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

LIU Jian^1,2, LIU Chun-xiu³, LUO Jin-ping³, LIU Ru-ping^2,4, TIAN Qing^2,4, CAI Xin-xia^2,4

1.School of Control Science and Engineering,Shandong University,Jinan 250061,China;2.State Key Lab of Transducer Technology,Institute of Electronics,Chinese Academy of Sciences,Beijing 100080,China;3.State Key Lab of Transducer Technology,Institute of Electronics,Chinese Academy of;4.Graduate University of Chinese Academy of Sciences,Beijing 100080,China



Abstract:

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 min 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 of E.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.

Key words:  quantum dots  immunoassay  escherichia coli  fluorescent probe  imaging

DOI£º10.11916/j.issn.1005-9113.2011.02.016

Clc Number:Q93;O471.1

Fund: