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© 2014 American Chemical Society. Surface-enhanced Raman scattering (SERS) spectroscopy was employed in the present work to elucidate the adsorption of two diisocyanide molecules: 1,4-phenylenediisocyanide (PDI) and 1,4′-terphenylenediisocyanide (TPDI) on nanogaps of Ag and Au nanoparticles (NPs). The main goal of this work was the study of the adsorption of these molecules and more specifically the coordination mechanism and the orientation of these molecules on the metal surface as well as the study of the effect of the above adsorbates on the aggregation and formation of interparticle junctions. To get more insight into the above phenomena, we have investigated different experimental variables such as the numbers of phenylene rings (monophenylene vs terphenylene), the nature of the metal (Au and Ag), the excitation wavelength (532 and 785 nm), and the surface coverage provided by different adsorbate concentrations. The experiments carried out at these conditions revealed the existence concentration of critical values at 0.1 and 3 μM corresponding to changes in the coordination and a complete surface coverage of interparticle junctions. Finally, we have also deduced the great importance of charge-transfer processes occurring between the metal surface and diisocyanide molecules. This charge transfer exhibits a strong dependence on the surface coverage., This work has been supported by the Spanish Ministerio de Economia y Competitividad ́ (grant FIS2010-15405). S. SanchezCortes acknowledges Overseas Research Fellowship organized by Catalysis Research Center, Hokkaido University.

A comparative study of different plasmonic nanoparticles with different morphologies (nanospheres and triangular nanoprisms) and metals (Ag and Au) was done in this work and applied to the ultrasensitive detection of aminoglutethimide (AGI) drug by surface enhanced Raman spectroscopy (SERS) and plasmon resonance. AGI is an aromatase inhibitor used as an antitumoral drug with remarkable pharmacological interest and also in illegal sport doping. The application of very sensitive spectroscopic techniques based on the localization of an electromagnetic field on plasmonic nanoparticles confirms the previous study of the adsorption of drugs onto a metal surface due to the near field character of these techniques. The adsorption of AGI on the above substrates was investigated at different pH values and surface coverages, and the results were analyzed on the basis of AGI/metal affinity, considering the interaction mechanism, the existence of two binding sites in AGI, and the influence of the interface on the adsorption in terms of surface charge due to the presence of other ions linked to the surface. Finally, a comparative quantitative detection of AGI was performed on both spherical and triangular nanoprism nanoparticles, and a limit of detection lower than those reported so far was deduced on the latter nanoparticles.