Separation, Purification, and Detection of cfDNA in a Microfluidic Device

Cell free DNA (cfDNA) is degraded DNA fragments found in the blood plasma of cancer patients. While cfDNA is a good marker for early diagnostics and cancer prognosis, the extraction of cfDNA from whole blood and sample preparation for later sequencing is still challenging. Here, we presented a microfluidic device for the removal of cells from a cfDNA sample in a first step. In a second step, carboxylated magnetic beads were used for cfDNA extraction and purification. Lastly, cfDNA was amplified using a low-power, plasmonic polymerase chain reaction (PCR) system. Using fluorescent-labeled beads, we demonstrated that the separation efficiency for cells was 99% and the mixing efficiency for purification of cfDNA was 94%. Captured cfDNA could be successfully amplified by PCR, as demonstrated by gel electrophoresis. We confirmed that the limit of detection of our microfluidic system was 10 ng/mL.