They found that TiNTA-CeNP2 with higher CAT mimic activity and lower Fenton-like activity can significantly reduce the content of reactive oxygen species (ROS) in osteoblasts under oxidative stress and protect the activity and differentiation ability of osteoblasts from oxidative damage, and TiNTA-CeNP2 can effectively reduce the production of oxidized substances in the tissue surrounding implants in osteoporotic rats, reduce the production of inflammatory fibrous tissue, and better promote bone regeneration.
This study made progress on nano-catalytic coatings for osteoporotic fracture repair.
Reference: Dandan Shao, Kai Li, Tao Hu, Shanjin Wang, Haowei Xu, Shubao Zhang, Shiwei Liu, Youtao Xie, Xuebin Zheng, Titania nanotube array supported nanoceria with redox cycling stability ameliorates oxidative stress-inhibited osteogenesis, Chemical Engineering Journal, Volume 415, 2021, 128913, ISSN 1385-8947, https://doi.org/10.1016/j.cej.2021.128913. (https://www.sciencedirect.com/science/article/pii/S1385894721005076)
Provided by Chinese Academy of Sciences