Use of Magnetic Nanoparticles as In Situ Mucus Property Probe

Magnetic nanoparticles (MNPs) are unique in their abilities to penetrate and interact with a wide range of liquid media. Because of their magnetic properties, MNPs can be directed to any area of interest, and interact with core structures deep inside the medium which is normally inaccessible. In this report, we investigate the behavior of MNPs in a specific biological fluid, namely in a mucus layer of air-liquid interface cultured primary normal human tracheobronchial epithelial cells. Using Fokker-Planck algorithm simulations and observing the behavior of MNPs from prior experiments, we found MNPs that are initially less than 100 nm in size, to aggregate into sizes of similar to 50 mu m and to deviate from the expected Fokker-Planck distribution due to the mucus structure. Based on our analysis, human tracheobronchial epithelial (NHTE) cell mucus viscosity ranges from 15 Pa.s to 150 Pa.s. The results not only confirm the possible use of MNPs as a means for medical drug delivery but also underline important consequences of MNP surface modifications.