Three analog solvatochromic probes, Laurdan, Prodan, and Acdan, are extensively used in the study of biological sciences. Their locations in lipid membranes vary greatly in depth, and their fluorescence responds to their surrounding environment based on their corresponding locations in the membrane. Utilizing the fluorescence lifetimes (τ) and emission peak positions (λ) acquired from the time-resolved emission spectrum, one can effectively determine the local lipid environment using the analytical approach, referred to as τ and λ plots. Herein, a τ and λ plot was created using the aforementioned probes to expand the analytical field according to their location. Furthermore, the solvent modeling method in the τ and λ plot was upgraded to artificially emulate the complex environment in lipid membranes by utilizing liquid paraffin and glycerol to assess the contribution of viscosity to each fluorescence distribution. According to the results from a series of solvent mixtures, the effect of solvent viscosity on lifetime values was confirmed in the short lifetime region (τ < 3 ns). However, it was impossible to emulate the longer than 4 ns lifetime values observed in lipid membranes containing 1,2-dipalmitoyl-sn-glycero-3-phosphocholine in the range of viscosity applied in this study. From the insight of the limiting anisotropy (r∞), the τ and λ plot was divided into a solvent-like region with an isotropic environment (r∞ < 0.15) and a region highly ordered enough to define it as an anisotropic environment (0.15 < r∞) at τ = 4 ns. Also, the membrane-specific distribution was illustrated as 4 ns < τ and λ < 460 nm from this work. An updated analytical model was created to visualize multiple fluorescence components of each probe in six types of lipid bilayers, confirming the different distributions between these probes. Our results well illustrate the multiplicity of lipid environments modeled with solvent and ordered environments in each lipid bilayer system.

中文翻译：

---

通过 DAS 反卷积和各向异性相结合进行多灶性脂质膜表征


三种类似物变色探针 Laurdan、Prodan 和 Acdan 广泛用于生物科学研究。它们在脂质膜中的位置深度差异很大，它们的荧光根据它们在膜中的相应位置对周围环境做出反应。利用从时间分辨发射光谱中获得的荧光寿命 （τ） 和发射峰位置 （λ），可以使用分析方法（称为 τ 和 λ 图）有效地确定局部脂质环境。在此，使用上述探针创建了 τ 和 λ 图，以根据它们的位置扩展解析场。此外，τ 和 λ 图中的溶剂建模方法升级为人工模拟脂质膜中的复杂环境，利用液体石蜡和甘油评估粘度对每种荧光分布的贡献。根据一系列溶剂混合物的结果，在短寿命区域 （τ < 3 ns） 证实了溶剂粘度对寿命值的影响。然而，在本研究中应用的粘度范围内，无法模拟在含有 1,2-二棕榈酰-sn-甘油-3-磷酸胆碱的脂质膜中观察到的超过 4 ns 的寿命值。根据极限各向异性 （r∞） 的洞察力，τ 和 λ 图被划分为具有各向同性环境 （r∞ < 0.15） 的溶剂状区域和一个高度有序的区域，足以将其定义为各向异性环境 （0.15 < r∞） 在 τ = 4 ns 处。此外，从这项工作中，膜特异性分布被描述为 4 ns < τ 和 λ < 460 nm。 创建了一个更新的分析模型，以可视化六种脂质双层中每个探针的多个荧光成分，从而确认这些探针之间的不同分布。我们的结果很好地说明了每个脂质双层系统中用溶剂和有序环境建模的脂质环境的多样性。