SERS-fluorescence dual mode nanotags for cervical cancer detection using aptamers conjugated to gold-silver nanorods

We describe nanotags suitable for both surface enhanced Raman scattering (SERS) and fluorescence detection and imaging. A fluorescently-labeled aptamer conjugated to gold-silver nanorods used for specific and sensitive detection of cervical cancer. NRs with different Au-Ag ratios were synthesized. The Raman reporter 4-aminothiophenol and fluorescently-labeled aptamers were assembled on the surface of NRs via a layer-by-layer process. The fluorescence and SERS signals can be generated independently using different excitation wavelengths, which can avoid the disturbance from each other. The nanotags were proven to be specific to the human protein tyrosine kinase-7 (PTK-7) expressed on Hela (cervical cancer) cells through aptamer-protein interaction. The binding of aptamers towards their targets induced the assembly of nanotags on the cell surface, resulting in strong fluorescence and SERS signals. However, the controls, randomized sequence oligonucleotide conjugated NRs, showed no detectable signal. Fluorescence and SERS mapping images were also performed to confirm targeting ability of the nanotags on the target cell membrane. The success of this method extends the feasibility of the dual mode nanotags for highly sensitive and specific cancer diagnostic.