There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Surface-enhanced Raman scattering (SERS) has become a mature vibrational spectroscopic technique during the last decades and the number of applications in the chemical, material, and in particular life sciences is rapidly increasing. This Review explains the basic theory of SERS in a brief tutorial and-based on original results from recent research-summarizes fundamental aspects necessary for understanding SERS and provides examples for the preparation of plasmonic nanostructures for SERS. Chemical applications of SERS are the centerpiece of this Review. They cover a broad range of topics such as catalysis and spectroelectrochemistry, single-molecule detection, and (bio)analytical chemistry.

Surface-enhanced Raman spectroscopy: concepts and chemical applications.

The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article.

/pdf/present-and-future-of-surface-enhanced-raman-scattering-34aqgcm385.pdf

Present and Future of Surface-Enhanced Raman Scattering

https://cyberleninka.org/article/n/894179.pdf

Gold nanoparticles: Optical properties and implementations in cancer diagnosis and photothermal therapy

: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Near infrared surface-enhanced Raman spectroscopy (SERS) was employed in the investigations of the chloroquine antimalarial drug upon hematin. Surface-enhanced Raman spectra of the two compounds were analyzed in order to drag conclusion about their functional groups involved in adsorption. The 1:1 molar ratio of the hematin/c hloroquine system was than investigated and based on the surface selection rules, a possible orientat ion geometry and binding site involved into the antimalarial mechanism was proposed.

Surface-enhanced raman spectroscopy employed in antimalarial mechanism of chloroquine drug upon hematin

Towards label-free and site-specific probing of the local pH in proteins: pH-dependent deep UV Raman spectra of histidine and tyrosine

The photochromic molecule 2-(2,4-dinitro-benzyl)-pyridine (α-DNBP) is characterized in solution by a combination of density functional theory employing a polarizable continuum model and polarization-resolved spontaneous and nonlinear Raman spectroscopies. By the comparison of theoretically predicted wavenumber positions and depolarization ratios with the experimental spectra acquired under electronically nonresonant conditions, polarized and depolarized Raman bands are assigned. Specifically, the symmetric stretching vibrations of the two nitro groups in ortho and para positions to the pyridine ring can be experimentally differentiated, mainly because of their different Raman depolarization ratios, which supports our prediction from theory. Compared to the polarization-resolved spontaneous Raman experiments, the vibrational spectroscopic differentiation of the two nitro groups is more pronounced in time-delayed polarization-resolved coherent anti-Stokes Raman scattering experiments. Overall, this linear and nonlinear vibrational spectroscopic characterization of the CH form paves the way for the interpretation of future time-resolved pump/nonlinear Raman probe studies on the ultrafast photoinduced intramolecular proton transfer in α-DNBP involving a nitro group as an intramolecular proton acceptor.

Vibrational Spectroscopic Characterization of 2-(2,4-Dinitrobenzyl)-pyridine (α-DNBP) in Solution by Polarization-Resolved Spontaneous Raman Scattering and Broadband CARS.

iSERS microscopy: point-of-care diagnosis and tissue imaging

Immuno-SERS (iSERS) microscopy is an emerging imaging technique in tissue-based cancer diagnostics, which is based on antibodies labelled with SERS-active noble metal nanoparticles (NPs) in conjunction with Raman microspectroscopy for localizing target proteins. Advantages of SERS over existing labeling approaches include its high capacity for spectral multiplexing (parallel detection of target molecules), quantification (based on the characteristic SERS signatures), high photostability (no or minimal photobleaching), minimization of autofluorescence from biological specimens (via red to near-infrared excitation), and the technical advantage of using only a single laser excitation line. In this book chapter, we will first give a very brief tutorial on the fundamentals of SERS, followed by an introduction into the concept and current designs of target-specific SERS probes based on noble metal NPs. Next, the fast developing applications of iSERS microscopy for tissue-based cancer diagnostics are highlighted, and finally the challenges and future perspectives of this emerging field are presented.

Sebastian Schlücker

Papers

Surface-enhanced raman spectroscopy employed in antimalarial mechanism of chloroquine drug upon hematin

Towards label-free and site-specific probing of the local pH in proteins: pH-dependent deep UV Raman spectra of histidine and tyrosine

Vibrational Spectroscopic Characterization of 2-(2,4-Dinitrobenzyl)-pyridine (α-DNBP) in Solution by Polarization-Resolved Spontaneous Raman Scattering and Broadband CARS.

iSERS microscopy: point-of-care diagnosis and tissue imaging

ISERS Microscopy for Tissue-Based Cancer Diagnostics with SERS Nanotags