Fabrication of DNAzyme-functionalized hydrogel and its application for visible detection of circulating tumor DNA

Circulating tumor DNA (ctDNA) is a promising biomarker for non-invasive access of tumor dynamics. However, most existing ctDNA analysis strategies depend on costly instrument. Therefore, we here report a visible strategy for ctDNA detection based on ctDNA-triggered and DNAzyme-functionalized hydrogel. On one hand, target ctDNA triggers the rolling circle amplification and finally synthesizes a DNA hydrogel with G-quadruplex structures, which as 3D macroscopical material could be observed easily by naked eye. On the other hand, by utilizing the DNAzyme activity of the G-quadruplex/heme complex, the hydrogel could catalyze the colorless ABTS to green oxidative product ABTS*. Quantitating ctDNA thus can be achieved by observing the color change. Our strategy for ctDNA detection is sensitive in a concentration from 1 pM to 10 nM and limit of detection down to 0.32 pM. Moreover, our visible strategy has been successfully applied to the simulate analysis of clinical blood samples. Importantly, our method does not require expensive equipment, thus not only exhibiting great potential application in some harsh circumstances with limited medical conditions, but also opening new insight into the development of visible detection method of DNA.