Sunlight-Activatable ROS Generator for Cell Death Using TiO₂/c-Si Microwires

Area of Science:

• Photocatalysis
• Water Purification
• Reactive Oxygen Species (ROS) Generation

Background:

• Solar-driven reactive oxygen species (ROS) generation offers a promising disinfection method for water purification.
• Existing photocatalysts often lack stability in aquatic environments and sufficient ROS diffusion length for effective pathogen damage.

Purpose of the Study:

• To develop a stable, solar-driven ROS generation system for efficient water disinfection.
• To characterize the ROS species and their diffusion length for targeted cell death.
• To evaluate the bactericidal efficacy of the developed system.

Main Methods:

• Fabrication of tapered crystalline silicon microwires coated with anatase titanium dioxide.
• Measurement of sunlight absorption spectrum (300-1100 nm).
• Logistic regression analysis of cellular survival data to determine ROS diffusion length.
• Quantitative analysis of bactericidal effect after light irradiation.

Main Results:

• The system demonstrated effective sunlight absorption (>95%) across a broad spectrum.
• Logistic regression indicated a ROS diffusion length of approximately 9 μm, identifying hydrogen peroxide (H2O2) as the dominant damaging species.
• 15 minutes of light irradiation achieved a bactericidal effect comparable to 3 mM H2O2.

Conclusions:

• The developed TiO2-coated silicon microwire system is a highly effective solar-driven ROS generator for water disinfection.
• The system produces localized H2O2 with significant bactericidal efficacy, comparable to conventional methods.
• This technology presents a viable solution for efficient and sustainable water purification.