Quantum dots-Ru complex assembling dyads for cancer cell detection and cellular imaging based on hybridization chain reaction

An easy and fluorescent strategy is developed for the detection of cancer cells and cellular imaging. This assay relies on the quenching of Ru complex toward quantum dots (QDs) and the amplification of hybridization chain reaction (HCR). In the presence of target cancer cells, folate-modified single-stranded DNA (F-DNA) links on the cell membranes through high affinity of folate and receptors. Hybridization reaction between pre-prepared HCR products and F-DNA immobilizes HCR products on the surfaces of target cells, resulting in large amount of Ru complex into HCR products and strong red fluorescence on the surfaces of target cells. Meanwhile, QDs-Ru complex assembling dyads in supernate are reduced, leading to the fluorescence restoration of QDs. Taking human cells lines HeLa as a model analyst, the linear response for HeLa cells in a concentration range from 100 to 105 cells mL−1 is obtained with a detection limit of 100 cells mL−1. The specificity of this assay for the detection of cancer cells is demonstrated against several cell competitors. Additionally, this assay is successfully applied to inhibitor screening for cancer cells in combination with cellular imaging, demonstrating the university of this design.