Synthesis of metal-organic framework hybrid nanocomposites based on MOFs@C3N4 with high selective separation ability for luteolin

Abstract

Complex substrates found in certain extracts-particularly those containing high phenolic compounds with significant medicinal value-pose considerable challenges to developing molecularly imprinted membranes (MIMs) with specific recognition abilities. In this study, UiO-66-NH2, a metal–organic structure (MOF), was chosen as an optimizer to enhance the basic support material C3N4. A composite imprinted membrane based on MOFs was then prepared for the targeted adsorption of luteolin (LTL). This not only increases the surface area and pore capacity of the composite membranes, but also ensures unprecedented control over the membranes structure and good stability. To maximize the proportion of imprinted sites, we utilize an advanced boron affinity sol–gel imprinting technique that capitalizes on the exceptional response of the bifunctional monomer. By finely manipulating the imprinting process, controlled distribution of imprinted sites was achieved. Furthermore, the incorporation of Ag nanoparticles into the composite matrix of MIMs enhances selectivity and efficiency due to their plasmonic properties and high affinity for phenolic compounds, providing increased adsorption surface area and additional binding sites. The results showed satisfactory rebinding ability (56.25 mg g−1) and superselective (βAG/LTL = 4.43 and βCT/LTL = 8.49). It was worth noting that incorporating Ag nanoparticles into composite MIMs for the selective adsorption of LTL demonstrates significant potential. This includes enhanced selectivity, efficiency, and hydrophilicity of the membrane surface. Thus, enhanced hydrophilicity can establish stronger non-covalent interactions, namely hydrogen bonding and van der waals forces, with the target molecules, thereby significantly improving the adsorption capacity of the MIMs. The feasibility of this method was demonstrated via in-situ infrared analysis of the chemical structure changes before and after adsorption.