SERS-based inverse molecular sentinel (iMS) nanoprobes for multiplexed detection of microRNA cancer biomarkers in biological samples
The development of sensitive and selective biosensing techniques is of great interest for clinical diagnostics. Here, we describe the development and application of a surface enhanced Raman scattering (SERS) sensing technology, referred to as "inverse Molecular Sentinel (iMS)" nanoprobes, for the detection of nucleic acid biomarkers in biological samples. This iMS nanoprobe involves the use of plasmonic-active nanostars as the sensing platform for a homogenous assay for multiplexed detection of nucleic acid biomarkers, including DNA, RNA and microRNA (miRNA). The "OFF-to-ON" signal switch is based on a non-enzymatic strand-displacement process and the conformational change of stem-loop (hairpin) oligonucleotide probes upon target binding. Here, we demonstrate the development of iMS nanoprobes for the detection of DNA sequences as well as a modified design of the nanoprobe for the detection of short (22-nt) microRNA sequences. The application of iMS nanoprobes to detect miRNAs in real biological samples was performed with total small RNA extracted from breast cancer cell lines. The multiplex capability of the iMS technique was demonstrated using a mixture of the two differently labeled nanoprobes to detect miR-21 and miR-34a miRNA biomarkers for breast cancer. The results of this study demonstrate the feasibility of applying the iMS technique for multiplexed detection of nucleic acid biomarkers, including short miRNAs molecules.
