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Joseph J, Spantzel L, Ali M, Moonnukandathil Joseph D, Unger S, Reglinski K, Krafft C, Müller AD, Eggeling C, Heintzmann R, Börsch M, Press AT, Täuber D. Nanoscale chemical characterization of secondary protein structure of F-Actin using mid-infrared photoinduced force microscopy (PiF-IR). SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 306:123612. [PMID: 37931494 DOI: 10.1016/j.saa.2023.123612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 08/15/2023] [Accepted: 11/01/2023] [Indexed: 11/08/2023]
Abstract
The recently developed photoinduced force microscopy for mid-infrared (PiF-IR) offers high spectral resolution in combination with surface sensitivity and a spatial resolution in the range of a few nanometers. Although PiF-IR has primarily been applied to polymer materials, this technology presents significant potential for the chemical characterization of cellular structures approaching single-molecule sensitivity. We applied PiF-IR to differently polymerized F-Actin samples finding general agreement with FTIR spectra from the same samples. Single PiF-IR spectra of F-Actin show variations in the amide I band spectral region, which is related to secondary protein structure. Local variations are also seen in PiF-IR hyperspectra in this region. Such high sensitivity is a necessary requirement for discriminating Actin organization into bundles and other networks in cells and tissue. We applied PiF-IR to mouse liver tissue ex vivo. Single-frequency PiF-IR scans at three different IR frequencies show significant variations in local contrast. However, the presence of other proteins and the unique spatial resolution of PiF-IR pose a challenge to interpreting and validating such data. Careful design of model systems and further theoretical understanding of PiF-IR data far from bulk averages are needed to fully unfold the potential of PiF-IR for high-resolution chemical investigation in the Life Sciences.
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Affiliation(s)
- Jesvin Joseph
- Leibniz Institute of Photonic Technology, Department of Microscopy, Jena, Germany; Friedrich Schiller University Jena, Institute of Physical Chemistry & Abbe Center of Photonics, Jena, Germany
| | - Lukas Spantzel
- Jena University Hospital, Single-Molecule Microscopy Group, Jena, Germany; Friedrich Schiller University Jena, Faculty of Medicine, Jena, Germany
| | - Maryam Ali
- Friedrich Schiller University Jena, Institute of Physical Chemistry & Abbe Center of Photonics, Jena, Germany
| | - Dijo Moonnukandathil Joseph
- Leibniz Institute of Photonic Technology, Department of Microscopy, Jena, Germany; Friedrich Schiller University Jena, Institute of Physical Chemistry & Abbe Center of Photonics, Jena, Germany
| | - Sebastian Unger
- Leibniz Institute of Photonic Technology, Department of Microscopy, Jena, Germany; Friedrich Schiller University Jena, Institute of Physical Chemistry & Abbe Center of Photonics, Jena, Germany
| | - Katharina Reglinski
- Leibniz Institute of Photonic Technology, Biophysical Imaging, Jena, Germany; Friedrich Schiller University Jena, Institute for Applied Optics and Biophysics, Jena, Germany
| | - Christoph Krafft
- Leibniz Institute of Photonic Technology, Department of Spectroscopy & Imaging, Jena, Germany
| | | | - Christian Eggeling
- Leibniz Institute of Photonic Technology, Biophysical Imaging, Jena, Germany; Friedrich Schiller University Jena, Institute for Applied Optics and Biophysics, Jena, Germany
| | - Rainer Heintzmann
- Leibniz Institute of Photonic Technology, Department of Microscopy, Jena, Germany; Friedrich Schiller University Jena, Institute of Physical Chemistry & Abbe Center of Photonics, Jena, Germany
| | - Michael Börsch
- Jena University Hospital, Single-Molecule Microscopy Group, Jena, Germany; Friedrich Schiller University Jena, Faculty of Medicine, Jena, Germany
| | - Adrian T Press
- Friedrich Schiller University Jena, Faculty of Medicine, Jena, Germany; Jena University Hospital, Department of Anesthesiology and Intensive Care Medicine, Jena, Germany
| | - Daniela Täuber
- Leibniz Institute of Photonic Technology, Department of Microscopy, Jena, Germany; Friedrich Schiller University Jena, Institute of Physical Chemistry & Abbe Center of Photonics, Jena, Germany; Friedrich Schiller University Jena, Institute of Solid State Physics, Jena, Germany.
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Baden N. Novel Method for High-Spatial-Resolution Chemical Analysis of Buried Polymer-Metal Interface: Atomic Force Microscopy-Infrared (AFM-IR) Spectroscopy with Low-Angle Microtomy. APPLIED SPECTROSCOPY 2021; 75:901-910. [PMID: 33739171 DOI: 10.1177/00037028211007187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
There is a great need for the analysis of the chemical composition, structure, functional groups, and interactions at polymer-metal interfaces in terms of adhesion, corrosion, and insulation. Although atomic force microscopy-based infrared (AFM-IR) spectroscopy can provide chemical analysis with nanoscale spatial resolution, it generally requires to thin a sample to be placed on a substrate that has low absorption of infrared light and high thermal conductivity, which is often difficult for samples that contain hard materials such as metals. This study demonstrates that the combination of AFM-IR with low-angle microtomy (LAM) sample preparation can analyze buried polymer-metal interfaces with higher spatial resolution than that with the conventional sample preparation of a thick vertical cross-section. In the LAM of a polymer layer on a metal substrate, the polymer layer is tapered to be thin in the vicinity of the interface, and thus, sample thinning is not required. An interface between an epoxyacrylate layer and copper wire in a flexible printed circuit cable was measured using this method. A carboxylate interphase layer with a thickness of ∼130 nm was clearly visualized at the interface, and its spectrum was obtained without any signal contamination from the neighboring epoxyacrylate, which was difficult to achieve on a thick vertical cross-section. The combination of AFM-IR with LAM is a simple and useful method for high-spatial-resolution chemical analysis of buried polymer-metal interfaces.
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Affiliation(s)
- Naoki Baden
- Nihon Thermal Consulting, Co., Ltd., 1-5-11 Nishishinjuku, Sinjuku-ku, Tokyo 160-0023, Japan
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