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Wu M, Flores-Fernandez JM, Wang Y, Ahmed H, Wille H, Stepanova M. SERS probing of fungal HET-s fibrils formed at neutral and acidic pH conditions. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 309:123817. [PMID: 38211445 DOI: 10.1016/j.saa.2023.123817] [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: 07/18/2023] [Revised: 11/06/2023] [Accepted: 12/23/2023] [Indexed: 01/13/2024]
Abstract
Advances in precision medical diagnostics require accurate and sensitive characterization of pathogens. In particular, health conditions associated with protein misfolding require an identification of proteinaceous amyloid fibrils or their precursors. These pathogenic entities express specific molecular structures, which require ultra-sensitive, molecular-level detection methods. A potentially transformative technique termed nanoplasmonics employs electro-optical phenomena in the vicinity of specially engineered metal nanostructures. A signature application of nanoplasmonics exploits enhancement of inelastic scattering of light in specific locations near metallic nanostructures, known as surface-enhanced Raman scattering (SERS). We applied SERS complemented with confocal microscopy imaging for ultra-sensitive, non-invasive, and label-free characterization of the fungal prion HET-s (218-289) as a model for β-sheet rich amyloid structures. This characterization employed Au-coated dielectric supports as plasmonic substrates. After confirming the formation of HET-s fibrils at both pH 7.5 and 2.8 using negative staining transmission electron microscopy, we subjected the fibril-containing solutions to multimodal analysis using confocal microscopy and SERS. The SERS spectral fingerprints from all HET-s samples expressed vibrational markers for β-structure, unstructured backbone, and aromatic side-chains. However, relative intensities of major SERS bands were pronouncedly different for the two pH levels. We have analyzed potential origins of the most pronounced SERS bands and proposed hypothetical mechanistic models that could explain the observed SERS fingerprints from HET-s fibrils grown at pH 7.5 and 2.8.
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Affiliation(s)
- Min Wu
- Department of Electrical and Computer Engineering, University of Alberta, Edmonton T6G 1H9, AB, Canada
| | - Jose Miguel Flores-Fernandez
- Department of Biochemistry & Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton T6G 2M8, AB, Canada; Department of Research and Innovation, Universidad Tecnológica de Oriental, Oriental 75020, Mexico
| | - YongLiang Wang
- Department of Biochemistry & Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton T6G 2M8, AB, Canada
| | - Haseeb Ahmed
- Department of Electrical and Computer Engineering, University of Alberta, Edmonton T6G 1H9, AB, Canada
| | - Holger Wille
- Department of Biochemistry & Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton T6G 2M8, AB, Canada; Neuroscience and Mental Health Institute, University of Alberta, Edmonton T6G 2E1, AB, Canada
| | - Maria Stepanova
- Department of Electrical and Computer Engineering, University of Alberta, Edmonton T6G 1H9, AB, Canada.
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Applications of Single-Molecule Vibrational Spectroscopic Techniques for the Structural Investigation of Amyloid Oligomers. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27196448. [PMID: 36234985 PMCID: PMC9573641 DOI: 10.3390/molecules27196448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 09/25/2022] [Accepted: 09/27/2022] [Indexed: 11/05/2022]
Abstract
Amyloid oligomeric species, formed during misfolding processes, are believed to play a major role in neurodegenerative and metabolic diseases. Deepening the knowledge about the structure of amyloid intermediates and their aggregation pathways is essential in understanding the underlying mechanisms of misfolding and cytotoxicity. However, structural investigations are challenging due to the low abundance and heterogeneity of those metastable intermediate species. Single-molecule techniques have the potential to overcome these difficulties. This review aims to report some of the recent advances and applications of vibrational spectroscopic techniques for the structural analysis of amyloid oligomers, with special focus on single-molecule studies.
