Monitoring the uptake and intracellular fate of nanovectors by microscopical technique

Nanovectors are receiving great attention for their potential in therapeutic and diagnostic applications as innovative systems for drug delivery and medical imaging. Their unique features allow them to pass through the biological barriers, to accumulate at the target sites, to protect the loaded drugs from enzymatic degradation and to modulate their release. To design effective and safe administration procedures of nanovectors it is obviously mandatory to assess their possible cytotoxicity, but it is also essential to elucidate the uptake mechanism(s), the intracellular trafficking pathway, the interactions with cell organelles and the intracellular persistence of nanovectors, paying particular attention to their degradation routes. Microscopy is especially suitable to describe the interaction of nanocarriers with the cell surface and their intracellular fate following internalization. Fluorochrome-labelled nanoparticles may be observed by conventional and confocal fluorescence microscopy, while the higher resolution of transmission electron microscopy allows to reveal the specific relationships of nanocomposites with the subcellular constituents. This work summarizes some studies performed by different microscopical techniques to evaluate the properties of nanoparticles intended for therapeutic and diagnostic purposes.