A DLVO-based framework for quantifying bovine serum albumin (BSA) binding on ion-exchange nanofibres

Electrospun nanofibre ion exchange (IEX) membranes have significant advantages for advancing protein separation, yet their low dynamic binding capacities have limited their practical applications. Understanding optimum membrane morphologies and binding interactions at the interface between nanofibres and proteins will provide vital knowledge for the design of those electrospun nanofibre IEX membranes. Herein, we employed computational fluid dynamics coupled with a discrete phase model to predict protein trajectories and simulate protein binding on IEX nanofibres based on the force balance. Using the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory, we incorporated van der Waals (vdW) and electrostatic forces into the simulations through user-defined scalars and user-defined functions in Ansys Fluent. The effect of pH on binding was significant due to the dominant electrostatic interaction between the proteins and nanofibres. For the model protein bovine serum albumin, maximum binding was achieved in the pH range of 7.5-8.5. Binding efficiencies are improved by 200% with the increase in the specific surface area of the membrane matrix from M10 to M3. This study provides significant insights into the parameter design of high-performance ion-exchange adsorptive nanofibrous membranes for high- throughput separation.