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Kato R, Yano TA, Tanaka T. Single-cell infrared vibrational analysis by optical trapping mid-infrared photothermal microscopy. Analyst 2023; 148:1285-1290. [PMID: 36811918 DOI: 10.1039/d2an01917e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Single-cell analysis by means of vibrational spectroscopy combined with optical trapping is a reliable platform for unveiling cell-to-cell heterogeneities in vast populations. Although infrared (IR) vibrational spectroscopy provides rich molecular fingerprint information on biological samples in a label-free manner, its application with optical trapping has never been achieved due to weak gradient forces generated by the diffraction-limited focused IR beam and strong background of water absorption. Herein, we present single-cell IR vibrational analysis that incorporates mid-infrared photothermal (MIP) microscopy with optical trapping. Optically trapped single polymer particles and red blood cells (RBCs) in blood could be chemically identified owing to their IR vibrational fingerprints. This single-cell IR vibrational analysis further allowed us to probe the chemical heterogeneities of RBCs originating from the variation in the intracellular characteristics. Our demonstration paves the way for the IR vibrational analysis of single cells and chemical characterization in various fields.
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Affiliation(s)
- Ryo Kato
- Institute of Post-LED Photonics, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima, Tokushima 770-0856, Japan. .,Innovative Photon Manipulation Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama 351-0198, Japan. .,Metamaterials Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Taka-Aki Yano
- Institute of Post-LED Photonics, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima, Tokushima 770-0856, Japan. .,Innovative Photon Manipulation Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama 351-0198, Japan. .,Metamaterials Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Takuo Tanaka
- Institute of Post-LED Photonics, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima, Tokushima 770-0856, Japan. .,Innovative Photon Manipulation Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama 351-0198, Japan. .,Metamaterials Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
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Kodera N, Ando T. Guide to studying intrinsically disordered proteins by high-speed atomic force microscopy. Methods 2022; 207:44-56. [PMID: 36055623 DOI: 10.1016/j.ymeth.2022.08.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 08/16/2022] [Indexed: 12/29/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) are partially or entirely disordered. Their intrinsically disordered regions (IDRs) dynamically explore a wide range of structural space by their highly flexible nature. Due to this distinct feature largely different from structured proteins, conventional structural analyses relying on ensemble averaging is unsuitable for characterizing the dynamic structure of IDPs. Therefore, single-molecule measurement tools have been desired in IDP studies. High-speed atomic force microscopy (HS-AFM) is a unique tool that allows us to directly visualize single biomolecules at 2-3 nm lateral and ∼ 0.1 nm vertical spatial resolution, and at sub-100 ms temporal resolution under near physiological conditions, without any chemical labeling. HS-AFM has been successfully used not only to characterize the shape and motion of IDP molecules but also to visualize their function-related dynamics. In this article, after reviewing the principle and current performances of HS-AFM, we describe experimental considerations in the HS-AFM imaging of IDPs and methods to quantify molecular features from captured images. Finally, we outline recent HS-AFM imaging studies of IDPs.
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Affiliation(s)
- Noriyuki Kodera
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Toshio Ando
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
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