Preparation Of CdSe Quantum Dots In Liquid Paraffin And Application In Drosophila Imaging

Research on biological interactions of molecules and early diagnosis need tracking in situ, in vivo and real-time scale. Therefore, Fluorescent material with biological compatibility, small size and fine optical property was needed in the fields of biological application. Quantum dots have excellent optical properties such as continuous absorption spectrum, the emission spectrum corresponding particle size and light resistance bleaching property. Quantum dots showed broad prospect of application in biomedical fields characteristics such as marking and testing of biological molecules, cells marking/imaging, living imaging, the diagnosis and treatment of tumor fields. However, it is difficult to preparate quantum dot with uniform size, fluorescence stable performance and biocompatibility. In this work, the synthesis and characterization of CdSe quantum dot with precise size and fine nanocrystallinty via easy temperature-control method in a matrix of liquid paraffin and oleic acid system is described. TEM, HRTEM, SEAD, XRD, PL and UV-VIS spectra were used to characterize the size, crystal structure and photoluminescence (PL) properties of CdSe nanocrystals. The PL spectra and TEM results revealed that the monodispersed and uniformed CdSe QDs with narrow size distribution were synthesized at a certain reaction temperature. HRTEM images combined with selected area electron diffraction (SAED) and XRD patterns illustrated that CdSe QDs showed near-perfect zinc-blende and wurtzite crystallinity at different temperatures.The size of CdSe QDs showed linear temperature dependent properties and optimized size for a certain temperature (2.3nn for140℃,3nm for180℃.3.3nm for210℃4.5nm for240℃). The thermodynamic calculation provided a theoretic explanation for the obtaining of uniform CdSe QDs by temperature-controlled method. The results illustrated that excessive oleic acid (OA:CdO>10:1) would damage the fluorescence performance because of the steric hindrance effect, and that suitable ligand (OA: CdO=4:1), higher temperature (>140℃) and proper reaction time would reduce the defect of CdSe quantum dots. Mercaptopropionic acid (MPA) was used to modify the surface property of CdSe quantum dots in order to improve biocompatibility. Then CdSe quantum dots were used to image the drosophila for observation distribution of CdSe quantum dots in the body of drosophila. The results showed that the size of modified CdSe quantum dots was30nm after dispersion in water. It was found that CdSe quantum dot mainly distributed in the intestinal tract of drosophila.