An intelligent solvent-responsive surface molecularly imprinted membrane with switchable adsorption/desorption performance for selective separation of psoralen and recognition mechanism

Psoralen (PSO), a natural product in Ficus carica L., exhibits remarkable pharmacological activity and clinical efficacy. However, achieving selective recognition and effective recovery in PSO separation process remains a challenge. In this study, an intelligent solvent-responsive surface molecularly imprinted membranes (SR-SMIMs) with switchable adsorption/desorption behavior was developed and applied to separate PSO. Cellulose membranes were modified with chitosan and polydopamine in sequence, followed by the construction of a surface molecularly imprinting layer using bi-functional monomers (AM and 4-VPBA) and solvent-responsive cross-linking agent (TEGDMA). The TEGDMA drives the swelling or shrinking of polymer chains, resulting in a switch in the adsorption/desorption behavior of SR-SMIMs. Hence, SR-SMIMs exhibited remarkable adsorption capacity of 40.69 mg·g-1 towards PSO in 25% methanol and can be efficiently desorbed with satisfactory efficiency in methanol. The molecular simulation and NMR analysis demonstrated that the recognition mechanism of SR-SMIMs was a synergistic effect of hydrogen bonding, π-π stacking and Van der Waals forces. Furthermore, the SR-SMIMs were effectively employed for the separation of PSO from Ficus carica L. leaves, exhibiting an impressive adsorption capacity of 20.51 mg·g-1 and a high elution recovery rate of 92.54%. This efficient and sustainable SR-SMIMs possessed promising potential for specific separation of target compound from complex natural plants extracts.