用乙二醇还原硝酸银,成功制备了平均边长约97 nm的银纳米立方体以用于诺丹明(RhB)分子的 荧光实验。实验中,将探针分子 RhB粉末掺杂于PMMA苯甲醚溶液中,制得不同厚度掺杂有RhB探针分子的PMMA薄膜,运用光谱技术和 共焦显微技术研究了银纳米立方体与荧光分子的间隔、银纳米立方体不同浓度分布对RhB分子的 荧光强度的影响。荧光光谱表明,荧光强度随PMMA厚度变薄而增强,当PMMA厚度为10 nm时, 荧光增强因子最大,获得了56倍的荧光增强效果,而继续减小PMMA厚度时,其荧光增强因子又变小, 说明发生了荧光猝灭效应。共焦荧光像则更直观地表现了银纳米立方体的浓度分布对荧光分子 辐射增强的影响。因而,可通过调控银纳米立方体与荧光分子的距离及银纳米立方体的分布优 化荧光增强因子以用于基于荧光的单分子探测,这一实验结果在生物成像和生物传感领域有潜在应用价值。

Silver nano-cubes of about 97 nm side-length were synthesized by reducing AgNO3 with ethylene glycol (EG) and used to modulate fluorescence intensity of Rhodamine B (RhB). The RhB (probe molecules) powder was dissolved into PMMA solution with different PMMA concentrations, which resulted in RhB doped PMMA films with different thickness. The distance between Ag nano-cubes and the fluorescence molecules and distribution of Ag nano-cubes has important influence on the fluorescence emission. The fluorescence spectrums show the enhancement and quenching effect with different thickness of PMMA film. The largest fluorescence enhancement factor (EF) is 56 for the structure of Ag nano-cubes absorbed on the RhB doped PMMA film as the thickness of PMMA is 10 nm. The confocal-images also verified the fluorescence enhancement. The EF is influenced by the distribution of silver nano-cubes on the PMMA film from the confocal-images. So the biggest EF can be obtained by optimizing the distance between silver nano-cubes and the fluorescence molecules or by tuning the distribution of silver nano-cubes, which may be used to single molecule detection. The experiment results have potential application in fluorescence based bio-sensing or bio-imaging.