A nanoflow cytometric strategy for sensitive ctDNA detection via magnetic separation and DNA self-assembly.

Circulating tumor DNA (ctDNA) is a tumor-derived fragmented DNA in the bloodstream that is not associated with cells. It has been greatly focused in the recent decade because of its potential clinical utility for liquid biopsies. Development of ctDNA analytical techniques with high sensitivity and cost-efficiency will undoubtedly promote the clinical spread of ctDNA testing. In this paper, we propose a novel flow cytometry-based ctDNA sensing strategy which combines enzyme-free amplification and magnetic separation. The target DNA is capable of triggering a hybridization chain reaction, producing a fluorescent long linear assembly of DNA, which can be further captured by magnetic beads to present fluorescent signals using flow cytometry. In comparison with some conventional methods, our strategy has the advantages of easy operation and cost-efficiency, and thereby shows a promising application in clinical diagnosis. Graphical abstract.