Micro- or nano-particles encapsulating hydrophobic quantum dots were prepared by the emulsion technique. Films containing quantum dots were also prepared by film casting methods. Quantum dots without hydrophilic coating were directly mixed with polymer solution to prepared extremely stable films or particles that do not phase-separate with time. The surface of the particles or films could be modified to have different hydrophilicity and/or functional groups. Particles with 1.5 ± 0.16 um and 320 ± 26 nm in diameters and films of 300 um in thickness were prepared. NIH 3T3 and EMT-6 were culture on the films containing quantum dots for 8 -20 h. Compared to the control, quantum dot were delivered directly and efficiently into the cells without toxicity. When implanted near tumor cells in Balb/C mice, quantum dots migrated from the films into the tumor cells for at least 3 days. Considering that the quantum dot dispersion in aqueous media is relatively unstable and difficult to handle, our stable particles or films containing hydrophobic quantum dots can become versatile probes for biological applications.