Interactive response analysis of transportation and deposition of engineered aerosol particle in airway

Inhalable immunization is a multidimensional colloidal delivery process, involving aerosol particle transport in the airways and interaction with mucus at the mucosal interface. Primarily, the impact of airway anatomy, airflow, and particle's physicochemical properties on aerosol deposition and deep lung delivery are highly desired. In this study, a human airway geometry model was constructed, and the airflow field distribution and turbulence characteristics based on airway anatomy were visualized through in silico simulation. The dimensionless numbers of Stokes number (Stk) and Schmidt number (Sc) were introduced to mechanistically demonstrate the particle deposition under the impact of multiple parameters, including inlet airflow rate (Q), particle size (dp), and particle density (rho). With the increasement of Stk and Sc, the mechanism transitioned from Brownian diffusion- to inertial impact-dominated deposition. The response surface methodology (RSM) analysis indicated that the Q and interaction term between particle size and inlet airflow rate (dpQ) were the most critical parameters that dominated deep lung transportation fraction (DLF). The proposed regression equation provided quantitative design guidance for parameter of airflow and particle. This in silico methodology provides a rational predictive design strategy for inhaled aerosol formulations for both therapeutic and prophylactic applications.