Preparation of photonic-magnetic responsive molecularly imprinted microspheres and their application to fast and selective extraction of 17β-estradiol

Magnetic molecularly-imprinted microspheres with a core-shell structure for the extraction of catalpol from both Rehmannia glutinosa Libosch and biological samples

We report on the successful development of a magnetic molecularly imprinted polymer (MMIP) for the separation and detection of catalpol in Rehmannia glutinosa extract and biological samples. Catalpol was used as the template molecule for the MMIPs, which were synthesized using the reverse prediction approach and differential UV-visible spectra to optimize the synthesis conditions. The resulting MMIPs were characterized using techniques including scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometry, which confirmed their excellent nuclear shell construction and simple rapid magnetic separation. Static and dynamic adsorption experiments were performed to assess the sensitivity, repeatability, and adsorption capacity of the MMIPs. Adsorption capacity was found to be high (59.09 µg/mg). The MMIPs also exhibited strong identification specificity for catalpol analogs (IF = 2.41). Magnetic solid phase extraction (MSPE) was optimized to establish an MSPE-HPLC approach based on the MMIPs. Under ideal conditions, the new method showed excellent determination coefficient (R2 > 0.99) in the ranges of 0.1-1.0 mg/mL and 0.03-0.18 mg/mL for R. glutinosa extract and biological material, respectively, with limits of detection of 5.4 ng/mL and 1.7 ng/mL. The novelty of this research lies in the preparation of magnetic surface MMIPs using a magnetic carrier. These MMIPs exhibit excellent magnetic properties and possess specific adsorption capability for catalpol, enabling rapid separation. They offer advantages such as low cost, high specificity, chemical stability, physical robustness, and recyclability (97.09%-106.53%, 91.32%-100.99%). The application of these polymers in the pretreatment method for determining the catalpol content in R. glutinosa extract and biological samples enhances the extraction efficiency and detection accuracy for catalpol. It eliminates interference and influences from other components in catalpol determination while exhibiting high sensitivity, good enrichment effects, excellent reusability, and a high recovery rate.

Preparation of Immobilised 17β-Estradiol-Imprinted Nanoparticles onto Bacterial Cellulose Nanofibres to Use for the Removal of 17β-Estradiol from Wastewater

Estradiol, a phenolic steroid oestrogen, is one of the endocrine-disrupting chemicals (EDCs) found in natural and tap waters. The detection and removal of EDCs is attracting attention daily as they negatively affect animals' and humans' endocrine functions and physiological conditions. Therefore, developing a fast and practical method for the selective removal of EDCs from waters is essential. In this study, we prepared 17β-estradiol (E2)-imprinted HEMA-based nanoparticles onto bacterial cellulose nanofibres (E2-NP/BC-NFs) to use for the removal of E2 from wastewater. FT-IR and NMR confirmed the structure of the functional monomer. The composite system was characterised by BET, SEM, µCT, contact angle, and swelling tests. Additionally, the non-imprinted bacterial cellulose nanofibres (NIP/BC-NFs) were prepared to compare the results of E2-NP/BC-NFs. Adsorption of E2 from aqueous solutions was performed in batch mode and investigated via several parameters for optimisation conditions. The effect of pH studies was examined in the 4.0-8.0 range using acetate and phosphate buffers and a concentration of E2 of 0.5 mg/mL. The maximum E2 adsorption amount was 254 µg/g phosphate buffer at 45 °C. The experimental data show that the Langmuir is a relevant isotherm model for E2 adsorption. Additionally, the relevant kinetic model was the pseudo-second-order kinetic model. It was observed that the adsorption process reached equilibrium in less than 20 min. The E2 adsorption decreased with the increase in salt at varying salt concentrations. The selectivity studies were performed using cholesterol and stigmasterol as competing steroids. The results show that E2 is 46.0 times more selective than cholesterol and 21.0 times more selective than stigmasterol. According to the results, the relative selectivity coefficients for E2/cholesterol and E2/stigmasterol were 8.38 and 86.6 times greater for E2-NP/BC-NFs than for E2-NP/BC-NFs, respectively. The synthesised composite systems were repeated ten times to assess the reusability of E2-NP/BC-NFs.

