Bio-inspired design on EGCG-selective membrane: An anchoring/imprinting strategy based on bi-interactions

In recent years, molecularly imprinted membrane (MIM) has exhibited superiority in industrial separation, drug purification, solid-phase extraction and even medical detection owing to its remarkable selectivity. For catechins, however, the reactivity with free radicals limits the traditional construction of MIM towards such molecules. Here in this work, we have developed a bio-inspired MIM towards Epigallocatechin gallate (EGCG, a representative catechin) by the anchoring/imprinting strategy. The covalent interactions based on boronate-affinity supplied an oriented anchoring effect, while the non-covalent interactions from l-cysteine promoted the formation of imprinted sites that are highly matched with template. Mild and efficient imprinting was carried out by self-polymerization of dopamine to avoid the destruction of templates. As a result, remarkable selectivity coefficients (2.70 and 4.58), permselectivity coefficients (more than 3.19 and 3.41) and separation factors (5.18 and 7.00) were achieved on the EGCG-imprinted membrane (EIM), accompanied by the impressive imprinting factor (10.14) and superior regeneration performance (only 4.4% of the decline in five cycles). For deep insight into selective recognition and separation, microscopic and visualized mechanisms of site formation and specific rebinding was proposed by molecular dynamics simulations. Approaches with such an anchoring/imprinting strategy will enrich the avant-garde molecular imprinting strategies, and also expand membrane-based applications.