We report a multilayer solution-processed blue light-emitting diode based on colloidal core/shell CdS/ZnS nanocrystal quantum dots (QDs). At a low-operating voltage of 5.5 V, the device emits spectrally pure blue radiation at 460 nm with a narrow full-width-at-half-maximum bandwidth of 20 nm and high brightness up to 1600 cd/m2. Broad-band, long-wavelength emission from the polymer components and deep traps in the QDs are minimized to less than 5% of the total emission.

A model which involves both bulk diffusion process and surface reaction process has been developed for describing the growth behaviour of nanoparticles. When the model is employed, hypothesising that either of the processes alone dominates the overall growth process is unnecessary. Conversely, the relative magnitude of contributions from both processes could be obtained from the model. Using this model in our system, the growth process of CdSe QDs demonstrated two different growth stages. During the first stage, the growth of CdSe QDs was dominated by bulk diffusion, whereas, neither the bulk diffusion process nor the surface reaction process could be neglected during the later stage. At last, we successfully modelled the Ostwald ripening of CdSe QDs with LSW theories.

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Breast cancer is the second most common type of cancer, the fifth most common cause of cancer deaths in the US and the world, and the most common cause of cancer death in women. Knowing the accurate stage of the breast cancer is critical for patient survival. Sufficient treatment during the early stages of breast cancer can prevent the spread and transfer of the cancer cells to other parts of the body. But, the cancer cells need to be diagnosed at the early stage in order to start treatment. We report the development of early stage detection of breast cancer cells using quantum dots (QDs) as fluorescent signal generator for detection. The QDs based imaging of breast cancer cells involved two kinds of antibodies: the first was for labeling the cells and the second was for imaging the breast cancer cells. Anti-Her2/neu (1 0 Ab) was used for labeling the captured SK-BR3 cells. The second antibody against antiHer2/neu (2 0 Ab) that was conjugated to QDs (2 0 Ab~QDs) forms the complete assay, SK-BR3 + 1 0 Ab + 2 0 Ab~QDs, to generate the fluorescent cells for imaging. Fluorescent images of the complete assay for SK-BR3 cells were evaluated under a microscope with a UV light source. The preliminary results showed that the breast cancer cell SK-BR3 in the complete assay were successfully observed as fluorescent cells that had brighter signals compared with those labeled with organic dye using similar parameters and the same number of cells. Future directions will involve elimination of non-specific signals, establishment of dynamic range of concentrations detected as well as limits of detection, and multiplex detection of different types cells and/or biomarkers of cancer.

We report in this article the microwave synthesis of relatively monodisperse, highly crystalline CdSe quantum dots (QDs) overcoated with Cd0.5Zn0.5S/ZnS multishells. The as-prepared QDs exhibited narrow photoluminescence bandwidth as the consequence of homogeneous size distribution and uniform crystallinity, which was confirmed by transmission electron microscopy. A high photoluminescence quantum yield up to 80% was measured for the core/multishell nanocrystals. Finally, the resulting CdSe/Cd0.5Zn0.5S/ZnS core/multishell QDs have been successfully applied to the labeling and imaging of breast cancer cells (SK-BR3).