(479a) Modeling Oligo-Dt Dynamic Capture and Elution of mRNA with Affinity Membranes

We have developed a mechanistic mathematical model to describe dynamic adsorption and elution of mRNA using microporous polymeric filtration membranes modified by graft polymerization of oligo-dT to promote affinity interactions between the oligo-dA tail of mRNA and the grafted oligo-dT ligand. The model accommodates a variety of sorption kinetics, boundary conditions, system nonidealities, and membrane configurations (flat sheet and hollow fiber). To better understand the response of the membrane adsorber, we first measured dispersion and other mixing phenomena in the system, including process tubing and the membrane holder. Dispersion and mixing were characterized using transport of conservative tracers, such as acetone, for both step and pulse inputs. A range of ideal (CSTR, PFR) and non-ideal reactors in combination were investigated to describe dispersion and transport. The best approach depended on operating conditions and the type of membrane holder.

The loading step of the membrane adsorber was described using a convection-dispersion-adsorption model with Langmuir kinetics to generate breakthrough curves. The elution step was described by a similar model with first-order elution kinetics. A unique rate constant was employed during elution to account for the changing composition as the loading buffer is displaced by the elution buffer. Figure 1 depicts successful fitting of the elution curve of mRNA to the transport model with first-order elution kinetic. The model was able to accurately predict the behavior of mRNA capture and elution, and the results demonstrate the usefulness of the modeling approach for understanding, guiding, and optimizing the performance of the oligo dT affinity microporous membranes for mRNA capture and purification.