Behavior of Self-Disintegrating Microparticles at the Air/Mucus Interface

In recent years, highly specialized nanoscopic drug carriers have been developed, which can, e.g., traverse biological barriers, protect drugs against harsh physiological conditions, and release such drugs in a controlled manner. However, for the delivery of particles via the respiratory pathway, aerodynamic diameters in the range of several micrometers are required to achieve good lung deposition and biodistribution. To combine the favorable properties of inhalable, micron-sized particles with the advantages of nanosized drug carriers, herein, dry-powder, hybrid microparticles (h-μPs), which disintegrate upon contact with moist surfaces (as present in the lung) to release the embedded nanoparticles into the mucosa, are introduced. Furthermore, a microfluidic setup, which mimics the air–gel interface of the mucosal airway epithelium, is presented. With this setup, the interaction of airborne h-μPs with the mucosal interface on a microscopic level is investigated. In detail, the influence of the h-μP charge on their deposition efficiency is tested and it is found that this process is governed by a combination of electrostatic interactions between the mucosal surface and the h-μPs as well as hygroscopic effects. Thus, this approach can help to optimize inhalable drug carriers to increase the efficiency of pulmonary drug administration via the respiratory pathway.