M. Peng, C. Niu, J. Ouyang
Beijing Normal University,
Keywords: plasmon-enhanced fluorescence, Single molecular, gold nanoparticles
Summary:Plasmon-enhanced fluorescence overcomes the intrinsic defects of weak fluorescence for most dyes, and has been developed into various sensors for bioapplications. Our group has explored excellent PEF biosensors based on Au[1-3] and Ag nanoantennas. Plasmonic-enhanced single molecular fluorescence (PESMF), working as an important method of single molecular detection (SMD), breaks the limitation of the average effect and reflects the single molecular message directly. This technology is promising in the study of biomacromolecule and biological detection. Here, we report a comparative study for the PESMF of Cy5.5 by four gold nanoantennas, gold triangular nanoplate (Au TNP), gold hexagonal nanoplate (Au HNP), gold nanorod (Au NR) and gold nanobipyramid (Au NBP), respectively. The Cy5.5-oligonucleotide-biotin is immobilized to the biotin disulfide tip-capped gold nanoparticles (Au NPs) by streptavidin-biotin recognition motif at the point of four Au NPs, in which the oligonucleotide is used to control the distance. The single-molecule experiment and finite-different time-domain (FDTD) simulation demonstrate that Au TNP, Au HNP and Au NBP are good PESMF substrates as Au NR which has been reported. And, the enhancement performance of the Au NPs is relate to the electric field induced by nanoantennas. In addition, the PESMF is also distance-dependent. The optimal distance was found by adjusting the distance between Cy5.5 and Au NP. Inspired by the superiority and distance-dependent of PESMF by Au TNP, we explored an Au TNP-based molecular beacon (MB) sensor to realize the SMD and imaging of intracellular telomerase activity in situ. The results indicate that shape and distance are the guiding factors in choosing the gold substrates to prepare PESMF-MB biosensors for SMD.