The limitations of current organic fluorophores have created a growing need for more flexible probes. Quantum dots (QD) offer several advantages over traditional fluorescent labels for intracellular tracking and biomedical imaging, such as high photostability and narrow emission spectra. However, insight into their effects on living cells and internalization pathways is important for their safe application. In the work presented, we utilized three types of QD composed of a core-shell of cadmium selenide-zinc sulfide (CdSe-ZnS) and functionalized with different polymer coatings (carboxyl, amino, and PEG). Human intestinal Caco-2 cells were treated with each QD to assess cytotoxicity and QD uptake. Four assays were performed to determine the effects of quantum dots on cell viability: a live-dead assay, LDH assay to test QD influence on membrane integrity, ROS assay, and WST-1 assay indicating cellular metabolic activity. In uptake experiments both undifferentiated and differentiated Caco-2 cells were used. The undifferentiated Caco-2 were incubated with 16 nM of QD for 24h, and differentiated Caco-2 for 24h, 48h, and 72h. Samples were then analyzed by confocal laser scanning microscopy to determine internalization and the intracellular location of particles with regard to proteins involved in endocytic uptake. Initial results indicate that QD types are taken up in different amounts. Going forward, we plan measure intracellular cadmium ion (Cd²⁺) concentration as well as the concentration of Cd²⁺ and QD that may have passed through the differentiated Caco-2 monolayer.