Scientists from the California NanoSystems Institute at UCLA have developed a nanoparticle delivery system for the antibiotic moxifloxacin that vastly improves the drug’s effectiveness against pneumonic tularemia, a type of pneumonia caused by inhalation of the bacterium Francisella tularensis. The study, which was published online on October 5, 2015 in the journal ACS Nano, shows how the nanoparticle system targets the precise cells infected by the bacteria and maximizes the amount of drug delivered to those cells. The article is titled “Mesoporous Silica Nanoparticles with pH-Sensitive Nanovalves for Delivery of Moxifloxacin Provide Improved Treatment of Lethal Pneumonic Tularemia.” Jeffrey Zink, Ph.D., Distinguished Professor of Chemistry and Biochemistry and a senior author on the study, developed the mesoporous silica nanoparticles used for drug delivery. Dr. Zink and his research team conducted an exhaustive process to find the best particle for the job. “The nanoparticles are full of deep empty pores,” Dr. Zink said. “We place the particles in drug solution overnight, filling the pores with drug molecules. We then block the pore openings on the nanoparticle’s surface with molecules called nanovalves, sealing the drug inside the nanoparticle.” When the drug-bearing nanoparticles are injected into the infected animal, in this case a mouse, the drug stays in the nanoparticles until they reach their target: white blood cells called macrophages. Macrophages ingest nanoparticles into compartments that have an acidic environment. The nanovalves, which are designed to open in response to the more acidic surroundings, then release the drug.
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