Silica smart bombs deliver knock-out t...( CHAPEL HILL Bacteria mutate for a l...),Health

CHAPEL HILL Bacteria mutate for a living, evading antibiotic drugs while killing tens of thousands of people in the United States each year. But as concern about drug-resistant bacteria grows, one novel approach under way at the University of North Carolina at Chapel Hill seeks to thwart the bug without a drug by taking a cue from nature.

Mark Schoenfisch and his lab of analytical chemists at UNC have created nano-scale scaffolds made of silica and loaded with nitric oxide (NO) an important molecule in mammals that plays a role in regulating blood pressure, neurotransmission and fighting bacterial infections, among other vital functions.

There was evidence that nitric oxide kills bacteria, but the difficult part involved storing it in a manner such that it could be delivered to bacterial cells, said Evan Hetrick, a doctoral student in Schoenfischs lab and lead author on a paper in the February issue of the American Chemical Societys journal ACS Nano.

While the body constantly produces NO, and can ramp up its production to fight infection, sometimes it cant produce enough to mount a sufficient defense. Previous research using small molecules to deliver NO hit roadblocks controlling the release of the compound was difficult and the molecules were potentially toxic to healthy cells in the body.

With silica scaffolds, nitric oxide stores easily and we could very carefully control the release, said Schoenfisch, an associate professor of chemistry in UNCs College of Arts and Sciences.

Schoenfisch, Hetrick and their colleagues tested their silica scaffolds head-to-head with small molecules against the bacteria Pseudomonas aeruginosa, which is commonly found in burn and other wound infections.

NO delivered by both methods completely killed the bacteria. But the silica nanoparticles delivered the NO right to the bacterias doorstep. In contrast, the small molecules released NO indiscriminately, and the concent
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