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The aqueous dispersion of ZnO quantum dots (QDs) with strong blue emission (quantum yield of 76%) was synthesized through a simple solution route. The water stability of such QDs is provided by the hydroxyl groups on their surface, and the strong blue emission is suggested to arise from the formation of surface ZnO/oleic acid complexes. Under irradiation, these complexes are thought to absorb the excitation light with 3.54 eV and then generate the blue emission with 2.82 eV.

ZnS/ZnO heteronanostructures were prepared to serve as the photoanode of the dye-sensitized solar cells. Two nanostructures, namely, ZnS/ZnO coaxial nanowires and ZnS/ZnO hierarchical nanowires (ZnS nanoparticles on ZnO nanowires), were successfully synthesized by chemical bath deposition and chemical etching processes, respectively. For both of the nanostructures, the ZnS coating can enhance photocurrent and conversion efficiency compared with the bare ZnO nanowires. We propose that ZnS layers in the two nanostructures take effect in different ways in that the ZnS compact layer in the coaxial structure retards the back transfer of electrons to the dye and electrolyte, while the coarse surface of ZnS nanoparticles in the hierarchical nanowires significantly enhances the adsorption of dye molecules. Hence, the ideal photoanode structure for high power-conversion efficiency should have both the compact shell layer and the high surface roughness.

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A series of amino acid monoester prodrugs of floxuridine was synthesized and evaluated for the improvement of oral bioavailability and the feasibility of target drug delivery via oligopeptide transporters. All floxuridine 5′-amino acid monoester prodrugs exhibited PEPT1 affinity, with inhibition coefficients of Gly-Sar uptake (IC50) ranging from 0.7 – 2.3 mM in Caco-2 and 2.0 – 4.8 mM in AsPC-1 cells, while that of floxuridine was 7.3 mM and 6.3 mM, respectively. Caco-2 membrane permeabilities of floxuridine prodrugs (1.01 – 5.31 x 10-6 cm/sec) and floxuridine (0.48 x 10-6 cm/sec) were much higher than that of 5-FU (0.038 x 10-6 cm/sec). MDCK cells stably transfected with the human oligopeptide transporter PEPT1 (MDCK/hPEPT1) exhibited enhanced cell growth inhibition in the presence of the prodrugs. This prodrug strategy offers great potential, not only for increased drug absorption but also for improved tumor selectivity and drug efficacy.