1,4-Benzenedithiol-Bridged Nanogap-Based Individual Particle Surface-Enhanced Raman Spectroscopy Mechanical Probe for Revealing the Endocytic Force.

1,4-Benzenedithiol (BDT)-bridged core-satellite assemblies, as surface-enhanced Raman spectroscopy (SERS) mechanical probes, can be employed for real-time monitoring of the dynamics of endocytic forces and the accompanying trajectory of nanoparticles during the endocytosis process. These mechanical probes exhibit good responses in terms of SERS intensity ratios while undergoing mechanical pressure. Force tracing and the accompanying trajectory of nanoparticles are resolved accurately to render the endocytosis process in live cells. Density functional theory simulation results further proved the sensing scheme due to the electrons transforming between BDT and gold nanoparticles. Furthermore, this SERS mechanical probe is a valid method to visualize endocytic forces at multiple locations and establish a direct criterion to discriminate between cancer cells and normal cells.