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Yamashita T, Miyamoto K, Yonenobu H. Verification of permeability for ionic liquid into biological specimens by using a mass spectrometer. Microscopy (Oxf) 2022; 71:334-340. [PMID: 35766877 DOI: 10.1093/jmicro/dfac035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 06/09/2022] [Accepted: 06/28/2022] [Indexed: 12/13/2022] Open
Abstract
The pretreatment method with ionic liquids (ILs) is convenient for scanning electron microscope (SEM) observation of biological specimens. It needs neither fixation nor vacuum vapor deposition of metals to prevent fracture, deformation and charge-up. Although it was pointed out that the reason why the specimens are not fractured or deformed under the vacuum without fixation is the penetration of the ILs into cells and replacement with the intercellular water of the specimen, the experimental results were not yet self-consistent. In this study, in order to verify this hypothesis, we investigated whether the components of 1-ethyl-3-methylimidazolium methylphosphonate ([EMIM][MePO3]) are detectable by using a time-of-flight secondary ion mass spectrometer (TOF-SIMS) and liquid chromatography. It was found that the components of [EMIM][MePO3] could be detected from inside of the biological specimens. Moreover, it was verified that there is no fracture and deformation of the specimen, whose residual concentration of the IL on the surface would be less than the limit of detection by TOF-SIMS. Therefore, these experimental results explicitly show that penetration of [EMIM][MePO3] into the specimen and subsequent replacement with the intercellular water inside the body is the reason for preventing fracture and deformation of the specimen under the vacuum.
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Affiliation(s)
- Taiji Yamashita
- The Joint Graduate School in Science of School Education, Hyogo University of Teacher Education, 942-1, Shimokume, Kato, Hyogo 673-1494, Japan
| | - Kenji Miyamoto
- Graduate School of Education, Naruto University of Education, 748, Takashima, Naruto, Tokushima 772-8502, Japan
| | - Hitoshi Yonenobu
- Graduate School of Education, Naruto University of Education, 748, Takashima, Naruto, Tokushima 772-8502, Japan
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DiCecco LA, D'Elia A, Miller C, Sask KN, Soleymani L, Grandfield K. Electron Microscopy Imaging Applications of Room Temperature Ionic Liquids in the Biological Field: A Review. Chembiochem 2021; 22:2488-2506. [PMID: 33690961 DOI: 10.1002/cbic.202100041] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 03/08/2021] [Indexed: 11/11/2022]
Abstract
For biological imaging using electron microscopy (EM), the use of room-temperature ionic liquids (RTILs) has been proposed as an alternative to traditional lengthy preparation methods. With their low vapor pressures and conductivity, RTILs can be applied onto hard-to-image soft and/or wet samples without dehydration - allowing for a more representative, hydrated state of material and opening the possibility for visualization of in situ physiological processes using conventional EM systems. However, RTILs have yet to be utilized to their full potential by microscopists and microbiologists alike. To this end, this review aims to provide a comprehensive summary of biological applications of RTILs for EM to bridge the RTIL, in situ microscopy, and biological communities. We outline future research avenues for the use of RTILs for the EM observation of biological samples, notably i) RTIL selection and optimization, ii) applications for live cell processes and iii) electron beam and ionic liquid interaction studies.
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Affiliation(s)
- Liza-Anastasia DiCecco
- Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L7, Canada
| | - Andrew D'Elia
- Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L7, Canada
| | - Chelsea Miller
- School of Biomedical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L7, Canada
| | - Kyla N Sask
- Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L7, Canada
- School of Biomedical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L7, Canada
| | - Leyla Soleymani
- School of Biomedical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L7, Canada
- Department of Engineering Physics, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L7, Canada
| | - Kathryn Grandfield
- Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L7, Canada
- School of Biomedical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L7, Canada
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Tsuda T, Kuwabata S. Electron microscopy using ionic liquids for life and materials sciences. Microscopy (Oxf) 2020; 69:183-195. [DOI: 10.1093/jmicro/dfaa013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Indexed: 11/14/2022] Open
Abstract
Abstract
An ionic liquid (IL) is a salt consisting of only cations and anions, which exists in the liquid state at room temperature. Interestingly ILs combine various favorable physicochemical properties, such as negligible vapor pressure, flame resistance, relatively high ionic conductivity, wide electrochemical window, etc. To take advantage of two specific features of ILs, viz. their nonvolatile and antistatic nature, in 2006, Kuwabata, Torimoto et al. reported a milestone study led to current IL-based electron microscopy techniques. Thereafter, several IL-based electron microscopy techniques have been proposed for life science and materials science applications, e.g. pretreatment of hydrous and/or non-electron conductive specimens and in situ/operando observation of chemical reactions occurring in ILs. In this review, the fundamental approaches for making full use of these techniques and their impact on science and technology are introduced.
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Affiliation(s)
- Tetsuya Tsuda
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Susumu Kuwabata
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
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A facile ionic-liquid pretreatment method for the examination of archaeological wood by scanning electron microscopy. Sci Rep 2019; 9:13253. [PMID: 31519966 PMCID: PMC6744487 DOI: 10.1038/s41598-019-49773-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 08/31/2019] [Indexed: 11/09/2022] Open
Abstract
Wood has been a crucial natural material for human civilization since prehistoric times. In archaeology, the examination of the wood microstructure is important for the study of architecture, musical instruments, sculptures, and so on. Scanning electron microscopy (SEM) examination is sometimes unsuitable for archaeological wood due to the limited amount of precious samples, which may be too small to be cut by microtomes and mounted on holders. Moreover, the conductive coating material cannot be uniformly deposited over uneven wood surfaces. To overcome these issues, a rapid and simple pretreatment method using room-temperature ionic liquids (RTIL) was proposed. Four common RTILs were evaluated for the pretreatment of wood chips for SEM examination. We found that water content, viscosity, density, and hydrophobicity of IL solutions were important factors affecting SEM image quality. A 7.5% solution of 1-butyl-1-methylpyrrolidium dicyanamide (BMP-DCA) in ethanol (v/v) was found to work very well. The IL pretreatment could be performed in a few minutes without special equipment. It is gentle enough to preserve delicate structures such as the torus/margo of pit membranes, even at elevated temperatures, without causing obvious damage or deformation. We successfully imaged hand-cut wood chips from 18th-century buildings, an 18th-century European violin, and a Chinese zither over 1000 years old. We therefore conclude that highly hydrophilic ionic liquids with low density and viscosity are suitable for use in SEM examinations of both modern and antique wood specimens.
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