We report five effective fluorescence resonance energy transfer (FRET) systems based on gold nanoparticles (AuNPs) and organic fluorescent dyes, including ionic [fluorescein sodium (FS) and Eosin B (EB)] and cationic [rhodamine 6G (Rh6G), acridine orange (AO), and safranine T (ST)] fluorescent dyes. The fluorescence intensity of the five FRET systems demonstrates that efficient quenching is possible. The quenching efficiencies of Rh6G and FS by FRET were nearly 100%, 89% for AO, 60% for EB, and 55% for ST. A series of UV absorbance spectra and fluorescence emission spectra were used to explain the mechanism of fluorescence quenching. We found that there were different degrees of overlap between the absorption spectrum of the AuNPs and the emission spectrum of fluorescence dyes. This outcome indicates that highly efficient FRET is the possible mechanism of fluorescence quenching. We applied the FRET system to establish a sensitive and simple strategy for the determination of mercury (Hg2+). The maximum excitation was at 523 nm (λex = 523 nm). The enhanced fluorescence intensity at 551 nm was proportional to the concentration of Hg2+ with a range of 0.44–100 nmol L−1. The detection limit was 0.13 nM. The linear regression equation was ΔF = 27.05c (nmol L−1) − 79.88, and the regression coefficient was 0.9954. The proposed method has high sensitivity and convenience and does not require complex and expensive instruments.

中文翻译：

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金纳米粒子有机荧光染料的荧光共振能量转移及其分析应用

我们报告了五种基于金纳米粒子 (AuNPs) 和有机荧光染料的有效荧光共振能量转移 (FRET) 系统，包括离子 [荧光素钠 (FS) 和曙红 B (EB)] 和阳离子 [罗丹明 6G (Rh6G)、吖啶橙(AO) 和番红 T (ST)] 荧光染料。五个 FRET 系统的荧光强度表明有效淬灭是可能的。FRET 对 Rh6G 和 FS 的淬灭效率接近 100%，AO 为 89%，EB 为 60%，ST 为 55%。一系列紫外吸收光谱和荧光发射光谱被用来解释荧光猝灭的机理。我们发现 AuNPs 的吸收光谱和荧光染料的发射光谱之间存在不同程度的重叠。这一结果表明高效的 FRET 是荧光猝灭的可能机制。我们应用 FRET 系统为测定汞 (Hg2+) 建立了一种灵敏而简单的策略。最大激发波长为 523 nm (λex = 523 nm)。551 nm 处增强的荧光强度与 Hg2+ 的浓度成正比，范围为 0.44–100 nmol L-1。检测限为 0.13 nM。线性回归方程为ΔF = 27.05c (nmol L−1) − 79.88，回归系数为0.9954。所提出的方法具有高灵敏度和方便性，并且不需要复杂和昂贵的仪器。551 nm 处增强的荧光强度与 Hg2+ 的浓度成正比，范围为 0.44–100 nmol L-1。检测限为 0.13 nM。线性回归方程为ΔF = 27.05c (nmol L−1) − 79.88，回归系数为0.9954。所提出的方法具有高灵敏度和方便性，并且不需要复杂和昂贵的仪器。551 nm 处增强的荧光强度与 Hg2+ 的浓度成正比，范围为 0.44–100 nmol L-1。检测限为 0.13 nM。线性回归方程为ΔF = 27.05c (nmol L−1) − 79.88，回归系数为0.9954。所提出的方法具有高灵敏度和方便性，并且不需要复杂和昂贵的仪器。