Design of DNA Aptamer-Functionalized Magnetic Short Nanofibers for Efficient Capture and Release of Circulating Tumor Cells

The isolation of viable circulating tumor cells (CTCs) from blood is of paramount significance for early stage detection and individualized therapy of cancer. Currently, CTCs isolated by conventional magnetic separation methods are tightly coated with magnetic materials even after attempted coating removal treatments, which is not conducive for subsequent analysis of CTCs. Herein, we developed DNA aptamer-functionalized magnetic short nanofibers (aptamer-MSNFs) for efficient capture and release of CTCs. In our work, polyethylenimine (PEI)-stabilized Fe3O4 nanoparticles with a mean diameter of 22.6 nm were first synthesized and encapsulated within PEI/poly(vinyl alcohol) nanofibers via a blended electrospinning process. After a homogenization treatment to acquire the MSNFs, surface conjugation of the DNA aptamer was performed through thiol-maleimide coupling. The formed aptamer-MSNFs, with a mean diameter of 350 nm and an average length of 9.6 mu m, display a saturated magnetization of 12.3 emu g(-1), are capable of specifically capturing cancer cells with an efficiency of 87%, and enable the nondestructive release of cancer cells with a release efficiency of 91% after nuclease treatment. In particular, the prepared aptamer-MSNFs displayed a significantly higher release efficiency than commercial magnetic beads. The designed aptamer-MSNFs may hold great promise for CTC capture and release as well as for other cell sorting applications.