Fig. 4.

Effects of beclomethasone dipropionate (BDP) at various concentrations on the molecular organization and lateral structure of Infasurf films. For ease of comparison, the first column repeats AFM topographic images of pure Infasurf at five characteristic surface pressures (π) of 20, 30, 40, 50, and 60 mN m⁻¹, as shown in the first column of the Fig. 3. Columns 2–4 show AFM topographical images of Infasurf mixed with 0.1%, 1%, and 10% BDP, respectively. Infasurf + BDP films were compared to pure Infasurf at identical π in each row. The AFM scan area was 20 × 20 μm for all images. The full z-range was set to be 5 nm for monolayers (i.e., π ≤ 40 mN m⁻¹) and 20 nm for multilayers (i.e., π > 40 mN m⁻¹). Characteristic relative heights of multilayers are indicated by arrows.