Amyloids are self-assembled protein structures implicated in a host of neurodegenerative diseases. Organisms can also produce "functional amyloids" to perpetuate life, and these materials serve as models for robust biomaterials. Amyloids are typically studied using fluorescent dyes, Fourier transform infrared (FT-IR), or Raman spectroscopy analysis of the protein amide I region, and X-ray diffraction (XRD) because the self-assembled β-sheet secondary structure of the amyloid can be easily identified with these techniques. Here, FT-IR and Raman spectroscopy analyses are described to characterize amyloid structures beyond just identification of the β-sheet structure. It has been shown that peptide mixtures can self-assemble into nanometer-sized amyloid structures that then continue to self-assemble to the micrometer scale. The resulting structures are flat tapes of low rigidity or cylinders of high rigidity depending on the peptides in the mixture. By monitoring the aggregation of peptides in solution using FT-IR spectroscopy, it is possible to identify specific amino acids implicated in β-sheet formation and higher order self-assembly. It is also possible to predict the final tape or cylinder morphology and gain insight into the structure's physical properties based on observed intermolecular interactions during the self-assembly process. Tapes and cylinders are shown to both have a similar core self-assembled β-sheet structure. Soft tapes also have weak hydrophobic interactions between alanine, isoleucine, leucine, and valine that facilitate self-assembly. Rigid cylinders have similar hydrophobic interactions that facilitate self-assembly and also have extensive hydrogen bonding between glutamines. Raman spectroscopy performed on the dried tapes and fibers shows the persistence of these interactions. The spectroscopic analyses described could be generalized to other self-assembling amyloid systems to explain property and morphological differences.
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http://dx.doi.org/10.1366/13-07059 | DOI Listing |
Nanoscale
January 2025
Department of Chemistry, Federal University of São Paulo (UNIFESP), Diadema, SP, Brazil.
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View Article and Find Full Text PDFNano Lett
January 2025
Key Laboratory of Light Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an 710129, China.
Tip-enhanced Raman spectroscopy (TERS) has been extensively employed to investigate the light-matter interaction at the nanoscale. However, the current TERS strategies lack the ability to excite the low-background inhomogeneous electromagnetic field with significant enhancement of electric field, electric field gradient, and optomagnetic field, simultaneously. To overcome this, we developed a fiber vector light-field-based TERS strategy aimed at exploring the multipole Raman scattering processes of molecules.
View Article and Find Full Text PDFNano Lett
January 2025
Department of Physics and Astronomy, University of Wyoming, Laramie, Wyoming 82071, United States.
Anisotropic materials with low symmetries hold significant promise for next-generation electronic and quantum devices. 2M-WS, which is a candidate for topological superconductivity, has garnered considerable interest. However, a comprehensive understanding of how its anisotropic features contribute to unconventional superconductivity, along with a simple, reliable method to identify its crystal orientation, remains elusive.
View Article and Find Full Text PDFACS Sens
January 2025
Center for Biomedical-photonics and Molecular Imaging, Advanced Diagnostic-Therapy Technology and Equipment Key Laboratory of Higher Education Institutions in Shaanxi Province, School of Life Science and Technology, Xidian University, Xi'an, Shaanxi 710126, China.
Functional nucleic acids constitute a distinct category of nucleic acids that diverge from conventional nucleic acid amplification methodologies. They are capable of forming intricate hybrid structures through Hoogsteen and reverse Hoogsteen hydrogen bonding interactions between double-stranded and single-stranded DNA, thereby broadening the spectrum of DNA interactions. In recent years, functional DNA/RNA-based surface-enhanced Raman spectroscopy (SERS) has emerged as a potent platform capable of ultrasensitive and multiplexed detection of a variety of analytes of interest.
View Article and Find Full Text PDFHeliyon
November 2024
Faculty of Physics, Shahrood University of Technology, 3619995161, Shahrood, Iran.
This study evaluates the deposition of diamond-like carbon (DLC) films with copper impurities on a glass substrate using simultaneous direct current (DC) and radio frequency (RF) magnetron sputtering. The structural, optical, electrical, and mechanical properties, as well as the surface topography of the films, were investigated under various DC power levels using Raman spectroscopy, ellipsometry, UV-VIS, I-V measurements, nanoindentation, AFM, and FESEM. Results indicate that increasing the DC power to the graphite target from 60 to 120 , while maintaining a constant 10 of RF power to the copper target, enhances the optical absorption coefficient of the films and increases the optical bandgap from 0.
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