A computational reaction-diffusion model for the analysis of transport-limited kinetics

Optical, evanescent wave biosensors have become popular tools for quantitat ively characterizing the kinetic properties of biomolecular interactions. A nalyzing data from biosensor experiments, however, is often complicated whe n mass-transfer influences the detection kinetics. We present a computation al, transport-kinetic model that can be used to analyze transport-limited b iosensor data. This model describes a typical biosensor experiment in which a soluble analyte diffuses through a flow chamber and binds to a receptor immobilized on the transducer surface. Analyte transport in the flow chambe r is described by the diffusion equation while the kinetics of analyte-surf ace association and dissociation are captured by a reactive boundary condit ion at the sensor surface. Numerical integration of the model equations and nonlinear least-squares fitting are used to compare model kinetic data to experimental results and generate estimates for the rate constants that des cribe analyte detection. To demonstrate the feasibility of this model, we u se it to analyze data collected for the binding of fluorescently labeled tr initrobenzene to immobilized monoclonal anti-TNT antibodies, A successful a nalysis of this antigen-antibody interaction is presented for data collecte d with a fluorescence-based fiber-optic immunoassay, The results of this an alysis are compared with the results obtained with existing methods for ana lyzing diffusion-limited kinetic data.