Real-time monitoring of phosphorylation kinetics with self-assembled nano-oscillators.

Phosphorylation is a post-translational modification that is involved in many basic cellular processes and diseases, but is difficult to detect in real time with existing technologies. A label-free detection of phosphorylation is reported in real time with self-assembled nano-oscillators. Each nano-oscillator consists of a gold nanoparticle tethered to a gold surface with a molecular linker. When the nanoparticle is charged, the nano-oscillator can be driven into oscillation with an electric field and detected with a plasmonic imaging approach. The nano-oscillators measure charge change associated with phosphorylation of peptides attached onto a single nanoparticle, allowing us to study the dynamic process of phosphorylation in real time without antibodies down to a few molecules, from which Michaelis and catalytic rate constants are determined.