I am trying to fix cells with paraformaldehyde in PBS. Everything goes well until the last phase, where I wash 1x PBS and 3x with water. Then I let the slide with fixed cells dry and the morphology changes, they seem to be puffed up. If the glass is wet, it is ok. I fix 1.5-4% PFA in PBS, 30 min, RT. The samples are for RAMAN and AFM on a round slide. How can I improve it so that the cell morphology does not change during drying?