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Czaja M, Chachaj-Brekiesz A, Skirlińska-Nosek K, Szajna K, Sofińska K, Lupa D, Kobierski J, Wnętrzak A, Szymoński M, Lipiec E. Fabrication of plasmonic probes for reproducible nanospectroscopic investigation of lipid monolayers - The electrochemical etching with DC-pulsed voltage. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 316:124323. [PMID: 38692104 DOI: 10.1016/j.saa.2024.124323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 04/12/2024] [Accepted: 04/21/2024] [Indexed: 05/03/2024]
Abstract
Tip-enhanced Raman spectroscopy (TERS) is a label-free analytical technique that characterizes molecular systems, potentially even with a nanometric resolution. In principle, the metallic plasmonic probe is illuminated with a laser beam generating the localized surface plasmons, which induce a strong local electric field enhancement in close proximity to the probe. Such field enhancement improves the Raman scattering cross-section from the sample volume localized near the probe apex. TERS provides a high spatial resolution and a great sensitivity, however, it is rather rarely used due to technical limitations causing unstable enhancement and the relative lack of data reproducibility. Despite many scientific efforts for the fabrication of effective TER probes providing robust TER enhancement still requires further investigations. In this work, we explore new possibilities based on preparation of scanning tunnelling microscopy (STM) plasmonic probes, since by nature of the tunnelling effect, they potentially could offer a very high spatial resolution in STM guided TERS experiments. Here we compare two methods of STM-TERS probe preparation for effective spectra acquisition. Our results strongly indicate that an application of square pulse voltage upon the etching procedure significantly improves the quality of the TER data over those obtained with a constant voltage one. To demonstrate the efficiency of our probes we present the results of hyperspectral TER mapping of the 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) monolayer deposited on an ultra-pure and atomically flat gold substrate.
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Affiliation(s)
- Michał Czaja
- Jagiellonian University, Faculty of Physics, Astronomy, and Applied Computer Science, M. Smoluchowski Institute of Physics, Łojasiewicza 11, Kraków 30-348, Poland; Jagiellonian University, Doctoral School of Exact and Natural Sciences, Kraków 30-387, Poland
| | - Anna Chachaj-Brekiesz
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, Kraków 30-387, Poland
| | - Katarzyna Skirlińska-Nosek
- Jagiellonian University, Faculty of Physics, Astronomy, and Applied Computer Science, M. Smoluchowski Institute of Physics, Łojasiewicza 11, Kraków 30-348, Poland; Jagiellonian University, Doctoral School of Exact and Natural Sciences, Kraków 30-387, Poland
| | - Konrad Szajna
- Jagiellonian University, Faculty of Physics, Astronomy, and Applied Computer Science, M. Smoluchowski Institute of Physics, Łojasiewicza 11, Kraków 30-348, Poland
| | - Kamila Sofińska
- Jagiellonian University, Faculty of Physics, Astronomy, and Applied Computer Science, M. Smoluchowski Institute of Physics, Łojasiewicza 11, Kraków 30-348, Poland
| | - Dawid Lupa
- Jagiellonian University, Faculty of Physics, Astronomy, and Applied Computer Science, M. Smoluchowski Institute of Physics, Łojasiewicza 11, Kraków 30-348, Poland
| | - Jan Kobierski
- Jagiellonian University Medical College, Faculty of Pharmacy, Department of Pharmaceutical Biophysics, Medyczna 9, Kraków 30-688, Poland
| | - Anita Wnętrzak
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, Kraków 30-387, Poland
| | - Marek Szymoński
- Jagiellonian University, Faculty of Physics, Astronomy, and Applied Computer Science, M. Smoluchowski Institute of Physics, Łojasiewicza 11, Kraków 30-348, Poland
| | - Ewelina Lipiec
- Jagiellonian University, Faculty of Physics, Astronomy, and Applied Computer Science, M. Smoluchowski Institute of Physics, Łojasiewicza 11, Kraków 30-348, Poland.
