# Quantitative SERS-Based Sandwich-Hybridization Assay for Nucleic Acid Detection

## TL;DR

This paper presents a new SERS-based method for detecting viral DNA using a sandwich-hybridization assay with high sensitivity and reliability.

## Contribution

A novel, commercially feasible SERS-based sandwich-hybridization assay for sensitive nucleic acid detection is developed.

## Key findings

- The assay uses TAMRA-labeled DNA and gold nanoparticles for sensitive detection of SARS-CoV-2 RNA.
- Both single-point peak-height and image-based analysis methods were effective for quantification.
- AFM results strongly correlate with SERS data, confirming the method's accuracy.

## Abstract

Surface-enhanced Raman spectroscopy (SERS) has great
potential
for quantifying biological molecules, particularly DNA. In this study,
we developed a SERS-based sandwich-hybridization assay for detecting
DNA corresponding to viral (SARS-CoV-2) RNA using commercially available
components and standard bioconjugation procedures; hence, no sophisticated
synthesis steps were required. The assay employs TAMRA-labeled DNA
conjugated to gold nanoparticles as nanoprobes and biotin-labeled
surface DNA strands. Upon hybridization with the target analyte, the
complete sandwich structure forms and is captured on a neutravidin-coated
glass via the avidin–biotin interaction. The observed Raman
signals originate from the TAMRA reporter dye, leveraging signal enhancement
from both resonance and plasmonic effects, enabling the sensitive
detection of the target analyte. Quantification of target DNA was
performed using both a conventional single-point peak-height spectral
analysis and a binary image-based analysis, with the latter providing
a reliable evaluation of the assay’s performance. Additionally,
atomic force microscopy (AFM) was employed to characterize the samples,
and the strong correlation between AFM and SERS results confirms the
accuracy and reliability of this approach.