Selective separation and inexpensive purification of paclitaxel based on molecularly imprinted polymers modified with ternary deep eutectic solvents

Properties, evaluation and application of naringin magnetic molecularly imprinted polymer based on synergistic imprinting strategy

A novel and facile surface molecularly imprinted polymer coated on magnetic chitosan (Fe3O4@CS@MIP) was fabricated for the selective recognition and enrichment of naringin (NRG). The Fe3O4@CS@MIP was prepared based on covalent-noncovalent synergistic imprinting strategies, utilizing 4-vinyl phenyl boric acid as covalent functional monomer, deep eutectic solvent (choline chloride/methacrylic acid [ChCl/MAA]) as non-covalent functional monomer and Fe3O4@CS nanoparticles as the magnetic support. The obtained Fe3O4@CS@MIP exhibited a uniform morphology, excellent crystallinity, outstanding magnetic properties, and high surface area. Owing to the double recognition abilities, the resultant polymer showed exceptional binding performance and rapid mass transfer in phosphate buffer (pH 7.0). The maximum binding amount of Fe3O4@CS@MIP was found to be 15.08 mg g-1, and the equilibrium adsorption could be achieved within 180 min. Moreover, they also exhibited stronger selectivity for NRG and satisfactory reusability, with only 11.0% loss after five adsorption-desorption cycles. Additionally, the Fe3O4@CS@MIP, serving as an adsorbent, presented practical application potential in the separation and enrichment of NRG from pummelo peel, with extraction efficiency in the range of 79.53% to 84.63%. This work provided a new strategy for improving the performance of MIP and contributed an attractive option for the extraction of NRG in complex samples.

Molecularly Imprinted Microspheres in Active Compound Separation from Natural Product

Molecularly Imprinted Microspheres (MIMs) or Microsphere Molecularly Imprinted Polymers represent an innovative design for the selective extraction of active compounds from natural products, showcasing effectiveness and cost-efficiency. MIMs, crosslinked polymers with specific binding sites for template molecules, overcome irregularities observed in traditional Molecularly Imprinted Polymers (MIPs). Their adaptability to the shape and size of target molecules allows for the capture of compounds from complex mixtures. This review article delves into exploring the potential practical applications of MIMs, particularly in the extraction of active compounds from natural products. Additionally, it provides insights into the broader development of MIM technology for the purification of active compounds. The synthesis of MIMs encompasses various methods, including precipitation polymerization, suspension polymerization, Pickering emulsion polymerization, and Controlled/Living Radical Precipitation Polymerization. These methods enable the formation of MIPs with controlled particle sizes suitable for diverse analytical applications. Control over the template-to-monomer ratio, solvent type, reaction temperature, and polymerization time is crucial to ensure the successful synthesis of MIPs effective in isolating active compounds from natural products. MIMs have been utilized to isolate various active compounds from natural products, such as aristolochic acids from Aristolochia manshuriensis and flavonoids from Rhododendron species, among others. Based on the review, suspension polymerization deposition, which is one of the techniques used in creating MIPs, can be classified under the MIM method. This is due to its ability to produce polymers that are more homogeneous and exhibit better selectivity compared to traditional MIP techniques. Additionally, this method can achieve recovery rates ranging from 94.91% to 113.53% and purities between 86.3% and 122%. The suspension polymerization process is relatively straightforward, allowing for the effective control of viscosity and temperature. Moreover, it is cost-effective as it utilizes water as the solvent.

Quantification of 2,4-dichlorophenoxyacetic acid in environmental samples using imprinted polyethyleneimine with enhanced selectivity as a selective adsorbent in ambient plasma mass spectrometry

Detection and quantification of various organic chemicals in the environment is critical to track their fate and control their levels. 2,4-Dichlorophenoxyacetic acid (2,4-D) is a widely applied phenoxy herbicide with potential toxicity to fish and other aquatic organisms. In this study, we address the need for improved detection of 2,4-D by introducing a novel analytical method for its quantification. This method relies on the selective extraction of 2,4-D using MIPs and their subsequent direct analysis using ambient plasma mass spectrometry. During the synthesis, MIPs with various degrees of glycidol (GLY) functionalization were obtained. Experimental data showed that MIPs with no GLY functionalization displayed the highest adsorption capacity. Conversely, MIPs with 30% GLY functionalization exhibited the greatest selectivity for 2,4-D, rendering them valuable for extraction of 2,4-D even in the presence of other contaminants. Finally, the obtained MIPs were applied for quantification of 2,4-D in various water samples through direct analysis using a specially designed ambient plasma mass spectrometry setup. This approach improved the detection limits by 200-fold compared to pure solution analysis. The quantification of 2,4-D in river water samples yielded highly satisfactory recoveries, demonstrating the effective utility of the proposed analytical setup for real-life water sample analysis.

