The low efficiency of Raman spectroscopy can be overcome by placing the active molecules in the vicinity of scatterers, typically rough surfaces or nanostructures with various shapes. This surface-enhanced Raman scattering (SERS) leads to substantial enhancement that depends on the scatterer that is used. In this work, we find fundamental upper bounds on the Raman enhancement for arbitrary-shaped scatterers, depending only on its material constants and the separation distance from the molecule. According to our metric, silver is optimal in visible wavelengths while aluminum is better in the near-UV region. Our general analytical bound scales as the volume of the scatterer and the inverse sixth power of the distance to the active molecule. Numerical computations show that simple geometries fall short of the bounds, suggesting further design opportunities for future improvement. For periodic scatterers, we use two formulations to discover different bounds, and the tighter of the two always must apply. Comparing these bounds suggests an optimal period depending on the volume of the scatterer.
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http://dx.doi.org/10.1364/OE.27.035189 | DOI Listing |
Anal Chem
January 2025
School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China.
Label-free surface-enhanced Raman spectroscopy (SERS) combined with machine learning (ML) techniques presents a promising approach for rapid pathogen identification. Previous studies have demonstrated that purine degradation metabolites are the primary contributors to SERS spectra; however, generating these distinguishable spectra typically requires a long incubation time (>10 h) at room temperature. Moreover, the lack of attention to spectral variations between strains of the same bacterial species has limited the generalizability of ML models in real-world applications.
View Article and Find Full Text PDFThe detection of mercury ions (Hg) is crucial due to its harmful effects on health and environment. In this article, what we believe to be a novel dual-mode optical fiber sensor incorporating surface plasmon resonance (SPR) and surface-enhanced Raman scattering (SERS) is proposed for ultra-trace Hg detection. The sensing probe comprises gold (Au)/graphene oxide (GO) composite membrane structure and Au nanospheres (AuNPs), which are connected via double-stranded DNA.
View Article and Find Full Text PDFThe optical properties of the 1D nanograting chip have been explored based on computational and experimental studies. Dispersion curve analysis demonstrates cavity and surface plasmon modes in the 1D nanograting chips with periods of 400 nm and 800 nm. In this grating period range, the cut-off period is at a grating period of 644 nm under excitation with a wavelength of 670 nm.
View Article and Find Full Text PDFCommun Chem
January 2025
Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, India.
Superoxide dismutase 1 (SOD1) aggregation is implicated in the development of Amyotrophic Lateral Sclerosis (ALS). Despite knowledge of the role of SOD1 aggregation, the mechanistic understanding remains elusive. Our investigation aimed to unravel the complex steps involved in SOD1 aggregation associated with ALS.
View Article and Find Full Text PDFACS Sens
January 2025
Department of Physics and Astronomy, Franklin College of Arts and Sciences, The University of Georgia, Athens, Georgia 30602, United States.
Multiple respiratory viruses can concurrently or sequentially infect the respiratory tract, making their identification crucial for diagnosis, treatment, and disease management. We present a label-free diagnostic platform integrating surface-enhanced Raman scattering (SERS) with deep learning for rapid, quantitative detection of respiratory virus coinfections. Using sensitive silica-coated silver nanorod array substrates, over 1.
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