Profiling Phenotypic\nHeterogeneity of Circulating\nTumor Cells through Spatially Resolved Immunocapture on Nanoporous\nMicropillar Arrays

The phenotype of circulating tumor cells (CTCs) offers\nvaluable\ninsights into monitoring cancer metastasis and recurrence. While microfluidics\npresents a promising approach for capturing these rare cells in blood,\nthe phenotypic profiling of CTCs remains technically challenging.\nHerein, we developed a nanoporous micropillar array chip enabling\nhighly efficient capture and in situ phenotypic analysis of CTCs through\nenhanced and tunable on-chip immunoaffinity binding. The nanoporous\nmicropillar array addresses the fundamental limits in fluidic mass\ntransfer, surface stagnant flow boundary effect, and interface topographic\nand multivalent reactions simultaneously within a single device, resulting\nin a synergistic enhancement of CTC immunocapture efficiency. The\nCTC capture efficiency increased by approximately 40% for cancer cells\nwith low surface marker expressing. By manipulating fluidic velocity\n(hydrodynamic drag force) on the chip, a cell adhesion gradient was\ngenerated in the capture chamber, enabling individual CTCs with varying\nexpression levels of epithelial cellular adhesion molecules to be\nimmunocaptured at the corresponding spatial locations where equilibrium\ndrag force is provided. The clinical utility of the nanoporous micropillar\narray was demonstrated by accurately distinguishing early and advanced\nstages of breast cancer and further longitudinally monitoring treatment\nresponse. We envision that the nanoporous micropillar array chip will\nprovide an in situ capture and molecular profiling approach for CTCs\nand enhance the clinical application of CTC liquid biopsy.