Probing Single-Cell\nAdhesion Kinetics and Nanomechanical\nForce with Surface Plasmon Resonance Imaging

Single cell adhesion plays a significant role in numerous\nphysiological\nand pathological processes. Real-time imaging and quantification of\nsingle cell adhesion kinetics and corresponding cell–substrate\nmechanical interaction forces are crucial for elucidating the cellular\nmechanisms involved in tissue formation, immune responses, and cancer\nmetastasis. Here, we present the development of a plasmonic-based\nnanomechanical sensing and imaging system (PNMSi) for the real-time\nmeasurement of single cell adhesion kinetics and associated nanomechanical\nforces with plasmonic tracking and monitoring of cell–substrate\ninteractions and the accompanying nanoscale fluctuations. Both the\nslow binding and dynamic nanomechanical interaction processes were\ntracked and analyzed with a thermodynamic model to determine the adhesion\nkinetic parameters and quantity the mechanical forces. To demonstrate\nthe capabilities of the PNMSi platform, we examined single cell binding\ninteractions across four different surface modifications, and obvious\nalterations in binding kinetics and corresponding nanomechanical forces\nwere observed, influenced by surface charges and interfacial hydrophilicity.\nAdditionally, we investigated changes in mechanical interaction forces\nof single cells during cytoskeleton modification, revealing the cross-linking-induced\ncell adhesion changes. Furthermore, to demonstrate the application\ncapability of the system, the adhesion profiling of primary tumor\nand metastatic tumor cells was explored, and obvious alterations were\nobserved in the kinetic forces of single cell–substrate interaction.\nThe PNMSi platform facilitates high-throughput single cell adhesion\nimaging and the quantification of adhesion interaction kinetics and\nnanomechanical forces with high sensitivity and serves as a promising\nplatform for identifying biomarkers for tumor metastasis and for screening\npotential therapeutic agents.