Molecularly Imprinted Polymer Nanospheres with Hydrophilic Shells for Efficient Molecular Recognition of Heterocyclic Aromatic Amines in Aqueous Solution

Heterocyclic aromatic amine molecularly imprinted polymer nanospheres with surface-bound dithioester groups (haa-MIP) were firstly synthesized via reversible addition-fragmentation chain transfer (RAFT) precipitation polymerization. Then, a series of core-shell structural heterocyclic aromatic amine molecularly imprinted polymer nanospheres with hydrophilic shells (MIP-HSs) were subsequently prepared by grafting the hydrophilic shells on the surface of haa-MIP via on-particle RAFT polymerization of 2-hydroxyethyl methacrylate (HEMA), itaconic acid (IA), and diethylaminoethyl methacrylate (DEAEMA). The haa-MIP nanospheres showed high affinity and specific recognition toward harmine and its structural analogs in organic solution of acetonitrile, but lost the specific binding ability in aqueous solution. However, after the grafting of the hydrophilic shells on the haa-MIP particles, the surface hydrophilicity and water dispersion stability of the polymer particles of MIP-HSs greatly improved. The binding of harmine by MIP-HSs with hydrophilic shells in aqueous solutions is about two times higher than that of NIP-HSs, showing an efficient molecular recognition of heterocyclic aromatic amines in aqueous solution. The effect of hydrophilic shell structure on the molecular recognition property of MIP-HSs was further compared. MIP-PIA with carboxyl groups containing hydrophilic shells showed the highest selective molecular recognition ability to heterocyclic aromatic amines in aqueous solution.

Core-Shell Magnetic Imprinted Polymers for the Recognition of FLAG-Tagpeptide

FLAG^® tag (DYKDDDDK) is a small epitope peptide employed for the purification of recombinant proteins such as immunoglobulins, cytokines, and gene regulatory proteins. It provides superior purity and recoveries of fused target proteins when compared to the commonly used His-tag. Nevertheless, the immunoaffinity-based adsorbents required for their isolation are far more expensive than the ligand-based affinity resin used in combination with the His-tag. In order to overcome this limitation we report herein the development of molecularly imprinted polymers (MIPs) selective to the FLAG^® tag. The polymers were prepared by the epitope imprinting approach using a four amino acids peptide, DYKD, including part of the FLAG^® sequence as template molecule. Different kinds of magnetic polymers were synthesised in aqueous and organic media also using different sizes of magnetite core nanoparticles. The synthesised polymers were used as solid phase extraction materials with excellent recoveries and high specificity for both peptides. The magnetic properties of the polymers confer a new, effective, simple, and fast method in the purification using FLAG^® tag.

Development of enzyme/titanate nanosheet complex coated with molecularly imprinted polydopamine for colorimetric quercetin assay

A novel hybrid material, which is an enzyme/inorganic nanosheet complex coated by molecularly imprinted polymer (MIP), was developed, and applied to colorimetric quercetin assay. First, an enzyme/inorganic nanosheet complex was prepared from horseradish peroxidase (HRP) enzyme and titanate nanosheet (TiOx), using electrostatic interactions between them in acetate buffer. In the next place, dopamine self-polymerization was performed in the presence of HRP/TiOx complex with quercetin as a template, to prepare MIP membrane onto the HRP/TiOx complex. After washing process, a new hybrid material, MIP-coated HRP/TiOx complex (MIP-HT) was obtained. MIP-HT adsorbed quercetin efficiently, compared with NIP-HT that is an HRP/TiOx complex coated with non-imprinted polydopamine. MIP-HT showed enzymatic activity for an oxidation reaction of guaiacol, which is a chromogenic substrate of HRP, whereas the enzymatic activity of NIP-HT was significantly suppressed. The amount of brown product, formed by the color reaction, reduced owing to the presence of quercetin in sample solution, and a good liner relationship was observed between the concentration of quercetin and the increment of absorbance at 470 nm. The investigation using several biomolecules indicates that MIP-HT has the ability to detect quercetin and its analogues with selectivity. Therefore, MIP-HT shows great promise as a new and attractive material for use in colorimetric assay of quercetin or quercetin analogues.

