This study reports an entirely new chemo‑thermal treatment that simultaneously imparts antibacterial activity and osteoconductivity to titanium and its alloys for orthopedic and dental implants. First, a bone‑inducing, layered calcium titanate (CaTiO₃‑based) film is generated by NaOH – CaCl₂ – heat treatment. The Ca²⁺ ions within this layer are then ion‑exchanged with I⁺/I₃⁺, introducing 0.7–10.5 mass % iodine in a controlled manner.
X‑ray photoelectron spectroscopy showed that most iodine is in a positively charged state, while abundant acidic and basic Ti–OH groups form on the surface, shifting the isoelectric point to pH 5.3. These acid–base functionalities accelerate apatite precipitation in simulated body fluid (SBF).
A Ti specimen carrying 8.6 mass % iodine released a total of 5.6 ppm iodine over 90 days and achieved > 99 % bactericidal efficacy against MRSA, Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli. Even after harsh durability tests—humid heat (80 °C, 95 % RH) and PBS immersion (37 °C, 6 months)—the inhibition rate against MRSA remained 97.3 %, proving long‑term anti‑infection capability.
Cell culture with MC3T3‑E1 pre‑osteoblasts and L929 fibroblasts revealed no significant cytotoxicity; osteoblast proliferation at day 3 was actually enhanced. All samples formed low‑crystalline apatite in SBF within three days, confirming strong in vitro bone‑bonding potential.
The iodine‑loaded calcium titanate layer can also be applied to medical alloys such as Ti‑6Al‑4V and Ti‑15Zr‑4Nb‑4Ta; scratch testing documented high adhesion and scratch resistance up to 119 mN. Collectively, these results demonstrate a multifunctional implant surface that promotes rapid bone integration while suppressing postoperative infection over extended periods—capabilities of particular clinical significance for high‑risk joint and dental implants.
Article information & citation
Seiji Yamaguchi, Phuc Thi Minh Le, Seine A. Shintani, Hiroaki Takadama, Morihiro Ito, Sara Ferraris, Silvia Sprianoi. Iodine-Loaded Calcium Titanate for Bone Repair with Sustainable Antibacterial Activity Prepared by Solution and Heat Treatment. Nanomaterials, 11(9), 2199, 2021.
https://doi.org/10.3390/nano11092199