title: Quantification of protein interaction kinetics in a micro droplet.
abstract: Characterization of protein interactions is essential to the discovery of disease biomarkers, the development of diagnostic assays, and the screening for therapeutic drugs. Conventional flow-through kinetic measurements need relative large amount of sample that is not feasible for precious protein samples. We report a novel method to measure protein interaction kinetics in a single droplet with sub microliter or less volume. A droplet in a humidity-controlled environmental chamber is replacing the microfluidic channels as the reactor for the protein interaction. The binding process is monitored by a surface plasmon resonance imaging (SPRi) system. Association curves are obtained from the average SPR image intensity in the center area of the droplet. The washing step required by conventional flow-through SPR method is eliminated in the droplet method. The association and dissociation rate constants and binding affinity of an antigen-antibody interaction are obtained by global fitting of association curves at different concentrations. The result obtained by this method is accurate as validated by conventional flow-through SPR system. This droplet-based method not only allows kinetic studies for proteins with limited supply but also opens the door for high-throughput protein interaction study in a droplet-based microarray format that enables measurement of many to many interactions on a single chip.
authors.affiliation: Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University, Tempe, Arizona 85287, USA.
authors.forename: L L
authors.initials: LL
authors.lastname: Yin
authors.affiliation: Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University, Tempe, Arizona 85287, USA.
authors.forename: S P
authors.initials: SP
authors.lastname: Wang
authors.affiliation: Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University, Tempe, Arizona 85287, USA.
authors.forename: X N
authors.initials: XN
authors.lastname: Shan
authors.affiliation: College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China.
authors.forename: S T
authors.initials: ST
authors.lastname: Zhang
authors.affiliation: Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University, Tempe, Arizona 85287, USA.
authors.forename: N J
authors.initials: NJ
authors.lastname: Tao
mesh_terms: D000818:Animals; D000937:Antigen-Antibody Reactions; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D040081:Protein Array Analysis / Q000295:instrumentation / Q000379:methods; D020349:Surface Plasmon Resonance / Q000295:instrumentation / Q000379:methods
chemical_list: D007074:Immunoglobulin G