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Pichois MD, Henning X, Hurier MA, Vomir M, Barsella A, Mager L, Donnio B, Gallani JL, Rastei MV. Photovoltaic and photothermal effects induced by visible laser radiation in atomic force microscopy probes. Ultramicroscopy 2022; 241:113601. [PMID: 36027687 DOI: 10.1016/j.ultramic.2022.113601] [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: 02/17/2022] [Revised: 06/09/2022] [Accepted: 08/10/2022] [Indexed: 10/31/2022]
Abstract
Excitation of electrons into higher energy states in solid state materials can be induced by absorption of visible light, a physical process generally studied by optical absorption spectroscopy. A promising approach for improving the spatial resolution of optical absorption spectroscopy beyond the diffraction limit is the detection of photoinduced forces by an atomic force microscope operating under wavelength-dependent light irradiation. Here, we report on a combined photovoltaic/photothermal effect induced by the absorption of visible light by the microscope probes. By monitoring the photoinduced modifications of the oscillation of the probes, it is found that the oscillation phase-voltage parabolic signals display specific fingerprints which depend on light intensity and the nature of the materials composing the probes. In particular, a localized surface photovoltage (SPV) is evidenced at the tip apex of uncoated Si probes, while none is observed on Au-coated Si probes. The photothermal effects are distinguished from photovoltaic effects by specific shifts of the phase-voltage parabolas. The findings are relevant for the whole range of atomic force microscopy techniques making use of visible light as an additional means of local optical characterization.
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Affiliation(s)
- M D Pichois
- Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS, Université de Strasbourg, 23 rue du Loess, F-67034 Strasbourg, France
| | - X Henning
- Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS, Université de Strasbourg, 23 rue du Loess, F-67034 Strasbourg, France
| | - M A Hurier
- Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS, Université de Strasbourg, 23 rue du Loess, F-67034 Strasbourg, France
| | - M Vomir
- Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS, Université de Strasbourg, 23 rue du Loess, F-67034 Strasbourg, France
| | - A Barsella
- Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS, Université de Strasbourg, 23 rue du Loess, F-67034 Strasbourg, France
| | - L Mager
- Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS, Université de Strasbourg, 23 rue du Loess, F-67034 Strasbourg, France
| | - B Donnio
- Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS, Université de Strasbourg, 23 rue du Loess, F-67034 Strasbourg, France
| | - J L Gallani
- Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS, Université de Strasbourg, 23 rue du Loess, F-67034 Strasbourg, France
| | - M V Rastei
- Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS, Université de Strasbourg, 23 rue du Loess, F-67034 Strasbourg, France.
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Talaga D, Cooney GS, Ury-Thiery V, Fichou Y, Huang Y, Lecomte S, Bonhommeau S. Total Internal Reflection Tip-Enhanced Raman Spectroscopy of Tau Fibrils. J Phys Chem B 2022; 126:5024-5032. [PMID: 35766112 DOI: 10.1021/acs.jpcb.2c02786] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Total internal reflection tip-enhanced Raman spectroscopy (TIR-TERS) has recently emerged as a promising technique for noninvasive nanoscale chemical characterization of biomolecules. We demonstrate that the TERS enhancement achieved in this experimental configuration is nearly 30 times higher than that in linear polarization and 8 times higher than that in radial polarization using traditional bottom-illumination geometry. TIR-TERS is applied to the study of Tau amyloid fibrils formed with the human full-length Tau protein mixed with heparin. This technique reveals the possibility to perform TERS imaging with 1-4 nm axial and 5-10 nm lateral spatial optical resolution. In these Tau/heparin fibrils, spectral signatures assigned to aromatic amino acid residues (phenylalanine, histidine, and tyrosine) and nonaromatic ones (e.g., cysteine, lysine, arginine, asparagine, and glutamine) are distinctly observed. Amide I and amide III bands can also be detected. In a fibril portion, it is shown that antiparallel β-sheets and fibril core β-sheets are abundant and are often localized in amino acid-rich regions where parallel β-sheets and random coils are present in lower proportions. This first TIR-TERS study on a nonresonant biological sample paves the way for future nanoscale chemical and structural characterization of biomolecules using this performant and original technique.
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Affiliation(s)
- David Talaga
- University of Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France
| | - Gary S Cooney
- University of Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France
| | - Vicky Ury-Thiery
- University of Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France
| | - Yann Fichou
- University of Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France
| | - Yuhan Huang
- University of Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France
| | - Sophie Lecomte
- University of Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France
| | - Sébastien Bonhommeau
- University of Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France
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