(Invited) Measure Single Protein Size and Binding Kinetics with Plasmonic Scattering Imaging

Abstract

Measuring individual protein properties is the most critical and challenging tasks for protein analysis. We show that it is possible to quantify single protein size and binding kinetics by plasmonic scattering imaging (PSM). The interference between the protein scattered light and the background light scattered by the rough substrate significantly enhances the signal intensity and contrast, which allows PSM to image single proteins, measure their sizes, and identify them based on their specific binding to antibodies. In addition, PSM can quantify protein binding kinetics by counting the binding of individual molecules, providing a digital method to measure binding kinetics and analyze heterogeneity of protein behavior. Furthermore, PSM can distinct specific and nonspecific binding processes by quantifying the mass and binding dynamics of individual bound analyte molecules, thus allowing the binding kinetic analysis in complex media such as serum. PSM can be implemented on top of an objective or a prism coupled surface plasmon resonance system, providing a convenient solution to realize high sensitivity single molecule imaging. We anticipate that PSM will become an important tool for single protein analysis, especially for low volume samples, such as single cells.