MOF-supported surface-imprinted polymer for hazard governance of aristolochic acids in herbal matrices: A...

Aristolochic acids are highly toxic compounds found in certain herbal medicines, posing significant safety risks. To address this, a UiO-66-NH₂(Zr)-supported surface molecularly imprinted polymer (SMIP) was developed, using indomethacin (IND) as a pseudo-template to create selective binding sites for aristolochic acid I (AA-I). Characterizations confirmed the formation of a thin imprinted layer and the successful removal of the pseudo-template. Adsorption fitting confirmed that physical monolayer adsorption predominated, with both imprinted and non-imprinted adsorption sites present. The SMIP exhibited a maximum adsorption capacity of 9.02 mg·g^-1 and an imprinting factor of 2.77. Selectivity tests demonstrated a pronounced preference for AA-I, with relative selectivity factors of 4.19 (vs p-nitrophenol) and 3.82 (vs tanshinone IIA). After five adsorption-desorption cycles, the adsorption efficiency remained above 94.15%, indicating good stability and reusability. The SMIP enabled effective recognition and adsorption of spiked AA-I from complex Caulis Clematidis Armandii extracts. Density functional theory calculations revealed that hydrogen bonding and van der Waals interactions played a dominant role in both imprinting and adsorption processes. Molecular dynamics simulations further visualized the solvent-dependent adsorption and elution behaviors of AA-I. Fukui mapping identified acceptor-rich carbonyl/nitro oxygen sites in IND/AA-I, reinforcing the bidirectional hydrogen-bonding motif and IND's mimicry of AA-I. In summary, this work proposes a reusable, mechanism-guided imprinting strategy that maintains high selectivity for materials while utilizing green pseudo-templates. It provides a useful reference for the selective monitoring and removal of toxic components and contaminants in complex herbal and related matrices.