Impact of Proteins on the Cellular Uptake of Carbon Nanodots

There are many reports in the literature on how a formed protein corona around colloidal nanoparticles affects their uptake by cells. There are however still details to be investigated, such as the role of a preformed protein corona versus the protein corona formed in serum-supplemented culture media, which is the topic of this work. Carbon nanodots (CDs) were preincubated with human serum albumin (HSA), and their cellular uptake was studied with flow cytometry and confocal laser scanning microscopy, in comparison to bare CDs. Measurements were carried out under serum-free and serum-containing conditions, leading to a 2 × 2 sample set: CDs with proteins (HSA preincubation + serum, serum, and HSA preincubation), and CDs without proteins. Serum-supplemented conditions lead to reduced uptake of CDs, whereas preincubation with HSA enhanced their internalization.