Dear Binish, as Christina suggestion, the cells were fixed in 2 % glutaraldehyde in 0.1 M PBS for 2 h at 4 C. After that, the cells post-fixed for 1 h at 4 C in 1 % osmium tetroxide in the same buffer. After thorough washing with PBS, samples were
dehydrated in a series of ethanol solutions (30–100 %). You can find detailed procedure for biofilm forming strains described by Nostro et. al. (2007).
Journal of Medical Microbiology (2007), 56, 519–523