This work demonstrated an effective strategy for the capture, identification and 
determination of multiple types of circulating tumor cells (CTCs) on functional 
and biocompatible immunomagnetic nanosphere interfaces (IMNs). The IMNs were 
achieved by functionalizing superparamagnetic iron oxide nanospheres (Fe3O4) 
with polymerized ionic liquid (PIL), and then coating with 
epithelial-cell-adhesion-molecule antibody (anti-EpCAM). The IMNs exhibited 
outstanding cell capture efficiency (above 95%) and specificity when employed to 
separate multiple EpCAM-positive tumor cells, due to the abundant carboxyl 
groups in the structure of PIL, which enhanced the coupling efficiency of MNs 
with anti-EpCAM by chemical bonding between carboxyls and amines, thereby 
enabling more target cells adhered onto IMNs. Under the optimized capture 
conditions, IMNs were shown an excellent cell capture performance in the range 
of 5-400 cells/mL in three different cases (e.g., PBS, MCF-7 and THP-1 mixed 
cell suspension, lysed blood). More significantly, our results indicated that 
with modification of PIL, in addition to the capture efficiency, the cell 
viability rate of CTCs was also greatly improved (98%) owing to the nontoxic and 
biocompatible properties of PIL, which realized the proliferation of the rare 
number CTCs for further molecular characterization. Finally, the IMNs were 
successfully applied to the isolation and detection of CTCs in cancer patient 
peripheral blood samples and as low as one CTC in the whole blood was captured 
and identified by the ICC method.