Hahn Megan A, Tabb Joel S, Krauss Todd D
Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.
Anal Chem. 2005 Aug 1;77(15):4861-9. doi: 10.1021/ac050641i.
Semiconductor quantum dots (QDs) have been used in a simple fluorometric assay to detect single cells of the pathogenic Escherichia coli O157:H7 serotype. Composed of CdSe/ZnS core/shell QDs conjugated to streptavidin, this system exhibits 2 orders of magnitude more sensitivity than a similar assay using a common organic dye. Selectivity for this pathogenic bacterial strain over a common lab strain (E. coli DH5alpha), which is gained from the use of specific biotinylated antibodies, is also demonstrated for QD labeling. Under continuous excitation, these QDs retain high fluorescence intensities for hours, whereas a typical organic dye bleaches within seconds, allowing for more rapid and accurate identification of E. coli O157:H7 in single-cell fluorescence-based assays. This indirect QD labeling method, based on antibody-antigen and streptavidin-biotin interactions, is flexible enough to expand to other systems and has great potential for use in simultaneous multicolor detection schemes.
半导体量子点（QDs）已被用于一种简单的荧光测定法，以检测致病性大肠杆菌O157:H7血清型的单个细胞。该系统由与链霉亲和素结合的CdSe/ZnS核壳量子点组成，与使用普通有机染料的类似测定法相比，其灵敏度高出两个数量级。通过使用特异性生物素化抗体，该系统还展示了对这种致病菌株相对于常见实验室菌株（大肠杆菌DH5α）的选择性，用于量子点标记。在连续激发下，这些量子点能保持数小时的高荧光强度，而典型的有机染料在几秒钟内就会褪色，从而在基于单细胞荧光的测定中能更快速、准确地鉴定大肠杆菌O157:H7。这种基于抗体-抗原和链霉亲和素-生物素相互作用的间接量子点标记方法足够灵活，可扩展到其他系统，在同时进行的多色检测方案中具有巨大的应用潜力。
