瑞典查尔默斯理工大学Christoph Langhammer、Barbora Špaková等研究人员合作开发出无标签纳米流体散射显微镜，可用于单个扩散分子和纳米颗粒的尺寸和质量研究。相关论文于2022年5月30日在线发表在《自然—方法学》杂志上。

据研究人员介绍，单个生物分子的无标签表征旨在补充荧光显微镜在标签影响数据解释、技术上具有挑战性或甚至不可能的情况下。然而，现有的方法要求被调查的物种与表面结合才能被看到，从而使很大一部分分析物未被检测到。

研究人员提出了纳米流体散射显微镜（NSM），它克服了这些限制，实现了对纳米流体通道内扩散的单个生物分子的无标签、实时成像。NSM有助于从测量的光学对比度中准确确定分子量，从测量的扩散率中准确确定流体动力学半径，从中可以推断出关于构象状态的信息。此外，研究人员以含有细胞外囊泡的条件性细胞培养液为例，证明了它对复杂生物流体分析的适用性。研究人员预计NSM将应用于监测单个生物分子的构象变化、聚集和相互作用，并分析单细胞分泌物。

附：英文原文

Title: Label-free nanofluidic scattering microscopy of size and mass of single diffusing molecules and nanoparticles

Author: pakov, Barbora, Klein Moberg, Henrik, Fritzsche, Joachim, Tenghamn, Johan, Sjsten, Gustaf, pov-Jungov, Hana, Albinsson, David, Lubart, Quentin, van Leeuwen, Daniel, Westerlund, Fredrik, Midtvedt, Daniel, Esbjrner, Elin K., Kll, Mikael, Volpe, Giovanni, Langhammer, Christoph

Issue&Volume: 2022-05-30

Abstract: Label-free characterization of single biomolecules aims to complement fluorescence microscopy in situations where labeling compromises data interpretation, is technically challenging or even impossible. However, existing methods require the investigated species to bind to a surface to be visible, thereby leaving a large fraction of analytes undetected. Here, we present nanofluidic scattering microscopy (NSM), which overcomes these limitations by enabling label-free, real-time imaging of single biomolecules diffusing inside a nanofluidic channel. NSM facilitates accurate determination of molecular weight from the measured optical contrast and of the hydrodynamic radius from the measured diffusivity, from which information about the conformational state can be inferred. Furthermore, we demonstrate its applicability to the analysis of a complex biofluid, using conditioned cell culture medium containing extracellular vesicles as an example. We foresee the application of NSM to monitor conformational changes, aggregation and interactions of single biomolecules, and to analyze single-cell secretomes. Nanofluidic scattering microscopy enables label-free, quantitative measurements of the molecular weight and hydrodynamic radius of biological molecules and nanoparticles freely diffusing inside a nanofluidic channel.

DOI: 10.1038/s41592-022-01491-6

Source: https://www.nature.com/articles/s41592-022-01491-6