近日，美国威斯康星大学麦迪逊分校的Randall H.Goldsmith及其研究团队取得一项新进展。经过不懈努力，他们实现单个溶液相分子的无标记检测和分析。相关研究成果已于2024年5月8日在国际权威学术期刊《自然》上发表。

该研究团队使用高精细纤维的Fabry–Pérot微腔中增强的光分子相互作用，来检测小至1.2kDa的单个生物分子，这是一种十氨基酸肽，信噪比(SNRs) >100，即使这些分子没有标记并且在溶液中自由扩散。这一方法提供了二维强度和时间分布，使混合样本中的亚种群得以区分。值得注意的是，研究人员观察到时间和分子半径之间的线性关系，释放了收集有关扩散和溶液相构象的关键信息的潜力。

此外，具有相同分子量和组成但不同构象的生物分子异构体的混合物也可以被解析。该研究通过创新的分子速度过滤窗口和动态热启动机制，利用光学、热动力学以及庞德-德雷弗-霍尔（PDH）腔锁定技术之间的相互作用，实现了分子运动的精准检测，即使在环境噪声被有效抑制的情况下也能实现。这一新方法为揭示分子构象、多样性和动力学提供了新的体外途径，并在生命与化学科学领域展现出了巨大的应用潜力。

据悉，大多数化学和生物学发生在溶液中，其中构象动力学和络合是行为和功能的基础。单分子技术特别适合于解析分子多样性，新的无标记方法正在重塑单分子测量的能力。一种能够揭示溶液中分子构象细节的无标记单分子方法，提供了前所未有的精细的新微观视角。

附：英文原文

Title: Label-free detection and profiling of individual solution-phase molecules

Author: Needham, Lisa-Maria, Saavedra, Carlos, Rasch, Julia K., Sole-Barber, Daniel, Schweitzer, Beau S., Fairhall, Alex J., Vollbrecht, Cecilia H., Wan, Sushu, Podorova, Yulia, Bergsten, Anders J., Mehlenbacher, Brandon, Zhang, Zhao, Tenbrake, Lukas, Saimi, Jovanna, Kneely, Lucy C., Kirkwood, Jackson S., Pfeifer, Hannes, Chapman, Edwin R., Goldsmith, Randall H.

Issue&Volume: 2024-05-08

Abstract: Most chemistry and biology occurs in solution, in which conformational dynamics and complexation underlie behaviour and function. Single-molecule techniques are uniquely suited to resolving molecular diversity and new label-free approaches are reshaping the power of single-molecule measurements. A label-free single-molecule method capable of revealing details of molecular conformation in solution would allow a new microscopic perspective of unprecedented detail. Here we use the enhanced light–molecule interactions in high-finesse fibre-based Fabry–Pérot microcavities to detect individual biomolecules as small as 1.2kDa, a ten-amino-acid peptide, with signal-to-noise ratios (SNRs) >100, even as the molecules are unlabelled and freely diffusing in solution. Our method delivers 2D intensity and temporal profiles, enabling the distinction of subpopulations in mixed samples. Notably, we observe a linear relationship between passage time and molecular radius, unlocking the potential to gather crucial information about diffusion and solution-phase conformation. Furthermore, mixtures of biomolecule isomers of the same molecular weight and composition but different conformation can also be resolved. Detection is based on the creation of a new molecular velocity filter window and a dynamic thermal priming mechanism that make use of the interplay between optical and thermal dynamics and Pound–Drever–Hall (PDH) cavity locking to reveal molecular motion even while suppressing environmental noise. New in vitro ways of revealing molecular conformation, diversity and dynamics can find broad potential for applications in the life and chemical sciences.

DOI: 10.1038/s41586-024-07370-8

Source: https://www.nature.com/articles/s41586-024-07370-8