Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada.
J Chem Phys. 2017 Sep 14;147(10):104105. doi: 10.1063/1.4989673.
Randomly rotating particles that have been isotropically labeled with rigidly linked fluorophores will undergo non-isotropic (patchy) photobleaching under illumination due to the dipole coupling of fluorophores with light. For a rotational diffusion rate D of the particle and a photobleaching time scale τ of the fluorophores, the dynamics of this process are characterized by the dimensionless combination Dτ. We find significant interparticle fluctuations at intermediate Dτ. These fluctuations vanish at both large and small Dτ or at small or large elapsed times t. Associated with these fluctuations between particles, we also observe transient non-monotonicities of the brightness of individual particles. These non-monotonicities can be as much as 20% of the original brightness. We show that these novel photobleach-fluctuations dominate over variability of single-fluorophore orientation when there are at least 10 fluorophores on individual particles.
随机旋转的粒子如果用刚性连接的荧光团各向同性标记，在光照下由于荧光团与光的偶极子耦合，将经历非各向同性（斑片状）的光漂白。对于粒子的旋转扩散速率 D 和荧光团的光漂白时间尺度 τ，该过程的动力学特征由无量纲组合 Dτ 来描述。我们发现中间 Dτ 处存在显著的粒子间波动。这些波动在 Dτ 较大或较小、或经过的时间 t 较大或较小时消失。与这些粒子间的波动相关，我们还观察到单个粒子亮度的瞬态非单调变化。这些非单调变化可以达到原始亮度的 20%。我们表明，当单个粒子上至少有 10 个荧光团时，这些新型的光漂白波动比单个荧光团方向的可变性更为重要。
