Surface-enhanced Raman scattering

Otto, A.; Mrozek, I.; Grabhorn, H.; Akemann, Walther

doi:10.1088/0953-8984/4/5/001

Cited by 1,338 publications

(1,160 citation statements)

References 453 publications

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“…Surface-enhanced Raman spectroscopy (SERS) has been widely applied for the study of molecules [13][14][15][16][17][18][19]. The enhancement of the Raman intensity is usually explained as a * ebarros@fisica.ufc.br combination of two effects, the first, and most important one, is the enhancement of the electromagnetic field by the light interaction with plasmons in the metallic surface (known as EM-SERS) [20].…”

Section: Introductionmentioning

confidence: 99%

Theory of Raman enhancement by two-dimensional materials: Applications for graphene-enhanced Raman spectroscopy

Barros

Dresselhaus

2014

Phys. Rev. B

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We propose a third-order time-dependent perturbation theory approach to describe the chemical surfaceenhanced Raman spectroscopy of molecules interacting with two-dimensional (2D) surfaces such as an ideal 2D metal and graphene, which are both 2D metallic monolayers. A detailed analysis is performed for all the possible scattering processes involving both electrons and holes and considering the different time orderings for the electron-photon and electron-phonon interactions. We show that for ideal 2D metals a surface enhancement of the Raman scattering is possible if the Fermi energy of the surface is near the energy of either the HOMO or the LUMO states of the molecule and that a maximum enhancement is obtained when the Fermi energy matches the energy of either the HOMO or the LUMO energies plus or minus the phonon energy. The graphene-enhanced Raman spectroscopy effect is then explained as a particular case of a 2D surface, on which the density of electronic states is not constant, but increases linearly with the energy measured from the charge neutrality point. In the case of graphene, the Raman enhancement can occur for any value of the Fermi energy between the HOMO and LUMO states of the molecule. The proposed model allows for a formal approach for calculating the Raman intensity of molecules interacting with different 2D materials.

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Section: Introductionmentioning

confidence: 99%

Theory of Raman enhancement by two-dimensional materials: Applications for graphene-enhanced Raman spectroscopy

Barros

Dresselhaus

2014

Phys. Rev. B

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“…10,11 Reporter-free SERS, especially involving spatially resolved maps, however, can generate large and complex data sets which require more sophisticated analysis methods to extract significant features. 3 An accompanying complication especially with the reporter-free SERS methodology in cells is that the variation in the state of aggregation can result in a large variation of the intensity and the spatial distribution of the measured spectra 12,13 making single or average spectra insufficient for complete sample characterization (or classification).…”

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confidence: 99%

Characterization and Visualization of Vesicles in the Endo-Lysosomal Pathway with Surface-Enhanced Raman Spectroscopy and Chemometrics

et al. 2015

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Surface-enhanced Raman spectroscopy (SERS) is an ultra-sensitive vibrational fingerprinting technique widely used in analytical and biosensing applications. For intracellular sensing, typically gold nanoparticles (AuNPs) are employed as transducers to enhance the otherwise weak Raman spectroscopy signals. Thus the signature patterns of the molecular nanoenvironment around intracellular unlabelled AuNPs can be monitored in a reporter-free manner by SERS. The challenge of selectively identifying molecular changes resulting from cellular processes in large and multidimensional data sets and the lack of simple tools for extracting this information has resulted in limited characterization of fundamental cellular processes by SERS. Here, this shortcoming in analysis of SERS data sets is tackled by developing a suitable methodology of reference-based PCA-LDA (principal component analysis-linear discriminant analysis). This method is validated and exemplarily used to extract spectral features characteristic of the endocytic compartment inside cells. The voluntary uptake through vesicular endocytosis is widely used for the internalisation of AuNPs into cells but the characterization of the individual stages of this pathway has not been carried out. Herein, we use reporter-free SERS to identify the stages of endocytosis of AuNPs in cells, visualize them and map the molecular changes via the adaptation and advantageous use of chemometric methods in combination with tailored sample preparation. Thus our study demonstrates the capabilities of reporter-free SERS for intracellular analysis and its ability to provide a way of characterizing intracellular composition. The developed analytical approach is generic and enables the application of reporter-free SERS to identify unknown components in different biological matrices and materials.3 During the last decade, nanoparticle-based surface-enhanced Raman spectroscopy (SERS) has been extensively employed to study biological systems such as cells and tissues. [1][2][3] There are primarily two approaches: The SERS reporter approach and the label-free (reporter-free) SERS approach. In the former, a molecule is functionalized as a self-assembled monolayer on the nanoparticle and the SERS detection of its characteristic spectrum serves to visualize the location of the nanoparticle(s) inside the cell or tissue. 1, 2 This SERS reporter approach has been used in a variety of applications including detection of pathologic cells and tissues such as in cancer 4-6 or cancer markers in biofluids such as blood. 7,8 The reporters can also serve as pH sensors by an appropriate choice of the functionalized molecule with an exchangeable H + . 9 On the other hand, reporter-free SERS samples the direct environment in the vicinity of the nanoparticles and makes the spectral features contributed by the multiple molecular components available for the identification and understanding of the molecular changes around them. The nanoparticle probes can be tailored, such as by sparse functionalizatio...

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“…Since its discovery in the late seventies SERS, which relies on a roughened noble metal substrate to enhance the sensitivity of Raman detection, has become a powerful tool in the early identification and diagnosis of disease [262][263][264][265][266][267][268][269][270][271][272]. The highly localized EM field of the metal, due to SPR, is known to enhance the Raman signal by 5-10 orders of magnitude [273][274][275][276].…”

Section: Surface Enhanced Raman Scattering (Sers) and Electromagneticmentioning

confidence: 99%

Controllable Cobalt Oxide/Au Hierarchically Nanostructured Electrode for Nonenzymatic Glucose Sensing

2016

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By electrodeposition and galvanic replacement reaction, we developed a facile, time-saving, cost-effective, and environmentally friendly, two-step synthesis route to obtain a controllable cobalt oxide/Au hierarchically nanostructured electrode for glucose sensing. The nanomaterials were characterized by transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, energy-dispersive spectrometry, and X-ray photoelectron spectroscopy, meanwhile, the sensing performance was investigated by cyclic voltammetry and amperometric response. The results revealed that this novel electrode exhibited excellent electrocatalytic performance toward glucose oxidation, with a wide double-linear range from 0.2 μM to 20 mM and a low detection limit of 0.1 μM based on a signal-to-noise ratio of 3, which was mainly attributed to the ability of loading a small amount of Au with good electron conductivity on the surface of cobalt oxide nanosheets with large active surface area and synergistic electrocatalytic activity of Au and cobalt oxide toward glucose electrooxidation. This facile, sensitive, and selective glucose sensor is also proven to be suitable for the detection of glucose in human serum.

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Surface-enhanced Raman scattering

Cited by 1,338 publications

References 453 publications

Theory of Raman enhancement by two-dimensional materials: Applications for graphene-enhanced Raman spectroscopy

Theory of Raman enhancement by two-dimensional materials: Applications for graphene-enhanced Raman spectroscopy

Characterization and Visualization of Vesicles in the Endo-Lysosomal Pathway with Surface-Enhanced Raman Spectroscopy and Chemometrics

Controllable Cobalt Oxide/Au Hierarchically Nanostructured Electrode for Nonenzymatic Glucose Sensing

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