title: Label-free probing of G-quadruplex formation by surface-enhanced Raman scattering.
abstract: 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.
authors.affiliation: Dipartimento di Scienze Fisiche, Complesso Universitario, Universitá di Napoli Federico II, Monte S. Angelo, Via Cinthia, I-80126 Napoli, Italy. giulia.rusciano@na.infn.it
authors.forename: Giulia
authors.initials: G
authors.lastname: Rusciano
authors.forename: Anna Chiara
authors.initials: AC
authors.lastname: De Luca
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pesce
authors.forename: Antonio
authors.initials: A
authors.lastname: Sasso
authors.forename: Giorgia
authors.initials: G
authors.lastname: Oliviero
authors.forename: Jussara
authors.initials: J
authors.lastname: Amato
authors.forename: Nicola
authors.initials: N
authors.lastname: Borbone
authors.forename: Stefano
authors.initials: S
authors.lastname: D'Errico
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Piccialli
authors.forename: Gennaro
authors.initials: G
authors.lastname: Piccialli
authors.forename: Luciano
authors.initials: L
authors.lastname: Mayol
mesh_terms: D002942:Circular Dichroism; D003102:Colloids / Q000737:chemistry; D054856:G-Quadruplexes; D012834:Silver / Q000737:chemistry; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D003102:Colloids; D012834:Silver