The attainable resolution of fluorescence microscopy has reached the subnanometer range, but this technique still fails to image the morphology of single proteins or small molecular complexes. Here, we expand the specimens at least tenfold, label them with conventional fluorophores and image them with conventional light microscopes, acquiring videos in which we analyze fluorescence fluctuations. One-step nanoscale expansion (ONE) microscopy enables the visualization of the shapes of individual membrane and soluble proteins, achieving around 1-nm resolution. We show that conformational changes are readily observable, such as those undergone by the ~17-kDa protein calmodulin upon Ca²⁺ binding. ONE is also applied to clinical samples, analyzing the morphology of protein aggregates in cerebrospinal fluid from persons with Parkinson disease, potentially aiding disease diagnosis. This technology bridges the gap between high-resolution structural biology techniques and light microscopy, providing new avenues for discoveries in biology and medicine.

荧光显微镜可达到的分辨率已达到亚纳米范围，但该技术仍然无法对单个蛋白质或小分子复合物的形态进行成像。在这里，我们将标本扩增至少十倍，用常规荧光团标记它们，并用常规光学显微镜对它们进行成像，获取我们分析荧光波动的视频。一步纳米级扩展 （ONE） 显微镜能够可视化单个膜和可溶性蛋白质的形状，实现约 1 nm 的分辨率。我们表明构象变化是很容易观察到的，例如 ~17-kDa 蛋白钙调蛋白在 Ca²⁺ 结合后所经历的变化。ONE 还应用于临床样本，分析帕金森病患者脑脊液中蛋白质聚集体的形态，可能有助于疾病诊断。这项技术弥合了高分辨率结构生物学技术和光学显微镜之间的差距，为生物学和医学的发现提供了新的途径。