Surface-enhanced Raman spectroscopy study on the structure changes of 4-mercaptopyridine adsorbed on silver substrates and silver colloids

Hu, Jiawen; Zhao, Bing; Xu, Weiqing; Li, Bofu; Ye, Fan

doi:10.1016/s1386-1425(02)00074-4

Cited by 161 publications

(183 citation statements)

References 34 publications

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“…The frequency of the ν(C-S) mode at 710 cm -1 is also shifted to lower frequency than in the bulk spectrum due to Ag-S bond formation. 36 It is clear that the obvious changes of both bands were interpreted by coordination of 4-Mpy with the metal surface through sulfur atom. Therefore we conclude that 4-Mpy may be adsorbed on CuO nanocrystals via the sulfur atom.…”

Section: Raman Spectra Of 4-mpy Surface-modified Cuo Nanocrystalsmentioning

confidence: 96%

Enhanced Raman Scattering as a Probe for 4-Mercaptopyridine Surface-modified Copper Oxide Nanocrystals

Wang

Jing

et al. 2007

ANAL. SCI.

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Section: Raman Spectra Of 4-mpy Surface-modified Cuo Nanocrystalsmentioning

confidence: 96%

Enhanced Raman Scattering as a Probe for 4-Mercaptopyridine Surface-modified Copper Oxide Nanocrystals

Wang

Jing

et al. 2007

ANAL. SCI.

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“…S3 †). 33,34 As is well known that the pyridinium cation could not be adsorbed efficiently when pyridine was adsorbed on the silver surface. 33 Thus, herein, Ag-S bond was the main interaction between 4-MPY and AgNPs.…”

Section: Resultsmentioning

confidence: 99%

Ultrasensitive surface-enhanced Raman scattering detection of trypsin based on anti-aggregation of 4-mercaptopyridine-functionalized silver nanoparticles: an optical sensing platform toward proteases

Chen

2013

Nanoscale

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In this work, a simple and sensitive surface-enhanced Raman scattering (SERS) strategy was developed for recognition and detection of trypsin, by using anti-aggregation of 4-mercaptopyridine (4-MPY)-functionalized silver nanoparticles (AgNPs) based on the interaction between protamine and trypsin.The polycationic protamine not only served as a substrate for enzyme hydrolysis but also worked as a medium for SERS enhancement, which could bind negatively charged 4-MPY-functionalized AgNPs and induce their aggregation. The hydrolysis catalyzed with trypsin in sample solution decreased the concentration of free protamine, resulting in the dispersion of AgNPs and thus decreasing the Raman intensity of 4-MPY, by which the trypsin could be sensed optically. A detection level down to 0.1 ng mL À1 for trypsin was obtained. The induced accumulation of AgNPs modified with Raman reporter 4-MPY largely enhanced the SERS responses. A good linearity was found within the wide range over five orders of magnitude and reasonable relative standard deviations (between 2.4 and 11.6%) were attained. By using trypsin as a model, the new concept can provide an excellent platform for ultrasensitive SERS measurements of various proteases/enzymes which can lead to nanoparticles stability change through catalyzed hydrolysis toward substrate.

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“…7 shows single-molecule Raman spectra of 4-mercaptopyridine as a function of time. The Raman spectra of 4-mercaptopyridine were assigned as shown by using the bulk Raman and surface-enhanced Raman scattering spectra (23). The strong temporal fluctuations in intensity and spectra, along with a study of spot density versus solute concentration, are evidence for single-molecule scattering.…”

Section: Resultsmentioning

confidence: 99%

The structural basis for giant enhancement enabling single-molecule Raman scattering

Wang

Pan

Krauss

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

209

162

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We find that giant surface-enhanced Raman scattering for adsorbates on silver surfaces is present only on surfaces that exhibit self-similar fractal topology as inferred from atomic force microscopy. The fractal character results in localizing the energy of incident photons to volumes of a few nanometers on a side, millions of times smaller than the diffraction limit. Consistent with this finding, we have found an enhancement in spontaneous Raman cross section of >13 orders of magnitude for adsorbates on silver surfaces demonstrated to be fractal. The location of ''hot spots'' on the fractal surfaces is found to be hypersensitive to incident wavelength and polarization even though the observed Raman scattering is strictly linear in incident intensity. These observations are consistent with localization of the photon energy facilitated by the disordered nature of fractal organization through interference between the incident wave and scattered radiation from silver nanoparticle surface plasmons. We also present a surface preparation method that consistently produces fractal topologies that support single-molecule Raman scattering. U ltra-sensitive spectroscopy to detect single molecules is of great interest in chemistry, biochemistry, and biophysics (1-3). The advent of single-molecule fluorescence studies was an important development, but requires that the molecules under investigation must be intrinsically fluorescent or chemically modified. The discovery that Raman spectroscopy could also be extended to single molecules (4) is an enormous advance because vibrational spectra contain significantly more structural information and can be used to specifically identify molecules. It is widely acknowledged that electromagnetic enhancement near metallic surfaces is a prerequisite to acquire single-molecule Raman spectra, but the detailed circumstances under which surfaces exhibit adequate enhancement remain poorly understood, and methods to prepare surfaces that will reproducibly exhibit the enhancement are cumbersome (5). Additional uncertainty exists over whether molecular resonance or charge transfer interactions with the metal are necessary to make single-molecule Raman detection viable (6).Cross sections for Raman scattering depend on the square of the incident and scattered fields and, if these are both enhanced, Raman intensities scale as the fourth power of the field (7). Surface plasmon resonance where the local field at metal nanoparticle surfaces experiences large enhancement is thought to be part of the mechanism by which Raman cross sections are increased. However, experimental studies (8) showed only increases of 10 6 in surface-enhanced Raman scattering intensities using isolated silver nanoparticles at the plasmon resonance, far too low for single-molecule detection. Experiment and theory appear to confirm that single-molecule Raman scattering is observed only in metal nanoparticle aggregates (9, 10) but there is not universal agreement (4). Experimental ProceduresPreparation of Raman Substrate Silver ...

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Surface-enhanced Raman spectroscopy study on the structure changes of 4-mercaptopyridine adsorbed on silver substrates and silver colloids

Cited by 161 publications

References 34 publications

Enhanced Raman Scattering as a Probe for 4-Mercaptopyridine Surface-modified Copper Oxide Nanocrystals

Enhanced Raman Scattering as a Probe for 4-Mercaptopyridine Surface-modified Copper Oxide Nanocrystals

Ultrasensitive surface-enhanced Raman scattering detection of trypsin based on anti-aggregation of 4-mercaptopyridine-functionalized silver nanoparticles: an optical sensing platform toward proteases

The structural basis for giant enhancement enabling single-molecule Raman scattering

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