Laboratory-Based Correlative Soft X-ray and Fluorescence Microscopy in an Integrated Setup

TL;DR

This paper introduces a compact laboratory-based soft X-ray microscope integrated with fluorescence imaging, enabling correlative, high-resolution, in-situ structural and functional imaging of biological samples without sample alteration.

Contribution

It presents a novel, integrated, tabletop soft X-ray and fluorescence microscopy setup that allows correlative imaging with nanoscale resolution in a laboratory environment.

Findings

Achieved 50 nm structural resolution.

Demonstrated multimodal imaging of nanoparticles and labeled cells.

Maintained sample integrity during modality switching.

Abstract

Correlative microscopy is a powerful technique that combines the advantages of multiple imaging modalities to achieve a comprehensive understanding of investigated samples. For example, fluorescence microscopy provides unique functional contrast by imaging only specifically labeled components, especially in biological samples. However, the achievable structural information on the sample in its full complexity is limited. Here, the intrinsic label-free carbon contrast of water window soft X-ray microscopy can complement fluorescence images in a correlative approach ultimately combining nanoscale structural resolution with functional contrast. However, soft X-ray microscopes are complex and elaborate, and typically require a large-scale synchrotron radiation source due to the demanding photon flux requirements. Yet, with modern high-power lasers it has become possible to generate sufficient photon flux from laser-produced plasmas, thus enabling laboratory-based setups. Here, we present a compact table-top soft X-ray microscope with an integrated epifluorescence modality for 'in-situ' correlative imaging. Samples remain in place when switching between modalities, ensuring identical measurement conditions and avoiding sample alteration or destruction. We demonstrate our new method by multimodal images of several exemplary samples ranging from nanoparticles to various multicolor labeled cell types. A structural resolution of down to 50 nm was reached.