Šubr Martin, Praus Petr, Kočišová Eva, Procházka Marek, Štěpánek Josef, Kuzminova Anna, Kylián Ondřej, Sureau Franck
Institute of Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague, Czech Republic.
Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 180 00 Prague, Czech Republic.
Nanomaterials (Basel). 2020 Apr 16;10(4):773. doi: 10.3390/nano10040773.
Surface-enhanced fluorescence (SEF) requires the absorption/emission band of the fluorophore, the localized surface plasmon resonance (LSPR) of the nanostructure and the excitation wavelength to fall in the same (or very close) spectral range. In this paper, we monitor the SEF intensity and lifetime dependence of riboflavin (vitamin B2) adsorbed on a spacer-modified Ag substrate with respect to the thickness of the spacer. The substrates were formed by silver nanoislands deposited onto magnetron-sputtered polytetrafluoroethylene (ms-PTFE). The spacer was formed by the ms-PTFE layer with the thickness ranging from ~5 to 25 nm. The riboflavin dissolved in dimethylsulfoxide (DMSO) at a 10 µM concentration forms, at the ms-PTFE surface, a homogeneous layer of adsorbed molecules corresponding to a monomolecular layer. The microspectroscopic measurements of the adsorbed layer were performed through a sessile droplet; our study has shown the advantages and limitations of this approach. Time-resolved fluorescence enabled us to determine the enhanced fluorescence quantum yield due to the shortening of the radiative decay in the vicinity of the plasmonic surface. For the 5 nm ms-PTFE layer possessing the largest (estimated 4×) fluorescence enhancement, the quantum yield was increased 2.3×.
表面增强荧光（SEF）要求荧光团的吸收/发射带、纳米结构的局域表面等离子体共振（LSPR）以及激发波长落在相同（或非常接近）的光谱范围内。在本文中，我们监测了吸附在间隔层修饰的银基底上的核黄素（维生素B2）的SEF强度和寿命随间隔层厚度的变化。基底由沉积在磁控溅射聚四氟乙烯（ms-PTFE）上的银纳米岛构成。间隔层由厚度在约5至25纳米范围内的ms-PTFE层形成。溶解在二甲基亚砜（DMSO）中浓度为10 µM的核黄素在ms-PTFE表面形成对应于单分子层的吸附分子均匀层。通过静滴法对吸附层进行微观光谱测量；我们的研究展示了这种方法的优点和局限性。时间分辨荧光使我们能够确定由于等离子体表面附近辐射衰减缩短而导致的增强荧光量子产率。对于具有最大（估计为4倍）荧光增强的5纳米ms-PTFE层，量子产率提高了2.3倍。
