Researchers Quantify the Uptake and Distribution of Targeted Nanoparticles

Nanoparticles linked to targeting molecules are increasingly being cited as potential chemotherapeutic agents, and a recent publication has now quantified how such molecules are distributed to various organelles within a target cell.

Investigators at Purdue University (West Lafayette, IN, USA) worked with nanorods constructed of gold and a magnetic material and coated with trastuzumab, an anticancer drug used to used to treat breast cancer that has metastasized in women whose tumor cells produce an overabundance of human epidermal growth factor receptor 2 (HER2). The location of the nanorods in cultured breast cancer cells was determined by a combination of magnetic resonance spectrometry and microscopy. In some experiments, the drug was marked with a fluorescent molecule, and localization was quantified and diffusion times evaluated in different cell organelles by using fluorescence correlation spectroscopy (FCS).

Results published in the November 5, 2009, online edition of the journal ACS Nano revealed that, that in treated breast cancer cells the conjugated nanoparticles co-localized with the endosome and lysosome but not with the Golgi apparatus. The nanorods had similar intracellular localization characteristics as the fluorescently labeled drug. These findings not only lay the foundations for a quantitative understanding of the fate of nanoparticle-based targeting but also provide new insights into the rational design of nanoparticle delivery systems for effective treatment.

"Each nanoparticle acts like a deliverer of a mail package, or dose, of the drug directly to the appropriate location," said senior author Dr. Joseph Irudayaraj, professor of biological engineering at Purdue University. "We have demonstrated the ability to track these nanoparticles in different cellular compartments of live cells and show where they collect quantitatively. Our methods will allow us to calculate the quantities of a drug needed to treat a cancer cell because now we know how these nanoparticles are being distributed to different parts of the cell."

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