Synchrotron-based X-ray fluorescence (S-XRF) is a powerful technique for imaging the distribution of many biologically relevant elements, as well as of "artificial" elements deliberately introduced into tissues and cells, for example through functionalized nanoparticles. In this study we explored the potential of S-XRF for chemical nanoimaging (100 nm spatial resolution, nanoXRF) of human cells, through the use of functionalized CdSe/ZnS quantum dots (QDs). We used a commercially available QD -- secondary antibody conjugate to label the cancer marker HER2 (Human Epidermal growth factor Receptor 2) on the surface of SKOV3 cancer cells, and beta-tubulin, a protein associated with cytoskeleton microtubules. We set up samples with epoxy inclusion and intracellular labeling, and samples without epoxy inclusion and with surface labeling. Epoxy inclusion, also used in electron microscopy, has the advantage to preserve cell morphology, and to guarantee long term stability. QDs proved to be suitable probes for nanoXRF, due to the Se emission band which is not in close proximity to any other emission band, and the signal specificity which is preserved in both types of labeling. Therefore, nanoXRF using QD-based markers can be very effective to colocalize specific intracellular targets with elements naturally present in the cell, and may complement confocal fluorescence microscopy in a synergistic fashion.