复合荧光CdSe量子点-脂质体的制备与表征

Preparation and Characterization of Fluorescence CdSe-Liposome Compound

通过脂质体方法成功地将三辛基氧化膦(TOPO)包覆的CdSe发光量子点从非极性有机溶剂转移到生物相容性的水溶液中。分别通过透射电镜(TEM)、荧光Mapping图像,以及光致发光(PL)光谱进行表征。TEM照片显示制备的CdSe核量子点为球形,具有良好的单分散特性,平均粒径约为3nm。CdSe-脂质体复合体的平均尺寸大约20nm,TEM清楚地显示了CdSe量子点被诱捕在脂质体中。荧光Mapping显示了CdSe-脂质体复合体的发光强度分布。脂质体方法转移TOPO包覆的CdSe量子点,借助了磷脂的双分子链与CdSe表面的TOPO配体之间的疏水相互作用,在CdSe的第一配体层外部形成第二配体层,保留了CdSe的存在环境,光致发光光谱表明,量子点-脂质复合体基本保持了CdSe核量子点的发射效率。

CdSe semiconductor QDs with diameters ranging between 1.5 and 8 nm exhibit strong and tunable luminescence. They have been widely investigated because of their potential use in sensors, laser materials, thin film light-emitting devices （ LEDs）, and biological labels. Among numerous possible applications of CdSe nanoparticles, biological labeling will be pointed out. However, highly luminescent CdSe nanocrystals were usually synthesized with hydrophobic organic capping agents, such as trioctylphosphine/trioctylphiosphine oxide （TOP/TOPO）, which limits their applications in biology. To overcome this limitation, several synthesis strategies have been used. This work presents that hydrophobic CdSe quantum dots （QDs） were successfully transferred from nonpolar organic solvent to biocompatible water buffer by liposome encapsulating technology. And this result has been confirmed via transmission electron microscopy （TEM）, fluorescence mapping, and photoluminescence （PL）, respectively. TEM image showed free CdSe QDs are spherical and nearly monodispersed, having an average diameter of 3 nm. Average size of QD-liposome is approximately 20 nm. TEM images showed that QDs have been encapsulated in the liposome. Fluorescence mapping successfully showed the luminescence intensity distribution of liposome-entrapped QDs （QD-liposome）. Photoluminescence indicated that QDs-Lip basically retain optics quality of free quantum. This phenomenon can be attributed to liposome transfer with TOPO molecules that stabilize the surface of QDs, via hydrophobic interaction between double molecule chain of lipid with CdSe surface on the TOPO ligand, form a bilayer structure with TOPO molecules that stabilize the surface of QDs, keep CdSe exist environment. As a result, QDs-Lip possesses high emission efficiency.