An integrated microfluidic chip for the capture, migration and molecular phenotyping of single circulating tumor...

Single-cell analysis of circulating tumor cells (CTCs) holds significant potential for elucidating tumor metastasis mechanisms, improving prognosis assessment, and advancing precision therapeutics. Microfluidic chips have emerged as essential tools for isolating and enriching CTCs. However, existing microfluidic techniques have limited capability to achieve in situ functional characterization of single CTCs. Moreover, most current systems ignore CTC co-capture, obscuring the inherent heterogeneity of individual CTCs. In this study, we developed a novel integrated microfluidic chip for CTC enrichment, single-cell capture, and migration and molecular heterogeneity. On the chip, a spiral inertial structure enables label-free CTC enrichment, while a symmetrical branching network and double-cross-shaped micropillars achieve high-throughput, high-efficiency single-cell capture. The platform allows in situ establishment of a spatial concentration gradient to quantitatively analyze single-CTC migration, coupled with immunofluorescence detection of epithelial-mesenchymal transition (EMT)-related markers. Experimental results demonstrate that the chip achieved a capture rate exceeding 80%, with a single-cell capture efficiency of over 70%. This integrated chip enables a direct single-cell resolution correlation between the migratory capacity and EMT phenotype of CTCs. Analysis of blood samples from 11 colorectal cancer patients reveals that both the migration speed of CTCs and the proportion of migratory CTCs are significantly higher in patients with metastatic disease. The integrated platform correlates the dynamic migratory function with static molecular phenotypes at single-cell resolution, offering a new method for investigating CTC heterogeneity in tumor metastasis.