Abstract:

Cell-free DNA（cfDNA）as one of the target detection substance for liquid biopsy can be used for disease detection. However,the concentration of cfDNA in a sample is low and difficult in fragment discrimination,thus it is difficult to separate cfDNA within specific fragment length by conventional methods. In this method for high-resolution cfDNA screening based on new magnetic separation technology,two different modified magnetic beads synthesized by ourself were used to separately have recovery of long- and short-fragments DNA under the action of sedimentation agent. This technology achieved the enrichment of cfDNA below 150 bp in plasma samples. We verified by clinical samples that this technology achieved the enrichment of fetal free DNA in maternal plasma. It could be applied in non-invasive prenatal testing（NIPT）to bring forward early detection and improve detection sensitivity,etc. DNA fragment screening is an indispensable part in the field of gene sequencing,and high resolution screening can reduce downstream sequencing depth and save sequencing cost,and applied in tumors screening,non-invasive prenatal diagnosis and immunodeficiency diseases screening.

Key words: DNA fragment screening, novel magnetic separation technique, cfDNA, liquid biopsy, non-invasive prenatal testing