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Fu BG, Zhou X, Lu Y, Quan WZ, Li C, Cheng L, Xiao X, Yu YY. Interfacial OOH* mediated Fe(II) regeneration on the single atom Co-N-C catalyst for efficient Fenton-like processes. JOURNAL OF HAZARDOUS MATERIALS 2024; 470:134214. [PMID: 38603908 DOI: 10.1016/j.jhazmat.2024.134214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 03/17/2024] [Accepted: 04/02/2024] [Indexed: 04/13/2024]
Abstract
Fe(II) regeneration is decisive for highly efficient H2O2-based Fenton-like processes, but the role of cobalt-containing reactive sites in promoting Fe(II) regeneration was overlooked. Herein, a single atom Co-N-C catalyst was employed in Fe(II)/H2O2 system to promote the degradation of diverse organic contaminants. The EPR and quenching experiments indicated Co-N-C significantly enhanced the generation of superoxide species, and accelerated hydroxyl radical generation for pollutant degradation. The electrochemical and surface composition analyses demonstrated the enhanced H2O2 activation and Fe(III)/Fe(II) recycling on the catalyst. Furthermore, in-situ Raman characterization with shell-isolated gold nanoparticles was employed to visualize the interfacial reactive intermediates and their time-resolved interaction. The accumulation of interfacial CoOOH* was confirmed when Co-N-C activated H2O2 alone, but it rapidly transformed into FeOOH* upon Fe(II) addition. Besides, the temporal variation of OOH* intermediates and the relative intensity of Co(III)-O and Co(IV)=O peaks depicted the dynamic interaction of reactive intermediates along the H2O2 consumption. With this basis, we proposed a mechanism of interfacial OOH* mediated Fe(II) regeneration, which overcame the kinetical limitation of Fe(II)/H2O2 system. Therefore, this study provided a primary effort to elucidate the overlooked role of interfacial CoOOH* in the Fenton-like processes, which may inspire the design of more efficient catalysts.
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Affiliation(s)
- Bao-Gang Fu
- School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
| | - Xiangtong Zhou
- School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
| | - Yilin Lu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
| | - Wen-Zhu Quan
- School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
| | - Chunmei Li
- Institute of Green Chemistry and Chemical Technology, School of Chemistry and Chemical Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
| | - Liang Cheng
- School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
| | - Xiang Xiao
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
| | - Yang-Yang Yu
- School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China; Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China.
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Buccini L, Proietti A, La Penna G, Mancini C, Mura F, Tacconi S, Dini L, Rossi M, Passeri D. Toward the nanoscale chemical and physical probing of milk-derived extracellular vesicles using Raman and tip-enhanced Raman spectroscopy. NANOSCALE 2024; 16:8132-8142. [PMID: 38568015 DOI: 10.1039/d4nr00845f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Tip-enhanced Raman spectroscopy (TERS) is an advanced technique to perform local chemical analysis of the surface of a sample through the improvement of the sensitivity and the spatial resolution of Raman spectroscopy by plasmonic enhancement of the electromagnetic signal in correspondence with the nanometer-sized tip of an atomic force microscope (AFM). In this work, TERS is demonstrated to represent an innovative and powerful approach for studying extracellular vesicles, in particular bovine milk-derived extracellular vesicles (mEVs), which are nanostructures with considerable potential in drug delivery and therapeutic applications. Raman spectroscopy has been used to analyze mEVs at the micrometric and sub-micrometric scales to obtain a detailed Raman spectrum in order to identify the 'signature' of mEVs in terms of their characteristic molecular vibrations and, therefore, their chemical compositions. With the ability to improve lateral resolution, TERS has been used to study individual mEVs, demonstrating the possibility of investigating a single mEV selected on the surface of the sample and, moreover, analyzing specific locations on the selected mEV with nanometer lateral resolution. TERS potentially allows one to reveal local differences in the composition of mEVs providing new insights into their structure. Also, thanks to the intrinsic properties of TERS to acquire the signal from only the first few nanometers of the surface, chemical investigation of the lipid membrane in correspondence with the various locations of the selected mEV could be performed by analyzing the peaks of the Raman shift in the relevant range of the spectrum (2800-3000 cm-1). Despite being limited to mEVs, this work demonstrates the potential of TERS in the analysis of extracellular vesicles.
