Nanoplasmonic sensing of multi-molecular protein interactions at physiological conditions
I will develop a single-molecule sensor that reveals multi-protein dynamics at micromolar concentrations to provide new understanding of how protein machinery functions in real-time. Proteins and their interactions are the cornerstone of biological processes. The dynamic cooperation between multiple species is key to most processes including chaperone-mediated protein folding, signal transduction, and metabolism. The dynamics of these processes is fast and adaptive due to a tailored combination of low affinity and high concentration. Current single-molecule sensors cannot capture these dynamics because (1) they only work in dilute solutions which perturbs the dynamics or (2) they only resolve a single species. Capturing dynamics of protein machinery at physiological conditions therefore remains one of the grand challenges in the field. 

MultiSense will develop a nanoplasmonic sensor to provide the opportunity to reveal multi-molecular protein dynamics at micromolar concentrations. This will be achieved by (a) developing technology to resolve and interpret multi-protein interactions and cooperation using Förster Resonance Energy Transfer in the confined near-field of a plasmonic particle, and (b) using this technology to provide the first real-time picture of chaperone-mediated protein folding at physiological conditions. This will contribute to unraveling why chaperones fail to induce proper folding or prevent protein aggregation in the context of diseases. 

The proposed method can be implemented on any research-grade microscope and can be generalized to any protein by applying the proper particle functionalization. This will inspire other researchers to study dynamic cooperation in protein machinery to unravel complex molecular mechanisms. In the long term the small size and biocompatibility of metal nanoparticles will enable studies of protein interactions at the single-molecule level in their natural environment, a living cell.