Advanced Adaptive Protein Membrane with Super-High Flux and Precise Molecular Sieving of Dyes from Salts

Precise separation of small organic molecules and electrolyte salts is critical for various industrial processes, necessitating advanced membranes with uniform pores. Proteins, as one typical nature polymer having the exactly same structure and molecular weight, offer a promising material for making such membranes. Here, hemoglobin (BHb) and lysozyme (Lyz) are utilized to fabricate precise nanofiltration membranes through amyloid-like co-assembly, triggered by Tris(2-carboxyethyl) phosphine. Molecular dynamics simulations reveal that BHb intercalates between Lyz molecules, enhancing tight assembly and reducing defects. The Lyz/BHb membrane exhibits a high void volume of 27.2% and achieves an exceptional permeance of 335 L m^-2 h^-1 bar^-1. Amazingly, the Lyz/BHb membrane achieves ultra-selective molecular sieving of dyes and salts with an unparalleled high separation factor of 1.25 × 10³ for the NaCl/Brilliant blue. The unique adaptive separation layer is formed by anchoring dye molecules into the larger pores and thus narrowing down the pore size distribution and enhancing electrostatic repulsion, endowing the membrane with a distinctive molecular sieving of dyes and salts. This study offers valuable insights to finely tailor the pore structure of the membrane by co-assembly of proteins and to significantly enhance the membrane perm-selectivity by creating an adaptive protein separation layer with a unique molecular sieving property.