Effects of different sterilization techniques and varying anodized TiO₂ nanotube dimensions on bacteria growth

Infection of titanium (Ti)-based orthopedic implants is a growing problem due to the ability of bacteria to develop a resistance to today's antibiotics. As an attempt to develop a new strategy to combat bacteria functions, Ti was anodized in the present study to possess different diameters of nanotubes. It is reported here for the first time that Ti anodized to possess 20 nm tubes then followed by heat treatment to remove fluorine deposited from the HF anodization electrolyte solution significantly reduced both S. aureus and S. epidermidis growth compared to unanodized Ti controls. It was further found that the sterilization method used for both anodized nanotubular Ti and conventional Ti played an important role in the degree of bacteria growth on these substrates. Overall, UV light and ethanol sterilized samples decreased bacteria growth, while autoclaving resulted in the highest amount of bacteria growth. In summary, this study indicated that through a simple and inexpensive process, Ti can be anodized to possess 20 nm tubes that no matter how sterilized (UV light, ethanol soaking, or autoclaving) reduces bacteria growth and, thus, shows great promise as an antibacterial implant material.