Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, CH-1015, Switzerland.
Center for Advanced Surface Analysis, Institute of Earth Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland.
BMC Biol. 2023 Jun 7;21(1):126. doi: 10.1186/s12915-023-01623-0.
The development of nanoscale secondary ion mass spectrometry (NanoSIMS) has revolutionized the study of biological tissues by enabling, e.g., the visualization and quantification of metabolic processes at subcellular length scales. However, the associated sample preparation methods all result in some degree of tissue morphology distortion and loss of soluble compounds. To overcome these limitations an entirely cryogenic sample preparation and imaging workflow is required.
Here, we report the development of a CryoNanoSIMS instrument that can perform isotope imaging of both positive and negative secondary ions from flat block-face surfaces of vitrified biological tissues with a mass- and image resolution comparable to that of a conventional NanoSIMS. This capability is illustrated with nitrogen isotope as well as trace element mapping of freshwater hydrozoan Green Hydra tissue following uptake of N-enriched ammonium.
With a cryo-workflow that includes vitrification by high pressure freezing, cryo-planing of the sample surface, and cryo-SEM imaging, the CryoNanoSIMS enables correlative ultrastructure and isotopic or elemental imaging of biological tissues in their most pristine post-mortem state. This opens new horizons in the study of fundamental processes at the tissue- and (sub)cellular level.
CryoNanoSIMS: subcellular mapping of chemical and isotopic compositions of biological tissues in their most pristine post-mortem state.
纳米二次离子质谱（NanoSIMS）的发展通过在亚细胞尺度上实现代谢过程的可视化和定量等，彻底改变了生物组织的研究方式。然而，相关的样本制备方法都会导致一定程度的组织形态变形和可溶性化合物的损失。为了克服这些限制，需要采用完全低温的样本制备和成像工作流程。
在这里，我们报告了 CryoNanoSIMS 仪器的开发，该仪器可以对经过高压冷冻玻璃化的生物组织的平坦块状表面的正、负离子进行同位素质谱成像，其质量和图像分辨率与传统的 NanoSIMS 相当。通过对淡水水螅组织摄取富含氮的铵后的氮同位素以及痕量元素的映射，说明了这一能力。
通过包括高压冷冻玻璃化、样本表面低温刨削和低温扫描电镜成像的低温工作流程，CryoNanoSIMS 能够以最原始的死后状态对生物组织进行超微结构以及同位素或元素的相关成像。这为在组织和（亚）细胞水平上研究基本过程开辟了新的视野。
CryoNanoSIMS：在最原始的死后状态下对生物组织的化学和同位素组成进行亚细胞级别的映射。
