title: Comparative study of hydrophilic and hydrophobic ionic liquids for observing cultured human cells by scanning electron microscopy.
abstract: An ionic liquid (IL) is a salt that remains in the liquid state at room temperature. It does not vaporize under vacuum and imparts electrical conductivity to samples for observation by scanning electron microscopy (SEM). Recently, the usefulness of ILs has been widely recognized. In our previous study, one of the ILs 1-ethyl-3-methylimidazolium tetrafluoroborate (EtMelm(+) BF(4)(-)) was used for SEM analysis of biological samples. In comparison with the conventional method, samples prepared using EtMelm(+) BF(4)(-) provided more detailed SEM images of the cell ultrastructure, enabling the observation of protrusions. In addition, the IL treatment is a less time consuming and simple method that does not include dehydration, drying, and conductivity treatments, which are an essential parts of the conventional method. In this study, we compared the usefulness of four hydrophobic and three hydrophilic ILs for SEM to observe fixed cultured human A549 cells. All ILs worked well to prevent "charge-up" effect for SEM observation. However, the hydrophilic ILs tended to provide clearer images than the hydrophobic ILs. We concluded that various ILs can be used for SEM sample preparation and their application to a wide range of fields is anticipated in future.
authors.affiliation: Medical Research Institute, Kanazawa Medical University, 1-1 Daigaku, Uchinada-machi, Kahoku-gun 920-0293, Japan.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Ishigaki
authors.forename: Yuka
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Teruaki
authors.initials: T
authors.lastname: Takehara
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kurihara
authors.forename: Hironori
authors.initials: H
authors.lastname: Koga
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Takegami
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nakagawa
authors.forename: Noriko
authors.initials: N
authors.lastname: Nemoto
authors.forename: Naohisa
authors.initials: N
authors.lastname: Tomosugi
authors.forename: Susumu
authors.initials: S
authors.lastname: Kuwabata
authors.forename: Shichiro
authors.initials: S
authors.lastname: Miyazawa
mesh_terms: D002460:Cell Line; D004847:Epithelial Cells / Q000648:ultrastructure; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D052578:Ionic Liquids / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D013048:Specimen Handling / Q000379:methods*
chemical_list: D052578:Ionic Liquids