Profiling of Single Cells on a Droplet Microfluidics–SERS Platform for Multiplexed Analysis of Oxidative and Inflammatory Stress

Breast cancer is a highly heterogeneous disease, with subtypes such as triple-negative (TNBC) and HER2-positive (HER2+) exhibiting distinct therapeutic responses and prognoses. Cellular stress and inflammatory signaling critically influence tumor progression and treatment outcomes. Here, we present a droplet microfluidics-SERS platform for single-cell analysis of oxidative stress and inflammatory signaling in TNBC (MDA-MB-231) and HER2+ (SK-BR-3) cells under combined electrical stimulation and cisplatin treatment. A SERS-based system was designed for simultaneous detection of H2O2, selected as a representative indicator of oxidative stress, and IL-6, selected as a representative inflammatory cytokine. H2O2 was monitored through the responsive spectral changes of 4-MPBA on the reporter probe, whereas IL-6 detection relied on target-mediated sandwich immunocomplex formation between the reporter and capture probes, resulting in SERS signal amplification. Single-cell measurements reveal pronounced oxidative and inflammatory activation in MDA-MB-231 cells, whereas SK-BR-3 cells display attenuated responses, highlighting subtype-specific heterogeneity. In addition, cisplatin treatment further modulated the stress-response patterns induced by electrical stimulation, indicating distinct subtype-dependent adaptability to combined physical and chemical perturbations. This platform demonstrates potential for broader applications in single-cell analysis, providing a powerful tool for dissecting cell-specific stress and inflammatory dynamics.