No, no, no! Do not use isopropanol to clean floppies--you'll wind up
with a soft oxide coating and a brown rag. Were these mine, I'd first
remove them from their jackets and then bake them and then clean them
with distilled water and perhaps a couple of drops of a wetting agent
(Kodak Photo-flo is a good) choice--a couple of drops goes a long way).
You should be good to go--at least my experience tells me that.
--Chuck