dA Tetrahedral DNA Nanostructures-based Microfluidic Platform for Detection of Pathogenic Escherichia Coli O157: H7

A microfluidic device for specifically capturing Escherichia coli O157 : H7 (E. coli O157 : H7) was developed. To capture E. coli O157 : H7 cells with the device, the surface of microfluidic chip was modified by the tetrahedral DNA nanostructures , and the nucleic acid aptamers as the capture probes were linked through the biotin-streptavidin reaction for detection of E. coli O157 : H7 cells. The microfluidic chip containing herringbone structures was designed to reduce the shear force when the bacteria were captured. Modification of DNA tetrahedron on the surface of polydimethylsiloxane (PDMS) chip could further regulate the distance between the probes and improved the recognition efficiency of the probes and bacteria. The successful preparation of DNA tetrahedron nanostructures and the construction of DNA tetrahedron-aptamers system were confirmed by agarose gel electrophoretic. Fluorescence microscopy was used to further imaging and analysis of the detection results. Finally, the tetrahedral DNA nanostructures-based microfluidic platform was also used for the detection of the real food samples. The results showed that without the assistance of large instruments or equipment and other signal amplification techniques, the detection system could be used to successfully detect E. coli O157 : H7 with a concentration of 10 CFU/mL under the ordinary optical microscope, and the detection time was no more than 2 h. Moreover, in the actual sample detection, the recoveries were 88.3% -108.3%. The developed strategy of microfluidic platform based on tetrahedral DNA nanostructure not only provided an effective detection method for food borne pathogens, but also had potential application value in other research fields such as potential food safety hazards and early diagnosis of diseases.