Surface Enhanced Raman Correlation Spectroscopy of Particles in Solution

Asiala, Steven M.; Schultz, Zachary D.

doi:10.1021/ac403882h

Cited by 35 publications

(60 citation statements)

References 37 publications

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“…This agrees with other results where SERS signals in solution were correlated with adsorbed molecules. 30 The dependence on Langmuir-type adsorption implies a nonlinear response that results in peak narrowing, which provides improved separation resolution. This peak-narrowing is valuable for resolving co-migrating species.…”

Section: Resultsmentioning

confidence: 99%

Online SERS detection and characterization of eight biologically-active peptides separated by capillary zone electrophoresis

Negri

Sarver

Schiavone

et al. 2015

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There is a need for low cost, sensitive and chemical specific detectors for routine characterization of biomolecules. In this study, we utilize sheath-flow surface-enhanced Raman scattering (SERS) to analyze a mixture of eight biologically-active peptides separated by capillary zone electrophoresis (CZE). Analysis of the SERS electropherogram resulting from online detection resolves the characteristic Raman bands attributed to the amino acid constituents of each peptide, which enables identification. The detection limit by SERS was found to be 10−8 M. Our results suggest that the structural information obtained from the detected vibrational modes provides complementary characterization to other chemically specific detectors like mass spectrometry and improved chemical identification over other commonly used optical-based post-chromatographic detection methods. In addition, the sheath-flow SERS detection results in band narrowing in the observed electropherogram that enables distinction of closely migrating species. The results presented here indicate that online SERS detection can provide fast, robust, reproducible, and chemical specific detection to facilitate the characterization of peptides.

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Section: Resultsmentioning

confidence: 99%

Online SERS detection and characterization of eight biologically-active peptides separated by capillary zone electrophoresis

Negri

Sarver

Schiavone

et al. 2015

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“…Previously reported data of a similarly sized vesicle freely diffusing around the surface showed a SNR of 7 using the C-C stretch of the DPPC vesicle. 12 Comparing the hydrodynamic confinement with line focusing detection to free diffusion with point detection, the SNR for our current result is greater; however, it includes a longer signal acquisition time. Correcting for the acquisition time, the SNR is nominally the same.…”

Section: Resultsmentioning

confidence: 76%

Increased SERS Detection Efficiency for Characterizing Rare Events in Flow

Jacobs

Schultz

2015

Anal. Chem.

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Improved SERS measurements of a flowing aqueous sample are accomplished by combining line focus optics with sheath-flow SERS detection. The straightforward introduction of a cylindrical lens into the optical path of the Raman excitation laser increases the efficiency of SERS detection and the reproducibility of SERS signals at low concentrations. The width of the line focus is matched to the width of the sample capillary from which the analyte elutes under hydrodynamic focusing conditions, allowing for increased collection across the SERS substrate while maintaining the power density below the damage threshold at any specific point. We show that a 4x increase in power spread across the line increases the signal to noise ratio by a factor of 2 for a variety of analytes, such as rhodamine 6G, amino acids, and lipid vesicles, without any detectable photodamage. COMSOL simulations and Raman maps elucidate the hydrodynamic focusing properties of the flow cell, providing a clearer picture of the confinement effects at the surface where the sample exits the capillary. The lipid vesicle results suggest that the combination of hydrodynamic focusing and increased optical collection enables the reproducible detection of rare events, in this case individual lipid vesicles.

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“…42, 44 SERS discriminates between the large number of molecules in the bulk solution in favor of the small number located in “hotspots” in the focal volume on the electrode surface. The affinity between the analyte and substrate is crucial, and signal arises from molecules that show a favorable interaction with the surface.…”

Section: Discussionmentioning

confidence: 99%

SERS speciation of the electrochemical oxidation–reduction of riboflavin

Bailey

Schultz

2016

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The reduction and oxidation of the flavin system is an important electron transfer reaction in biological systems. Several reaction pathways exist to connect oxidized to fully reduced riboflavin, each with unique intermediates including a semi-quinone radical. By performing surface-enhanced Raman scattering (SERS) with simultaneous electrochemical detection of riboflavin at different pH values, we are able to correlate reversible changes in spectral features to the current changes observed in the cyclic voltammetry. Multivariate curve resolution analysis of the SERS spectra indicates that three distinct components were present at the SERS electrode at each pH during the potential sweep. To verify and better understand the variations in Raman bands across the voltammogram, density functional theory (DFT) calculations were performed to model the effect of pH and oxidation state on the riboflavin Raman spectrum. The calculated spectra show qualitative agreement with the species identified in the chemometric analysis. This combination of results indicates the presence of the oxidized, semi-quinone, and reduced forms of riboflavin and provides insight into the mechanism of the flavin redox system.

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Surface Enhanced Raman Correlation Spectroscopy of Particles in Solution

Cited by 35 publications

References 37 publications

Online SERS detection and characterization of eight biologically-active peptides separated by capillary zone electrophoresis

Online SERS detection and characterization of eight biologically-active peptides separated by capillary zone electrophoresis

Increased SERS Detection Efficiency for Characterizing Rare Events in Flow

SERS speciation of the electrochemical oxidation–reduction of riboflavin

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