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Affiliation(s)
- Luca Buccini
- Department of Basic and Applied Sciences for Engineering, Sapienza University of Rome, Via A. Scarpa 14, 00161 Rome, Italy.
| | - Anacleto Proietti
- Department of Basic and Applied Sciences for Engineering, Sapienza University of Rome, Via A. Scarpa 14, 00161 Rome, Italy.
| | - Giancarlo La Penna
- Department of Basic and Applied Sciences for Engineering, Sapienza University of Rome, Via A. Scarpa 14, 00161 Rome, Italy.
| | - Chiara Mancini
- Department of Basic and Applied Sciences for Engineering, Sapienza University of Rome, Via A. Scarpa 14, 00161 Rome, Italy.
| | - Francesco Mura
- Department of Basic and Applied Sciences for Engineering, Sapienza University of Rome, Via A. Scarpa 14, 00161 Rome, Italy.
- Research Center for Nanotechnology Applied to Engineering of Sapienza University of Rome (CNIS), Piazzale A. Moro 5, 00185 Rome, Italy
| | - Stefano Tacconi
- Department of Biology and Biotechnology "C. Darwin", Sapienza University of Rome, 00185 Rome, Italy
| | - Luciana Dini
- Department of Biology and Biotechnology "C. Darwin", Sapienza University of Rome, 00185 Rome, Italy
| | - Marco Rossi
- Department of Basic and Applied Sciences for Engineering, Sapienza University of Rome, Via A. Scarpa 14, 00161 Rome, Italy.
- Research Center for Nanotechnology Applied to Engineering of Sapienza University of Rome (CNIS), Piazzale A. Moro 5, 00185 Rome, Italy
| | - Daniele Passeri
- Department of Basic and Applied Sciences for Engineering, Sapienza University of Rome, Via A. Scarpa 14, 00161 Rome, Italy.
- Research Center for Nanotechnology Applied to Engineering of Sapienza University of Rome (CNIS), Piazzale A. Moro 5, 00185 Rome, Italy
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Cooney GS, Talaga D, Ury-Thiery V, Fichou Y, Huang Y, Lecomte S, Bonhommeau S. Chemical Imaging of RNA-Tau Amyloid Fibrils at the Nanoscale Using Tip-Enhanced Raman Spectroscopy. Angew Chem Int Ed Engl 2023; 62:e202314369. [PMID: 37905600 DOI: 10.1002/anie.202314369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 10/27/2023] [Accepted: 10/31/2023] [Indexed: 11/02/2023]
Abstract
In the presence of cofactors, tau protein can form amyloid deposits in the brain which are implicated in many neurodegenerative disorders. Heparin, lipids, and RNA are used to recreate tau aggregates in vitro from recombinant protein. However, the mechanism of interaction of these cofactors and the interactions between cofactors and tau are poorly understood. Herein, we use tip-enhanced Raman spectroscopy (TERS) to visualize the spatial distribution of adenine, protein secondary structure, and amino acids (arginine, lysine and histidine) in single polyadenosine (polyA)-induced tau fibrils with nanoscale spatial resolution (<10-20 nm). Based on reference unenhanced and surface-enhanced Raman spectra, we show that the polyA anionic cofactor is incorporated in the fibril structure and seems to be superficial to the β-sheet core, but nonetheless enveloped within the random-coiled fuzzy coat. TERS images also prove the colocalization of positively charged arginine, lysine, and histidine amino acids and negatively charged polyA, which constitutes an important step forward to better comprehend the action of RNA cofactors in the mechanism of formation of toxic tau fibrils. TERS appears as a powerful technique for the identification of cofactors in individual tau fibrils and their mode of interaction.