Preparation of lightweight daisy-like magnetic molecularly imprinted polymers via etching synergized template immobilization for enhanced rapid detection of trace 17β-estradiol

17β-estradiol (E2), as one of the pharmaceutical and personal care product, frequently contaminates environmental water as estrogen pollutant and possesses great risk to human survival as well as the sustainable development of the ecosystem. Herein, to achieve an effective adsorbent system for the selective removal of E2 from the environmental water, Fe₃O₄ nanoparticles are subjected to chemical etching to reduce the overall mass and then employed as carriers to prepare a novel type of lightweight daisy-like magnetic molecularly imprinted polymers (LD-MMIPs) adopting template immobilization strategy. The LD-MMIPs based etched magnetic nanoparticles not only exhibit light mass but also have plentiful imprinted sites in the etched channels, which significantly increases the adsorption capacity for E2. The daisy-like LD-MMIPs own strong magnetic responsiveness, well crystallinity, fast binding kinetics, high adsorption amount, and excellent selectivity. Moreover, combining with HPLC, the LD-MMIPs as adsorbents have been successfully used to specifically recognize and detect trace E2 in environmental water. Thus, the proposed LD-MMIPs with high adsorption capacity hold great potential in monitoring water pollution. Additionally, this work also provides an alternative strategy for improving the adsorption capacity of magnetic molecularly imprinted polymers through a convenient chemical etching technology.

Preparation of multiresponsive hydrophilic molecularly imprinted microspheres for rapid separation of gardenia yellow and geniposide from gardenia fruit

In this work, a robust method for the separation of gardenia yellow and geniposide from gardenia fruit was developed based on a molecularly imprinted solid phase extraction (MISPE) procedure. First, hydrophilic molecularly imprinted microspheres (HMIMs) were prepared using gardenia yellow as the template via reversible addition fragmentation chain transfer (RAFT) precipitation polymerization. The resultant HMIMs demonstrated the multiresponsiveness to pH, temperature, and magnetism, achieving controllable uptake and release of gardenia yellow and easy recovery by external magnets. Meanwhile, the HMIMs possessed high adsorption capacity, fast binding kinetics, specific recognition, and reusability. Finally, a MISPE approach using HMIMs as adsorbent was developed for extraction of gardenia yellow and purification of geniposide after optimization of the adsorption and elution conditions. Thus, efficient separation of gardenia yellow and geniposide with relative purities of 99.77 ± 0.05% (94.04 ± 0.10% recovered) and 94.50 ± 0.62% (95.40 ± 0.86% recovered), respectively, was achieved.

A comparative study of photoresponsive molecularly imprinted polymers with different shell thicknesses: Effects on 6-O-α-maltosyl-β-cyclodextrin separation

Photoresponsive surface molecularly imprinted polymers (PSMIPs) with controlled nanoshell thicknesses were synthesized using different amounts of precursor materials to determine the effects of polymer shell layer thickness on the separation and purification of 6-O-alpha-maltosyl-beta-cyclodextrin (Mal-β-CD). The physicochemical properties and adsorption and desorption capacities of PSMIPs with different shell thicknesses were studied. Interestingly, the uniform thickness of the imprinted polymer shell layer could be adjusted from 10 to 60 nm by varying the amount of polymerization precursors, and the average mesopore diameter of PSMIPs was not significantly affected by shell thickness. However, the removal efficiency and selective capacity of PSMIPs on Mal-β-CD were strongly correlated to their shell thickness. The adsorption behavior of PSMIPs on Mal-β-CD fitted well with the Langmuir adsorption model and pseudo-second-order kinetic model. Based on the obtained results, PSMIPs with a 30-nm imprinted layer were found to be an excellent adsorbent for Mal-β-CD separation, with an adsorption capacity of 18.12 mg/g. They can therefore be used for industrial chromatographic separations of Mal-β-CD in the future. PRACTICAL APPLICATION: This article clearly demonstrated that the shell thickness of core-shell molecularly imprinted materials affected the degree and rate of cyclodextrin separation. Determining the optimal thickness is of great significance for the material in the separation and purification of cyclodextrin.

