Rapid and sensitive detection of Escherichia coli O157:H7 using coaxial channel-based DNA extraction and microfluidic PCR.

In this study, a rapid and sensitive method for detection of Escherichia coli O157:H7 using the coaxial channel-based DNA extraction and the microfluidic PCR was proposed and verified. The magnetic silica beads were first pumped into the coaxial channel, which was captured in the coaxial channel more uniformly by applying the multiring high-gradient magnetic field. After the E. coli O157:H7 cells were lysed with the lysis buffer to release the DNA, the improved coaxial channel was used to efficiently extract the DNA, followed by washing with ethanol to remove the residual proteins and eluting with a small volume of deionized water to obtain the purified and concentrated DNA. Finally, the obtained DNA was amplified and determined using the microfluidic PCR. This proposed bacteria detection method was able to detect E. coli O157:H7 as low as 12 cfu/mL when the large volume (10 mL) of bacterial sample was used, and the recovery of E. coli O157:H7 in the spiked milk samples ranged from 97.4 to 100.6%. This proposed bacteria detection method has shown great potential to detect lower concentration of E. coli O157:H7 from larger volumes of sample.