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Many separation or detection techniques, such as chromatography or detection on a sensor, are based upon the interaction between analyte molecules and immobilized ligand molecules on the surface of a microfluidic channel. Typically, the aim is to capture an analyte with the maximum possible binding to the ligands. Here, we elaborate a mathematical model for the binding kinetics of analyte molecules passing through a microchannel with simultaneous association to ligand molecules on its surface to provide deeper understanding and prediction of experimental behavior. The focus and contribution of this work is on analytes that are not discrete units, but are grouped as binding sites (e.g. antigens on the outer cell membrane), while our results can also find application for functionalized micro particles. We apply and validate the model for the case where analytes are grouped on Salmonella cells, and ligands are anti-Salmonella antibodies. A simple equation is developed with variables the flow rate, microchannel dimensions, concentrations, and the active area-ratio increase when a rough microchannel is used. The model is used to fit the association rate constants with spatially varying experimental data of number densities (cells/mm2) of Green Fluorescent Protein (GFP)-Salmonella cell binding in a microfluidic device. The model is also used to predict cell binding in various microchannels with different geometries, and to design microfluidics for specific operations. © 2017 Elsevier B.V. |
