Researchers have found a way to use magnetic nanoparticle clusters to punch through biofilms to reach bacteria that can foul water treatment systems.

The nanoclusters then deliver bacteriophages—viruses that infect and propagate in bacteria—to destroy the bacteria, usually resistant to chemical disinfection.

Without the pull of a magnetic host, these “phages” disperse in solution, largely fail to penetrate biofilms and allow bacteria to grow in solution and even corrode metal, a costly problem for water distribution systems.

The Rice University lab of environmental engineer Pedro Alvarez and colleagues in China developed and tested clusters that immobilize the phages. A weak magnetic field draws them into biofilms to their targets.

“This novel approach, which arises from the convergence of nanotechnology and virology, has a great potential to treat difficult-to-eradicate biofilms in an effective manner that does not generate harmful disinfection byproducts,” Alvarez says.

Biofilms can be beneficial in some wastewater treatment or industrial fermentation reactors owing to their enhanced reaction rates and resistance to exogenous stresses, says graduate student and co-lead author Pingfeng Yu.

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Magnetic Graphene

New research could lead to new multi-functional electronic devices.

New research could lead to new multi-functional electronic devices.

Graphene is regarded by many as a wonder material and hosts a multitude of amazing properties, but magnetism has never been one of them. The only way to make the material magnetic is by doping it with magnetic imputrites, but that tends to negatively impact its electronic properties. Now, a team of physicists at the University of California, Riverside decided to address this issue by finding a way to induce magnetism in graphene while also preserving its magnetic properties.

To do this, the team brought a graphene sheet very close to a magnetic insulator – an electrical insulator with magnetic properties.

“This is the first time the graphene has been made magnetic this way,” said Jing Shi, a professor of physics and astronomy, whose lab led the research. “The magnetic graphene acquires new electronic properties so that new quantum phenomena can arise. These properties can lead to new electronic devices that are more robust and multi-functional.”

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