Multi-Shell Structured Fluorescent–Magnetic Nanoprobe for Target Cell Imaging and On-Chip Sorting

In this paper, we have developed a core-triple-shell structured multi-functional nanoprobe Fe3O4/SiO2/CdSeTe@ZnS-SiO2/polydopamine with strong fluorescence and a fast magnetic response for specifically recognizing, fluorescently labeling, and magnetically sorting target tumor cells on a microfluidic chip. The outer polydopamine layer not only effectively alleviated the quenching effect of the interlayer quantum dots but also provided a convenient and versatile functional interface to readily conjugate with the recognizing model molecules of aptamer KH1C12 with amine, thiol, or carboxyl groups. Moreover, the polydopamine isolation and PEG decoration equipped the as-fabricated nanoprobes with little cytotoxicity and nonspecific affinity, leading to the effective and specific profiling of the protein epitopes expressed on the target tumor cells. Taking advantage of the magnetic property and specific recognition, the modified nanoprobe was utilized to label and isolate HL-60 cells from a homogeneous cell mixture of HL-60 and K562 cells on a microfluidic chip. Combining with the high throughput of the microfluidic chip, 1.0 × 10(4) HL-60 cells were readily separated from 2.0 × 10(4) cells in only 10 min with 98% separation efficiency, markedly improved in comparison with conventional strategies. This study presents an innovative strategy for developing highly integrated nanoprobes of strong fluorescence and magnetic controllability, opening up a promising probe-based avenue for biological imaging and separation.