Tip-Enhanced Raman Spectra of Picomole Quantities of DNA Nucleobases at Au(111)

Abstract

We show that label-free detection of picomole amounts of the four nucleobases, respectively, adsorbed at atomically smooth Au(111) is straightforward with tip-enhanced Raman (TER) spectroscopy. In addition to TER spectra that allow identification of the corresponding DNA base, topographic images of the nanometer-sized sample can be obtained. Only 130 adenine molecules present in the enhanced field region in the tip−sample gap are sufficient to record the adenine fingerprint, that is, the Raman band of the characteristic ring-breathing mode at 734 cm-1.

Surface-enhanced Raman spectroscopy at single-molecule scale and its implications in biology

“…They claimed that they can attain SM sensitivity because the Raman band from brilliant cresyl blue shows fluctuations in intensity and to a minor extent also in frequency [83,86], which is a possible indicator for SM behaviour as discussed in §2 (the characteristics of SM-SERS). Another popular dye used for SM-TERS study is malachite green isothiocyanate [58,87,88], which has a strong adsorption band centred around the excitation line at 632.8 nm and exhibits strong fluorescence as reported by Domke et al [89]. Therefore, dyes are a specific class of molecules for SM-SERS or SM-TERS investigation because of the resonance contribution.…”

Raman spectroscopy: techniques and applications in the life sciences

“…Copyright 2008 American Chemical Society.). study adsorbed DNA nucleobases [363]. Line-profile spectra are also commonly used to indicate the nanoscale spatial variation of chemical constituents.…”

Tip enhanced Raman scattering: plasmonic enhancements for nanoscale chemical analysis

“…Proper configuration of the gap provides an enhancement that is sufficiently strong to detect the Raman scattering from a single molecule [5]. The use of a metal surface to enhance TERS signals has become known as gap-mode TERS and it has seen use with both STM [39][40][41][42][43][44] and AFM [45,46] based TERS instruments. In the absence of a gap-mode, most TERS measurements require acquisitions on the order of a few seconds to generate appreciable signals from collections of molecules [47,48].…”

“…One of the original reports was the TERS spectra of the pyrimidine bases (thymine and cytosine), which suggested TERS signals could be used for DNA sequencing [125]. All four DNA bases were detected in picomole quantities using gap-mode TERS [40]. A single strand of RNA homopolymer [4] and small DNA fragments [126] were imaged further showing the utility of TERS for sequencing.…”