利用不同形狀金/銀奈米顆粒製備Langmuir-Blodgett薄膜及螢光增強測試

Abstract

金屬螢光增強(Metal-Enhanced Fluorescence，MEF)應用於生物傳感器已經有了許多深入的研究，其設計了各種金屬奈米結構來改變近場的電磁場強度，以用來增強鄰近分子的螢光強度。金屬奈米結構，例如金和銀等材料對螢光有著強烈的影響，像是金屬奈米材料可以與近端螢光團相互作用可以增加其量子產率、降低螢光生命週期、增加光穩定性和增加螢光共振能量轉移的距離等等，通常兩者距離約在10nm時有最佳螢光增強效果。在本實驗中透過製備金奈米棒、金/銀-核/殼奈米長方體結構及金-金銀合金奈米搖鈴型結構，且以Langmuir-Blodgett (LB)將金屬奈米材料沉積在金島狀及羧酸化玻璃片的兩種基板上。用四種不同的壓力控制奈米材料在基板上的密度，分別為5mN/m、8mN/m、14mN/m、17mN/m。使用Cy5、IR800這兩種螢光染劑觀察金屬螢光增強現象。發現了5mN/m-金/銀-核/殼結構-羧酸化玻璃-IR800有著最高的螢光倍率，其螢光增強倍率可達177倍。期望在未來能應用於生化檢測。

Metal enhanced fluorescence (MEF) has been intensively applied in the field of fluorescence-based biosensing. Various metal nanostructures have been developed to increase the fluorescence intensities by placing the fluorophores within the enhanced electromagnetic field at the near-field range. Metal nanomaterials, such as gold and silver, have been demonstrated a strong influence on fluorescence. Metal nanostructures can interact with the proximal fluorophores to increase quantum yield, reduce fluorescence lifetime, increase photostability, and increase the distance of fluorescence resonance energy transfer. Generally, when the distance between the metal surface and fluorophore is about 10 nm, fluorescence intensities show the best enhancement. In this study, we utilized the Langmuir-Blodgett (LB) technique to deposit three different nanoparticles, including gold nanorods, Au@Ag core-shell nanocuboids and Au-Ag nanorattles, on two kinds of substrates (gold nanoisland films and carboxylated polysine slides (glass)). Four different pressures (5 mN/m, 8 mN/m, 14 mN/m and 17 mN/m) were controlled to manipulate the particle densities on the prepared metal films. Further, for the fluorescence enhancement, Cy5 and IR800 fluorescent dyes were used as the fluorophores to calculate their enhancement factors. The highest fluorescence enhancement of 177-fold was obtained for IR800 dyes, when the substrate was prepared by depositing Au@Ag core-shell nanocuboids on the glass substrate at a pressure of 5 mN/m. The promising fluorescence enhancement showed the potential for the application of biochemical detection.