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Affiliation(s)
- Gary Sean Cooney
- University of Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, 33400, Talence, France
| | - David Talaga
- University of Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, 33400, Talence, France
| | - Vicky Ury-Thiery
- University of Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, 33600, Pessac, France
| | - Yann Fichou
- University of Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, 33600, Pessac, France
| | - Yuhan Huang
- University of Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, 33400, Talence, France
| | - Sophie Lecomte
- University of Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, 33600, Pessac, France
| | - Sébastien Bonhommeau
- University of Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, 33400, Talence, France
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Mohd Nor Ihsan NS, Abdul Sani SF, Looi LM, Cheah PL, Chiew SF, Pathmanathan D, Bradley DA. A review: Exploring the metabolic and structural characterisation of beta pleated amyloid fibril in human tissue using Raman spectrometry and SAXS. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2023:S0079-6107(23)00059-7. [PMID: 37307955 DOI: 10.1016/j.pbiomolbio.2023.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 05/12/2023] [Accepted: 06/09/2023] [Indexed: 06/14/2023]
Abstract
Amyloidosis is a deleterious condition caused by abnormal amyloid fibril build-up in living tissues. To date, 42 proteins that are linked to amyloid fibrils have been discovered. Amyloid fibril structure variation can affect the severity, progression rate, or clinical symptoms of amyloidosis. Since amyloid fibril build-up is the primary pathological basis for various neurodegenerative illnesses, characterization of these deadly proteins, particularly utilising optical techniques have been a focus. Spectroscopy techniques provide significant non-invasive platforms for the investigation of the structure and conformation of amyloid fibrils, offering a wide spectrum of analyses ranging from nanometric to micrometric size scales. Even though this area of study has been intensively explored, there still remain aspects of amyloid fibrillization that are not fully known, a matter hindering progress in treating and curing amyloidosis. This review aims to provide recent updates and comprehensive information on optical techniques for metabolic and proteomic characterization of β-pleated amyloid fibrils found in human tissue with thorough literature analysis of publications. Raman spectroscopy and SAXS are well established experimental methods for study of structural properties of biomaterials. With suitable models, they offer extended information for valid proteomic analysis under physiologically relevant conditions. This review points to evidence that despite limitations, these techniques are able to provide for the necessary output and proteomics indication in order to extrapolate the aetiology of amyloid fibrils for reliable diagnostic purposes. Our metabolic database may also contribute to elucidating the nature and function of the amyloid proteome in development and clearance of amyloid diseases.
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Affiliation(s)
- N S Mohd Nor Ihsan
- Department of Physics, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - S F Abdul Sani
- Department of Physics, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia.
| | - L M Looi
- Department of Pathology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - P L Cheah
- Department of Pathology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - S F Chiew
- Department of Pathology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Dharini Pathmanathan
- Institute of Mathematical Sciences, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - D A Bradley
- Centre for Applied Physics and Radiation Technologies, Sunway University, 46150 PJ, Malaysia; Department of Physics, School of Mathematics & Physics, University of Surrey, Guildford, GU2 7XH, UK
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Fernández-Galiana Á, Bibikova O, Vilms Pedersen S, Stevens MM. Fundamentals and Applications of Raman-Based Techniques for the Design and Development of Active Biomedical Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2210807. [PMID: 37001970 DOI: 10.1002/adma.202210807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 03/03/2023] [Indexed: 06/19/2023]
Abstract
Raman spectroscopy is an analytical method based on light-matter interactions that can interrogate the vibrational modes of matter and provide representative molecular fingerprints. Mediated by its label-free, non-invasive nature, and high molecular specificity, Raman-based techniques have become ubiquitous tools for in situ characterization of materials. This review comprehensively describes the theoretical and practical background of Raman spectroscopy and its advanced variants. The numerous facets of material characterization that Raman scattering can reveal, including biomolecular identification, solid-to-solid phase transitions, and spatial mapping of biomolecular species in bioactive materials, are highlighted. The review illustrates the potential of these techniques in the context of active biomedical material design and development by highlighting representative studies from the literature. These studies cover the use of Raman spectroscopy for the characterization of both natural and synthetic biomaterials, including engineered tissue constructs, biopolymer systems, ceramics, and nanoparticle formulations, among others. To increase the accessibility and adoption of these techniques, the present review also provides the reader with practical recommendations on the integration of Raman techniques into the experimental laboratory toolbox. Finally, perspectives on how recent developments in plasmon- and coherently-enhanced Raman spectroscopy can propel Raman from underutilized to critical for biomaterial development are provided.
