On-chip isolation and enrichment of circulating cell-free DNA using microfluidic device.

Circulating cell-free DNA (cfDNA), containing cancer-specific DNAs derived from tumor cells, plays an important role in real-time monitoring of disease progression. Due to the abnormal growth of cancer and the promotion of cancer cell apoptosis by chemotherapy, the higher cfDNA concentration than healthy individuals is closely correlated with the diagnosis and treatment of cancer. Also, the mutation detection in tumor cell-derived cfDNA can be used to predict tumor progression. Human blood contains many blood cells (red blood cells, white blood cells, and platelets), proteins, extracellular vesicles, and so on. These blood components act as the inhibitors when the cfDNA is analyzed using polymerase chain reaction. So, analysis of cfDNA using whole blood directly may affect the sensitivity of the analysis or result in false-negative. The conventional methods of cfDNA isolation, such as silica absorption and polymer-mediated enrichment, are labor-intensive and time-consuming processes that can also lead to the loss of cfDNA in cumbersome procedures. Here, we designed an integrated microfluidic chip capable of on-chip cfDNA extracting to reduce sample loss and processing time. Our proposed device minimizes the number of experimental steps from 5 to 1, the total processing time from 42 to 19 min, and the required volume of washing reagents from 2 to 0.4 ml for cfDNA enrichment compared to the conventional method.