Toxic nanoparticles kill drug resistant bacteria

12th July 2017

FAPESP

Enaie Azambuja

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A team of Brazilian scientists may have come up with a practical way of killing off resistant bacteria by targeting them with toxic silver-silica nanoparticles coated with an antibiotic. Since antibiotics don’t have the full punch to eliminate bacteria resistant to them, the researchers instead used the antibiotic ampicillin as a mechanism to deliver the killer nanoparticles to the pathogens.

Normally, silver-silica nanoparticles would be toxic to the body, but because they’re coated with ampicillin they seem to be inert to the body’s cells and don’t affect how they divide and multiply.

Bacterial cells, on the other hand, receive a large dose of the antibiotic coupled with a silver-silica nanoparticle attack. In the laboratory study, the combined effect was powerful enough to overcome bacterial drug resistance of a strain of E. coli, an impressive feat.

The bacterial killing properties of these functionalised nanoparticles were also enhanced by positioning the antibiotic molecules on the surface of silver-silica nanoparticle cores so that the sides that most affect bacterial membranes end up on the outside.

“There are commercial drugs that contain nanoparticles, which typically serve to coat the active ingredient and extend its lifetime inside the organism. Our strategy is different. We decorate the surface of the nanoparticles with certain chemical groups that direct them to the site where they’re designed to act, so they’re highly selective,” said Mateus Borba Cardoso, lead study author and a researcher at Brazil’s National Energy & Materials Research Center (CNPEM).

Testing the toxicity of the so called 'nanoantibiotic,' the researchers exposed human liver cells to the nanoparticles and showed that they don’t seem to be toxic to the cells.