Nanoparticles Shown to Super-Charge Antibiotics

(CN) – In the latest salvo against multidrug-resistant bacteria like E. coli and salmonella, researchers have turned to a new, smaller ally: light-activated nanoparticles.

Drug-resistant superbugs, which evolve quicker than new antibiotic treatments can be developed to treat them, cost the United States an estimated $20 billion in direct health care costs and another $35 billion in lost productivity in 2013 alone.

In order to mount a successful defense, researchers have boosted existing antibiotics for certain bacteria by incorporating nanoparticles that can be used selectively and activated or deactivated by using specific wavelengths of light.

These nanoparticles, also known as quantum dots, release superoxide – a chemical species that disrupts the bacteria’s cellular and metabolic processes, triggering a fight response that leaves it more vulnerable to antibiotics, the team reports Thursday in the journal Science Advances.

“We’ve developed a one-two knockout punch,” said the study’s co-lead author, Prashant Nagpal, an assistant professor at the University of Colorado, Boulder. “The bacteria’s natural fight reaction [to the dots] actually leaves it more vulnerable.”

The infections’ resistance to antibiotics was 1,000 times less effective after administering the dots, which did not produce any adverse side effects, according to the findings.

“We are thinking more like the bug,” said co-lead author Anushree Chatterjee, who is also an assistant professor at CU Boulder. “This is a novel strategy that plays against the infection’s normal strength and catalyzes the antibiotic instead.”

Unlike other antibiotic treatments, which attack the bacteria indiscriminately, the dots are able to work selectively on an intracellular level. This is helpful against salmonella, for example, as the bacteria grows and reproduces inside host cells. The dots are small enough to enter the cells and help clear the infection from within.

“These super-resistant bugs already exist right now, especially in hospitals,” Nagpal said. “It’s just a matter of not contracting them. But they are one mutation away from becoming much more widespread infections.”

Above all, the dots offer clinicians another tool that can be used as part of an adaptable, multifaceted approach to battling infections that already strain the limits of existing treatments, Chatterjee said.

“Disease works much faster than we do,” she said. “Medicine needs to evolve as well.”

The team views the dots as a kind of platform technology that can be modified and scaled to fight a wide range of infections. They could also potentially be expanded to other therapeutic applications.

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