Raman and surface-enhanced Raman spectroscopic studies of the 15-mer DNA thrombin-binding aptamer

Cynthia V. Pagba, Stephen M. Lane, Sebastian Wachsmann-Hogiu

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

Aptamers are single-stranded oligonucleotides that selectively bind to their target molecules owing to their ability to form secondary structures and shapes. The 15-mer (5′-GGTTGGTGTGGTTGG-3′) DNA thrombin-binding aptamer (TBA) binds to thrombin following the formation of a quadruplex structure via the Hoogsten-type G-G interactions. In the present study, Raman and SERS spectra of TBA and thiolated TBA (used to facilitate covalent bonding to metal nanoparticle) in different conditions are investigated. The spectra of the two analogs exhibit vibrations, such as the C8 N7-H2 deformation band at ~1480 cm-1 of the guanine tetrad, that are characteristic of the quadruplex structure in the presence of K+ ions or at low temperature. Interestingly, SERS spectra of the two analogs differ markedly from their respective normal Raman spectra, possibly due to changes in the conformation of the aptamer upon binding, as well as to the specific interaction of individual vibrational modes with the metal surface. In addition, the SERS spectra of the thiolated aptamer show significant changes with different concentrations, which maybedue to different orientation of the molecule with respect to the metal surface. This study provides useful information for the development of label-free aptamer-based SERS sensors and assays.

Original languageEnglish (US)
Pages (from-to)241-247
Number of pages7
JournalJournal of Raman Spectroscopy
Volume41
Issue number3
DOIs
StatePublished - Mar 2010

Keywords

  • Aptamer
  • Biosensors
  • Quadruplex
  • Raman spectra
  • SERS spectra

ASJC Scopus subject areas

  • Spectroscopy
  • Materials Science(all)

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