Molecularly imprinted solid-phase extraction combined with non-ionic hydrophobic deep eutectic solvents dispersed liquid-liquid microextraction for efficient enrichment and determination of the estrogens in serum samples.

Hormonal drugs in biological samples are usually in low concentration and highly intrusive. It is of great significance to enhance the sensitivity and specificity of the detection process of hormone drugs in biological samples by utilizing appropriate sample pretreatment methods for the detection of hormone drugs. In this study, a sample pretreatment method was developed to effectively enrich estrogens in serum samples by combining molecularly imprinted solid-phase extraction, which has high specificity, and non-ionic hydrophobic deep eutectic solvent-dispersive liquid-liquid microextraction, which has a high enrichment ability. The theoretical basis for the effective enrichment of estrogens by non-ionic hydrophobic deep eutectic solvent was also computed by simulation. The results showed that the combination of molecularly imprinted solid-phase extraction and deep eutectic solvent-dispersive liquid-liquid microextraction could improve the sensitivity of HPLC by 33∼125 folds, and at the same time effectively reduce the interference. In addition, the non-ionic hydrophobic deep eutectic solvent has a relatively low solvation energy for estrogen and possesses a surface charge similar to that of estrogen, and thus can effectively enrich estrogen. The study provides ideas and methods for the extraction and determination of low-concentration drugs in biological samples and also provides a theoretical basis for the application of non-ionic hydrophobic deep eutectic solvent extraction.

Photo-crosslinked enhanced double-network hydrogels based on modified gelatin and oxidized sodium alginate for diabetic wound healing.

The diabetic wound is hard to repair due to bacterial infection, lasting inflammation, and so on. Therefore, it is vital to fabricate a multi-functional hydrogel dressing for the diabetic wound. In this study, a kind of dual-network hydrogel loaded with gentamicin sulfate (GS) based on sodium alginate oxide (OSA) and glycidyl methacrylate gelatin (GelGMA) was designed through the Schiff base bonding and photo-crosslinking to promote the diabetic wound healing. The hydrogels exhibited stable mechanical properties, high water absorbency, and good biocompatibility and biodegradability. Antibacterial results showed that gentamicin sulfate (GS) had a remarkable antibacterial effect on Staphylococcus aureus and Escherichia coli. In a diabetic full-thickness skin wound model, the GelGMA-OSA@GS hydrogel dressing dramatically decreases inflammation and accelerated re-epithelialization and granulation tissue formation, promising applications in promoting diabetic wound healing.

Dummy-template Pickering emulsion imprinted microspheres online pretreatment and analysis for the estrogens in cosmetics.

Estrogens are a class of steroid hormone with strong physiological activity. Due to the pronounced beauty effect, such drugs are highly susceptible to illegal addition and cause other adverse effects. To avoid template leakage and the negative impacts on the environment caused by the estrogens, diosgenin was selected as the dummy template due to its similar skeleton structure. The Pickering emulsion polymerization was used to obtain the dummy-template molecularly imprinted polymers (dt-MIPs). Scanning electron microscopy, optical microscopy, specific surface area testing, Fourier transform infrared spectroscopy and adsorption experiments were used to characterize the apparent morphology and the recognition performance of the microspheres. Then, the prepared microspheres and commercial fillers were used to construct an on-line solid phase extraction (on-line SPE) analytical system coupled with HPLC via a two-position switching valve. On-line solid phase extraction-HPLC analytical methods were established and verified, for the simultaneous determination of four estrogens in cosmetic samples. The accuracy and precision RSDs for the established methods using the imprinted sorbents were 92.00-104.02% and less than 9.12%, respectively. All four estrogens exhibited good linearity in the range of 0.05 to 5 µg/mL with a coefficient of determination R2 greater than 0.9810. The method comparison results suggest that the established analytical method is simple in pre-treatment, easy to automate, and has excellent sensitivity to meet the analytical requirements of complex samples.

Facile synthesis of novel helical imprinted fibers based on zucchini-derived microcoils for efficient recognition of target protein in biological sample.

