High-Performance Electronic Measurements of Protein Kinetics and Affinity

We utilize high-performance field-effect transistors (FETs) for label-free biochemical measurements of both the affinity and kinetics of protein-ligand interactions. The kinetics of the inter-molecular interactions were extracted from a single time-course by leveraging a physical model of protein-ligand binding. This approach is in contrast to conventional measurements that often require multiple measurements at different ligand concentrations and can be hindered by the lack of adequate time-resolution. We demonstrate our approach using the biotin streptavidin model system. Thiol-modified biotin was conjugated to a gold surface to form a self-assembled monolayer (SAM). The interactions of streptavidin with the SAM were then measured dynamically. A mathematical model describes the physiochemical properties of the system and the time-evolved interaction between the proteins and ligands was fit to the time-series data and used to extract the rate constants as well as diffusion constant that characterize the interaction. Our results will enable the technique to broadly benefit biomolecular interactions of proteins with ligands, antibodies with antigens and numerous other systems to drive new applications in drug discovery and diagnostics of disease.