A new approach for synthesis of high quality core/shell nanocrystals, "thermal-cycling coupled single precursor" (TC-SP), was developed. It was applied for the synthesis of high efficiency, good color purity, nearly monodisperse, alloying-free, and stable CdS/ZnS core/shell nanocrystals with their emission peak tunable between 375 and 475 nm. A comparison study on TC-SP versus the classic successive ionic layer adsorption and reaction (SILAR), both in one pot, revealed that, although the reaction temperature was significantly reduced and the procedure was simplified for TC-SP, the overall quality of the CdS/ZnS core/shell nanocrystals yielded by TC-SP was found to be superior. A quantitative chemical etching method was developed for determining the radial distribution of elements in bandgap/composition engineered nanocrystals.

The work described a new colorimetric sensor for the quantitative detection of clindamycin based on Au@Ag core–shell nanoparticles (Au@Ag NPs). The obtained Au@Ag NPs were characterized by transmission electron microscopy (TEM) and ultraviolet and visible spectrophotometry (UV–vis). When Au@Ag NPs were added to a clindamycin solution, it can be observed that the color immediately changed from bright yellow to gray-blue and the absorption spectrum also changed, realizing the visual detection of clindamycin. Under optimal conditions, the absorption ratio (A 546/A 400) of the UV–vis spectra increased linearly with the concentration of clindamycin ranging from 6.25 × 10–7 to 7.50 × 10–6 mol/L (R 2 = 0.9945), with a limit of detection (LOD) of 2.00 × 10–7 mol/L and good recovery of 100.0–102.0% (relative standard deviation (RSD) < 2%). The detection process was convenient without complicated instruments. Compared with other analytes, the Au@Ag NPs detection system has good selectivity for clindamycin. In addition, the Au@Ag NPs colorimetric sensor was successfully used to determine clindamycin in human urine samples. This study provides a simple, rapid, intuitive, and low-cost visualization analysis method of clindamycin, which was helpful for the visualization detection of other targets.

ZnSe quantum dots (QDs) with high intrinsic fluorescence quantum efficiency (QY) and low defect luminescence were prepared by hydrothermal method assisted with ammonia, in which the selenium powder and zinc acetate were used as Se and Zn source, and the mercaptopropionic acid (MPA) was used as ligand. Effect of ammonia amount, Zn/Se ratio, Zn/MPA ratio, and reaction time was investigated in detail in this study. The as-prepared ZnSe QDs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible absorption spectrum (UV-Vis), fluorescence spectrum (PL). ZnSe QDs assisted with ammonia were sphalerite, and with emission peak in the range of 380~405nm. The optimal condition was following: Zn/Se ratio was 5, Zn/MPA ration was 0.25, reaction temperature was 110 °C and reaction time was 6 h. Under the optimal condition, ZnSe QDs with intrinsic emission QY of 47% and diameter of 3.8±0.3 nm can be obtained. The ZnSe QDs prepared in this study were expected to replace toxic Cd-related QDs in biomarkers, violet and blue light solid luminescent devices, and provide excellent parent materials for the doped ZnSe QDs system.

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