University of Houston researchers developed a new, photothermal technique to kill bacteria.
The technique uses gold disks and light to hit bacteria with an “instantaneous thermal shock”. The gold disks are tiny - only a few hundred nanometers in diameter - and can be formed into numerous shapes. The gold nanodisks absorb light and convert it into heat (we’re talking over 200
oC!).
The group tested the technique on three types of bacteria: E. coli, Bacillus subtilis, and the heat-resistant Exiguobacterium (species of this genus have been found in hot springs at Yellowstone National Park). They placed bacterial cells on the gold surface and applied infrared light.
According to study author Wei-Chuan Shih,”we showed that all of the bacteria were killed pretty quickly ... within 5 to 25 seconds. That's a very fast process". Of the species tested, E. coli proved to be the most vulnerable, having been killed within just 5 seconds. This is a huge improvement over other nanoparticle-based technologies that typically require 1-20 minutes to kill cells.
It’s clear that these gold nanodisks have many biomedical applications - catheters and other medical devices, for example. “Any sort of light activated procedure would be much easier to implement at the bedside of a patient”, says Shih.
Sources: Optical Materials Express,
The Optical Society,
Wikipedia
