Sensitive CTC analysis and dual-mode MRI/FL diagnosis based on a magnetic core-shell aptasensor

Synergizing the sensitive circulating tumor cell (CTC) capture, detection, release and the specific magnetic resonance/fluorescence (MR/FL) imaging for accurate cancer diagnosis is of great importance for cancer treat-ment. Herein, EcoR1-responsive complementary pairing of two ssDNA with a fluorescent P0 aptamer, which can specifically bind with the overexpressed MUC1 protein on cancer cells, was covalently modified to SiO2@C-coated magnetic nanoparticles for preparing a special nanoparticle-mediated FL turn-on aptasensor (FSC-D-P0). This aptasensor can selectively capture/enrich CTC and thus achieve sensitive CTC detection/imaging in even the blood due to its stable targeting, unique magnetic properties and the regulated interactions between the quencher and the fluorescent groups. Meanwhile, FSC-D-P0 can release the captured CTC for further downstream analysis upon the EcoR1 enzyme-triggered cleavage of the double-stranded DNA (dsDNA). Most importantly, this aptasensor can distinctly avoid false positivity of MRI via multiple targeting mechanisms. Thus, the sensitive CTC capture, detection, release and accurate MR/FL imaging were synergistically combined into a single platform with good biocompatibility, promising a robust pattern for clinical tumor diagnosis in vitro and in vivo.

Automated summary

In this study, a nanoparticle-based aptasensor was developed for the sensitive capture, detection, release, and accurate imaging of circulating tumor cells (CTCs) in blood. The aptasensor showed stable targeting ability and could avoid false positivity of magnetic resonance imaging (MRI) through multiple targeting mechanisms.