Synthesis and characterization of magnetic molecularly imprinted polymers for enrichment of sanguinarine from the extraction wastewater of M. cordata

A novel electrochemical sensor based on dual-functional MMIP-CuMOFs for both target recognition and signal reporting and its application for sensing bisphenol A in milk

In this work, novel magnetic molecularly imprinted CuMOFs (MMIP-CuMOFs) were synthesized and applied to construct an electrochemical bisphenol A sensor. The constructed sensor used an electrode modified with reduced graphene oxide (RGO/GCE) as the sensing platform to improve its stability and sensitivity. The Fe3O4 nanoparticles in magnetic MOFs simplified the preparation process. Moreover, the combination of CuMOFs and molecular imprinting methodology was beneficial for improving the detection specificity, and the electroactive copper hexacyanoferrate generated by the reaction of Cu2+ in CuMOFs with potassium ferricyanide was used as the signal probe. The sensor showed a good linear relationship in the range of 0.5 to 500 nmol/L, with a low detection limit of 0.18 nmol/L. In addition, the sensor had good selectivity, repeatability (RSD = 2.59 %), and a good recovery rate for actual milk sample detection (99.8-102.49 %). This technique holds great promise for the detection of detrimental substances in food.

Determination of chloramphenicol in food using nanomaterial-based electrochemical and optical sensors-A review

Chloramphenicol (CAP) is a widely used antibiotic for the treatment of sick animals owing to its potent action and low cost. However, the accumulation of CAP in the human body can cause irreversible aplastic anemia and hematopoietic toxicity. Accordingly, development of various analytical techniques for the rapid detection of CAP in animal products and the related processed foods is necessary. Among these analytical techniques, electrochemical and optical sensors offer many advantages for CAP detection, including high sensitivity, simple operation and fast analysis speed. In this review, we summarize recent application of carbon nanomaterials, metal nanoparticles, metal oxide nanoparticles and metal organic framework in the development of electrochemical and optical sensors for CAP detection (2010-2022). Based on the advantages and disadvantages of nanomaterials, electrochemical and optical sensors are summarized in this review. The preparation and synthesis of electrochemical and optical sensors and nanomaterials in the field of rapid detection are prospected.

Preparation of magnetic yolk-shell structured metal-organic framework material and its application in pharmacokinetics study of alkaloids

In this study, a magnetic yolk-shell structured metal-organic framework material (Fe₃O₄@YS-UiO-66-NH₂) is prepared by the directional etching of Co²⁺/peroxymonosulfate and in situ magnetization. The characteristic properties of the material were investigated by using field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometer, Brunauer-Emmett-Teller, and contact angle test. The Fe₃O₄@YS-UiO-66-NH₂ shows the advantages of large surface area, good magnetic property, and satisfactory stability, as well as giving high affinity to alkaloids (ALs) via hydrophilic interaction, hydrogen bonding, and π-π interaction. The results of static adsorption experiment indicate that the Fe₃O₄@YS-UiO-66-NH₂ possesses high adsorption capacity towards ALs and the adsorption behaviors are fitted with Langmuir adsorption isotherm model. Furthermore, a magnetic solid-phase extraction using Fe₃O₄@YS-UiO-66-NH₂ and HPLC method was developed for the analysis of ALs in spiked samples with the recovery of 89.6-100.8%. In addition, the proposed method was successfully applied in the pharmacokinetics study of berberine, coptisine, and palmatine in the rat. In short, the developed method might be used for high-efficient recognition and determination of ALs in plasma sample, which would also provide a new way to fabricate magnetic functionalized metal-organic framework in separation science.

Molecularly Imprinted Polymers for Dispersive (Micro)Solid Phase Extraction: A Review

The review describes the development of batch solid phase extraction procedures based on dispersive (micro)solid phase extraction with molecularly imprinted polymers (MIPs) and magnetic MIPs (MMIPs). Advantages and disadvantages of the various MIPs for dispersive solid phase extraction and dispersive (micro)solid phase extraction are discussed. In addition, an effort has also been made to condense the information regarding MMIPs since there are a great variety of supports (magnetite and magnetite composites with carbon nanotubes, graphene oxide, or organic metal framework) and magnetite surface functionalization mechanisms for enhancing MIP synthesis, including reversible addition-fragmentation chain-transfer (RAFT) polymerization. Finally, drawbacks and future prospects for improving molecularly imprinted (micro)solid phase extraction (MIMSPE) are also appraised.

Synthesis and evaluation of mesoporous silica/mesoporous molecularly imprinted nanoparticles as adsorbents for detection and selective removal of imidacloprid in food samples

The double-mesoporous-layer imprinted polymer of mesoporous silica/mesoporous molecularly imprinted nanoparticles (MIP), with high specific surface area, rich porosity, excellent mass transfer rate and selectivity, were synthesized using imidacloprid (IDP) as a template. Under the optimal conditions of pH, contact time, concentration and temperature, MIP showed high adsorption capacity of 13.86 μg·mg^-1 toward IDP and the imprinting factor reached 3.5. The adsorption process model including binding isotherm and kinetics was investigated. MIP exhibited excellent regeneration and its adsorption and selectivity were outstanding among its structurally pesticide analogues. The recovery of spiked IDP for MIP in fortified real samples can reach 96.0 ± 8.5% for cabbage and 105.0 ± 9.9% for apple. The limit of detection of the enrichment method can be as low as 0.037 μg·mL-¹ with a good linear relationship (R² = 0.996) from 0.30 to 10.0 μg·mL^-1. The results indicated that the proposed method allowed class-specific detection of IDP in food samples.

