Thermosensitive magnetic molecularly imprinted polymers for selective recognition and detection of sinomenine in traditional Chinese medicines and biological sample

A thermo-responsive magnetic molecularly imprinted polymer (TMMIP) based on magnetic graphene oxide (MGO) was prepared via surface molecular imprinting technique for selective recognition of sinomenine (SIN) in various complex matrices. The obtained nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometry (VSM), and thermogravimetric analysis (TGA). The results indicated that the TMMIP exhibited a typical core-shell structure, comprising a molecularly imprinted shell, and demonstrated both magnetic susceptibility and excellent stability. The adsorption performance of TMMIP was also studied via adsorption kinetics, adsorption isotherms and selectivity experiments. The TMMIP exhibited high adsorption capacity, high selectivity for SIN, and mild acidic elution conditions. Under the optimal conditions, an analytical methodology combining TMMIP based dispersive solid-phase microextraction with high-performance liquid chromatography (HPLC) was subsequently established. TMMIP can rapidly adsorb SIN in solution and easily collected with assistance of outer magnetic field. The analysis method exhibited linearity across 0.05-150 μg/mL with a correlation coefficient of 0.9993, while demonstrating detection sensitivity at 0.1 ng/mL (DL) and quantification capability at 0.3 ng/mL (QL). Validation using Caulis sinomenii , oral liquid and blood samples acquired recoveries of 88.8–110.4%. This integrated approach demonstrates high efficiency for SIN extraction and detection in complex matrices and provided an efficient, eco-friendly strategy for SIN analysis.