Huygens-Kamerlingh Onnes Laboratory, Leiden University, 2300 RA Leiden, The Netherlands.
Nano Lett. 2022 May 25;22(10):4215-4222. doi: 10.1021/acs.nanolett.2c01219. Epub 2022 May 16.
We demonstrate two-photon-excited single-molecule fluorescence enhancement by single end-to-end self-assembled gold nanorod dimers. We employed biotinylated streptavidin as the molecular linker, which connected two gold nanorods in end-to-end fashion. The typical size of streptavidin of around 5 nm separates the gold nanorods with gaps suitable for the access of fresh dyes in aqueous solution, yet small enough to give very high two-photon fluorescence enhancement. Simulations show that enhancements of more than 7 orders of magnitude can be achieved for two-photon-excited fluorescence in the plasmonic hot spots. With such high enhancements, we successfully detect two-photon-excited fluorescence for a common organic dye (ATTO 610) at the single-molecule, single-nanoparticle level.
我们通过单个端到端自组装的金纳米棒二聚体展示了双光子激发的单分子荧光增强。我们使用生物素化链霉亲和素作为分子接头，将两个金纳米棒以端到端的方式连接起来。链霉亲和素的典型尺寸约为 5nm，将金纳米棒隔开，间隙适合水溶液中新鲜染料的进入，但又小到足以产生非常高的双光子荧光增强。模拟表明，在等离子体热点中，双光子激发荧光可以实现超过 7 个数量级的增强。通过如此高的增强，我们成功地在单分子、单纳米颗粒水平上检测到常见有机染料（ATTO 610）的双光子激发荧光。
