Article: Kang, P; Schein, P; Serey, X; O’Dell, D; Erickson, D; (2015) “Nanophotonic Detection of Freely Interacting Molecules on a Single Influenza Virus”, Scientific Reports, 5
Abstract: Biomolecular interactions, such as antibody-antigen binding, are fundamental to many biological processes. At present, most techniques for analyzing these interactions require immobilizing one or both of the interacting molecules on an assay plate or a sensor surface. This is convenient experimentally but can constrain the natural binding affinity and capacity of the molecules, resulting in data that can deviate from the natural free-solution behavior. Here we demonstrate a label-free method for analyzing free-solution interactions between a single influenza virus and specific antibodies at the single particle level using near-field optical trapping and light-scattering techniques. We determine the number of specific antibodies binding to an optically trapped influenza virus by analyzing the change of the Brownian fluctuations of the virus. We develop an analytical model that determines the increased size of the virus resulting from antibodies binding to the virus membrane with uncertainty of +/- 1-2 nm. We present stoichiometric results of 26 +/- 4 (6.8 +/- 1.1 attogram) anti-influenza antibodies binding to an H1N1 influenza virus. Our technique can be applied to a wide range of molecular interactions because the nanophotonic tweezer can handle molecules from tens to thousands of nanometers in diameter.
Funding Acknowledgement: NIH [1R01GM106420-01]; National Science Foundation [ECCS-0335765]; NSF MRSEC program [DMR-1120296]
Funding Text: This work was supported by the NIH under Grant 1R01GM106420-01. The fabrication of the photonic crystal resonator was performed at the Cornell NanoScale Facility, a member of the National Nanotechnology Infrastructure Network, which is supported by the National Science Foundation (Grant ECCS-0335765). TEM imaging of influenza A virus was performed at the Cornell Center for Materials Research Shared Facilities which are supported through the NSF MRSEC program (DMR-1120296). Embedded Python Molecular Viewer (ePMV) was used for visualization of proteins and viruses. We would like to thank Dr. Manfred Lindau in the department of Applied and Engineering Physics at Cornell for discussion to develop the analytical model. We also appreciate Dr. Eric Richards in Boyce Thompson Institute for Plant Research at Cornell for allowing the use of resources for fluorescent conjugation of influenza viruses in preliminary experiments.