Development of magnetic molecularly imprinted polymers for selective extraction of Benzoxazolinone-type alkaloids from acanthus plants

Benzoxazolinone-type alkaloids found in Acanthus ebracteatus and Acanthus ilicifolius Linnaeus possess various beneficial properties, such as antileishmanial, antipyretic, analgesic, antibacterial, and antioxidant effects. In this study, we employed a surface imprinting technique on nanomaterials. We utilized functionalized Fe3O4@SiO2-NH2 as a scaffold, with 2-benzoxazolinone and 2H-1,4-benzoxazin-3(4H)-one serving as dual templates, methacrylic acid (MAA) as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as a crosslinker, and 2,2-azodiisobutyric nitrile (AIBN) as the initiator. Prior to polymerization, we screened functional monomers using ultraviolet (UV) spectroscopy. The resulting magnetic surface molecular imprinting polymer (Fe3O4@SiO2@MIP) was thoroughly characterized using Fourier transform infrared spectrometry (FT-IR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). We also conducted assessments of its adsorption isotherms, dynamics, and selective binding capabilities. Our findings indicate that the MIPs exhibited exceptional selective recognition performance. Through meticulous screening and optimization of extraction and separation conditions, we established an LC‒MS/MS method based on magnetic solid-phase extraction technology. The method exhibited a recovery range of 78.80-106.99% (RSD, 0.46-3.31%) for 2-benzoxazolinone, with a limit of detection (LOD) and limit of quantification (LOQ) of 2.85 and 9.00 μg L−1, respectively. For 2H-1,4-benzoxazin-3(4H)-one, the method yielded a recovery range of 84.75-103.53% (RSD, 0.07-5.96%), with an LOD and LOQ of 3.60 and 12.60 μg L−1, respectively, in real samples. The resulting Fe3O4@SiO2@MIP demonstrated a high capacity for class-specific adsorption.