Multicolor SERS-encoded immuno-cocktail for longitudinal precise tracking of CTCs phenotypes in lung cancer therapeutics.

Tumor heterogeneity and drug resistance remain major obstacles to the implementation of personalized therapeutic strategies in lung cancer. Circulating tumor cell (CTC)-based liquid biopsy provides a powerful, minimally invasive tool for tracking dynamic changes in tumor heterogeneity and elucidating mechanisms of treatment response and drug resistance. Herein, we present a portable, field-deployable surface-enhanced Raman scattering (SERS) immunoprobe platform capable of multiplexed detection of CTC membrane biomarkers to monitor tumor heterogeneity throughout the course of therapy. Utilizing a cocktail of multicolor-encoded immunoprobes, the platform achieves single-cell phenotypic resolution via antigen-specific spectral fingerprinting, validated by flow cytometry. It demonstrates ultra-sensitive CTC quantification (limit of detection of 1.7 cells/mL) and precise molecular subtyping across four cell lines (HCC827, A549, BEAS-2B, and HeLa). Integrated with orthogonal partial least squares discriminant analysis (OPLS-DA), the platform accurately distinguishes clinically relevant cell types with 99 % classification accuracy, successfully stratifying metastatic versus non-metastatic lung cancer (n = 24) and capturing treatment-driven CTC evolution in longitudinal studies (n = 7). Our results highlight a transformative strategy for real-time interception of drug resistance trajectories, positioning dynamic CTC phenotyping as a critical tool for adaptive therapy and prognostic assessment in precision oncology.