Probing Single-Cell Adhesion Kinetics and Nanomechanical Force with Surface Plasmon Resonance Imaging.

Single cell adhesion plays a significant role in numerous physiological and pathological processes. Real-time imaging and quantification of single cell adhesion kinetics and corresponding cell-substrate mechanical interaction forces are crucial for elucidating the cellular mechanisms involved in tissue formation, immune responses, and cancer metastasis. Here, we present the development of a plasmonic-based nanomechanical sensing and imaging system (PNMSi) for the real-time measurement of single cell adhesion kinetics and associated nanomechanical forces with plasmonic tracking and monitoring of cell-substrate interactions and the accompanying nanoscale fluctuations. Both the slow binding and dynamic nanomechanical interaction processes were tracked and analyzed with a thermodynamic model to determine the adhesion kinetic parameters and quantity the mechanical forces. To demonstrate the capabilities of the PNMSi platform, we examined single cell binding interactions across four different surface modifications, and obvious alterations in binding kinetics and corresponding nanomechanical forces were observed, influenced by surface charges and interfacial hydrophilicity. Additionally, we investigated changes in mechanical interaction forces of single cells during cytoskeleton modification, revealing the cross-linking-induced cell adhesion changes. Furthermore, to demonstrate the application capability of the system, the adhesion profiling of primary tumor and metastatic tumor cells was explored, and obvious alterations were observed in the kinetic forces of single cell-substrate interaction. The PNMSi platform facilitates high-throughput single cell adhesion imaging and the quantification of adhesion interaction kinetics and nanomechanical forces with high sensitivity and serves as a promising platform for identifying biomarkers for tumor metastasis and for screening potential therapeutic agents.