Synthesis, characterization and bioimaging of fluorescent labeled polyoxometalates

Abstract

A fluorescent labeled Wells–Dawson type POM ({P₂W₁₇O₆₁Fluo}) was newly synthesized and characterized by a wide range of analytical methods. {P₂W₁₇O₆₁Fluo} was functionalized with fluorescein amine through a stable amide bond, and its long time stability was verified by UV/vis spectroscopic techniques at physiologically relevant pH values. No significant impact on the cell viability or morphology of HeLa cells was observed for POM concentrations up to 100 μg mL⁻¹. Cellular uptake of fluorescent {P₂W₁₇O₆₁Fluo} was monitored by confocal laser scanning microscopy. POM uptake occurs mainly after prolonged incubation times of 24 h resulting in different intracellular patterns, i.e. randomly distributed over the entire cytoplasm, or aggregated in larger clusters. This direct monitoring strategy for the interaction of POMs with cells opens up new pathways for elucidating their unknown mode of action on the way to POM-based drug development.