Targeting of drugs and therapeutic materials to target cells or designated intracellular locations relies upon their cellular / sub-cellular targeting and trafficking. The ideal optical properties of quantum dots offer the possibility of using them as fluorescent probes to study the intracellular uptake and pathway of drugs or biomolecules. Quantum dots, ZnS coated CdSe, were synthesized and successfully incorporated into polystyrene (PS) particles grafted with carboxyl groups and folic acid was attached to the nanoparticle surfaces. The nanocomposites were monodisperse and highly luminescent, and their intracellular uptake to cancer cells was investigated using confocal microscopy.