A real-time imaging system has enabled scientists at Beth Israel Deaconess Medical Center (BIDMC) and the Harvard School of Public Health to track near-infrared (NIR) fluorescent nanoparticles as they moved from the airspaces of the lungs, into the body and out again. The resulting knowledge promises to help develop therapeutic agents to treat pulmonary disease, as well as offer a greater understanding of the health effects of air pollution.1
The study aimed 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 bloodstream, and eventually to other organs. The researchers used the FLARE (Fluorescence-Assisted Resection and Exploration) imaging system and systematically varied the chemical composition, size, shape and surface charge of a group of NIR fluorescent nanoparticles to compare them. The team then tracked the nanoparticles' movement in the lungs of rat models, and verified results using conventional radioactive tracers. 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 with equal positive and negative charge traveled to the draining lymph nodes within just a few minutes, and were subsequently cleared by the kidneys.
These findings promise to help drug makers design and optimize particles for delivery by inhalation, and may also guide assessment of the health effects of particulate pollutants.
1. H.S. Choi et al., Nature Biotechnology 28: 1300-1303 (2010)