Bacteria are adapting to antibiotics, and it’s becoming a serious public health threat. A considerable part of the reason is that the bacteria continue to pass resistance genes to each other. Thankfully, scientists at Rice University developed a system that uses graphene-oxide wrapped nanoparticles to kill the bugs and their resistance genes that pollute wastewater.
When bacteria figure out how to resist antibiotics, they don’t keep that information to themselves; instead, they spread the knowledge to others to help them survive. These community-minded organisms can persist in environments from natural waterways to wastewater plants, supercharging bacteria that haven’t directly encountered the drugs themselves.
The new study, detailed in the journal Water Research, demonstrates a new disinfecting system for use in wastewater treatment plants. The base of the method involves photocatalysts in the form of “nano-spheres,” which are made of oxygen, carbon, and bismuth. When the spheres are stimulated by light, they produce molecules known as reactive oxygen species (ROS). These molecules are deadly against antibiotic-resistance genes (ARGs) and bacteria alike.
When the team conducted tests against multi-drug-resistant E. coli, they found that the nano-spheres were more efficient if wrapped in a protective graphene-oxide based shell. This simple layer of graphene-oxide prevented ROS from getting destroyed while allowing them to produce three times more ROS than the spheres without the protective shell. When the researchers added nitrogen to these shells, it provided a boost and helped the spheres capture more bacteria.
Pingfeng Yu, the study’s co-lead author, explained:
Wrapping improved bacterial affinity for the microspheres through enhanced hydrophobic interaction between the bacterial surface and the shell. This mitigated ROS dilution and scavenging by background constituents and facilitated immediate capture and degradation of the released ARGs.
The spheres are large enough to be filtered out of the water and can be reused several times before losing its efficiency. In the laboratory, the team reused the spheres ten times, and the majority of their photocatalytic activity remained.
