In the treatment of cancer etc., lesion tissue is collected as a preliminary examination and biopsy is performed.Instead of this surgical biopsy, liquid biopsy, which examines body fluids such as blood, is attracting attention, and it is possible to determine the presence or absence of pathogenic DNA in a sample mainly using cfDNA as a biomarker.However, extraction and purification of cfDNA was a difficult task due to its low abundance and shortness.In addition, a general "solid-phase extraction method" cannot obtain a DNA fragment of 200 base pairs (bp) or less, which is the basic unit of DNA, and a highly sensitive detection method has been required.

　The research team has now developed an open fluid system that detects pathogenic DNA from human plasma samples using a method called "transient isotachophoresis (tITP)".This makes it possible to easily establish tITP from plasma, which has been difficult until now, and to accurately extract the separated cfDNA fragment. DNA separated and purified via tITP can be easily extracted as a piece of gel capable of PCR (DNA replication and amplification).Demonstration experiments showed high recovery, accurate isolation, and sensitivity to trace amounts of cfDNA fragments with short chains (100-200 bp).

　This makes it possible to quickly and repeatedly inspect and accurately diagnose diseases and infectious diseases from a small amount of blood sample at each treatment stage without burdening the patient.At present, attempts are being made to automate the process from device preparation to migration / sample extraction by a robot for practical use.In addition, the company will continue to collaborate with Stanford University on attempts to extract cfDNA from body fluids such as urine other than blood.

Paper information:[Analytica Chimica Acta] A modular and reconfigurable open-channel gated device for the electrokinetic extraction of cell-free DNA assays