Quantum dot biolabeling coupled with immunomagnetic separation for detection of Escherichia coli O157:H7.
A sensitive, specific, and rapid method for the detection of E. coli O157:H7 was demonstrated using quantum dots (QDs) as a fluorescence marker coupled with immunomagnetic separation. Magnetic beads coated with anti-E. coli O157 antibodies were employed to selectively capture the target bacteria, and biotin-conjugated anti-E. coli antibodies were added to form sandwich immuno complexes. After magnetic separation, the immuno complexes were labeled with QDs via biotin-streptavidin conjugation. This was followed by a fluorescence measurement using a laptop-controlled portable device, which consisted of a blue LED and a CCD-array spectrometer. The peak intensity of the fluorescence emission was proportional to the initial cell concentration of E. coli O157:H7 in the range of 10(3)-10(7) CFU/mL with a detection limit at least 100 times lower than that of the FITC-based method. The total detection time was less than 2 h. Neither E. coli K12 nor Salmonella typhimurium interfered with the detection of E. coli O157:H7.
Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, Arkansas 72701, USA.
Xiao-Li
XL
Su
Yanbin
Y
Li
D019453:Escherichia coli O157 / Q000254:growth & development / Q000302:isolation & purification*; D018189:Immunomagnetic Separation / Q000379:methods; D007202:Indicators and Reagents; D011789:Quantum Theory; D012449:Safety; D012486:Salmonella typhimurium / Q000302:isolation & purification; D013050:Spectrometry, Fluorescence / Q000379:methods
D007202:Indicators and Reagents