Nano strategy fights superbugs for wastewater plants

A three-step method developed by Rice University researchers to produce molecular-imprinted graphitic carbon nitride nanosheets can help catch and kill free-floating antibiotic resistant genes found in secondary effluent produced by wastewater plants.

By Mike Williams March 18, 2020

It’s not enough to take antibiotic-resistant bacteria out of wastewater to eliminate the risks they pose to society. The bits they leave behind have to be destroyed as well.

Researchers at Rice University’s Brown School of Engineering have a new strategy for “trapping and zapping” antibiotic resistant genes, the pieces of bacteria that, even though theirs hosts are dead, can find their way into and boost the resistance of other bacteria.

The team led by Rice environmental engineer Pedro Alvarez is using molecular-imprinted graphitic carbon nitride nanosheets to absorb and degrade these genetic remnants in sewage system wastewater before they have the chance to invade and infect other bacteria.

The researchers targeted plasmid-encoded antibiotic-resistant genes (ARG) coding for New Delhi metallo-beta-lactamase 1 (NDM1), known to resist multiple drugs. When mixed in solution with the ARGs and exposed to ultraviolet light, the treated nanosheets proved 37 times better at destroying the genes than graphitic carbon nitride alone.

The work done under the auspices of the Rice-based Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment (NEWT) is detailed in the American Chemical Society journal Environmental Science and Technology.

“This study addresses a growing concern, the emergence of multidrug resistant bacteria known as superbugs,” said Alvarez, director of the NEWT Center. “They are projected to cause 10 million annual deaths by 2050.

At left, a scanning electron microscope image shows the mesoporous structure of molecular-imprinted graphitic carbon nitride nanosheets. At right, a transmission electron microscope image shows the sheet’s edge and its crystalline structure. Rice researchers imprinted the nanosheets to catch and kill free-floating antibiotic resistant genes found in secondary effluent produced by wastewater plants. Courtesy: Alvarez Research Group[/caption]

There is room to improve the current process, despite its extraordinary initial success. “We have not yet attempted to optimize the photocatalytic material or the treatment process,” Zhang said. “Our objective is to offer proof-of-concept that molecular imprinting can enhance the selectivity and efficacy of photocatalytic processes to target eARGs.”

Qingbin Yuan of Nanjing Tech University, China, is co-lead author of the paper. Co-authors are Rice graduate students Ruonan Sun and Hassan Javed, and Gang Wu, an assistant professor of hematology at The University of Texas Health Science Center at Houston’s McGovern Medical School. Pingfeng Yu, a postdoctoral researcher at Rice, is co-corresponding author. Alvarez is the George R. Brown Professor of Civil and Environmental Engineering and a professor of chemistry and of chemical and biomolecular engineering.

Rice University

– Edited by Chris Vavra, associate editor, Control Engineering, CFE Media and Technology,

Author Bio: Mike Williams is a senior media relations specialist in Rice University's Office of Public Affairs.