中央研究院 原子與分子科學研究所

Containing an ensemble of nitrogen-vacancy centers in crystal matrices, fluorescent nanodiamonds (FNDs) are a new type of photostable markers that have found wide applications in light microscopy.  The nanomaterial also has a dense carbon core, making it visible to electron microscopy.  Here, we show that FNDs encapsulated in biotinylated lipids (bLs) are useful for sub-diffraction imaging of antigens on cell surface with correlative light-electron microscopy (CLEM).  The lipid encapsulation enables not only good dispersion of the particles in biological buffers but also high specific labeling of live cells.  By employing the bL-encapsulated FNDs to target CD44 on HeLa cell surface through biotin-mediated immunostaining, we obtained the spatial distribution of these antigens by CLEM with a localization accuracy of ~50 nm in routine operations.  A comparative study with dual-color imaging, in which CD44 was labeled with FND and MICA/MICB was labeled with Alexa Fluor 488, demonstrated the superior performance of FNDs as fluorescent fiducial markers for CLEM of cell surface antigens.

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