TiO ₂ Decorated SiO ₂ Nanoparticles as Efficient Antibacterial Materials: Enhanced Activity under Low Power UV Light

TiO 2 based photocatalytic materials show effective antibacterial activity typically under a high‐power UV light. However, exposure to high‐intensity radiation may be detrimental to biological as well as non‐biological materials. In this work, we demonstrate a significantly higher antibacterial activity at even low power UV where TiO 2 nanoparticles are decorated on silica nanoparticles. The antibacterial activity of the nanoparticles with varying Si : Ti molar compositions were explored against E. coli to obtain effective antibacterial activity with minimal power of UV radiation (8 W). The nanoparticles with a molar ratio of SiO 2 : TiO 2 =2 : 1 (Si2Ti) showed the best antibacterial activity. The minimum inhibitory concentration (MIC) of the Si2Ti catalyst was also determined for varying duration of exposure to 8 W UV radiation. Even at a very low concentration of 5 mg/mL Si2Ti sample, where the active catalyst amount was only 1.66 mg/mL, 100 % killing of E. coli was observed after 90 minutes of UV exposure. For the exposure time of 120 minutes, MIC was reduced even further to 3 mg/mL with an active catalyst amount of 1 mg/mL. The excellent antibacterial activity is attributed to the small crystallite size of TiO 2 along with enhanced interaction with bacteria owing to the presence of SiO 2 . In addition, Si2Ti showed good biocompatibility with more than 87 % cell viability with fibroblast cells for 500 μg/mL of the sample.