Fig. 3.

Photo (A) and schematic drawing (B) of the vertical diffusion chambers. A thin CF sputum layer was placed between the donor and acceptor sides using modified snapwells. Snapwells containing a polycarbonate membrane (pore size 3 µm) were modified by gluing a 220 µm thick ring on their borders. This ring was filled with CF sputum and sealed with a second polycarbonate membrane. Finally, the modified snapwell was placed between the donor and acceptor side. The diffusion experiments were started by filling the donor side with nanoparticles or NANs and the acceptor side with buffer. Subsequently the transport of nanoparticles or NANs through the sputum layer was followed by measuring, at the desired time points, their concentration at the acceptor side.