Effect of fluidic transport on the reaction kinetics in lectin microarrays

Lectins are the proteins which can distinguish glycosylation patterns. They are frequently used as biomarkers for progressions of several diseases including cancer. As the lectin microarray based prognosis devices miniaturize the process of glycoprofiling, it is anticipated that their performance can be augmented by integration with microfluidic framework. This is analogous to microfluidics based DNA arrays. However, unlike small oligonucleotide microarrays, it remains uncertain whether the binding reaction-kinetic parameters can be considered invariant of imposed hydrodynamics, for relatively larger and structure sensitive molecules such as lectins. Here we show, using two standard lectins namely Concanavalin A and Abrus Agglutinin, that the steady state binding efficiency unexpectedly declines beyond a critical shear rate magnitude. This observation can be explained only if the associated reaction constants are presumed to be functions of hydrodynamic parameters. We methodically deduce the shear rate dependence of association and dissociation constants from the comparison of experimental and model-simulation trends. The aforementioned phenomena are perceived to be the consequences of strong hydrodynamic perturbations, culminating into molecular structural distortion. The exploration, therefore, reveals a unique coupling between reaction kinetics and hydrodynamics for biomacromolecules and provides a generic scheme towards futuristic microfluidics-coupled biomedical assays.