Luminescence investigation of endothelial cells using metallic and semiconductor nanocrystals

Our aim is to use nanocrystals (NC) to study endothelial cell biology, in particular, the cell surface receptor Tie2. Tie2 is highly expressed in endothelial cells and is critical for angiogenesis and vascular maintenance. Conjugating NCs to the Tie2 ligands, the angiopoietins, and tracking their characteristic luminescence lines will allow us to study the regulation of Tie2 in vitro and in vivo. To study NC behavior in a relevant biological system, endothelial cells were grown and cultured in vitro. Two different types of NC were made and tested: two-color core-shell CdSe/ZnS and more complicated nanostructures containing also Au clusters. Measurements were performed in specially prepared media with different pH values, as well as in the cell growth medium. The positions of NC-related luminescence lines were not influenced by the kind of media which makes them suitable for biolabeling the cell surface receptor Tie2. At the same time, the relative magnitude of the NC peaks depends on the pH of the medium and can therefore be used for characterization of the latter. Confocal microscopic images show that NCs with different ligands demonstrate different distributions inside living cells.