Efficient extraction and purification of benzo[c]phenanthridine alkaloids from Macleaya cordata (Willd) R. Br. by combination of ultrahigh pressure extraction and pH-zone-refining counter-current chromatography with anti-breast cancer activity in vitro

INTRODUCTION

Macleaya cordata (Willd) R. Br. (Papaveraceae family) is a well-known traditional Chinese medicine used to treat muscle pain, inflamed wounds, and bee bites. Benzo[c]phenanthridine alkaloids are the main active ingredients in M. cordata. In this work, sanguinarine and chelerythrine were efficiently extracted and purified by ultrahigh-pressure extraction (UHPE) technique and pH-zone-refining counter-current chromatography (PZRCCC) from M. cordata.

OBJECTIVE

To develop an efficient UHPE method followed by an efficient separation technique using PZRCCC for benzo[c]phenanthridine alkaloids from the study plant species, and to evaluate the study samples for anti-breast cancer activity.

METHODOLOGY

The optimal extraction conditions were optimised as extraction pressure 200 MPa, extraction solvent 95% ethanol, solid-liquid ratio 1:30 (g/mL) and extraction time 2 min. A two-phase n-hexane/ethyl acetate/i-propanol/water (1:3:1.5:4.5, v/v) solvent system was optimised with 10 mmol triethylamine in the upper phase and 10 mmol trifluoroacetic acid in lower phase in PZRCCC. The sample loading was optimised as 2.50 g. Moreover, the samples were evaluated for anti-breast cancer activity later on.

RESULTS

The 2.50 g sample loading yielded 0.45 g of sanguinarine and 0.59 g chelerythrine in one-step separation using PZRCCC. The anti-breast cancer activities of sanguinarine and chelerythrine were found stronger than positive control (vincristine 5.04 μg/mL) with half-maximal inhibitory concentration values of 0.96 and 3.00 μg/mL, respectively.

CONCLUSION

This study showed that the established methods were efficient in extraction (UHPE) and separation (PZRCCC) of the sanguinarine and chelerythrine from M. cordata.

Recent applications of magnetic solid phase extraction in sample preparation for phytochemical analysis

Sample preparation such as isolation and pre-concentration is a crucial step for the phytochemical analysis. Magnetic solid-phase extraction (MSPE) has received considerable attention, mainly due to its phase separation more conveniently by facile magnetic decantation as compared to traditional SPE. This review focused on the recent applications of MSPE in sample preparation for the analysis of phytochemical compounds in plants, biological samples and Chinese herbal preparations. In addition, the enzymes immobilized on the magnetic materials and used for the biospecific extraction of enzyme inhibitors were also discussed. The information summarized in this article may provide a reference to the further applications of MSPE in phytochemical analysis.

Effects of prepolymerization on surface molecularly imprinted polymer for rapid separation and analysis of sulfonamides in water

This work systematically investigated the effects of prepolymerization on the property of multi-templates surface molecularly imprinted polymer (MIP), which was utilized to quickly and simultaneously separate and detect six sulfonamides (sulfadiazine, sulfathiazole, sulfamerazine, sulfamethazine, sulfamethoxazole and sulfadoxine) in real waters. The MIPs were prepared using the six sulfonamides as the templates, mesoporous silica supported onto the surface of magnetic graphene oxide as the carrier and 4-vinylbenzoic as the functional monomer, with and without prepolymerization of templates with functional monomer. The preparation and adsorption conditions were optimized. It was found that the adsorption capacities of the selected six sulfonamides on the MIP (pre) prepared with prepolymerization were apparently higher than those on the MIP (no pre) synthesized without prepolymerization. Subsequently, the MIPs were utilized as adsorbents for SPE of these sulfonamides, and coupled with high performance liquid chromatography (HPLC) for the determination of sulfonamides. The developed analytical method showed outstanding applicability for the detection of trace sulfonamides in real water samples. The spiked recoveries and relative standard deviations (RSDs) of the six sulfonamides using MIP (no pre) and MIP (pre) were 73.34-99.43% and 87.37-102.34%, 2.28-7.77% and 3.18-6.49%, respectively.

Synthesis of Molecularly Imprinted Polymers for the Selective Extraction of Polymyxins from Environmental Water Samples

The emergence of colistin resistance gen has aroused public concern. It is significant to assess the concentrations of polymyxins residues in aquatic environment since resistant bacteria carrying colistin resistance gen are frequently isolated from wastewater; surface water and ground water. However; no literature on the determination of polymyxins in water is available; probably due to the absence of an efficient extraction method. Accordingly; molecularly imprinted polymers were synthesized by precipitation polymerization with colistin as the template. The polymers were successfully used as sorbents for the determination of polymyxins from water based on molecularly imprinted solid-phase extraction and high-performance liquid chromatography-ultraviolet detection. The molecularly imprinted cartridge showed excellent affinity and cross-reactivity to analytes in aqueous media. Recoveries obtained from water samples were between 65.9% and 90.1%, with relative standard deviations lower than 10.2%. Limits of detection were between 1.0 and 2.0 μg L^-1 concentration levels. Compared with C₁₈ cartridge; the molecularly imprinted cartridge could remove more interference from co-extracted matrices. This method is practical for the routine monitoring of polymyxin residues in environmental water; which will benefit studies on drug-resistance and occurrence of polymyxins in the environment.