Highly selective recognition and purification of target proteins from complex biological matrices remains a challenging subject in natural and life sciences. Compared with natural recognition receptors, artificial imprinted polymers are an ideal alternative candidate. In this study, we report a novel method to prepare helical protein imprinted fibers (HPIFs) with zucchini-derived microcoils as a carrier, firstly. Inspired by the self-polymerization of adhesive proteins in mussels, dopamine and 3,4-dihydroxyphenylacetic acid were chosen as bifunctional monomers for the first time to form a biocompatible imprinted layer. The chemical/physical properties and recognition performance of HPIFs were studied in a series of experiments. Additionally, the practicability of HPIFs was verified by specifically recognizing target protein in complex egg white sample. The one-step synthesis process and excellent binding performance of HPIFs make them a promising material for protein recognition and purification, and endow HPIFs with potential application value in the food, chemical and pharmaceutical fields.

Thermosensitive molecularly imprinted polymer coupled with HPLC for selective enrichment and determination of matrine in traditional Chinese medicine.

In this study, a temperature-sensitive molecularly imprinted polymer was prepared by using the bifunctional monomer with the critical phase transition characteristics. Infrared spectrometry, scanning electron microscopy, and specific surface area testing were used to characterize the polymers. Then, the recognizing properties of the polymers were studied. Based on the prepared smart polymers, an SPE-HPLC analytical method for the determination of quinolizidine alkaloids in the extracts of Sophora flavescens was established and verified. Finally, the smart polymers were applied to the enrichment of quinolizidine alkaloids in plant extracts. By changing the temperature and solvents of the solid phase extraction conditions, the extraction process can increase the concentration of quinolizidine alkaloids by 4.3 to 5.2 folds. The extraction process has mild conditions and less time consumption, avoiding the use of a large number of toxic reagents, which indicate that the extraction process are more efficient and environmentally friendly.

Preparation of biocompatible molecularly imprinted film on biowaste-derived magnetic pomegranate rind carbon for protein recognition in biological sample.

Nowadays, the research on the recognition and separation of proteins has attracted extensive attention in the fields of materials science, bioengineering and life science. Protein imprinted polymers are ideal recognition materials, due to its high selectivity, good stability, easy preparation, and low cost. Herein, novel surface imprinting biowaste-derived molecularly imprinted polymers (BD-MIPs) were synthesized for specific recognition and purification of lysozyme (Lyz). This is the first time that magnetic pomegranate rind-derived carbon was used as a carrier to immobilize Lyz. Then, with the self-polymerization of dopamine, a large number of biocompatible recognition sites were generated under mild conditions. The physical/chemical properties and surface morphologies of the synthetic BD-MIPs were characterized, indicating that the imprinted film was successfully synthesized, and the BD-MIPs had good thermal stability and magnetic property. To investigate the recognition performance of BD-MIPs, four adsorption experiments were performed. The results show that BD-MIPs had a high adsorption capacity of 301.87 mg g-1, fast equilibrium time within 40 min, satisfactory selectivity and good reusability for Lyz. Furthermore, the practicability of BD-MIPs was confirmed by the isolation of Lyz from a biological sample. The good adsorption capacity and gentle one-step preparation make the BD-MIPs attractive for Lyz recognition, which shows potential values in basic biomedical research, industrial protein purification and clinical diagnostics.

Rapid detection of aflatoxin B1 by dummy template molecularly imprinted polymer capped CdTe quantum dots.

A novel and sensitive fluorescent sensor was synthesized for the rapid and specific recognition of aflatoxin B1 (AFB1) by our combining molecular imprinting techniques with quantum dot technology. Molecularly imprinted polymers coated CdTe quantum dots (MIP@CdTe QDs) were prepared through the Stöber method with 5,7-dimethoxycoumarin as a dummy template. 3-Aminopropyltriethoxysilane was selected as the functional monomer, and tetraethyl orthosilicate was used as the cross-linking agent. The best molar ratio of 5,7-dimethoxycoumarin to functional monomer to cross-linker was 4:20:15. The MIP@CdTe QD composites were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and fluorescence spectroscopy. Under the optimum conditions, the relative fluorescence intensity of the MIP@CdTe QDs showed adequate linearity with AFB1 concentration over the range from 80 to 400 ng/g. The detection limit is 4 ng/g, according to 3s/K. Finally, the method was successfully applied to the quantitative determination of AFB1 in real samples. The spike recoveries at different spiking levels ranged from 99.20% to 101.78%, which were consistent with those measured by ultrahigh-performance liquid chromatography-mass spectrometry. The method developed for AFB1 detection lays the foundation for rapid detection of trace amounts of other exogenous harmful substances in a complicated matrix.

