Enhancement of in vitro antibacterial activity and bioactivity of iodine‐loaded titanium by micro‐scale regulation using mixed‐acid treatment

Abstract

Postoperative infection and subsequent device loss are serious complications in the use of titanium dental implants and plates for jawbone reconstruction. We have previously reported that NaOH–CaCl2–thermal–ICl3–treated titanium (NaCaThIo) has a nano‐scale surface and exhibits antibacterial activity against Staphylococcus aureus. The present study examined the surface properties of mixed‐acid treated and then iodine‐treated titanium (MA–NaCaThIo), and evaluated oral antibacterial activity and cytotoxicity compared with the results obtained with NaCaThIo. MA‐NaCaThIo formed a surface layer with a nano‐scale network structure having microscale irregularities, and both the thickness of the surface layer (1.49 ± 0.16 μm) and the average surface roughness (0.35 ± 0.03 μm) were significantly higher than those of NaCaThIo. Furthermore, MA‐NaCaThIo maintained high hydrophilicity with a contact angle of 7.5 ± 1.7° even after 4 weeks, as well as improved apatite formation, iodine ion release, and antibacterial activity against Prevotella intermedia compared to NaCaThIo. Cell culture test revealed that MA‐NaCaThIo exhibited no cytotoxicity against MG‐63 and Vero cells, while increased cell proliferation, ALP activity and mineralization of MG‐63 compared to NaCaThIo. This treated titanium is expected to be useful for the development of next‐generation titanium devices having both bone‐bonding and antibacterial properties.