mRNA-lipid nanoparticles (LNPs) are promising for pulmonary delivery; however, mesh nebulization induces mechanical and interfacial stresses that lead to LNP deformation and mRNA leakage. Here, we investigated the destabilization mechanisms using physicochemical characterization and phase-field computational fluid dynamics (CFD) simulations.

mRNA-LNPs were prepared via microfluidic mixing, and poly(vinyl alcohol) (PVA) formulations were screened based on post-nebulization size and encapsulation efficiency (EE). Interfacial properties, including surface tension and Marangoni effects, as well as aerosol droplet size (Dv90), were measured. CFD simulations modeled droplet collision dynamics using experimental Weber numbers (3.33 for 0% PVA and 5.35 for 1% PVA).

LNPs exhibited appropriate size and high EE. The addition of 1% PVA reduced surface tension and Dv90. CFD showed that droplets without PVA underwent complete coalescence, generating high pressure (~20,000 Pa), whereas 1% PVA promoted rebound, preventing coalescence and lowering pressure to ~12,000 Pa (1.6-fold reduction, p < 0.0001).

These results identify collision-induced pressure as a key driver of LNP destabilization. PVA stabilization mitigates this effect, restoring in vitro transfection and enhancing in vivo pulmonary mRNA expression. This study suggests an effective interfacial strategy to improve nebulized lung gene delivery.