In Situ SERS Monitoring of Membrane Protein Homo- and Hetero-Dimerizations at the Single-Cell Level

Dimerization of cell membrane receptors governs essential cellular processes─including signal transduction, growth, proliferation, and apoptosis─yet precise discrimination between homo- and heterodimers remains a persistent technical challenge. To address this, we developed an in situ surface-enhanced Raman scattering (SERS) imaging strategy that integrates aptamer recognition, proximity ligation assay (PLA), rolling circle amplification (RCA), and SERS tags, enabling simultaneous monitoring of membrane protein homo- and heterodimerization dynamics at the single live-cell level. As a proof of concept, we used c-Met homodimerization on the cell membrane surface as a model to construct and validate the feasibility of the proposed SERS strategy for visual detection of c-Met homodimer on the cell membrane surface at the single-cell level, as well as the intercellular HGF/c-Met signaling pathway based on c-Met dimerization detection. Furthermore, by adapting this strategy to multiplexed detection, we achieved concurrent visualization of HER2-HER2 homodimers and HER2-HER3 heterodimers on intact cell membranes. Critically, this SERS methodology provides unprecedented insights into cancer cell–stromal cell communication through real-time tracking of HER2-HER3 heterodimerization on SK-BR-3 cells. Its capability to resolve transient protein interactions within native cellular microenvironments underscores broad utility in intercellular signaling network analysis, molecular diagnostics, and targeted therapy development.