Recent developments in sample preparation techniques combined with high-performance liquid chromatography: A critical review

This review article compares and contrasts sample preparation techniques coupled with high-performance liquid chromatography (HPLC) and describes applications developed in biomedical, forensics, and environmental/industrial hygiene in the last two decades. The proper sample preparation technique can offer valued data for a targeted application when coupled to HPLC and a suitable detector. Improvements in sample preparation techniques in the last two decades have resulted in efficient extraction, cleanup, and preconcentration in a single step, thus providing a pathway to tackle complex matrix applications. Applications such as biological therapeutics, proteomics, lipidomics, metabolomics, environmental/industrial hygiene, forensics, glycan cleanup, etc., have been significantly enhanced due to improved sample preparation techniques. This review looks at the early sample preparation techniques. Further, it describes eight sample preparation technique coupled to HPLC that has gained prominence in the last two decades. They are (1) solid-phase extraction (SPE), (2) liquid-liquid extraction (LLE), (3) gel permeation chromatography (GPC), (4) Quick Easy Cheap Effective Rugged, Safe (QuEChERS), (5) solid-phase microextraction (SPME), (6) ultrasonic-assisted solvent extraction (UASE), and (7) microwave-assisted solvent extraction (MWASE). SPE, LLE, GPC, QuEChERS, and SPME can be used offline and online with HPLC. UASE and MWASE can be used offline with HPLC but have also been combined with the online automated techniques of SPE, LLE, GPC, or QuEChERS for targeted analysis. Three application areas of biomedical, forensics, and environmental/industrial hygiene are reviewed for the eight sample preparation techniques. Three hundred and twenty references on the eight sample preparation techniques published over the last two decades (2001-2021) are provided. Other older references were included to illustrate the historical development of sample preparation techniques.

Highly sensitive determination of endocrine disrupting chemicals in foodstuffs through magnetic solid-phase extraction followed by high-performance liquid chromatography-tandem mass spectrometry

BACKGROUND

Endocrine disrupting chemicals (EDCs), proved to be potential carcinogenic threats to human health, have received great concerns in food field. It was essential to develop effective methods to detect EDCs in food samples. The present study proposed an efficient method to determine trace EDCs including estrone (E1), 17β-estradiol (E2), estriol (E3) and bisphenol A (BPA) based on magnetic solid-phase extraction (MSPE) coupled high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) in meat samples.

RESULTS

Fe₃ O₄ @COF(TpBD)/TiO₂ nanocomposites were synthesized via functionalization of magnetic covalent organic frameworks (COFs) with titanium dioxide (TiO₂ ) nanoparticles, and used as absorbents of MSPE to enrich EDCs. The efficient EDCs enrichment relies on π-π stacking interaction, hydrogen bonding, and the interaction between titanium ions (IV, Ti⁴⁺ ) and hydroxyl groups in EDCs, which improves the selectivity and sensitivity. Under the optimized conditions, target EDCs were rapidly extracted through MSPE with 5 min. Combining Fe₃ O₄ @COF(TpBD)/TiO₂ based MSPE and HPLC-MS/MS to determine EDCs, good linearities were observed with correlation coefficient (R² ) ≥ 0.9989. The limits of detection (LODs) and limits of quantification (LOQs) were 0.13-0.41 μg kg^-1 and 0.66-1.49 μg kg^-1 , respectively. Moreover, the proposed method was successfully applied to real samples analysis.

CONCLUSIONS

The established MSPE-HPLC-MS/MS method was successfully applied to determine EDCs in meat samples with rapidness, improved selectivity and sensitivity. It shows great prospects for EDCs detection in other complicated matrices. © 2020 Society of Chemical Industry.

Exploration of a Molecularly Imprinted Polymer (MIPs) as an Adsorbent for the Enrichment of Trenbolone in Water

The presence of endocrine disruptors in surface waters can have negative implications on wildlife and humans both directly and indirectly. A molecularly imprinted polymer (MIP) was explored for its potential to enhance the UV-Vis determination of trenbolone in water using solid-phase extraction (SPE). The synthesized MIP was studied using Fourier transform infrared spectra (FTIR) and scanning electron microscopy (SEM). Using the MIP resulted in a preconcentration and enrichment factor of 14 and 8, respectively. Trenbolone binding on the MIP was shown to follow a Langmuir adsorption and had a maximum adsorption capacity of 27.5 mg g−1. Interference studies showed that the MIP selectivity was not compromised by interferences in the sample. The MIP could be recycled three times before significant loss in analyte recovery.

