Use of Ionic Liquid for Scanning Electron Microscopy of Protists

Hideki Ishida, Yukari Gobara, Mayumi Kobayashi, Toshinobu Suzaki

We investigated the use of ionic liquids to observe the cell surface of protists rapidly and conveniently. By using ionic liquid, SEM observation is possible without complicated pretreatment such as drying of sample or metal coating. Therefore, it has been shown so far that it is particularly useful for observation of biological samples. It has been shown that good results can be obtained for some biological samples with hard surface structures such as foraminifera and pollen. However, for other unicellular organisms this method has not been validated. In this paper, it is shown that by adding ionic liquid directly after fixation, good results are obtained with diatoms and dinoflagellates without metal coating. In unicellular organisms such as ciliates with soft cells, however, significant shrinkage of the samples was observed.