Imaging of biomolecules guides our understanding of their diverse structures and functions 1 , 2 . Real-space imaging at sub-nanometre resolution using cryo-electron microscopy has provided key insights into proteins and their assemblies 3 , 4 . Direct molecular imaging of glycans—the predominant biopolymers on Earth, with a plethora of structural and biological functions 5 —has not been possible so far 6 . The inherent glycan complexity and backbone flexibility require single-molecule approaches for real-space imaging. At present, glycan characterization often relies on a combination of mass spectrometry and nuclear magnetic resonance imaging to provide insights into size, sequence, branching and connectivity, and therefore requires structure reconstruction from indirect information 7 – 9 . Here we show direct imaging of single glycan molecules that are isolated by mass-selective, soft-landing electrospray ion beam deposition and imaged by low-temperature scanning tunnelling microscopy 10 . The sub-nanometre resolution of the technique enables the visualization of glycan connectivity and discrimination between regioisomers. Direct glycan imaging is an important step towards a better understanding of the structure of carbohydrates. An imaging method combining soft-landing electrospray ion beam deposition and low-temperature scanning tunnelling microscopy resolves the structures of glycans at sub-nanometre resolution, revealing the connectivity of glycan chains and the types of linkages.

中文翻译：

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成像单聚糖

生物分子的成像指导我们了解它们不同的结构和功能 1 、 2 。使用低温电子显微镜在亚纳米分辨率下进行的真实空间成像提供了对蛋白质及其组件 3、4 的关键见解。聚糖的直接分子成像——地球上主要的生物聚合物，具有大量的结构和生物功能 5——到目前为止还不可能 6。固有的聚糖复杂性和骨架灵活性需要单分子方法进行实空间成像。目前，聚糖表征通常依赖于质谱和核磁共振成像的组合来提供对大小、序列、分支和连通性的洞察，因此需要从间接信息 7 - 9 进行结构重建。在这里，我们展示了通过质量选择性软着陆电喷雾离子束沉积分离并通过低温扫描隧道显微镜 10 成像的单个聚糖分子的直接成像。该技术的亚纳米分辨率能够实现聚糖连接的可视化和区域异构体之间的区分。直接聚糖成像是更好地了解碳水化合物结构的重要一步。一种结合软着陆电喷雾离子束沉积和低温扫描隧道显微镜的成像方法以亚纳米分辨率解析聚糖的结构，揭示聚糖链的连接性和连接类型。该技术的亚纳米分辨率能够实现聚糖连接的可视化和区域异构体之间的区分。直接聚糖成像是更好地了解碳水化合物结构的重要一步。一种结合软着陆电喷雾离子束沉积和低温扫描隧道显微镜的成像方法以亚纳米分辨率解析聚糖的结构，揭示聚糖链的连接性和连接类型。该技术的亚纳米分辨率能够实现聚糖连接的可视化和区域异构体之间的区分。直接聚糖成像是更好地了解碳水化合物结构的重要一步。一种结合软着陆电喷雾离子束沉积和低温扫描隧道显微镜的成像方法以亚纳米分辨率解析聚糖的结构，揭示聚糖链的连接性和连接类型。