Mass spectrometry imaging of untreated wet cell membranes in solution using single-layer graphene.

We report a means by which atomic and molecular secondary ions, including cholesterol and fatty acids, can be sputtered through single-layer graphene to enable secondary ion mass spectrometry (SIMS) imaging of untreated wet cell membranes in solution at subcellular spatial resolution. We can observe the intrinsic molecular distribution of lipids, such as cholesterol, phosphoethanolamine and various fatty acids, in untreated wet cell membranes without any labeling. We show that graphene-covered cells prepared on a wet substrate with a cell culture medium reservoir are alive and that their cellular membranes do not disintegrate during SIMS imaging in an ultra-high-vacuum environment.

Single-Molecule Rotation for EGFR Conformational Dynamics in Live Cells.

Monitoring the dynamics of proteins in live cells on appropriate spatiotemporal scales may provide key information regarding long-standing questions in molecular and cellular regulatory mechanisms. However, tools capable of imaging the conformational changes over time have been elusive. Here, we present a single-molecule stroboscopic imaging probes by developing gyroscopic plasmonic nanoparticles, allowing for replication of protein-protein interactions and the conformational dynamics based on rotational and lateral velocities.