A Scheme for Detecting Every Single Target Molecule with Surface-Enhanced Raman Spectroscopy

Abstract

Surface-enhanced Raman spectroscopy (SERS) is now a well-established technique for the detection, under appropriate conditions, of single molecules (SM) adsorbed on metallic nanostructures. However, because of the large variations of the SERS enhancement factor on the surface, only molecules located at the positions of highest enhancement, so-called hot-spots, can be detected at the single-molecule level. As a result, in all SM-SERS studies so far only a small fraction, typically less than 1%, of molecules are actually observed. This complicates the analysis of such experiments and means that trace detection via SERS can in principle still be vastly improved. Here we propose a simple scheme, based on selective adsorption of the target analyte at the SERS hot-spots only, that allows in principle detection of every single target molecule in solution. We moreover provide a general experimental methodology, based on the comparison between average and maximum (single molecule) SERS enhancement factors, to verify the efficiency of our approach. The concepts and tools introduced in this work can readily be applied to other SERS systems aiming for detection of every single target molecule.

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

“…As indicated, the EF value can vary by an order of magnitude over distances comparable rstb.royalsocietypublishing.org Phil Trans R Soc B 368: 20120026 to a few molecular dimensions, which is a universal property of gap hot spots resulting in a long tail probability distribution that determines most of the basic characteristics of SM-SERS statistics. More recently, Le Ru et al [36] proposed a simple scheme based on selective adsorption of the target analyte at the SERS hot spots for detection of every single target molecule in solution and verified by comparing the average and maximum (SM) SERS EF.…”

Tailoring the interplay between electromagnetic fields and nanomaterials toward applications in life sciences: a review

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“…29 These fields are considered to be responsible for the huge SERS effect, with EF of the order of 10 8 to 10 9 , thus opening the route to single molecule detection by SERS. 3,30 …”