Combined magnetic porous molecularly imprinted polymers and deep eutectic solvents for efficient and selective extraction of aristolochic acid I and II from rat urine.

Aristolochia and related plants contain nephrotoxins and mutagens in the form of aristolochic acids (AAs). However, there is still lack of a fast and specific method for monitoring AAs in biological samples. Herein, we synthesized a hybrid magnetic mesoporous carbon-molecularly imprinted polymers (MMC@MIPs) as a novel magnetic solid-phase extraction (MSPE) adsorbent for selective recognition of aristolochic acid I and II from rat urine samples. The choline chloride/glycol-based deep eutectic solvent (DES) and indomethacin were used as the eluent and dummy template molecule accordingly. The morphology, structure property and surface groups of the prepared materials were investigated in sequence, and the optimum conditions of the MMC@MIPs-MSPE procedure were also optimized well. Results showed that the proposed method had a relatively satisfactory recovery (86.7-94.3%), with low standard deviation (<4.85%) and acceptable correlation coefficients (0.991-0.996). Overall, this work not only provides an inexpensive and eco-friendly method to fabricate MMC@MIPs, but also develops a highly promising approach for the detection of aristolochic acid I and II in biological samples.

Berberine Upregulates P-Glycoprotein in Human Caco-2 Cells and in an Experimental Model of Colitis in the Rat via Activation of Nrf2-Dependent Mechanisms.

Downregulation of P-glycoprotein (P-gp) is implicated in the pathophysiology of inflammatory bowel disease (IBD). Berberine, a principal isoquinoline alkaloid extracted from Berberis species, has been reported to exhibit therapeutic potential in IBD. In this study, we used a dextran sulfate sodium (DSS)-induced colitis rat model to evaluate the effect of berberine on P-gp and explore its mechanism of action. Berberine treatment improved DSS-induced colitis symptoms, attenuated inflammatory markers (myeloperoxidase, tumor necrosis factor-α, and interleukin-1ß and -6), and enhanced P-gp expression in a dose-dependent manner. Although colonic expression of the P-gp-related nuclear receptor pregnane X receptor and transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) were downregulated in the colitis model, gene and protein expression analysis revealed that berberine treatment reversed only the downregulation of Nrf2. In vitro studies using Caco-2 cells showed that the multidrug resistance 1 (MDR1) gene and P-gp protein were upregulated by berberine in a dose- and time-dependent manner. Significant upregulation of the MDR1 gene by berberine was abrogated by Nrf2 silencing, indicating that the Nrf2-mediated pathway was responsible for this activation. Luciferase assays showed a dose-dependent increase in Nrf2 reporter gene activity after berberine treatment in Caco-2 cells, with a significant 2-fold elevation at 2.5 µM berberine, suggesting that berberine is a strong Nrf2 activator. These results indicate the possible involvement of Nrf2-mediated upregulation of P-gp in the therapeutic effect of berberine on colitis and highlight the potential of P-gp and/or Nrf2 as new therapeutic targets for IBD.

Hybrid-type carbon microcoil-chitosan composite for selective extraction of aristolochic acid I from Aristolochiaceae medicinal plants.

Aristolochic acid I is a nephrotoxic compound widely existing in many kinds of traditional Chinese medicines, especially in Aristolochiaceae medicinal plants. In this study, chitosan modified carbon microcoils were designed and prepared for the selective separation of aristolochic acid I from medicinal herbs. Successful modification of carbon microcoils was confirmed by scanning electron microscopy, Fourier-transfer infrared spectroscopy, elemental analysis, X-ray photoelectron spectroscopy, and thermogravimetric analyses. The effects of adsorption conditions were investigated and it was determined that the adsorption of aristolochic acid I was controlled by pH. Adsorption isotherms, kinetics, and selectivity tests were performed to evaluate the adsorption capacity and selectivity of the modified carbon microcoils. The chitosan modified carbon microcoils exhibited excellent binding ability (77.72 mg g-1) and satisfactory selectivity. Finally, this material was used in solid phase extraction combined with HPLC to enrich and detect aristolochic acid I from medicinal plants. The detector response for aristolochic acid I was linear from 0.5 to 150 mg L-1, and the recoveries of aristolochic acid I ranged from 73.61 to 77.73% with the relative standard deviations of less than 5%. Thus, chitosan modified carbon microcoils were ideal adsorbents for the selective extraction of aristolochic acid I from Aristolochiaceae plants.

