Preparation of magnetic molecularly imprinted polymers functionalized carbon nanotubes for highly selective removal of aristolochic acid.

In this work, we presented the preparation of magnetic carbon nanotubes (MCNTs) functionalized with molecularly imprinted polymers (MIPs) for effective removal of aristolochic acid I (AAI) in traditional Chinese medicine (TCM). MCNTs@AAI-MIPs was obtained via a facile and environmental friendly sol-gel process. Firstly, MCNTs were synthesized by a solvothermal method. Then, the template molecules were self-assembled with the functional monomer phenyltrimethoxysilane (PTMOS) in the presence of ethanol and water. Finally, AAI-MIPs film was coated on the MCNTs to obtain product MCNTs@AAI-MIPs using tetraethyl-orthosilicate (TEOS) as cross-linker. The morphology and structure of prepared MIPs were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen gas adsorption and vibrating sample magnetometer (VSM). The adsorption properties were demonstrated by kinetic, isothermal and selective adsorption experiments. The results showed that the imprinted nanocomposites exhibited fast separation rate (10 s), high adsorption capacity (18.54 μg∙mg-1), short kinetic equilibrium time (15 min), and good selectivity to template molecule with imprinting factor (IF) of 3.17. A regression equation (y=57294x-4734.1) with good linearity was obtained in the concentration range of 0.1-200 μg∙mg-1 for AAI with a correlation coefficient (R2) of 0.9998. The limit of detection (LOD, S/N=3) was 0.034 μg∙mg-1. Moreover, high recoveries ranged from 80% to 110% (RSD=3.27%-8.16%) were received in spiked TCM samples. The results suggested that the proposed MCNTs@AAI-MIPs could efficiently and specifically capture AAI from an actual complex TCM samples.