As a powerful tool for studying molecular dynamics in bioscience,single-molecule fluorescence detection providesdynamical information buried in ensemble experiments.Fluorescence in the near-infrared(NIR)is particularl...As a powerful tool for studying molecular dynamics in bioscience,single-molecule fluorescence detection providesdynamical information buried in ensemble experiments.Fluorescence in the near-infrared(NIR)is particularly usefulbecause it offers higher signal-to-noise ratio and increased penetration depth in tissue compared with visiblefluorescence.The low quantum yield of most NIR fluorophores,however,makes the detection of single-moleculefluorescence difcult.Here,we use asymmetric plasmonic nano-antenna to enhance the fluorescence intensity ofAlEE1000,a typical NIR dye,by a factor up to 405.The asymmetric nano-antenna achieve such an enhancement mainlyby increasing the quantum yield(to~80%)rather than the local field,which degrades the molecules'photostability.Our coupled-mode-theory analysis reveals that the enhancements stem from resonance-matching between antennaand molecule and,more importantly,from optimizing the coupling between the near-and far-ield modes withdesigner asymmetric structures.Our work provides a universal scheme for engineering single-molecule fluorescence inthe near-infrared regime.展开更多
基金Y.-W.T.is supported by National Natural Science Foundation of China(Nos.21773039 and 11104039)Shanghai Municipal Science and Technology Major Project(No.2018SHZDZX01)+5 种基金SCI&TECH Project(No.20ZR1405800)ZJLab.L.Zhou and Q.He are supported by National Key Research and Development Program of China(No.2017YFA0303504 and NO.2017YFA0700201)Natural Science Foundation of Shanghai(No.18ZR1403400 and NO.2020JC1414601)Fudan University-CIOMP Joint Fund(No.FC2018-006)S.Xiao is supported by the National Natural Science Foundation of China(No.11704240)Natural Science Foundation of Shanghai(17ZR1409500 and 18QA1401800)
文摘As a powerful tool for studying molecular dynamics in bioscience,single-molecule fluorescence detection providesdynamical information buried in ensemble experiments.Fluorescence in the near-infrared(NIR)is particularly usefulbecause it offers higher signal-to-noise ratio and increased penetration depth in tissue compared with visiblefluorescence.The low quantum yield of most NIR fluorophores,however,makes the detection of single-moleculefluorescence difcult.Here,we use asymmetric plasmonic nano-antenna to enhance the fluorescence intensity ofAlEE1000,a typical NIR dye,by a factor up to 405.The asymmetric nano-antenna achieve such an enhancement mainlyby increasing the quantum yield(to~80%)rather than the local field,which degrades the molecules'photostability.Our coupled-mode-theory analysis reveals that the enhancements stem from resonance-matching between antennaand molecule and,more importantly,from optimizing the coupling between the near-and far-ield modes withdesigner asymmetric structures.Our work provides a universal scheme for engineering single-molecule fluorescence inthe near-infrared regime.