Fabrication of a novel magnetic mesoporous molecularly imprinted polymer based on pericarpium granati-derived carrier for selective absorption of bromelain.

Bromelain, a cysteine endopeptidase enzyme of great commercial value, has been widely used in food, pharmaceutical, and cosmetic industries. Conventional methods for purification of bromelain are still limited by a low binding efficiency, time-consuming process, and expensive equipment. Therefore, for selective absorption of bromelain, we developed a facile and effective method to fabricate magnetic mesoporous molecularly imprinted polymers using pericarpium granati-derived carbon as the carrier for the first time. The characterizations of the imprinted polymers indicated that a polydopamine layer was coated on the surface of the carrier and the crystallinity of the carrier did not change. The obtained imprinted polymers exhibited favourable saturation magnetization, a high adsorption capacity of 135.96 mg g-1, a fast equilibrium time, and satisfactory reusability. The imprinted polymers were prepared by an eco-friendly method and exhibited rapid separation and good adsorption performance, thus making the method applicable to biomacromolecular separation, proteomic analysis, and biomedical research.

Molecularly imprinted membrane extraction combined with high-performance liquid chromatography for selective analysis of cloxacillin from shrimp samples.

Nowadays, the abuse of antibiotics in aquaculture has generated considerable problems for food safety. Therefore, it is imperative to develop a simple and selective method for monitoring illegal use of antibiotics in aquatic products. In this study, a method combined molecularly imprinted membranes (MIMs) extraction and liquid chromatography was developed for the selective analysis of cloxacillin from shrimp samples. The MIMs was synthesized by UV photopolymerization, and characterized by scanning electron microscope, Fourier transform infrared spectra, thermo-gravimetric analysis and swelling test. The results showed that the MIMs exhibited excellent permselectivity, high adsorption capacity and fast adsorption rate for cloxacillin. Finally, the method was utilized to determine cloxacillin from shrimp samples, with good accuracies and acceptable relative standard deviation values for precision. The proposed method was a promising alternative for selective analysis of cloxacillin in shrimp samples, due to the easy-operation and excellent selectivity.

Facile preparation of magnetic molecularly imprinted polymers for the selective extraction and determination of dexamethasone in skincare cosmetics using HPLC.

Dexamethasone-imprinted polymers were fabricated by reversible addition-fragmentation chain transfer polymerization on the surface of magnetic nanoparticles under mild polymerization conditions, which exhibited a narrow polydispersity and high selectivity for dexamethasone extraction. The dexamethasone-imprinted polymers were characterized by scanning electron microscopy, transmission electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive spectrometry, and vibrating sample magnetometry. The adsorption performance was evaluated by static adsorption, kinetic adsorption and selectivity tests. The results confirmed the successful construction of an imprinted polymer layer on the surface of the magnetic nanoparticles, which benefits the characteristics of high adsorption capacity, fast mass transfer, specific molecular recognition, and simple magnetic separation. Combined with high-performance liquid chromatography, molecularly imprinted polymers as magnetic extraction sorbents were used for the rapid and selective extraction and determination of dexamethasone in skincare cosmetic samples, with the accuracies of the spiked samples ranging from 93.8 to 97.6%. The relative standard deviations were less than 2.7%. The limit of detection and limit of quantification were 0.05 and 0.20 µg/mL, respectively. The developed method was simple, fast and highly selective and could be a promising method for dexamethasone monitoring in cosmetic products.

Facile preparation of polydopamine-coated imprinted polymers on the surface of SiO2 for estrone capture in milk samples.