Facile covalent preparation of carbon nanotubes / amine-functionalized Fe3O4 nanocomposites for selective extraction of estradiol in pharmaceutical industry wastewater

As a typical steroid hormone drug, estradiol (E2) is also one of the most frequently detected endocrine disrupting chemicals (EDCs) in the aquatic environment. Herein, in response to the potential risk of E2 in steroid hormone pharmaceutical industry wastewater to human and wildlife, a novel carbon nanotubes / amine-functionalized Fe₃O₄ (CNTs/MNPs@NH₂) nanocomposites with magnetic responsive have been developed for the enrichment and extraction of E2 in pharmaceutical industry wastewater, where amino-functionalized Fe₃O₄ magnetic nanoparticles (MNPs@NH₂) were used as a magnetic source. The resultant CNTs/MNPs@NH₂ possessed both the features of CNTs and desired magnetic property, enabling to rapidly recognize and separate E2 from pharmaceutical industry wastewater. Meanwhile, the CNTs/MNPs@NH₂ had good binding behavior toward E2 with fast binding kinetics and high adsorption capacity, as well as exhibited satisfactory selectivity to steroidal estrogen compounds. Furthermore, the change of pH value of aqueous phase in adsorption solvent hardly affected the adsorption of E2 by CNTs/MNPs@NH₂, and the adsorption capacity of E2 ranged from 19.9 to 17.2 mg g^-1 in the pH range of 3.0 to 11.0, which is a latent advantage of the follow-up development method to detect E2 in pharmaceutical industry wastewater. As a result, the CNTs/MNPs@NH₂ serving as a solid phase extraction medium were successfully applied to efficiently extract E2 from pharmaceutical industry wastewater. Therefore, the CNTs/MNPs@NH₂ nanocomposites could be used as a potential adsorbent for removing steroidal estrogens from water. More importantly, the developed method would provide a promising solution for the monitoring and analysis of EDCs in pharmaceutical industry wastewater.

Synthesis of magnetic metal organic framework/covalent organic framework hybrid materials as adsorbents for magnetic solid-phase extraction of four endocrine-disrupting chemicals from milk samples

RATIONALE

Endocrine-disrupting chemicals (EDCs), widespread and easily ingested through the simple food chain, have been suggested to pose potential carcinogenic threats to human health. Considering food safety and public health, it is urgent to establish a sensitive and effective method to enrich and determine EDCs in food samples.

METHODS

Novel hybrid nanocomposites Fe₃ O₄ @A-TpBD@NH₂ -MIL-125(Ti) were synthesized through the formation of amide bonds. The as-prepared Fe₃ O₄ were innovatively encapsulated with 4-aminobenzoic acid functionalized COF(A-TpBD) to generate bare carboxyl (-COOH), which formed amide bonds with the NH₂ -MIL-125(Ti), generating well-defined and hierarchical hybrid materials. The Fe₃ O₄ @A-TpBD@NH₂ -MIL-125(Ti) materials were used as the adsorbents for magnetic solid-phase extraction (MSPE) coupled with high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) to enrich and determine EDCs (E1, E2, E3 and BPA) from milk samples.

RESULTS

Fe₃ O₄ @A-TpBD@NH₂ -MIL-125(Ti) exhibited improved adsorption efficiency and selectivity based on π-π stacking interaction, hydrogen bonding, electrostatic interaction, and the interaction between the hydroxyl group in EDCs and titanium ions (IV, [Ti]⁴⁺ ). Under the optimized conditions, Fe₃ O₄ @A-TpBD@NH₂ -MIL-125(Ti)-based MSPE coupled with HPLC/MS/MS showed good linearity with correlation coefficient (R² ) ≥0.9983 and high sensitivity with limits of detection (LODs) in the range of 0.37-0.85 μg/L. Moreover, the developed method was successfully employed to detect EDCs in milk samples.

