利用连续离子层吸附技术合成了水溶性的CdTe/CdS核壳量子点.通过CdS壳层的包覆,量子点的量子效率由原来的15%(裸核)提高到38%(核壳),这种核壳结构量子点的化学和光学性质具有更好的稳定性,可以用于生物标记.本文采取共价连接与静电吸附两种方法,实现了量子点的生物标记,电泳技术已证明,应用这种量子点成功地实现了对蛋白质分子的生物标记.通过对量子点与蛋白质偶联前后的荧光光谱分析,发现量子点与蛋白质作用后荧光增强是由于蛋白质对量子点进行了表面修饰,从而降低了表面缺陷引起的非辐射跃迁几率所致.通过共价连接量子点的荧光峰位红移,主要是由于偶极-偶极相互作用引起的;量子点与蛋白质静电吸附作用引起的荧光峰位蓝移主要起因于量子点表面电荷量的降低.
Aqueous CdTe/CdS core/shell quantum dots(QDs) were synthesized via successive ion layer adsorption and reaction. The quantum yield was increased from 15% (CdTe) to 38% (CdTe/CdS) after the passivation of the CdS shell. Compared with the bare core, the core/shell QDs were more photostable and suitable for bio-labeling. Both covalent conjugation and electrostatic adsorption were adopted to couple the QDs with the protein, which could be proved well by the agarose gel electrophoresis method. The photoluminescenee (PL) of the CdTe/CdS core/shell QDs were also studied after the bio-conjugation. The PL intensity of the QDs was enhanced after coupled with proteins by the two methods. Due to the dipole-dipole interactions, the covalent coupling will lead to the red-shift of the PL peak of the core/shell QDs. On the contrary, because of the decrease of the surface charge, electrostatic adsorption will cause the blue-shift of the PL peak.