Xiaoyu Xie

Synthesis of magnetic molecularly imprinted polymers by reversible addition fragmentation chain transfer strategy and its application in the Sudan dyes residue analysis

Magnetic molecularly imprinted polymers (MMIPs) have become a hotspot owing to the dual functions of target recognition and magnetic separation. In this study, the MMIPs were obtained by the surface-initiated reversible addition fragmentation chain transfer (RAFT) polymerization using Sudan I as the template. The resultant MMIPs were characterized by transmission electron microscope, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, vibrating sample magnetometer, and X-ray diffraction. Benefiting from the controlled/living property of the RAFT strategy, the uniform MIP layer was successfully grafted on the surface of RAFT agent-modified Fe3O4@SiO2 nanoparticles, favoring the fast mass transfer and rapid binding kinetics. The developed MMIPs were used as the solid-phase extraction sorbents to selectively extract four Sudan dyes (Sudan I, II, III, and IV) from chili powder samples. The recoveries of the spiked samples in chili powder samples ranged from 74.1 to 93.3% with RSD lower than 6.4% and the relative standard uncertainty lower than 0.029. This work provided a good platform for the extraction and removal of Sudan dyes in complicated matrixes and demonstrated a bright future for the application of the well-constructed MMIPs in the field of solid-phase extraction.

Preparation of molecularly imprinted polymers based on magnetic nanoparticles for the selective extraction of protocatechuic acid from plant extracts

In this study, highly selective core-shell molecularly imprinted polymers on the surface of magnetic nanoparticles were prepared using protocatechuic acid as the template molecule. The resulting magnetic molecularly imprinted polymers were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and vibrating sample magnetometry. The binding performances of the prepared materials were evaluated by static and selective adsorption. The binding isotherms were obtained for protocatechuic acid and fitted by the Langmuir isotherm model and Freundlich isotherm model. Furthermore, the resulting materials were used as the solid-phase extraction materials coupled to high-performance liquid chromatography for the selective extraction and detection of protocatechuic acid from the extracts of Homalomena occulta and Cynomorium songaricum with the recoveries in the range 86.3-102.2%.

Overview of online two-dimensional liquid chromatography based on cell membrane chromatography for screening target components from traditional Chinese medicines

Cell membrane chromatography is a simple, specific, and time-saving technique for studying drug-receptor interactions, screening of active components from complex mixtures, and quality control of traditional Chinese medicines. However, the short column life, low sensitivity, low column efficiency (so cannot resolve satisfactorily mixture of compounds), low peak capacity, and inefficient in structure identification were bottleneck in its application. Combinations of cell membrane chromatography with multidimensional chromatography such as two-dimensional liquid chromatography and high sensitivity detectors like mass have significantly reduced many of the above-mentioned shortcomings. This paper provides an overview of the current advances in online two-dimensional-based cell membrane chromatography for screening target components from traditional Chinese medicines with particular emphasis on the instrumentation, preparation of cell membrane stationary phase, advantages, and disadvantages compared to alternative approaches. The last section of the review summarizes the applications of the online two-dimensional high-performance liquid chromatography based cell membrane chromatography reported since its emergence to date (2010-June 2016).

Characterization the affinity of α1A adrenoreceptor by cell membrane chromatography with frontal analysis and stoichiometric displacement model

As a bionic chromatographic method, cell membrane chromatography (CMC) has been used widely in screening active components in traditional Chinese medicine. Nevertheless, few studies have characterized the affinity between drug and receptor by CMC model. In this study, the alpha 1 adrenoreceptor (α1A AR) high expression CMC method, combined with frontal analysis and stoichiometric displacement model respectively, was established for characterizing the affinity of seven alkaloids binding to the α1A AR. The results indicate that the seven alkaloids have similar interaction strengths with tamsulosin hydrochloride (α1A AR antagonist) between them and α1A AR. In addition, electrostatic force is the main intermolecular forces between tamsulosin hydrochloride and seven alkaloids and α1A AR. The study provides a versatile approach for the characterization the affinity between drug and receptor by CMC model.

A novel cell membrane affinity sample pretreatment technique for recognition and preconcentration of active components from traditional Chinese medicine

We describe a novel biomembrane affinity sample pretreatment technique to quickly screen and preconcentrate active components from traditional Chinese medicine (TCM), which adopts cell membrane coated silica particles (CMCSPs) as affinity ligands which benefit the biomembrane’s ability to maximize simulation of drug-receptor interactions in vivo. In this study, the prepared CMCSPs formed by irreversible adsorption of fibroblast growth factor receptor 4 (FGFR4) cell membrane on the surface of silica were characterized using different spectroscopic and imaging instruments. Drug binding experiments showed the excellent adsorption rate and adsorption capacity of FGFR4/CMCSPs compared with non-coated silica particles. The FGFR4/CMCSPs were used as solid-phase extraction sorbents to pretreat the TCM Aconitum szechenyianum Gay. The resultant FGFR4/CMCSPs exhibited good performance. In addition, high selectivity and recognition ability of the FGFR4/CMCSPs were determined by selectivity experiments. Four alkaloid were screened and identified, one of these alkaloid, napellonine, showed favorable anti-tumor activity in preliminary pharmacological verification trials including cell proliferation and molecular docking assays. The proposed cell membrane affinity sample pretreatment method is a reliable, effective and time-saving method for fast screening and enriching active compounds and can be extended to pretreat other TCMs as leading compounds resources.

