Preparation and evaluation of magnetic graphene oxide molecularly imprinted polymers (MIPs-GO-Fe3O4@SiO2) for the analysis and separation of tripterine

Abstract

In this study, the novel magnetic molecularly imprinted polymers (MMIPs) with a specific tripterine recognition ability have been synthesized via molecular imprinting technology. The MMIPs were prepared using graphene oxide (GO) with Fe3O4 nanoparticles coated with silica shell as the magnetic component, tripterine as the template molecule, methacrylamide (MAM) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, acetonitrile (ACN) as the pore-forming agent, and 2,2′-azobisisobutyronitrile (AIBN) as the initiator. Several polymerization parameters were systematically investigated, including the ratio of template/functional monomer/cross-linker, the dosage of the pore-forming agent and the initiator, and the time of prepolymerization. The morphology, structure and stability of the resultant MMIPs were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Saturation magnetization value of MIPs was 37.10 emu/g by superconducting quantum interference magnetometer, exhibiting good magnetic property. The selectivity, separation performance and adsorption mechanism were also studied. These results showed that MIPs exhibit good recognition of tripterine compared to non-imprinted polymer (NIPs). The binding process of MIPs was very fast and the maximum adsorption capacity to tripterine was 30.73 mg/g. Pseudo-second-order kinetic model fitted well with the kinetic data and binding isotherm was well described by Langmuir isotherm model. HPLC-UV analysis results revealed the application of MIPs was sufficiently specific, rapid and sensitive in the extraction, separation and quantitative determination of tripterine. This work also provided an important reference for the separation, enrichment and purification of specific constituent in complicated Traditional Chinese medicine (TCM) samples.