Nanoparticle-Based Sensing of Weak Protein Interactions

Weak protein interactions regulate diverse protein condensation behavior (e.g., crystallization and aggregation), yet they are notoriously difficult to characterize, especially in a high-throughput manner. We seek to exploit the separation-dependent optical properties of gold nanoparticles as a novel approach for rapidly characterizing self-interactions between proteins immobilized on nanoparticles. In this presentation, we will discuss robust approaches for immobilizing antibodies and related proteins on nanoparticles that stabilize both the immobilized proteins and gold colloid. Moreover, we will demonstrate that protein self-interactions can be characterized using Plasmonic measurements of protein-gold conjugates in qualitative agreement with measurements of osmotic second virial coefficients, and discuss our current efforts to make this method more quantitative. Finally, we will discuss our use of this method to rapidly analyze the self-association behavior of a library of homologous antibody fragments with the goal of improving the design and selection of aggregation-resistant antibodies.