Multiplex detection of disease biomarkers using SERS molecular sentinel-on-chip

Developing techniques for multiplex detection of disease biomarkers is important for clinical diagnosis. In this work, we have demonstrated for the first time the feasibility of multiplex detection of genetic disease biomarkers using the surface-enhanced Raman scattering (SERS)-based molecular sentinel-on-chip (MSC) diagnostic technology. The molecular sentinel (MS) sensing mechanism is based upon the decrease of SERS intensity when Raman labels tagged at 3'-ends of MS nanoprobes are physically displaced from the nanowave chip's surface upon DNA hybridization. The use of bimetallic layer (silver and gold) for the nanowave fabrication was investigated. SERS measurements were performed immediately following a single hybridization reaction between the target single-stranded DNA sequences and the complementary MS nanoprobes immobilized on the nanowave chip without requiring target labeling (i.e., label-free), secondary hybridization, or post-hybridization washing, thus shortening the assay time and reducing cost. Two nucleic acid transcripts, interferon alpha-inducible protein 27 and interferon-induced protein 44-like, are used as model systems for the multiplex detection concept demonstration. These two genes are well known for their critical role in host immune response to viral infection and can be used as molecular signature for viral infection diagnosis. The results indicate the potential of the MSC technology for nucleic acid biomarker multiplex detection.