Diamonds as electron microscopy and integrated microscopy labels

Integrated microscopy combines light and electron microscopy (EM). With this approach, we can label cells and identify them optically but also visualize their membrane structure with EM.

A major problem with this approach is that conventional optical labels bleach during the sample preparation for EM. We found that defect centers in fluorescent nanodiamonds can survive heavy metal staining for EM undisturbed1. As a result, we can study uptake mechanisms or the fate of diamond particles but also investigate cellular processes.

In this study, we also found the diamond defects can not only be excited by light but also with the electron beam. This so-called cathodoluminescence offers greater spatial resolution than optical imaging. We also demonstrated life time measurements based on cathodoluminescence2. Similar to optical lifetime imaging, this technique offers an additional parameter to distinguish particles or to eliminate background