Advanced Materials Engineering and Modelling Group, Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspaińskiego 27, 50-370 Wrocław, Poland.
Electron Microscopy Laboratory, Faculty of Mechanical Engineering, Wrocław University of Science and Technology, Wybrzeże Wyspaińskiego 27, 50-370 Wrocław, Poland.
Biomater Sci. 2022 Mar 15;10(6):1554-1561. doi: 10.1039/d1bm01768c.
Protein misfolding products - amyloids - tend to form distinct fibrillar structures of the characteristic fold for a given neurodegenerative disease or pathology. Moreover, amyloids (also in the intermediate or distorted state) can act as secondary nuclei for fibrillation. Such secondary nucleation amplifies plaque development correlated with various diseases. Therefore, a versatile and non-destructive method of detection and differentiation between distinct fibrillar structures is of great importance. Amyloids exhibit unique optical properties, green-blue autofluorescence, which can also be induced by two-photon excitation. Herein, we use this label-free technique to resolve local fibrillar ordering in amyloid superstructures - spherulites. With polarization-dependent two-photon excited amyloid autofluorescence, we resolved fibrillar orientation in the spherulite corona and discussed the presence of amorphous aggregates, distorted fibrils or amyloid intermediate species within the spherulite core. Our polarization sensitive two-photon microscopy investigations are supported by TEM imaging and provide a promising tool for the detection and differentiation between well-developed amyloid fibrils and amorphous/distorted structures present at different stages of the formation of amyloid superstructures and plaques.
蛋白质错误折叠产物——淀粉样纤维——往往会形成特定神经退行性疾病或病理学特征的独特纤维状结构。此外，淀粉样纤维（也处于中间或扭曲状态）可以作为纤维形成的次级核。这种次级成核放大了与各种疾病相关的斑块发展。因此，一种通用且非破坏性的检测和区分不同纤维状结构的方法非常重要。淀粉样纤维表现出独特的光学特性，即蓝绿色自发荧光，也可以通过双光子激发来诱导。在此，我们使用这种无标记技术来解析淀粉样超结构——球晶中的局部纤维有序性。通过与偏振相关的双光子激发的淀粉样自发荧光，我们解析了球晶冠状物中的纤维取向，并讨论了球晶核心中是否存在无定形聚集体、扭曲纤维或淀粉样中间态物质。我们的偏振敏感双光子显微镜研究得到了 TEM 成像的支持，为检测和区分成熟的淀粉样纤维与在淀粉样超结构和斑块形成的不同阶段存在的无定形/扭曲结构提供了一种有前途的工具。
