The work is devoted to photoluminescent investigation of arterial walls in order to create a new navigation method for minimally invasive treatment of cardiovascular decease in the presence of chronic total occlusions. The method uses the distinct photoluminescent properties of arterial wall and chronic total occlusion plaque to alert the interventionalist when a fiber-optic equipped catheter is in contact with the vessel wall. We conducted a study to compare the photoluminescence properties of healthy and stenosed vessel walls, and a typical chronic total occlusion plaque in the spectral range 300-700 nm. All samples were obtained from human tibial arteries. These groups of arterial samples showed easily differentiable luminescence amplitude and spectral characteristics. The photoluminescent properties of intact and intentionally damaged vessel walls were also investigated to permit detection of artery perforation that could take place during the revascularization. Using optical excitation of different wavelength gives additional opportunities of detecting arterial plaques requiring laser treatment. The results presented are complemented with micro-computed tomography images and histology of the segments analyzed.
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 <i>in vitro</i> and <i>in vivo</i>. To study NC behavior in a relevant biological system, endothelial cells were grown and cultured <i>in vitro</i>. 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.