Previous work by Frangioni and first author Hak Soo Choi, PhD, an Instructor of Medicine at HMS, had established the characteristics of nanoparticles that regulate clearance from the body. "To be of value clinically, nanoparticles must be able to either biodegrade into biologically inert compounds, or be efficiently cleared from the body," says Choi, explaining that accumulation of nanoparticles can be toxic.
The aim of this new study was to determine the characteristics and parameters of inhaled nanoparticles that mediate their uptake into the body -- from the external environment, across the alveolar lung surface and into the lymphatic system and blood stream and eventually to other organs. To do this, the scientists made use of the FLARE (Fluorescence-Assisted Resection and Exploration) imaging system, systematically varying the chemical composition, size, shape and surface charge of a group of near-infrared fluorescent nanoparticles to compare the physiochemical properties of the various engineered particles. The investigators then tracked the movement of the varying nanoparticles in the lungs of rat models over a period of one hour, and also verified results using conventional radioactive tracers.
"The FLARE system enabled us to cut the number of experiments in half while performing direct comparisons of nanoparticles of different sizes, shapes and rigidities," explains Frangioni, whose laboratory developed the FLARE system for use in image-guided cancer surgery as well as other applications.
Their results established that non-positively charged nanoparticles, smaller than 34 nm in diameter, appeared in the lung-draining lymph nodes within 30 minutes. They also found that nanoparticles smaller than 6 nm in diameter w
|Contact: Bonnie Prescott|
Beth Israel Deaconess Medical Center