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Aptasensors for rapid detection of Escherichia coli O157:H7 and Salmonella typhimurium

Wen-he Wu1, Min Li1, Yue Wang1, Hou-xian Ouyang1, Lin Wang1, Ci-xiu Li1, Yu-chen Cao1, Qing-he Meng12* and Jian-xin Lu1*

Author Affiliations

1 Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, Wenzhou Medical College, Wenzhou, Zhejiang, 325035, China

2 Department of Laboratory Medicine, The University of Texas, MD Anderson Cancer Center, Houston, Texas, 77030, USA

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Nanoscale Research Letters 2012, 7:658  doi:10.1186/1556-276X-7-658

Published: 29 November 2012


Herein we reported the development of aptamer-based biosensors (aptasensors) based on label-free aptamers and gold nanoparticles (AuNPs) for detection of Escherichia coli (E. coli) O157:H7 and Salmonella typhimurium. Target bacteria binding aptamers are adsorbed on the surface of unmodified AuNPs to capture target bacteria, and the detection was accomplished by target bacteria-induced aggregation of the aptasensor which is associated as red-to-purple color change upon high-salt conditions. By employing anti-E. coli O157:H7 aptamer and anti-S. typhimurium aptamer, we developed a convenient and rapid approach that could selectively detect bacteria without specialized instrumentation and pretreatment steps such as cell lysis. The aptasensor could detect as low as 105colony-forming units (CFU)/ml target bacteria within 20 min or less and its specificity was 100%. This novel method has a great potential application in rapid detection of bacteria in the near future.

Colorimetric detection; Aptasensor; E. coli O157:H7; Salmonella typhimurium; AuNPs