Improved cell membrane bioaffinity sample pretreatment technique with enhanced stability for screening of potential allergenic components from traditional Chinese medicine injections

Aiming at improving reliability and tedious analysis time in conventional cell membrane chromatography, an improved bioaffinity sample pretreatment technique with enhanced stability was developed to fast screen and extract potential allergenic components from traditional Chinese medicine injections. In this study, rat basophilic leukemia-2H3 cell membrane coated silica particles (RBL-2H3/CMCSPs) were fabricated by irreversible adsorption between the cell membrane and silica and self-fusion of the cell membrane, which could simulate drug-receptor interactions in vitro. Also, benefiting from the use of paraformaldehyde, the average recoveries of the six batches of RBL/CMCSPs were 90.2% with a relative standard deviation of less than 7.8%, showing that the stability of the materials was remarkably improved compared to materials without fixation. After the successful characterization by spectroscopic and imaging instruments, the prepared RBL-2H3/CMCSPs exhibited desirable adsorption capacity and selectivity. The RBL-2H3/CMCSPs combined with high performance liquid chromatography coupled with time of flight mass spectrometry were then successfully applied to screen and identify two potential allergenic components from huangqi injection, the allergenic activities of which were further investigated by β-hexosaminidase release assay and histamine release assay in vitro. Overall, this work provides a good platform for the fabrication of bioaffinity sample pretreatment materials with high stability and a long lifespan, which can be a time-saving and energy-saving bioaffinity method to rapidly screen and preconcentrate target compounds from complex samples.

Fast and high-efficiency magnetic surface imprinting based on microwave-accelerated reversible addition fragmentation chain transfer polymerization for the selective extraction of estrogen residues in milk

A novel microwave-accelerated reversible addition fragmentation chain transfer (RAFT) polymerization strategy has been introduced to shorten reaction time and improved polymerization efficiency of the conventional molecularly imprinting technology based on RAFT. Magnetic molecular imprinted polymers (MMIPs) were successfully synthesized much more efficiently using 17β-estradiol (E2) as a template for the determination of estrogen residues. The resultant MMIPs had well-defined thin imprinted film, favoring the fast mass transfer. Moreover, the reaction time, which was just 1/24 of the time taken by conventional heating, was significantly decreased, improving the reaction efficiency and reducing the probability of side reactions. Meanwhile, the obtained polymers have good capacity of 6.67 mg g-1 and satisfactory selectivity to template molecule with the imprinting factor of 5.11. As a result, a method combination of the resultant MMIPs as solid phase extraction sorbents and high-performance liquid chromatography was successfully set up to determinate three estrogen residues in milk samples. For E2, estrone, and estriol, the limit of detections were calculated to be 0.03, 0.08, and 0.06 ng mL-1, respectively, and the limit of quantifications were 0.11, 0.27, and 0.21 ng mL-1, respectively. At the spiked level of 1, 5, and 10 ng mL-1, the recoveries of the three estrogens were ranged from 69.1% to 91.9% and the intra-day relative standard deviation (RSD) was less than 5.7%. In addition, the resultant MMIPs exhibited good reproducibility and reusability with the inter-batch RSD of 5.3% and the intra-batch RSD of 6.2%, respectively. Overall, the realization of this strategy facilitates the preparation of MMIPs with good architecture and high reaction efficiencies for the analysis of complicated real samples.

Molecularly imprinting: a tool of modern chemistry for analysis and monitoring of phenolic environmental estrogens

Abstract Phenolic environmental estrogen (PEE) is one of the most common endocrine disrupting chemicals whose interference with the normal function of the endocrine system in animals and humans raised concern to their potential impact on wildlife and humans health. Research on PEEs calls for a high selectivity analytical methods. Molecularly imprinted polymers (MIPs) are synthetic polymers having a predetermined selectivity for a given analyte, or group of structurally related compounds, which make them ideal materials to be used in analysis of PEEs. During the past few years, a huge amount of papers have been published dealing with the use of MIPs in the analysis of PEEs. In this review, we focus on the recent applications of MIPs to analyze PEEs. We describe the preparation of MIPs and discuss different methods of polymerization. We highlight the latest applications of MIPs in the analysis of PEEs, including nanomaterial MIPs as sorbent for solid-phase extraction and MIPs as electrochemical sensors. This review provides a good platform for the analysis and monitoring of PEEs in complicated matrixes and offers suggestions for future success in the field of MIPs.

Simultaneous determination of camptothecin and 10-hydroxycamptothecine in the Camptotheca acuminate, its medicinal preparation and in rat plasma by liquid chromatography with fluorescence detection

Camptotheca acuminata Decne is an important medicinal plant that contains various cytotoxic alkaloids, such as camptothecine (CPT) and 10-hydroxycamptothecine (HCPT). A rapid and sensitive liquid chromatography with fluorescence detection (LC-FLD) method for the quantification of CPT and HCPT is described. The separation was carried out on a DL-Cl8 column (4.6 × 150 mm, 5 µm), with the mobile phase of acetonitrile-sodium dihydrogen phosphate buffer (10 mm) using an gradient elution at the flow rate of 0.6 mL/min. The LC-FLD method was validated for linearity, sensitivity, accuracy and precision, and then used to determine the content of the above components. The lower detection limits of CPT and HCPT were 0.4 and 0.1 ng/mL, respectively. The precision was <1.58% and the mean recovery of the analytes was 96.0-98.6%. The LC-FLD method was successfully applied to determine CPT and HCPT in real samples including C. acuminate, HCPT injection and rat plasma.