Aptamer-Mediated Surface-Enhanced Raman Spectroscopy Intensity Amplification

Abstract

A bifunctional adenosine-sensitive double-stranded DNA aptamer was used to create and control a surface-enhanced Raman spectroscopy (SERS) hot spot between a bulk Au surface and a gold nanoparticle (Au NP) attached to the aptamer via a biotin-avidin linkage. The Au NP was decorated with 4-aminobenzenethiol (4-ABT), a Raman reporter molecule. In the presence of adenosine, the target molecule, the SERS spectrum of 4-ABT increased in intensity by (concentration-dependent) factors as large as ∼4; in situ, atomic force microscopy imaging showed the mean height of the Au NP-bearing aptamer to decrease by ∼5 nm consistent with the observed SERS intensity change. Because the aptamer's geometrical change is induced by one or two molecules, while the resulting SERS intensity changes involve many reporter molecules residing in the modified hot spot, the aptamer amplifies the SERS effect.

Plasmon-enhanced optical sensors: a review

“…Many efforts have therefore been devoted to tailoring the SERS substrate. 206–217 A recent study has investigated the effect of the Au nanoparticle shape on the SERS enhancement. 19 The results have showed that nanorods have a larger enhancement than nanospheres (Figure 9c), and Au nanostars exhibited the strongest SERS enhancement, which is attributed to the highly concentrated EM field in the sharp tips, similar to a lightning rod.…”

“…186, 187,189,206,247–255 As seen in Figure 12a, Au nanostar@Raman reporter@SiO 2 sandwich SERS tags were used for detection of adenosine triphosphate (ATP) by bringing the SERS tags in proximity to a gold chip. 187 In this SERS sensor, the aptamer labeled with the SERS tag was hybridized with complementary single-stranded DNA on the Au chip to form a rigid duplex DNA.…”

Recent advances in plasmonic nanostructures for sensing: a review

“…In addition to the development of patterned arrays (already described), there has also been a great deal of recent research into the development of isolated SERS active nanoparticle dimers 68,[88][89][90][91] and target-triggered, ordered nanoparticle aggregates. 69,[92][93][94][95] Such isolated dimers and ordered aggregates offer the potential of significantly enhanced SERS signals over individual particles or larger ordered arrays, with good reproducibility.…”

“…5(i)]. 92,[93][94][95] This sensing strategy was first developed as a colorimetric detection platform in which the analyteinduced aggregation resulted in a measurable color change, 96,97 but has since been applied to solution-based oligonucleotide sensing applications via SERS. In the SERS-based version of this technique, two different batches of ssDNA and Raman reporter molecule-bound SERS nanoparticles are fabricated.…”

“…92 Similarly, aptamers have also recently been employed as the analyte-targeting sequence responsible for nanoparticle dimerization, allowing for this concept of analyte-induced aggregation to be expanded beyond DNA and RNA sensing applications to other target species such as proteins. 94 Even more recently, the possibility of using hydrodynamic forces to trap analyte molecules in a SERS active nanogap has been demonstrated. 69 In this work, SERS active nanostructures, known as nanofingers [see Fig.…”