Fig. 6. Excipient combinations transform porous film base into an amorphous solid.

(A) Scanning electron micrograph of porous surface of thin film consisting only of base excipient (formulation 25, table S1). (B) Surface of two component film (formulation 14) in the absence of virus. (C) Large noncrystalline pockets in film (formulation 27), which foster stabilization of vp. (D) Adenovirus particles (arrows) suspended in amorphous film matrix of optimized formulation 28. Perforations in the film surface are artifacts from extended electron bombardment on the surface of the thin film.