Antibiotic-resistant bacteria are becoming a serious public health threat, in part because they can pass on drug-resistant genes to each other,media New Atlas reported. Now, researchers at Rice University have developed a system that uses nanoparticles wrapped in graphene oxide to kill superbugs in wastewater and their free-floating drug-resistant genes.
Bacteria are group-conscious creatures, so when some of them come up with how to fight antibiotics, they quickly spread the ability to other bacteria to help them survive. These antibiotic resistance genes (ARGs) can persist in environments such as sewage plants and escape into natural waterways, giving super-power to bacteria that do not have direct contact with the drug themselves. This means that killing bacteria alone is often not enough — loose genes only spawn more superbugs. So scientists are studying how to prevent bacteria from spreading these genes, and how to clean up both bacteria and ARGs.
The new study, which belongs to the latter, describes a new disinfection system for sewage treatment plants. At the heart of the new technology is a photocatalyst in the form of “nanospheres” made of vanadium, oxygen and carbon. Stimulated by light, these photocatalysts produce molecules called reactive oxygen species (ROS), which are deadly to both bacteria and ARG.
In tests on multidrugresistant E. coli, the team found that these “nanospheres” were better performed if they were wrapped in protective shells made of graphene oxide. This layer of protection reduces the number of Ros destroyed in the environment, allowing them to produce three times as many Ros as unwrapped spheres.
As an additional improvement, adding these graphene oxide shells to nitrogen helps the sphere capture more bacteria, giving them more time to kill the bacteria and the ARG that may fall after death.
“The package improves the affinity of bacteria to microspheres by enhancing hydrophobic interactions between the surface and shell of bacteria,” said Pingfeng Yu, co-author of the study. “This reduces the dilution and removal of background components to ROS and facilitates the direct capture and degradation of released ARGs.”
The researchers also say the spheres are large enough to filter out from water and reuse them multiple times. In tests, the team showed that even after being reused 10 times, the sphere retained most of its photocatalytic activity.
The study was published in the journal Water Research.