CONCLUSIONS

Fe₃ O₄ @A-TpBD@NH₂ -MIL-125(Ti) possess good adsorption capability and selectivity for EDCs. In addition, the proposed MSPE-HPLC/MS/MS method based on Fe₃ O₄ @A-TpBD@NH₂ -MIL-125(Ti) is effective and sensitive for the determination of EDCs in real samples, which can be used as a robust alternative method to monitor EDCs in complex matrices.

Application of stimuli-responsive materials for extraction purposes

Stimuli-responsive materials, frequently designated as "smart/intelligent materials", can modify their structure or properties by either a biological, physical, or chemical stimulus which, if properly controlled, could be used for specific applications. Such materials have been studied and exploited in several fields, like electronics, photonics, controlled drugs administration, imaging and medical diagnosis, among others, as well as in Analytical Chemistry where they have been used as chromatographic stationary phases, as part of sensors and for extraction purposes. This review article pretends to provide an overview of the most recent applications of these materials (mostly polymeric materials) in sample preparation for extraction purposes, as well as to provide a general vision of the current state-of-the-art of this field, their potential use and future applications.

Selective enrichment-release of trace dibutyl phthalate via molecular-imprinting based photo-controlled switching followed by high-performance liquid chromatography analysis

A novel intelligent photo-controlled molecularly imprinted polymers were synthesized, based on the magnetic core-shell structure, with 4-[(4-methacryloyloxy) phenylazo] benzenesulfonic acid as the functional monomer and ethylene glycol dimethyl acrylate as the cross-linking agent. Subsequently, a series of light-controlled enrichment-release performance showed that it only took about 30 and 10 min to reach the equilibrium photosensitive characteristic peak, respectively. The photo-controlled polymers could intelligently select target molecules, the maximum adsorption capacity for dibutyl phthalate was 3.88 mg/g. However, the adsorption capacity for its structural analogue dicyclohexyl phthalate was only 0.88 mg/g. The Freundlich and Langmuir isothermal equations were discussed for the specific enrichment process. Finally, the photo-controlled molecularly imprinted polymers were successfully applied to the selective detection of dibutyl phthalate, with the recovery rate of 95.4-98.4%. It could be used for the analysis of trace dibutyl phthalate in actual samples.

Effective preparation of magnetic molecularly imprinted polymer nanoparticle for the rapid and selective extraction of cyfluthrin from honeysuckle

Cyfluthrin is a widely used pesticide. In this study, a sensitive and efficient magnetic molecularly imprinted polymer (MMIP) was prepared by surface molecular imprinting, which used functionalized Fe₃O₄ particles as magnetic cores. Cyfluthrin was extracted and enriched using magnetic molecularly polymer for analyzing pesticide residue of Chinese herbal medicines. The crystal type, microstructure, particle size, saturation magnetization, and characteristic functional groups of the synthesized MMIPs were analyzed by analysis equipment. The results of isothermal adsorption and kinetic adsorption indicated that MMIPs reached adsorption equilibrium at 30 min, with a maximum capacity of 4.9 mg g^-1, which had good adsorption performance, while selective adsorption experiments showed that MMIPs had higher affinity for cyfluthrin. Under the optimized conditions, the limit of detection (LOD) and the limit of quantification (LOQ) were 32.987 ng ml^-1 and 109.955 ng ml^-1, respectively. And linear range (30-3000ng ml^-1) of cyfluthrin with correlation coefficient R²=0.9979, and MMIPs were used in honeysuckle, the recoveries were 91.5%∼97.2%, and RSD was 5.35%∼8.32% (n = 3). It is indicated that the magnetic molecularly imprinted polymer can be used as an effective material for the specific separation of cyfluthrin from honeysuckle.

