Direct visualization of the protein corona using carbon nanodots as a specific contrasting agent

The cellular uptake of the nanoparticles is greatly affected by the formation of protein corona. As a result, an in-depth knowledge of direct visualization of the corona and quantification thereof is extremely important. Although transmission electron microscopy is one of the best techniques for visualization, the heavy metals that are used to increase the contrast of protein are non-specific and may lead to artifacts and erroneous conclusions. Here, we present a new strategy using carbogenic nanodots that showed excellent contrast, under a transmission electron microscope for the direct visualization and quantification of the single particle protein corona.