(683h) the Roles of Competing Dissolution, Diffusion and Transient Marangoni Convection Fluxes in Surfactant-Enhanced Spreading of Aerosols for Pulmonary Delivery

We are formulating aerosols for pulmonary delivery with surfactants to overcome aerodynamic limitations when treating obstructive lung diseases such as cystic fibrosis. The added surfactant is designed to establish transient Maragoni flows which can convect drug laterally after aerosol droplets are deposited onto airway surface liquid (ASL) and disease-associated mucus plaques. We have used a combination of aerosol droplet deposition experiments with mock systems (entangled (bio)polymer solution subphases mimicking the ASL, fluorophores mimicking drugs, multiple surfactant species) and numerical transport simulations (via COMSOL) to examine the competing roles of surfactant dissolution, diffusion and transient Marangoni convection fluxes in determining the extent of drug spreading. Large dissolution and diffusion fluxes lead to significant net drug transport, but poor spreading while small dissolution and diffusion fluxes lead to poor drug transport and poor spreading; extensive drug spreading occurs when dissolution and diffusion fluxes are similar in magnitude to the transient Marangoni convection flux. Several combinations of mock subphases, surfactants, and mock drugs will be discussed along with implications for delivery via both liquid and solid aerosols.