High-sensitivity fluorescence detection for lung cancer CYFRA21-1 DNA based on accumulative hybridization of quantum dots.

Sensitive detection of circulating tumor DNA (ctDNA) in vitro has attracted growing attention owing to its potential application in diagnostics of cancer. In this study, we synthesized hydrophilic AgInS 2 @ZnS core-shell quantum dot nanocrystals and magnetic Fe 3 O 4 nanoparticles, and then the ctDNA triggered hybridization chain reaction was used to detect the CYFRA21-1 DNA associated with lung cancer. In the presence of CYFRA21-1 DNA, three hairpin structures were activated to turn on successively, resulting in the accumulation of quantum dots and eliciting considerable changes of the fluorescence signal. Compared with the conventional fluorescence detection, Fe 3 O 4 provides magnetic adsorption properties and a large surface area for immobilizing and aggregating quantum dot nanoparticles attached to single-stranded DNA. The concentration of CYFRA21-1 is closely related to the number of quantum dots remaining after magnetic adsorption, which provides a promising approach for ctDNA quantification.