Magnetised viruses attack harmful bacteria

 

Researchers have revealed images of magnetic nanoparticle clusters that can punch through biofilms to reach the bacteria that foul water treatment systems.

 

Phage-enhanced nanoparticles, developed by researchers at Rice University and the University of Science and Technology of China, carry bacteriophages - viruses that infect and propagate in bacteria - and deliver the cellular organisms to targets that generally resist chemical disinfection.

 

Without the pull of a magnetic host, these phages disperse in solution, fail to penetrate biofilms and allow bacteria to grow in solution.

 

Tests from Rice environmental engineer, Professor Pedro Alvarez, and colleagues show that the clusters immobilise the phages, while a weak magnetic field draws them into biofilms, and to the targets.

 

 

The researchers used polyvalent phages - that can attack more than one type of bacteria - to target lab-grown films that contained strains of Escherichia coli associated with infectious diseases and Pseudomonas aeruginosa, which is prone to antibiotic resistance.

 

The phages were combined with nanoclusters of carbon, sulphur and iron oxide, modified with amino groups.

 

Crucially, the amino-coating prompted the phages to bond with the clusters head-first, which left the infectious tails exposed and able to infect bacteria.

 

The researchers used a relatively weak magnetic field to push the nanoclusters into the film.

 

Analyses revealed the method killed more than 90% of E. coli and P. aeruginosa, while phages alone killed less than 40%.

 

“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,” adds Alvarez.

 

Research is published in Environmental Science: Nano