Functionalization of Ag nanoparticles with dithiocarbamate calix [4] arene as an effective supramolecular host for the surface-enhanced Raman scattering detection of … (original) (raw)
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Physical Chemistry Chemical Physics, 2009
The absorption and self-assembly of a dithiocarbamate calix[4]arene derivative (DTCX) on Ag nanoparticles (NPs) was characterized in this work by surface-enhanced Raman scattering (SERS). This study was carried out on Ag NPs prepared by chemical reduction of silver nitrate with two different reducing agents: sodium citrate or hydroxylamine hydrochloride. SERS was able to discriminate between the different conformations and interaction geometries adopted by DTCX when adsorbed and self-assembled on Ag NPs at different surface coverings. The identification of structural marker bands was crucial in this study. Furthermore, the structure adopted by DTCX is important to determine the activity of this calixarene as a molecular host to detect pollutants, such as pyrene (PYR), since an excessively open or closed cavity is not efficient regarding the analyte detection.
Journal of Physical Chemistry B, 2004
Trace concentrations of polycyclic aromatic hydrocarbons (PAHs) have been successfully detected using surface-enhanced Raman scattering (SERS) spectroscopy. For such purpose, new SERS substrates have been developed, consisting of Ag nanoparticles, either in suspension or immobilized on glass, obtained by a new method and covered by adsorbed self-assembled calix[4]arene molecules. Among the assayed calix[4]arenes, the 25,27-dicarboethoxy-26,28-dihydroxy-p-tert-butylcalix[4]arene host molecule displays analytical selectivity to the PAH guest systems bearing four benzene rings, mainly pyrene. The host-guest interaction mechanism seems to take place through a π-π stacking interaction leading to a charge transfer between the complex and the metallic surface, which may also induce a notable influence on the surface charge of the metallic nanoparticle.
Langmuir, 2005
Surface-enhanced IR (SEIR) and Raman scattering (SERS) have been employed to study the adsorption of ester functionalized tert-butyl calix[4]arenes on Ag and Au nanostructured surfaces as well as their complexes with pyrene. The influence of adsorption and complexation with pyrene on the host calixarene structure was tested for two different calixarene molecules bearing carboethoxy groups (CH3CH2COOCH2-) in the low rim at positions 1,3-and 1,2,3,4-. The results obtained with SEIR were compared to those obtained with SERS, to better understand the interaction mechanism of the studied calixarenes with the metallic surfaces and the ligand as well as to investigate the structure/selectivity relationship of these two surface techniques in the analysis of recognition problems in which these ester functionalized calixarene molecules are involved.
Journal of Applied Physics, 2011
In this paper, we study the relationship between nanoparticles' structure/composition and the chemical nature of the molecules to be identified in surface enhanced Raman scattering (SERS) spectroscopy. Three types of nanoparticles (NPs) were synthesized, including Ag, Au, and silver coated by gold (Ag@Au), in order to study the resulting enhancement effects. When a rhodamine 6G dye molecule was used to assemble the NPs, it was found that Ag NPs exhibited the highest enhancement activity. However, when a thiol containing 3-amino-1,2,4-triazole-5-thiol molecule was used to assemble the NPs, it was found that the Ag@Au NPs exhibited high Raman activity as well as the Ag NPs. The results give insight into how the chemical properties of the molecules to be analyzed play an important role in the SERS detection. An additional parameter of the analysis reveals the relative stability of the three types of NP probes synthesized with regard to oxidation in the presence of different mediating molecules and varying salt concentrations. The results are of interest in designing and employing NP probes to detect biological molecules using colorimetric and SERS based approaches.
