Vitale Nicholas H, Hassibi Arjang, Soh Hyongsok Tom, Murmann Boris, Lee Thomas H
Department of Electrical Engineering, Stanford University, Stanford, California, United States of America.
Department of Radiology, Stanford University, Stanford, California, United States of America.
PLoS One. 2024 Dec 23;19(12):e0313949. doi: 10.1371/journal.pone.0313949. eCollection 2024.
We present a model for the noise and inherent stochasticity of fluorescence signals in both continuous wave (CW) and time-gated (TG) conditions. When the fluorophores are subjected to an arbitrary excitation photon flux, we apply the model and compute the evolution of the probability mass function (pmf) for each quantum state comprising a fluorophore's electronic structure, and hence the dynamics of the resulting emission photon flux. Both the ensemble and stochastic models presented in this work have been verified using Monte Carlo molecular dynamic simulations that utilize the Gillespie algorithm. The implications of the model on the design of biomolecular fluorescence detection systems are explored in three relevant numerical examples. For a given system, the quantum-limited signal-to-noise ratio (QSNR) and limits of detection are computed to demonstrate how key design tradeoffs are quantified. We find that as systems scale down to micro- and nano- dimensions, the interplay between the fluorophore's photophysical qualities and use of CW or TG has ramifications on optimal design strategies when considering optical component selection, measurement speed, and system energy requirements. While CW systems remain a gold standard, TG systems can be leveraged to overcome cost and system complexity hurdles when paired with the appropriate fluorophore.
我们提出了一个适用于连续波（CW）和时间门控（TG）条件下荧光信号噪声及固有随机性的模型。当荧光团受到任意激发光子通量作用时，我们应用该模型并计算构成荧光团电子结构的每个量子态的概率质量函数（pmf）的演变，从而得出产生的发射光子通量的动力学。本工作中提出的系综模型和随机模型均已通过使用吉莱斯皮算法的蒙特卡罗分子动力学模拟进行了验证。在三个相关的数值示例中探讨了该模型对生物分子荧光检测系统设计的影响。对于给定系统，计算量子极限信噪比（QSNR）和检测限，以展示关键设计权衡是如何量化的。我们发现，随着系统缩小到微米和纳米尺寸，在考虑光学组件选择、测量速度和系统能量需求时，荧光团的光物理性质与CW或TG的使用之间相互作用会对最佳设计策略产生影响。虽然CW系统仍然是金标准，但当与合适的荧光团配对时，TG系统可用于克服成本和系统复杂性障碍。