Nanoporous imprinted polymers (nanoMIPs) for controlled release of cancer drug

In this article, a new approach to directly synthesize drug molecule imbedded in the nanometer sized polymer particles is reported. Molecular imprinting is used to prepare polymers for drug specific for selectively loading of a desired drug. Computer simulations were performed to provide mechanistic insights on the binding modalities of model cancer drug, amygdalin with the polymer precursors. Controlled release of amygdalin from nanoMIPs was studied in vitro cell test and monitoring the absorbance at λ_em of 390 nm by fluorescence. The nanoparticles imprinted with amygdalin (nanoMIPs) showed high drug loading (0.98 mg g^-1) and also releases drug in a controlled way without burst release. The polymer releases amygdalin 0.095 μg (5 min), 0.120 μg (30 min), 0.180 μg (180 min), 0.205 μg in 300 min in de-ionized water and similar pattern of release was observed in buffer 2 and 7. The sustained release of drug from nanoMIPs follows Fickian diffusion; and uniformity in nanoMIPs size have significant impact on release of drug. Swelling of nanoMIP is one of the dominant factors influencing the drug release patterns. The imprinting procedure and the studies reported in this study would be highly useful in future for cancer drug administration.

Temperature-Responsive Magnetic Nanoparticles for Enabling Affinity Separation of Extracellular Vesicles

Small magnetic nanoparticles that have surfaces decorated with stimuli-responsive polymers can be reversibly aggregated via a stimulus, such as temperature, to enable efficient and rapid biomarker separation. To fully realize the potential of these particles, the synthesis needs to be highly reproducible and scalable to large quantity. We have developed a new synthesis for temperature-responsive magnetic nanoparticles via an in situ co-precipitation process of Fe2+/Fe3+ salts at room temperature with poly(acrylic acid)- block-poly( N-isopropylacrylamide) diblock co-polymer template, synthesized via the reversible addition-fragmentation chain-transfer polymerization method. These particles were 56% polymer by weight with a 6.5:1 Fe/COOH ratio and demonstrated remarkable stability over a 2 month period. The hydrodynamic diameter remained constant at ∼28 nm with a consistent transition temperature of 34 °C, and the magnetic particle separation efficiency at 40 °C was ≥95% over the 2 month span. These properties were maintained for all large-scale synthesis batches. To demonstrate the practical utility of the stimuli-responsive magnetic nanoparticles, the particles were incorporated into a temperature-responsive binary reagent system and efficiently separated a model protein biomarker (mouse IgG) as well as purified extracellular vesicles derived from a human biofluid, seminal plasma. The ease of using these particles will prove beneficial for various biomedical applications.

Novel controllable hydrophilic thermo-responsive molecularly imprinted resin adsorbent prepared in water for selective recognition of alkaloids by thermal-assisted dispersive solid phase extraction

A novel controllable hydrophilic thermo-responsive molecularly imprinted resin (T-MIR) with a switchable zipper-like architecture was synthesized in the aqueous phase and applied to the selective recognition and extraction of alkaloids by positive temperature regulation. In this synthesis process of T-MIR, 2-acrylamide-2- methylpropanesulfonic acid (AMPS) and acrylamide (AAm) were coupled as zipper-like thermo-responsive monomers, resorcinol, and melamine as hydrophilic monomers, formaldehyde as a cross-linker, and berberine chloride (BerbC) as the template. The resulting T-MIR achieved the controlled rebinding and release of BerbC from temperature stimuli (25-45 °C) and the adsorption process followed the Langmuir isotherm (R²>0.99856) and pseudo-second-order kinetic model (R²>0.98138). The highest theory adsorption ability (33.44 mg/g) and recognition ability (imprinting factor: 4.71) of T-MIR was activated between poly(AMPS) and poly(AAm) in the zipper-like architecture at 35 °C. T-MIR was then applied to the selective recognition alkaloids by dispersive solid phase extraction. The limit of detection and limit of quantitation of the method were less than 0.025 mg/L and 0.082 mg/mL, respectively. The recoveries of the proposed method at three spiked levels were 96.8-100.8%, with a relative standard deviation of less than 4.8%. In contrast to previous thermo-responsive materials, this switchable zipper-like hydrophilic T-MIR with good adsorption, specificity recognition, and excellent temperature controllable properties provides a unique alternative to the selective recognition and controlled rebind-release alkaloids by the temperature signal.

