A droplet of each sample was transferred onto a planchet and left to settle for 15 min, after
which the planchets were gently rinsed in water. The adhered protein
was fixed by a drop of 2.0% glutaraldehyde in Sorensen’s phosphate
buffer for 15 min, and thereafter was washed 3 times with
the same buffer. Subsequently a drop of 1% osmium tetroxide in
phosphate buffer was dropped onto the sample