Are you looking for an alternative cryo-fixation method to freeze your biological specimens such as cells, free-living bacteria, yeast cells, unicellular organisms etc. in their native environment without any specific preparation or addition of cryo-protectants, which could alter the initial physiological balance of the sample?
If yes, then you can cryo-immobilize them directly after being isolated from their natural habitat with the Leica EM SPF Self Pressure Freezer. U-tubes as specimen carriers keep the low density ice located predominately in the leg areas, whereas the arc area of the U-tube freezes last under high pressure.