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Affiliation(s)
- Álvaro Fernández-Galiana
- Department of Materials, Department of Bioengineering, Imperial College London, SW7 2AZ, London, UK
| | - Olga Bibikova
- Department of Materials, Department of Bioengineering, Imperial College London, SW7 2AZ, London, UK
| | - Simon Vilms Pedersen
- Department of Materials, Department of Bioengineering, Imperial College London, SW7 2AZ, London, UK
| | - Molly M Stevens
- Department of Materials, Department of Bioengineering, Imperial College London, SW7 2AZ, London, UK
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Inhibition to dual enzyme-like activities of Ag/CeO2 nanozymes for the detection of thiourea. Microchem J 2022. [DOI: 10.1016/j.microc.2022.108251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Umakoshi T, Kawashima K, Moriyama T, Kato R, Verma P. Tip-enhanced Raman spectroscopy with amplitude-controlled tapping-mode AFM. Sci Rep 2022; 12:12776. [PMID: 35896604 PMCID: PMC9329313 DOI: 10.1038/s41598-022-17170-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 07/21/2022] [Indexed: 11/24/2022] Open
Abstract
Tip-enhanced Raman spectroscopy (TERS) is a powerful tool for analyzing chemical compositions at the nanoscale owing to near-field light localized at a metallic tip. In TERS, atomic force microscopy (AFM) is commonly used for tip position control. AFM is often controlled under the contact mode for TERS, whereas the tapping mode, which is another major operation mode, has not often been employed despite several advantages, such as low sample damage. One of the reasons is the low TERS signal intensity because the tip is mostly away from the sample during the tapping motion. In this study, we quantitatively investigated the effect of the tapping amplitude on the TERS signal. We numerically evaluated the dependence of the TERS signal on tapping amplitude. We found that the tapping amplitude had a significant effect on the TERS signal, and an acceptable level of TERS signal was obtained by reducing the amplitude to a few nanometers. We further demonstrated amplitude-controlled tapping-mode TERS measurement. We observed a strong dependence of the TERS intensity on the tapping amplitude, which is in agreement with our numerical calculations. This practical but essential study encourages the use of the tapping mode for further advancing TERS and related optical techniques.
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Affiliation(s)
- Takayuki Umakoshi
- Department of Applied Physics, Osaka University, Suita, Osaka, 565-0871, Japan. .,Institute for Advanced Co-creation Studies, Osaka University, Suita, Osaka, 565-0871, Japan. .,PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, 332-0012, Japan.
| | - Koji Kawashima
- Department of Applied Physics, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Toki Moriyama
- Department of Applied Physics, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Ryo Kato
- Institute of Post-LED Photonics, Tokushima University, Tokushima, Tokushima, 770-8506, Japan
| | - Prabhat Verma
- Department of Applied Physics, Osaka University, Suita, Osaka, 565-0871, Japan
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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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Lu F, Zhang W, Sun L, Mei T, Yuan X. Enhancing electromagnetic field gradient in tip-enhanced Raman spectroscopy with a perfect radially polarized beam. OPTICS EXPRESS 2022; 30:21377-21385. [PMID: 36224858 DOI: 10.1364/oe.460394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 05/18/2022] [Indexed: 06/16/2023]
Abstract
Tip-enhanced Raman spectroscopy (TERS) is a promising label-free super-resolving imaging technique, and the electric field gradient of nanofocusing plays a role in TERS performance. In this paper, we theoretically investigated the enhancement and manipulation of the electric field gradient in a bottom-illumination TERS configuration through a tightly focused perfect radially polarized beam (PRPB). Improvement and manipulation in electric field enhancement and field gradient of the gap-plasmon mode between a plasmonic tip and a virtual surface plasmons (SPs) probe are achieved by adjusting the ring radius of the incident PRPB. Our results demonstrate that the method of optimizing the ring radius of PRPB is to make the illumination angle of incident light as close to the surface plasmon resonance (SPR) excitation angle as possible. Under the excitation of optimal parameters, more than 10 folds improvement of field enhancement and 3 times of field gradient of the gap-plasmon mode is realized compared with that of the conventional focused RPB. By this feat, our results indicate that such a method can further enhance the gradient Raman mode in TERS. We envision that the proposed method, to achieve the dynamic manipulation and enhancement of the nanofocusing field and field gradient, can be more broadly used to control light-matter interactions and extend the reach of tip-enhanced spectroscopy.
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