In this work, the superparamagnetic Fe 3 O 4 particles prepared by the coprecipitation method were coated successively by SiO 2 , vinyl end groups and molecularly imprinted polymer (MIP) shells to afford a pomegranate-like core/shell superparamagnetic particle (Fe 3 O 4 @SiO 2 @MIP), and the MIP shell preparation conditions were optimized by multi-objective response surface methodology. In order to simultaneously enrich and separate the four taxoids (10-DAB, baccatin III, cephalomannine and paclitaxel), cephalomannine was selected as the template because of its similar chemical structure to other three taxoids and relative inexpensiveness. Especially, to avoid template leaking which may influence the accuracy of identification and quantitation of the analytes, we selected paclitaxel as the target molecular during the investigation of the adsorption property of Fe 3 O 4 @SiO 2 @MIP particles. This strategy was similar to the dummy molecular imprinting technique in which the dummy molecularly imprinted polymer was prepared by using a dummy template, structural analog of the target analyte. The as-prepared Fe 3 O 4 @SiO 2 @MIP particles were characterized by transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FTIR). The adsorption kinetics, isotherms and reusability were also investigated. Finally, the Fe 3 O 4 @SiO 2 @MIP particles were successfully applied to simultaneously enrich and separate these four taxoids in the extract of Taxus × media ( T. × media ).
We have developed a novel and economical electrochemical sensor to measure Gram-negative bacterial quorum signaling molecules (AHLs) using magnetic nanoparticles and molecularly imprinted polymer (MIP) technology. Magnetic molecularly imprinted polymers (MMIPs) capable of selectively absorbing AHLs were successfully synthesized by surface polymerization. The particles were deposited onto a magnetic carbon paste electrode (MGCE) surface, and characterized by electrochemical measurements. Differential Pulse Voltammetry (DPV) was utilized to record the oxidative current signal that is characteristic of AHL. The detection limit of this assay was determined to be 8×10 −10 mol L −1 with a linear detection range of 2.5×10 −9 mol L −1 to 1.0×10 −7 mol L −1 . This Fe 3 O 4 @SiO 2 -MIP-based electrochemical sensor is a valuable new tool that allows quantitative measurement of Gram-negative bacterial quorum signaling molecules. It has potential applications in the fields of clinical diagnosis or food analysis with real-time detection capability, high specificity, excellent reproducibility, and good stability.