Functional and biocompatible polymeric ionic liquid (PIL) - Decorated immunomagnetic nanospheres for the efficient capture of rare number CTCs.

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 (FeO) 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.