Estrone molecularly imprinted polymers were synthesized through the self-polymerization of dopamine on the surface of silica gels, which had the characteristics of mild polymerization conditions, simple reaction procedure and good specific recognition ability for estrone. The estrone molecularly imprinted polymers were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis and nitrogen adsorption-desorption tests. The characterization confirmed that the imprinted polymers were successfully grafted on the surface of silica gels. Through investigating the adsorption performance, the prepared estrone molecularly imprinted polymers exhibited high adsorption capacity, fast mass transfer, as well as excellent selectivity toward estrone. The estrone molecularly imprinted polymers as the solid-phase extraction adsorbent coupled with high-performance liquid chromatography was developed to determine estrone from the milk samples. The developed estrone molecularly imprinted polymer solid-phase extraction with high-performance liquid chromatography method exhibited satisfactory specificity, precision, accuracy and good linearity relationship in the range of 0.2-20 µg/mL. The developed method is simple, fast, effective and high specificity method and it provides a new method to detect the residues of estrone in animal foods.

On-Line two dimensional liquid chromatography based on skeleton type molecularly imprinted column for selective determination of sulfonylurea additive in Chinese patent medicines or functional foods.

Substandard and counterfeit anti-diabetic medicines directly influence the health and impose a great danger to individual patients and to public health. Counterfeiting has become a serious and underreported problem in the pharmaceutical industry. There are a large number of counterfeit medicines flooded in anti-diabetic markets which effect human health directly and indirectly. Therefore, some novel analytical techniques are necessary to be established for detecting these counterfeit drugs. In this study, a novel skeleton type molecularly imprinted column was successfully prepared. Based on the column, a simple, fast and reliable two-dimensional chromatography analytical system was established for selective determination of the illegal sulfonylurea additive in traditional Chinese patent medicines and functional foods. The developed method was validated. The linearitiesof the method were tested with calibration curves using ten calibration points in the concentration range of 0.25-12.5µg/g. The LODs were 0.0125µg/g and 0.01µg/g for tolbutamide and glibenclamide respectively. The five batches of Chinese patent medicines and dietary supplements obtained from different markets and online websites were tested by the validated method. With good retention time and spectral confirmation, chemical anti-diabetic substances were identified and quantified in traditional Chinese medicine and in dietary supplements.

Selective analysis of aristolochic acid I in herbal medicines by dummy molecularly imprinted solid-phase extraction and HPLC.

In this study, surface molecularly imprinted polymers were prepared as the selective sorbents for separation of aristolochic acid I in herbal medicine extracts by a facile approach. A less toxic dummy template, ofloxacin, was used to create specific molecule recognition sites for aristolochic acid I in the synthesized polymers. The polymers were characterized by Fourier-transfer infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, elemental analysis, and nitrogen adsorption-desorption test. The adsorption capacity was calculated using adsorption kinetics, selectivity, and recycling experiments. The obtained polymers exhibited high thermostability, fast equilibrium time, and excellent binding ability. Subsequently, the polymers applied as the solid-phase extraction absorbent was proposed and used for the enrichment and analysis of aristolochic acid I in herbal plants. The result showed that the aristolochic acid I was enriched up to 16 times after analysis by using high-performance liquid chromatography. The good linearity for aristolochic acid I was obtained in the range of 0.1-200 µg/mL (R2  = 0.9987). The recovery and precision values were obtained (64.94-77.73%, RSDs% ≤ 0.8%, n = 3) at three spiked concentration levels. This work provided a promising method for selective enrichment, extraction, and purification of aristolochic acid I from complex herbal plants.

Molecularly Imprinted Solid Phase Extraction using Bismethacryloyl-ß-cyclodextrin and Methacrylic Acid as Double Functional Monomers for Selective Analysis of Glycyrrhizic Acid in Aqueous Media.

