Abstract
We describe the synthesis and characterization of element-encoded polystyrene nanoparticleswith diameters on the order of 100 nm and a narrow size distribution. Individual particles contain ca. 103chelated lanthanide ions, of either a single element or a mixture of elements. These particles were effectivelyinternalized by nonspecific endocytosis into three cell lines associated with human leukemia. Using anassay based upon ICP-MS detection, we could monitor quantitatively cell adhesion induced by celldifferentiation of THP-1 cells in response to phorbol ester stimulation (PMA) in single cell type or mixedcultures.