Protein-coated particle capture within a membrane during filtration : simulations

Abstract

Improving selectivity between different particles during membrane microfiltration has been a seminal goal for the past 100 years since Sartorius commercialized the first synthetic microporous membranes in Germany. This work is a continuation of the recent approach by Sorci et al. of linking membrane microstructure with filtration performance (Sorci et al., 2019). While they used 2D computational fluid and particle drag mechanics with particle and membrane force measurements described by classical DLVO theory in aqueous solutions, we (i) extend their simulations to 3D using a fluid mechanics simulation program for 3D particle fluid dynamics called MFiX (Multiphase Flow with Interphase eXchanges), and (ii) adapt the extended-DLVO (xDLVO) theory to model the behavior of a plethora of intermolecular force-distance curves between membranes (modified poly(ether sulfone), mPES) and polystyrene particles coated with covalently attached streptavidin at different pH values and salt concentrations. These intermolecular force-distance measurements (including short-term attraction) were obtained using atomic force microscopy (AFM) in force mode by Dr. Mirco Sorci in Dr. Georges Belfort’s research group. The simulation results of particle capture efficiency qualitatively correlated with the magnitude of the short-term attractive forces with a model membrane internal structure comprising an array of spheres. Thus, stronger attractive forces lead to higher particle capture. We also demonstrate, for the first time, that the xDLVO theory describes these jump-in attractive forces, given the solution conditions and net charge on the particle.