Magnetic molecularly imprinted polymer nanoparticles for simultaneous extraction and determination of 6-mercaptopurine and its active metabolite thioguanine in human plasma

Cytotoxic drugs used in cancer chemotherapy require the continuous monitoring of their plasma concentration levels for dose adjustment purposes. Such condition necessitates the presence of a sensitive technique for accurate extraction and determination of these drugs together with their active metabolites. In this study a novel solid phase extraction technique using magnetic molecularly imprinted nanoparticles (MMI-SPE) is combined with liquid chromatography tandem mass spectrometry (LC-MS/MS) to extract and determine the anti-leukemic agent; 6-mercaptopurine (6-MP) and its active metabolite thioguanine (TG) in human plasma. The magnetic molecularly imprinted nanoparticles (Fe₃O₄@MIP NPs) were synthesized via precipitation polymerization technique and were characterized using different characterization methods A computational approach was adopted to help in the choice of the monomer used in the fabrication process. The Fe₃O₄@MIPs NPs possessed a highly improved imprinting efficiency, fast adsorption kinetics following 2nd order kinetics and good adsorption capacity of 1.0 mg/g. The presented MMI-SPE provided the optimum approach in comparison to other reported ones to achieve good extraction recovery and matrix effect of trace levels of 6-MP and TG from plasma. Chromatographic separation was carried out using a validated LC-MS/MS assay and recovery, matrix effect and process efficiency were evaluated. Recovery of 6-MP and TG was in the range of 85.94-103.03%, while, matrix effect showed a mean percentage recovery of 85.94-97.62% and process efficiency of 85.54-96.18%. The proposed extraction technique is simple, effective and can be applicable to the extraction and analysis of other pharmaceutical compounds in complex matrices for therapeutic drug monitoring applications.

Nanosized Difunctional Photo Responsive Magnetic Imprinting Polymer for Electrochemically Monitored Light-Driven Paracetamol Extraction

Herein, a novel photoresponsive magnetic electrochemical imprinting sensor for the selective extraction of paracetamol from biological samples was designed. In particular, nanosized photoresponsive molecular imprinted polymers were prepared on the surface of magnetic Fe₃O₄ nanoparticles through living radical polymerization of azobenzene. The introduction of a magnetic-controlled glassy carbon electrode makes the immobilization and removal of nanosized photoresponsive molecular imprinted polymers on the magnetic-controlled glassy carbon electrode surface facilely operational. With the photoresponsive property, the sensor undergoes reversible release and uptake of paracetamol upon alternative irradiation at 365 and 440 nm basing on a configurational change of azobenzene monomer in the photoresponsive molecular imprinted polymers receptor sites. Simultaneously, these processes are monitored by the photoresponsive changes of electrochemical signal from paracetamol. Two linear ranges from 0.001 to 0.7 mmol L^-1 (R² = 0.96) and 0.7 to 7 mmol L^-1 (R² = 0.95) for paracetamol determination were obtained with a quantification limit of 0.000 86 mmol L^-1 and a detection limit of 0.000 43 mmol L^-1. The recoveries of paracetamol in the urine as determined by photoresponsive molecular imprinted polymers extraction were varied between 87.5% and 93.3%. As a consequence, combining photocontrolled selective extraction, interfacial stability from magnetic adsorption, and specifically electrochemical response, the photoresponsive molecular imprinted polymers sensor shows significant advantages for simultaneous separation, enrichment, and detection of trace paracetamol in biological samples.

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.

Recent configurations and progressive uses of magnetic molecularly imprinted polymers for drug analysis

Since the introduction of the molecularly imprinting technology (MIT) in the 1970s, it becomes an emerging technology with the potential for wide-ranging applications in drug determination. With the rise of green chemistry, many researchers began to focus on the application and development of green materials which led to the breakthrough of molecularly imprinted polymers (MIPs) in the green chemistry. Because of the low concentration levels in the human matrices, almost adequate analytical methods should be used for quantification of drugs at the trace levels. In recent years there have been reported benefits of combining MIPs with additional features, e.g. magnetic properties, through the build-up of this type of material on magnetite particles. Magnetic molecularly imprinted polymer (MMIP) is a new material which is composed of magnetic material and non-magnetic polymer material and shares the characteristics of high adsorption capacity to template molecule, special selective recognition ability, and the magnetic adsorption property. These materials have been widely used in the different fields such as chemical, biological and medical science. This review describes the novel configurations and progressive applications of magnetic molecularly imprinted polymers to the drug analysis. Also, the advantages and drawbacks of each methodology, as well as the future expected trends, are evaluated.