Gold Nanodisks and Laser Light Team Up to Kill Bacteria

An artist’s interpretation of how bacteria cells on a nanoporous gold disk array are killed after exposure to near-infrared light. Credit: Greggy M. Santos and Wei-Chuan Shih

In the search for alternatives to antibiotics, researchers at University of Houston have created new gold nanoparticles that have shown an excellent ability at killing bacteria. The tiny gold disks, only a few nanometers in diameter, have holes throughout their surface. These gold nanoparticles have an impressive ability at converting light into heat, so that when a laser is directed toward them they get so hot that nearby bacteria get cooked to death.

The researchers tested these disks by placing on them E. coli and a couple heat resistant bacteria that survive within hot springs. The researchers showed that within 25 seconds of a laser illuminating the disks, all the bacteria was declared dead. E. coli was deactivated even faster, within five seconds. The investigators used viability tests and a scanning electron microscope to confirm the results.

Now there’s talk of integrating these gold nanoparticles onto the surface of urinary catheters and using a laser shining through the catheter to kill any bacteria within.

SEM images of E. coli (a, b and c), B. subtilis (d, e and f) and Exiguobacterium sp. AT1b (g, h and I) cells deposited on nanoporous gold disk arrays. Bacteria cells in images A, D and G were not exposed to near-infrared light. All other cells were exposed for 25 seconds. Credit: Greggy M. Santos and Wei-Chuan Shih

Study in Optical Materials Express: Photothermal inactivation of heat-resistant bacteria on nanoporous gold disk arrays…

Source: Optical Society…