2D Biomimetic Membranes Constructed by Charge Assembly and Hydrogen Bonding for Precise Ion Separation

Abstract

Designing well-ordered, multifunctional layered membranes with high selectivity and long-term stability remains a significant challenge. Here, a simple strategy is introduced that utilizes charge repulsion between graphene oxide (GO) and engineered bacteria to induce liquid crystal formation, enabling their layer-by-layer self-assembly on a polyethersulfone membrane. The interlayer pressure flattens the bacteria, removing interlayer water and forming a densely packed structure. This compression decreases the spacing between functional groups, leading to a robust hydrogen bonding network and a significant enhancement in mechanical properties (12.42 times tensile strength increase). Notably, the pressure preserves the activity of the super uranyl-binding protein of engineered bacteria, which selectively coordinates with uranyl (UO₂ ²⁺) through high-affinity coordination bonds, enabling recognition and sieving of target ions. The membrane demonstrates near 100% rejection of UO₂ ²⁺, K/U, and V/U selectivity of ≈140 and ≈40, respectively, while maintaining long-term stability. This strategy provides a versatile platform for the precise design of high-performance membranes, advancing the field of molecular transport in energy and environmental applications.