量子点标记链霉亲和素及其生物活性检测

选用无机盐为前驱体,在水相中合成CdTe量子点,并用此量子点标记链霉亲和素,通过SephadexG-100层析分离纯化量子点标记的链霉亲和素,采用磁颗粒标记的链霉亲和素与量子点标记的链霉亲和素竞争结合辣根过氧化酶标记的生物素,即酶联免疫竞争抑制分析法检测链霉亲和素标记量子点后的生物活性,计算约70.3%的链霉亲和素标记到量子点上,且具有生物活性。每毫克量子点大约可偶联0.14 mg的链霉亲和素。采用荧光光谱研究量子点标记前后的荧光变化,标记后量子点的最大发射波长蓝移了8 nm,而发射光谱的半峰宽基本不变,说明量子点与链霉亲和素结合后粒子没有团聚,分散性好。

Labeling of Quantum Dots with Streptavidin and Its Bioactivity Measurement

CdTe nanocrystals synthesized in aqueous solution were used to label streptavidin(SA).The CdTe-SA composite can be purified by a SephadexG-100 column.Competitive inhibition enzyme-linked immunosorbent assay(ELISA) method of magnetic particles-SA and CdTe-SA to Biotin-horseradish peroxidase(HRP) was used to detect the biologic activity of streptavidin after labeling.The results showed that about 70.3% SA was labeled with quantum dots and remained the bioactivities.The SA amount coated onto 1 mg CdTe was(about) 0.14 mg.The change of emission and absorption spectra of CdTe quantum dots before and after labeling SA was studied by ultraviolet and fluorescence spectrophotometry.While the emission spectrum of CdTe-SA solution showed a blue-shift in the emission peak,the intrinsic emission band width was unchanged.It was proved that the shift of the emission peak was the result of the conjugation between CdTe nanoparticles and SA.Furthermore,it was also proved that the CdTe-SA composite was not agglomerated and had good(dispersivity).