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Label-Free Probing of G-Quadruplex Formation by Surface-Enhanced Raman Scattering

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journal contribution
posted on 01.09.2011, 00:00 by Giulia Rusciano, Anna Chiara De Luca, Giuseppe Pesce, Antonio Sasso, Giorgia Oliviero, Jussara Amato, Nicola Borbone, Stefano D’Errico, Vincenzo Piccialli, Gennaro Piccialli, Luciano Mayol
In this work, we establish the use of surface-enhanced Raman scattering (SERS) as a label-free analytical technique for the direct detection of G-quadruplex formation. In particular, we demonstrate that SERS analysis allows the evaluation of the relative stability of G quadruplexes that differ for the number of G tetrads and investigate several structural features of quadruplexes, such as the orientation of glycosidic bonds, the identification of distortions in the sugar–phosphate backbone, and the degree of hydrogen-bond solvation. Herein, the fluctuation of the SERS spectra, due to the specific interaction of vibrational modes with the SERS-active substrate, is quantitatively analyzed before and after quadruplex formation. The results of this study suggest a perpendicular orientation of the quadruplexes (with or without the 3′-tetra end linker) with respect to the silver colloidal surface, which opens new perspectives for the use of SERS as a label-free analytical tool for the study of the binding mode between quadruplexes and their ligands.