Optical imaging of size, charge, mobility and binding of single proteins

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PROJECT SUMMARY Protein analysis is essential to the understanding of molecular scale processes in living systems, the diagnosis of diseases based on molecular biomarkers, and the treatment of diseases with drugs. The basic tasks of protein analysis include detecting a protein, identifying it and determining its interactions with other proteins or molecular ligands. Various technologies have been developed to perform these tasks, but the most indispensable ones are gel and capillary electrophoresis, Western Blot (WB) and enzyme linked immunosorbent assay (ELISA). These technologies separate and identify proteins based on a protein’s charge, size, and specific binding to antibodies. For molecular interaction analysis, surface plasmon resonance and other detection technologies are the current choices. Although ubiquitous in both research labs and industry, these platforms must be combined to provide complete analysis of proteins, which is complicated and time consuming. In addition, they lack single molecule analysis capability required for studying heterogenous processes and for achieving precision diagnosis, especially for low volume samples. The present project aims to develop one detection platform that can perform the key functions of the above technologies with single molecule detection capability. The proposed technology images single proteins without labels, measures the size, charge and mobility of each protein simultaneously, identifies the protein based on its specific binding to antibodies, and quantifies its interactions with other proteins in real time. The team at the Biodesign Center for Bioelectronics and Biosensors, ASU, has carried out substantial experiments to demonstrate the proposed technology. In this R01 project, the team will address remaining technical challenges, build a complete prototype and validate it for single protein analysis on single cells.