Chip-Assisted Single-Cell Biomarker Profiling of Heterogeneous Circulating Tumor Cells Using Multifunctional Nanospheres.

Profiling the heterogeneous phenotypes of individual circulating tumor cells (CTCs) from patients is a very challenging task, but it paves new ways for cancer management, especially personalized anticancer therapy. Herein, we propose a chip-assisted multifunctional-nanosphere system for efficient and reliable biomarker phenotype analysis of individual heterogeneous CTCs. Red fluorescent magnetic biotargeting multifunctional nanospheres and green fluorescent biotargeting nanospheres targeting to two kinds of CTC biomarkers are used for convenient dual-fluorescence labeling of CTCs along with magnetic tags. By integrating magnetic enrichment with a size-selective single-cell-trapping microfluidic chip (SCT-chip), over 90% of CTCs, even when the concentrations is as low as 10 CTCs per milliliter of blood, can be individually trapped at highly ordered micropillars, spatially separated from the minimal residual blood cells. Such single CTCs offer easy-readout fluorescence signals, facilitating efficient identification and reliable phenotype analysis in accordance with their biomarker expressions. Therefore, the phenotypes of breast tumor cells in terms of the expression level of human epidermal-growth-factor receptor 2, an important target of clinical anticancer drugs, are accurately assessed, and over 82% of them can be classified into corresponding cell subpopulations. Furthermore, this system demonstrates successful detection and subpopulation analysis of heterogeneous CTCs from seven breast cancer patients, which provides a promising new means for single-cell profiling of CTC-biomarker phenotypes and guiding of personalized anticancer therapy.