– Anoushka Dasgupta
Drug-resistant bacteria can lead to mortality and economic loss, and are a cause for concern in the fields of healthcare and food processing. They often spread through surfaces such as doorknobs, public seats and medical equipment like stethoscopes.
Previous attempts to develop antibacterial surfaces, by coating them with chemicals, have led to bacteria becoming drug-resistant. Another approach involves surfaces using photocatalysts such as titanium dioxide (TiO2), which on exposure to UV light generate chemically reactive molecules called Reactive Oxygen Species (ROS) that kill bacteria by disrupting their cell membranes. However, in its commonly used configuration, a TiO2-based surface is an inefficient light absorber and produces few ROS.
To counter such problems, researchers at the Centre for Nano Science and Engineering (CeNSE), IISc, devised a comprehensive design principle for a surface that can kill bacteria using nanostructures with a TiO2 coating.
Optimization of photocatalytic-coated antibacterial nanopillars (Credit: authors/ACS Applied Materials and Interfaces)
Through simulations and experiments, the researchers maximised ROS production using TiO2-coated, non-absorbing nanostructures of a particular height, and found that the best underlying material for these nanostructures is a transparent non-photoreactive material such as Black Silica (SiO2).
These design rules can be used to build highly efficient antibacterial surfaces in hospitals, airports, public transport, and other areas.
Jagriti Singh, Shubham Jadhav, Sushobhan Avasthi and Prosenjit Sen, Designing Photocatalytic Nanostructured Antibacterial Surfaces: Why Is Black Silica Better than Black Silicon? ACS Applied Materials and Interfaces, 2020, 12, 18.
Lab website: http://www.cense.iisc.ac.in/mflab/
Microfluidic Devices & Heterogeneous Systems Lab Group Photo (Credit: Saransh Arora)