Opt Express. 2022 Jun 6;30(12):22051-22065. doi: 10.1364/OE.456557.
The orientation of a single molecule provides valuable information on fundamental biological processes. We report a technique for the simultaneous estimation of single-molecule 2D position and 2D orientation with ultra-high localization precision (∼2-nm precision with ∼500 photons under a typical 100-nm diameter of excitation beam pattern), which is also compatible with tracking in living cells. In the proposed method, the theoretical precision limits are calculated, and the localization and orientation performance along with potential applications are explored using numerical simulations. Compared to other camera-based orientation measurement methods, it is confirmed that the proposed method can obtain reasonable estimates even under very weak signals (∼15 photons). Moreover, the maximum likelihood estimator (MLE) is found to converge to the theoretical limit when the total number of photons is less than 100.
单分子的取向提供了关于基本生物过程的有价值的信息。我们报告了一种同时估计单分子 2D 位置和 2D 取向的技术，具有超高的定位精度（在典型的 100nm 直径激发光束模式下，约 2nm 的精度，使用约 500 个光子），同时也与活细胞中的跟踪兼容。在提出的方法中，计算了理论精度极限，并使用数值模拟探索了定位和取向性能以及潜在应用。与其他基于相机的取向测量方法相比，即使在非常弱的信号（约 15 个光子）下，也可以确认该方法可以获得合理的估计。此外，当光子总数小于 100 时，发现最大似然估计器（MLE）收敛到理论极限。
