Voltage-sensitive fluorescent dyes such as di-8-ANEPPS (di-8-aminonaphthylethylenepyridinium propylsulfonate) are powerful tools to study biological membranes. Its fluorescence is affected by changes in the membrane potential and other factors, requiring extensive calibration to extract meaningful quantitative results. The amphiphilic di-8-ANEPPS molecule is expected to bind at the membrane-solution interface. However, atomic-level information is sparse about its position and orientation in the membrane, especially in regards to how the latter dynamically fluctuates to affect the observed fluorescence. In the present work, molecular dynamics simulations of the ground and excited states of di-8-ANEPPS embedded in a DPPC membrane as represented by classical force fields were used to investigate how the fluorescence is affected by externally applied potential. The calculations reproduce the shifts in the wavelength of emission as a function of voltage that are observed experimentally, indicating that the approach can help better understand the various factors that can affect the fluorescence of membrane-bound dyes.

中文翻译：

---

模拟脂质膜中 Di-8-ANEPPS 的电压依赖性荧光

电压敏感荧光染料，例如 di-8-ANEPPS（二-8-氨基萘基乙烯吡啶丙磺酸盐）是研究生物膜的强大工具。其荧光受到膜电位变化和其他因素的影响，需要进行大量校准才能提取有意义的定量结果。两亲性 di-8-ANEPPS 分子预计会在膜-溶液界面结合。然而，关于其在膜中的位置和方向的原子级信息很少，特别是关于后者如何动态波动以影响观察到的荧光。在目前的工作中，使用经典力场代表的嵌入 DPPC 膜中的 di-8-ANEPPS 的基态和激发态的分子动力学模拟来研究荧光如何受到外部施加的电势的影响。计算再现了实验观察到的发射波长随电压变化的变化，表明该方法可以帮助更好地理解影响膜结合染料荧光的各种因素。