Sustainable Defect-Engineered Imprinted UiO-66-NH₂ for Selective Removal of Aristolochic Acids from Medicinal Herbs

Abstract

Aristolochic acid I (AA-I), a known nephrotoxin and carcinogen, is commonly found in certain medicinal plants, posing significant safety concerns. In this work, defect-engineered, molecularly imprinted UiO-66-NH 2 was synthesized via a one-pot hydrothermal method using indomethacin (IND) as a green alternative template. The resulting imprinted metal–organic framework effectively mitigates matrix interference, enabling highly selective recognition and the efficient adsorption of AA-I. Structural characterization confirmed that the imprinting process and template removal did not compromise the framework integrity of UiO-66-NH 2 . Spectroscopic analysis revealed that AA-I recognition was governed by Zr coordination, electrostatic interactions, and spatially confined recognition sites within the porous framework. Density functional theory calculations further elucidated the interaction mechanisms involved in the adsorption process. The imprinted UiO-66-NH 2 exhibited a maximum adsorption capacity of 42.74 mg/g and an imprinting factor of 2.48. In real sample analysis, the material achieved recovery rates of 96.7–103.5% and excellent selectivity in Clematis armandii extracts. The adsorption efficiency remained above 80% after five adsorption–desorption cycles, indicating good structural stability and reusability. This work offers a promising and sustainable strategy for improving herbal medicine safety through the rational design of ecofriendly MOF-based adsorbents.