A ternary deep eutectic solvent-modified magnetic mixed iron hydroxide@MIL-101(Cr)-NH2 composite as a sorbent in magnetic solid phase extraction of organochlorine pesticides prior to GC-MS

A green solvent of ternary deep eutectic solvent (menthol-thymol-dodecanoic acid) was prepared and used as a functional reagent to modify a magnetic mixed iron hydroxide@MIL-101(Cr)-NH2 composite. The proposed sorbent (MIH@MIL-101(Cr)-NH2-TDES) was applied in magnetic solid phase extraction (MSPE) for the enrichment of organochlorine pesticides. The analytes were quantitively analyzed by GC-MS. The relationships of experimental parameters for preparing the proposed sorbent and the MSPE method were studied through a Box-Behnken design and a central composite design, respectively. Their optimized conditions were investigated using response surface methodology. Application of the MIH@MIL-101(Cr)-NH2-TDES sorbent in MSPE successfully enhanced the sensitivity of GC-MS analysis, giving enrichment factors in the range of 56-168. The MSPE/GC-MS method was developed using MIH@MIL-101(Cr)-NH2-TDES as a sorbent and was successfully employed for the preconcentration/determination of organochlorine residues in honey and tea samples. The satisfactory detection limits were in the ranges of 0.07-0.80 ng g-1 and 0.7-8.5 ng g-1 for honey and tea samples, respectively. Acceptable recoveries were obtained in the ranges of 81.7-107.3% and 85.4-109.3% for the spiked honey and tea samples, respectively, with RSDs lower than 10.0%.

An edible molecularly imprinted material prepared by a new environmentally friendly deep eutectic solvent for removing oxalic acid from vegetables and human blood

A novel deep eutectic solvent-magnetic molecularly imprinted polymer (DES-MMIP) for the specific removal of oxalic acid (OA) was prepared by an environmentally friendly deep eutectic solvent, consisting of betaine, citric acid, and glycerol, which acted as the functional monomer for polymerization. The structure and morphology of DES-MMIPs were studied by X-ray diffraction, scanning and transmission electron microscopy, thermal gravimetric analysis, Fourier transform infrared spectroscopy, and vibrating sample magnetometer. DES-MMIPs had a core-shell structure, with magnetic iron oxide as the core, and showed good thermal stability and high adsorption capacity (18.73 mg/g) for OA. The adsorption process of OA by DES-MMIPs followed the pseudo-second-order kinetic model and Langmuir isotherm model. DES-MMIPs had significant selectivity for OA and their imprinting factor was 3.26. When applied to real samples, high performance liquid chromatography analysis showed that DES-MMIPs could remove OA from both spinach and blood serum. These findings provide potential methods for removal of OA from vegetables and for specific removal of OA in renal dialysis.

Development and evaluation of a hydrogenated rosin (β-acryloxyl ethyl) ester-bonded silica stationary phase for high-performance liquid chromatography separation of paclitaxel from yew bark

Paclitaxel (PTX) is a complex diterpenoid anticancer drug whose separation from yew biomass poses a significant challenge. In this study, a new stationary phase comprising hydrogenated rosin (β-acryloxyl ethyl) ester (HRE)-bonded silica (HRE@SiO₂) is developed to separate and purify PTX from crude yew-bark extract using high-performance liquid chromatography. In HRE@SiO₂, HRE molecules, which are functional ligands, are bonded to the surface of a silica gel matrix using a coupling agent, (3-mercaptopropyl)trimethoxysilane. The proposed HRE@SiO₂ stationary phase was characterized by Fourier-transform infrared spectroscopy, elemental analysis, thermogravimetric analysis, scanning electron microscopy, laser diffraction granulometry, and nitrogen gas adsorption. The HRE@SiO₂ column exhibited excellent chromatographic performance, satisfactory performance reproducibility, and typical reversed-phase chromatographic behavior. An HRE@SiO₂ column was used to separate PTX and its analogs, achieving resolutions exceeding 7.43 for consecutively eluted species. Stoichiometric displacement theory for retention (SDT-R), the van Deemter equation, and van 't Hoff plots were used to analyze the separation mechanism and properties of the HRE@SiO₂ column. The results showed that hydrophobic interactions determine the analyte retention and the separation of PTX and its analogs on an HRE@SiO₂ column is an exothermic process driven by enthalpy. Furthermore, an HRE@SiO₂ column was employed to separate and purify PTX from crude yew-bark extract, increasing PTX purity from 6% to 82%. The findings of this study provide insights for developing rosin-based stationary phases for the separation of natural products.

Green molecularly imprinted polymers for sustainable sample preparation

The use of molecularly imprinted polymers in sample preparation as selective sorbent materials has received great attention during the last years leading to analytical methods with unprecedented selectivity. However, with the progressive implementation of Green Analytical Chemistry principles, it is necessary to critically review the greenness of synthesis and further use of molecularly imprinted polymers in sample preparation. Accordingly, in the present review, the different steps and strategies for the preparation of molecularly imprinted polymers, the used reagents, as well as their incorporation to microextraction techniques are reviewed from a green perspective and recent alternatives to make the use of molecularly imprinted polymers more sustainable are provided.