Imaging Escherichia coli using streptavidin functionalized quantum dots as a Nano-fluorescent probe

It is extremely important for bacteria detection in many fields, such as medical diagnosis and food safety. In this paper, streptavidin functionalized quantum dots (SA-QDs) , as a nano-fluorescent probe, were used to attach with Escherichia coli (E. Coli) for the detection and identification of bacteria with immunoreactions and biotin-streptavidin affinity. Fluorescent images of the bacteria and the fluorescence intensity were used to evaluate the conjugation effect with different incubation time. Our results showed that 20 rain is a reasonable incubation time for the SA-QDs coupling to E. Coli cells. The fluorescent images, which produce a greatly amplified and enhanced signal off. Coli cells, were obtained through the immunological amplification and fluorescent probe enrichment steps. In addition, the bleaching process of SA-QDs without any encapsulation at room temperature was clearly observed during 10 min of being excited. Our work provided a modularized sample treatment method using SA-QDs as a nano-fluorescent probe in cellular imaging and bio-labeling.