In this work, a new molecularly imprinted solid phase extraction protocol was developed for the selective extraction and purification of glycyrrhizic acid from liquorice roots in aqueous media. The molecularly imprinted polymers (MIPs) for glycyrrhizic acid were prepared by using bismethacryloyl-ß-cyclodextrin and methacrylic acid as double functional monomers and characterized by Fourier transform infrared spectroscopy, scanning electron microscope, thermo gravimetric analysis, nitrogen adsorption and elemental analysis. In aqueous media, the adsorption properties of MIPs including adsorption kinetics, adsorption isotherms and selectivity adsorption were investigated. The characterization of imprinted polymers indicated that the prepared MIPs had good stability and many cavity structures. The results of adsorption experiments illustrated the MIPs had high adsorption capacity of glycyrrhizic acid (69.3 mg g-1) with the imprinting factor 3.77, and it took ~5 min to get adsorption equilibrium. The MIPs could be used as an solid phase extraction sorbent absorbent for enrichment and purification of glycyrrhizic acid from the crude extraction of licorice roots, and the results showed promising practical value.

Enrichment of total steroidal saponins from the extracts of Trillium tschonoskii Maxim by macroporous resin and the simultaneous determination of eight steroidal saponins in the final product by HPLC.

An effective and simple method was established for the separation and enrichment of steroidal saponins from Trillium tschonoskii Maxim. The adsorption and desorption properties of seven macroporous resins were investigated. Among the tested resins, AB-8 resin showed the best adsorption and desorption capacities. The adsorption of steroidal saponins on AB-8 at 25°C was quite consistent with both the Freundlich isotherm model and the pseudo-second-order kinetics model. By optimizing the dynamic adsorption and desorption parameters, the content of steroidal saponins increased from 5.20% in the crude extracts to 51.93% in the final product, with a recovery yield of 86.67%. Furthermore, by scale-up separation, the concentration and recovery of total steroidal saponins were 43.8 and 85.5%, respectively, which suggested that AB-8 resin had great industrial and pharmaceutical potential because of its high efficiency and cost-effectiveness. In addition, a high-performance liquid chromatography method for the simultaneous determination of eight steroidal saponins was established for the first time, which was employed to qualitatively and quantitatively analyze the final product. Based on the methodological validation results, the high-performance liquid chromatography method can be widely applied to the quality control of steroidal saponins from Trillium tschonoskii Maxim due to its excellent accuracy, stability, and repeatability.

Development of molecular imprinted column-on line-two dimensional liquid chromatography for selective determination of clenbuterol residues in biological samples.

A novel method coupling molecular imprinted monolithic column with two-dimensional liquid chromatography was developed and validated for the analysis of clenbuterol in pork liver and swine urine samples. The polymers were characterized by using Fourier transform infrared spectroscopy, nitrogen adsorption desorption analyses, frontal analysis and the adsorption of selectivity. The results indicated that the imprinted columns were well prepared and possessed high selectivity adsorption capacity. Subsequently, the MIMC-2D-LC (molecular imprinted monolithic column-two dimensional liquid chromatography) method was developed for the selective analysis of clenbuterol in practical samples. The accuracy ranged from 94.3% to 99.7% and from 93.7% to 99.6% for liver and urine, respectively. The relative standard deviation (RSD) of repeatability was lower than 8.6% for both analyses. The limit of detections was 16ng·mL(-1) for liver and 25ng·mL(-1) for urine, respectively. Compared with the reported methods, the disturbance of endogenous impurity could be avoided by the 2D-LC method.

Development of molecularly imprinted column-on line-two dimensional liquid chromatography for rapidly and selectively monitoring estradiol in cosmetics.

Nowadays, the illegal use of estradiol in cosmetics has caused a series of events which endangering public health seriously. Therefore, it is imperative to establish a simple, fast and specific method for monitoring the illegal use of estradiol in cosmetics. In current study, we developed a molecular imprinted monolithic column two dimensional liquid chromatography method (MIMC-2D-LC) for rapid and selective determination of estradiol in various cosmetic samples. The best polymerization, morphology, structure property, surface groups, and the adsorption performance of the prepared material were investigated. The MIMC-2D-LC was validated and successfully used for detecting estradiol in cosmetic samples with good selectivity, sensitivity, efficiency and reproducibility. The linear range of the MIMC-2D-LC for estradiol was 0.5-50µgg-1 with the limit of detection of 0.08µgg-1. Finally, six batches of cosmetic samples obtained from local markets were tested by the proposed method. The test results showed that the illegal use of estradiol still existed in the commercially available samples.