Floating Immunomagnetic Microspheres for Highly Efficient Circulating Tumor Cell Isolation under Facile Magnetic Manipulation

Among circulating tumor cell enrichment strategies, immunomagnetic beads (IMBs) have received great attention due to their excellent performance. However, traditional strategies using IMBs normally require an additional mechanical stirring device to fully mix the IMBs and specimens, and this step may cause mechanical cellular damage. In this study, by changing the architecture and motion trajectory control strategy of the IMBs, floating immunomagnetic microspheres (FIMMs) and their matching rotary magnetic manipulation device were proposed to achieve highly efficient CTC capture under a cell-friendly condition. Generally, the FIMMs were prepared through layer-by-layer assembly of the individual functional components, and their stress state governed by either buoyancy or magnetic force was tuned by the rotary magnetic manipulation device. Consequently, recognition of FIMMs and target cells as well as CTC recovery can be simply realized through external magnetic manipulation. Accordingly, satisfactory enrichment efficiencies for CTCs with varied epithelial expression levels were obtained as 92.93 ± 3.23% for MCF-7, 79.93 ± 3.31% for A549, and 92.57 ± 5.22% for HepG2. Besides, an extremely low detection limitation of 5 cells mL-1 can be achieved from complex sample conditions, even the whole blood. In addition, FIMMs successfully enriched 23-56 CTCs from 1.5 mL of blood samples from cancer patients.