Convection-Diffusion-Adsorption Model for the Description of the Analyte-Binding Reactions on a Membrane

The performance of many biomedical assays strongly depends on the transport of analyte molecules to the surface where the binding reactions occur. In some experimental systems, liquid flow can drastically improve the detection limit and decrease the analysis time. This is true for many membrane-based analyses, such as dot-blotting and immunofiltration, in which the sample flows through a porous membrane and adsorbs onto the polymer surface in the pores. Here, we use the convection-diffusion-adsorption equation to calculate the amount of the adsorbed analyte as a function of time. The analyte-binding efficiency is compared for the two sample loading procedures-pressure-driven flow and incubation. Computation shows that when the liquid flow rate reaches a certain threshold, the pressure-driven flow setup ensures higher analyte adsorption than incubation. The convection can drastically decrease the time necessary to capture a small detectable amount of the analyte. However, the infinite increase of the flow rate seems useless because it cannot overcome the kinetic limitation of the adsorption. The model proposed here is in good agreement with the experimental data and can be valuable for the development of membrane-based biosensors.