Analytica Chimica Acta, 2008
Viologen Lucigenin Molecular recognition Surface-enhanced Raman scattering Nanosensors Organochlorine pesticides a b s t r a c t Organochlorine pesticide endosulfan has been detected for the first time by using surfaceenhanced Raman scattering (SERS) at trace concentrations. The bis-acridinium dication lucigenine was successfully used as a molecular assembler in the functionalization of metal nanoparticles to facilitate the approach of the pesticide to the metal surface. From the SERS spectra valuable information about the interaction mechanism between the pesticide and lucigenin can be deduced. In fact, endosulfan undergoes an isomerization upon adsorption onto the metal, while the viologen undergoes a rotation of the acridinium planes to better accommodate the pesticide molecule. An interaction between the N atom of the central acridinium ring and the pesticide Cl-C C-Cl fragment is verified through a charge-transfer complex. The present study affords important information which can be applied to the design of chemical sensor systems of persistent organic pollutants based on the optical detection on functionalized metal nanoparticle.
SERS is a thirty years old physical phenomenon that has become one of the most exciting analytical techniques with a wide range of applications in physics, chemistry and biology, and the corresponding applied sciences. This ultrasensitive analytical tool covers the complete scale of sensitive analysis and diagnostics down to the limit of single molecule detection (SMD). There are now thousands of SERS publications in a wide range of scientifi c journals (for instance, SERS papers can be found in all the journals published by the ACS). The applications are relevant to trace analysis, environmental monitoring, nanobioscience among many others. The fi eld is intrinsically connected with the optical properties of nanostructures and SERS techniques are also used for nanostructure characterization, since it can be discussed in terms of surface plasmon resonance of nanoparticles, nanoshells or voids, leading to nanophotonics, plasmonics and single-molecule detection. Therefore, nowadays, no attempt or claim can be made to review the fi eld exhaustively in its entirety nor to cover all applications. Some of the above invited speakers contributed to the present issue. The speakers and the audience were able to exchange their views and newly acquired results in lively and sometimes heated discussions. The poster session was also quite active and successful. A total of 49 posters were displayed during the symposium. The following presentations received the Poster Awards. H. K. Park et al. "Silver-Particle-Based Surface-Enhanced Raman Scattering Spectroscopy for Biomolecular Sensing and Recognition" M. Meyer et al. "Can the Orientation of Molecules be Measured with SERS?" A. Maio et al. "SERRS measurement and Structural Characterization of J-and H-Aggregates in Langmuir-Blodgett (LB) Films Containing Merocyanine Dye"
Langmuir
Labile ligands such as thiols and carboxylates are commonly used to functionalise AuNPs, though little control over the composition is possible when mixtures of ligands are used. It was shown recently that robustly functionalised AuNPs can be obtained through the reductive grafting of calix[4]arenes bearing diazonium groups on the large rim. Here, we report a calix[4]arene-tetra-diazonium decorated by four oligo(ethylene glycol) chains on the small rim, which upon grafting gave AuNPs with excellent stability thanks to the C-Au bonds. Mixtures of this calixarene and one with four carboxylate groups were grafted on AuNPs. The resulting particles were analysed by infra-red spectroscopy, which revealed that the composition of the ligand shell clearly reflected the ratio of calixarenes that was present in solution. This strategy opens the way to robustly protected AuNPs with well-defined numbers of functional or postfunctionalisable groups.
Optics and Photonics Journal, 2013
While Raman spectroscopy is a useful method for analyzing many organic compounds, it is limited by relatively low sensitivity. Therefore, Surface Enhanced Raman Spectroscopy (SERS) based on the adsorption of organic analytes onto gold or silver nanostructures has been used to enhance the signal of chemicals presented at very low concentrations. Although the plasmonic effect of SERS has been shown to play a large role in signal enhancement, the significance of the chemical effect due to the analyte chemisorption on the gold or silver surface is less well understood. In this study, the role of aniline substituents is examined by probing the SERS intensities of various anilines in silver and gold colloids using a Raman spectrometer with an excitation wavelength of 785 nm. The SERS enhancement factors and detection limits for aniline and its mono-and di-substituted ortho derivatives are determined and compared. Both the steric requirements of chemisorption and the inductive effects of electron-withdrawal due to the substituents affect the signal intensities of various vibrational modes of the amino group and the aromatic ring. The degree of enhancement is also related to the methods for preparing the silver and gold colloids, which are characterized by probing the nanoparticle morphology and its degree of aggregation using transmission electron microscopy (TEM).