Hsiang Jung-Cheng, Fleischer Blake C, Dickson Robert M
School of Chemistry & Biochemistry and Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States.
J Phys Chem Lett. 2016 Jul 7;7(13):2496-501. doi: 10.1021/acs.jpclett.6b00940. Epub 2016 Jun 20.
Excitation of few-atom Ag cluster fluorescence produces significant steady-state dark state populations that can be dynamically optically depopulated with long wavelength coillumination. Modulating this secondary illumination dynamically repopulates the ground state, thereby directly modulating nanodot fluorescence without modulating background. Both fast and slow modulation enable unmodulated background to be quantitatively removed in fluorescence correlation spectroscopy (FCS) through simple correlation-based averaging. Such modulated dual-laser FCS enables recovery of pure Ag nanodot fluorescence correlations even in the presence of strong, spectrally overlapping background emission. Fluorescence recovery is linear with Fourier amplitude of the modulated fluorescence, providing a complementary approach to background-free quantitation of modulatable emitter concentration in high background environments. Using the expanding range of modulatable fluorophores, such methodologies should facilitate biologically relevant studies in both complex autofluorescent environments and multiplexed assays.
少数原子银团簇荧光的激发会产生显著的稳态暗态布居，这些暗态布居可以通过长波长共照射动态地进行光学清空。动态调制这种二次照射会使基态重新布居，从而直接调制纳米点荧光而不调制背景。快速和慢速调制都能通过基于简单相关性的平均在荧光相关光谱法（FCS）中定量去除未调制的背景。这种调制双激光FCS即使在存在强烈的、光谱重叠的背景发射的情况下也能恢复纯银纳米点荧光相关性。荧光恢复与调制荧光的傅里叶振幅呈线性关系，为在高背景环境中对可调制发射体浓度进行无背景定量提供了一种补充方法。利用不断扩大的可调制荧光团范围，此类方法应有助于在复杂的自发荧光环境和多重分析中开展与生物学相关的研究。
