Integrating aptamer-transduced signal amplification and superwettable droplet microarrays for single-cell detection of cell surface vimentin.

Metastasis is a leading cause of cancer-related mortality, with epithelial-mesenchymal transition (EMT) playing a critical role in this process. Cell surface vimentin (CSV) has emerged as a promising biomarker for detecting aggressive and metastatic tumor cells, requiring optimized analytical methods for its detection. Herein, we report a platform that combines aptamer-mediated enzymatic cycling amplification with a superwettable droplet microarray (SDM) chip for sensitive CSV detection at the single-cell level. It features synergistic engineering of enzymatic nucleic acid cleavage for signal amplification and the confinement of the analytes within the ultrasmall volume of the microdroplet reactors on the chip. Our SDM assay achieves a limit of detection (LOD) as low as a single tumor cell and shows applicability across the tested cancer cell lines (MDA-MB-231, MCF-7, and PANC-1). Furthermore, it can detect CSV changes associated with TGF-β-induced phenotypic transition in a PANC-1 EMT model, and preserve cell proliferative capacity. This work provides a proof-of-concept approach for single-cell level CSV analysis, with the potential to support biomedical research on tumor cell sub-phenotypes and inform potential diagnostic strategies for personalized medicine.