Washington, February 26 : Silica nanoparticles might offer an effective way of delivering nitric oxide (NO) into the cells to kill bacteria, said researchers.
"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 at the University of North Carolina at Chapel Hills.
While stressing the advantages of silica nanoparticles in a paper published in the American Chemical Society's journal ACS Nano, Hetrick said that the body constantly produces NO, and can ramp up its production to fight infection.
However, sometimes the body might fail to produce enough of NO to mount a sufficient defence, and warrant its delivery from external sources, he added.
Hetrick worked in the lab of Mark Schoenfisch, an associate professor of chemistry in UNC's College of Arts and Sciences, to create nano-scale scaffolds from silica, which they say can effectively deliver NO to bacterial cells.
"With silica scaffolds, nitric oxide stores easily and we could very carefully control the release," said Schoenfisch.
The researchers said that their silica scaffolds appeared to be more promising than small molecules that were found to be potentially toxic to healthy cells in the body in previous studies.
While experimenting on the commonly found bacteria Pseudomonas aeruginosa, the researchers found that the silica nanoparticles delivered the NO right to the bacteria's doorstep. In contrast, the small molecules released NO indiscriminately, and the concentration of NO was lost as it made its way toward bacterial cells.
"With the silica particles, more NO actually reached the inside of the cells, enhancing the efficacy of the nanoparticles compared to the small molecule. So, the overall amount of NO needed to kill bacteria is much less with silica nanoparticles. And, with small molecules, you're left with potentially toxic byproducts," Schoenfisch said.
While experimenting on mouse cells, the researchers also showed that the silica nanoparticles were not toxic to healthy cells, but the small molecules were.
Schoenfisch said that the amount and rate of NO release could be easily modified and controlled by using different silica nanoparticles.
"Release rates are a function of the precursors used to make the nanoparticles. It depends entirely on how we build the silica structures," Schoenfisch said.
The researchers said that their future research would include studying additional bacterial strains, active targeting, preferential uptake, and biodistribution studies.