Instituto de Ciencias Aplicadas y Tecnología, Universidad Nacional Autónoma de México, Av. Universidad 3000, Coyoacán, 04510 CDMX, Mexico.
Instituto de Física "Manuel Sandoval Vallarta", 78000 San Luis Potosí, Mexico.
Colloids Surf B Biointerfaces. 2021 Jul;203:111763. doi: 10.1016/j.colsurfb.2021.111763. Epub 2021 Apr 14.
Rapid diagnosis provides better clinical management of patients, helps control possible outbreaks, and increases survival. The study of deposits produced by the evaporation of droplets is a useful tool in the diagnosis of some health problems. With the aim to improve diagnostic time in clinical practice where we use the evaporation of droplets, we explored the effects of substrate temperature on pattern formation of dried droplets in globular protein solutions. Three deposit groups were observed: "functional" patterns (from 25 to 37 C), "transition" patterns (from 44 to 50 C), and "eye" patterns (from 58 to 63 C). The dried droplets of the first two groups show a ring structure ("coffee-ring") that confines a great diversity of aggregates such as needle-like structures, tiny blade-shape crystals, highly symmetrical crystallization patterns, and amorphous salt aggregates. In contrast, the "eye" patterns are deposits with a large inner aggregate surrounded by a coffee ring, and they can appear from the evaporation of droplets in protein binary mixtures and blood serum. Interestingly, the unfolding proteins correlates with the formation of "eye" patterns. We measured stain diameter, "coffee-ring" thickness, radial density profile, and entropy computed by GLCM-statistics to quantify the structural differences among deposit groups. We found that "functional" patterns are structurally indistinguishable among them, but they are clearly different from elements of the other deposit groups. An exponential decay function describes pattern formation time as a function of substrate temperature, which is independent from protein concentration. Patterns formation at 32 C takes place up to 63% less time and preserves the structural characteristics of dried droplets in proteins formed at room temperature. Therefore, we argue that droplet evaporation at this substrate temperature could be an excellent candidate to make a more efficient diagnosis based on droplet evaporation of biofluids.
快速诊断为患者提供了更好的临床管理，有助于控制可能的爆发，并提高生存率。研究液滴蒸发产生的沉积物是诊断某些健康问题的有用工具。为了提高我们在临床实践中使用液滴蒸发时的诊断时间，我们探索了基底温度对球状蛋白溶液中干燥液滴图案形成的影响。观察到了三组沉积物图案：“功能”图案（25 到 37°C）、“过渡”图案（44 到 50°C）和“眼睛”图案（58 到 63°C）。前两组的干燥液滴显示出环状结构（“咖啡环”），该结构限制了各种聚集体，如针状结构、微小的叶片状晶体、高度对称的结晶图案和无定形盐聚集体。相比之下，“眼睛”图案是由大内部聚集体和咖啡环组成的沉积物，它们可以从蛋白质二元混合物和血清的液滴蒸发中出现。有趣的是，展开的蛋白质与“眼睛”图案的形成相关。我们测量了染色直径、“咖啡环”厚度、径向密度分布和通过 GLCM-统计计算的熵，以量化沉积物组之间的结构差异。我们发现“功能”图案在它们之间结构上无法区分，但它们与其他沉积物组的元素明显不同。指数衰减函数将图案形成时间表示为基底温度的函数，该函数与蛋白质浓度无关。在 32°C 下，图案形成时间减少了 63%，并且保留了在室温下形成的蛋白质中干燥液滴的结构特征。因此，我们认为在这种基底温度下进行液滴蒸发可能是一种很好的候选方法，可以基于生物液滴蒸发进行更有效的诊断。
