On-site extraction and purification of bacterial nucleic acids from blood samples using an unpowered microfluidic device

摘要

Molecular diagnostics is a powerful technique for detecting pathogens with high sensitivity, but it has complicated sample preparation procedures that rely not only on a manual operation by experts but also on bulky equipment. Here, we report the use of an unpowered, microfluidic sample preparation device in on-site molecular diagnosis without the necessity of expertise and electrical devices. The device is assembled with two units, a plasma separation chip, and a nucleic acid extraction and purification chip. As a model pathogen, Escherichia coli (E. coli) O157:H7 was first separated from the blood sample using the unpowered plasma separation chip, and then the DNA was extracted and purified from the separated bacteria by using the finter-actuated nucleic acid extraction and purification chip. 10~3 to 10~8 CFU/mL of E. coli O157:H7 was infiltered from the blood sample with ～ 1% of permeation efficiency. The extracted DNA was successfully purified and confirmed by gel elec-trophoresis after the polymerase chain reaction. This unpowered sample pretreatment method is precise and reliable, even at low concentrations of down to 10~3 CFU/mL of E. coli in the blood sample.