Biomimetic Mineralization BSA@ZIF-8 Composites for the Fabrication of Membranes with Enhanced Chiral Separation Performance

A novel chiral mixed matrix membrane (MMM) was prepared by biomimetic mineralization to encapsulate bovine serum albumin (BSA) within ZIF-8, followed by film formation. In this process, a new ratio of ZIF-8 material and two biocomposites with different precursor ratios were synthesized via a one-pot co-precipitation method under ambient conditions. BSA@ZIF-8 (Zn 2+ /2-methylimidazolate (2-mIM) = 40:320 mM) demonstrated the optimal separation of 1-phenylethanol (PE), with an enantiomeric excess ( ee ) of 52.79%. Subsequently, the combination of BSA@ZIF-8 with polyethersulfone (PES) to form a chiral MMM was investigated, and the effects of the concentration of the feed solution, the proportion of biocomposite in the membrane, the thickness of the membrane and the permeation time of the chirality on the enantiomeric separation were examined. The chiral MMM achieved complete enantioseparation ( ee = 100 %). Both the biocomposite-containing membrane and the free biocomposite retained this performance throughout the stability tests, demonstrating that immobilizing BSA within ZIF-8 markedly enhanced the robustness of the biomacromolecule. Finally, molecular docking studies revealed the presence of hydrogen bonding and hydrophobic forces, especially hydrogen bonding, between BSA@ZIF-8 and the racemate, which explained the selective chiral recognition ability of BSA@ZIF-8 towards the racemate PE.