本研究利用不同長寬比3.5以及4.6之金奈米棒(其吸收波長分別是750nm和890nm)，包覆一層二氧化矽於側邊上，並露出兩端點，形成一種類似“熱狗”的構型，探討其應用於螢光增強之效應。由於侷域化表面電漿共振的現象，金奈米棒可以增強螢光分子的螢光放光強度，尤其是金奈米棒的端點，可以提供較高的電場環境，因此端點上的螢光分子能有較高的螢光增強倍率。
在不同長寬比之金奈米棒的螢光增強測試中，以較長之金奈米棒的螢光增強倍率最佳。相較於長寬比為3.5的金奈米棒的螢光增強倍率(最高倍率為2.81倍)，長寬比4.6的金奈米棒可以有效增強螢光訊號至6.81倍。長度較長之金奈米棒之所以能有較高的增強倍率，是因為較長的金奈米棒端點能提供更強的電場環境，使得螢光分子與金奈米棒產生較強的電磁耦合現象，得到強度較強的螢光放光。然而利用二氧化矽選擇性包覆在金奈米棒上的特性，使得螢光分子能集中在金奈米棒的端點上，得到最大的螢光增強效果。

In this study, the fluorescence enhancement effects of hot dog shaped Au nrs with different aspect ratios of 3.5 and 4.6 coated with a silica layer on the lateral side to expose the two endpoints were studied. Owing to the localized surface plasmon resonance (LSPR) phenomenon of the Au nrs, light intensity of the adjacent fluorescent molecules can be either enhanced or quenched within a certain controlled distance. At the endpoint of the Au nrs where a higher electric field environment can be aroused, the fluorophore with a suitable distance from the metal surface can have an increased excitation and radiative decay rate, leading to the higher fluorescence intensity.
In this study, IR-800-conjugated streptavidin was used as the fluorophore and thiolated-PEG was used as the spacer to control the distance. Comparing the fluorescence enhancement results of dye-conjugated Au nrs with aspect ratios of 3.5 and 4.6, the fluorescence intensities was increased from 2.8 to 6.8 folds. Because of the higher local electric fields at endpoints of the longer Au nrs, the stronger electromagnetic coupling with IR-800 molecules result in an increased fluorescence intensity. Utilizing the side selectively covered silica on the Au nrs, the fluorophores can be confined on the endpoint in order to get the maximum fluorescence enhancement effect.

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