LAUSR

The label-free localized surface plasmon resonance (LSPR) detection technique has been identified as a powerful means for in situ investigation of biological processes and localized chemical reactions at single particle level with high spatial and temporal resolution. Herein, a core-satellites assembled nanostructure of Au50@Au13 was designed for in situ detection and intracellular imaging of telomerase activity by combining plasmonic resonance Rayleigh scattering spectroscopy with dark-field microscope (DFM). The Au50@Au13 was fabricated by using 50 nm gold nanoparticles (Au50) as core and 13 nm gold nanoparticles (Au13) as satellites, both of them were functionalized with single chain DNA and gathered proximity through the highly specific DNA hybridization with a nicked hairpin DNA (O1) containing a telomerase substrate (TS) primer as linker. In the presence of telomerase, the telomeric repeated sequence of (TTAGGG)n extended at the 3'-end of O1 would hybridized with its complementary sequences at 5'-ends. This led the telomerase extension product of O1 be folded to form a rigid hairpin structure. As a result, the Au50@Au13 was disassembled with the releasing of O1 and Au13-S from Au50-L, which dramatically decreased the plasmon coupling effect. The remarkable LSPR spectral shift was observed accompanied by a detectable color change from orange to green with the increase of telomerase activity at single particle level with a detection limit of 1.3 × 10-13 IU. The ability of Au50@Au13 for in situ imaging intracellular telomerase activity, distinguishing cancer cells from normal cells, in situ monitoring the variation of cellular telomerase activity after treated with drugs were also demonstrated.