Monodisperse restricted access material with molecularly imprinted surface for selective solid-phase extraction of 17ß-estradiol from milk.

In this study, novel monodisperse restricted access media-molecularly imprinted polymers were successfully prepared by surface initiated reversible addition-fragmentation chain transfer polymerization using monodisperse crosslinked poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate) microspheres as the carrier and acryloyl chloride-modified ß-cyclodextrin as the hydrophilic functional monomer. The surface morphology, protein exclusion, and adsorption properties of the molecularly imprinted polymers were investigated. The results show that the material has excellent monodispersity and hydrophilicity, and simultaneously exhibit high adsorption capacity, fast binding kinetics, high selectivity, and significant thermal stability. The molecularly imprinted polymers as dispersive solid-phase extraction adsorbent combined with reversed-phase high-performance liquid chromatography was used to selectively enrich, separate, and analyze trace 17ß-estradiol in milk samples. The recovery of 17ß-estradiol is 88-95% with relative standard deviation of <4%, and the limits of detection and quantification of this method are 2.08 and 9.29 µg/L, respectively. The novel restricted access media-molecularly imprinted polymer adsorbents provide an effective method for the selective extraction and detection of 17ß-estradiol directly from complex samples.

Molecularly imprinted polymer coating on metal-organic frameworks for solid-phase extraction of fluoroquinolones from water.

In this work, a novel surface molecularly imprinted polymer with high adsorption capacity, high adsorption rate, and high selectivity for fluoroquinolones was prepared on the surface of UiO-66-NH2 , which is a kind of metal-organic framework. The surface morphology and adsorption properties of this molecularly imprinted polymer were investigated. The maximum adsorption capacity was 99.19 mg/g, and adsorption equilibrium was achieved within 65 s. Combined with reversed-phase high-performance liquid chromatography, the molecularly imprinted polymer was used to selectively enrich, separate and analyze fluoroquinolones present in lake water. The results showed that the recoveries of the four fluoroquinolones were 92.6-100.5%, and the relative standard deviations were 2.9-6.4% (n = 3). The novel molecularly imprinted polymer is an excellent adsorbent and has broad application prospects in the enrichment and separation of trace analytes in complex samples.

Highly sensitive electrochemical sensing of norfloxacin by molecularly imprinted composite hollow spheres.

Poly (3,4-ethylenedioxythiophene) (PEDOT)-based molecularly imprinted electrochemical sensors have attracted widespread attention for monitoring contaminants in food and the environment. However, there are still problems such as poor hydrophilicity, easy agglomeration, and low selectivity in its preparation. In this work, a novel molecularly imprinted composite hollow sphere was prepared by a molecular imprinting technique using nitrogen-doped hollow carbon spheres as matrix material, and PEDOT and poly(methacrylic acid) as monomers. The selective binding capabilities and mechanism of the material to norfloxacin (NOR) were systematically investigated. Then the material-based sensor was constructed, and its electrochemical detection performance toward NOR was thoroughly studied. The sensor exhibited a wide linear range (0.0005-31 µM), a low detection limit (0.061 nM), satisfactory immunity to interference and stability. Besides, the sensor displayed better sensitivity and reliability (spiked recoveries of 98.0-105.2%, relative standard deviation of 3.45-5.69%) for detecting NOR in lake water, honey, and milk than high-performance liquid chromatography. This work provides a new strategy for developing poly(3,4-ethylenedioxythiophene)-based molecularly imprinted electrochemical sensors.

Chromosome-scale assembly and whole-genome sequencing of 266 giant panda roundworms provide insights into their evolution, adaptation and potential drug targets.

Helminth diseases have long been a threat to the health of humans and animals. Roundworms are important organisms for studying parasitic mechanisms, disease transmission and prevention. The study of parasites in the giant panda is of importance for understanding how roundworms adapt to the host. Here, we report a high-quality chromosome-scale genome of Baylisascaris schroederi with a genome size of 253.60 Mb and 19,262 predicted protein-coding genes. We found that gene families related to epidermal chitin synthesis and environmental information processes in the roundworm genome have expanded significantly. Furthermore, we demonstrated unique genes involved in essential amino acid metabolism in the B. schroederi genome, inferred to be essential for the adaptation to the giant panda-specific diet. In addition, under different deworming pressures, we found that four resistance-related genes (glc-1, nrf-6, bre-4 and ced-7) were under strong positive selection in a captive population. Finally, 23 known drug targets and 47 potential drug target proteins were identified. The genome provides a unique reference for inferring the early evolution of roundworms and their adaptation to the host. Population genetic analysis and drug sensitivity prediction provide insights revealing the impact of deworming history on population genetic structure of importance for disease prevention.

Preparation of monodisperse, restricted-access, media-molecularly imprinted polymers using bi-functional monomers for solid-phase extraction of sarafloxacin from complex samples.

Monodisperse restricted-access media bi-functional monomers with molecularly imprinted polymers (RAM-MIPs) were constructed using surface-initiated atom transfer radical polymerization. They were used as solid-phase extraction (SPE) adsorbents to enrich sarafloxacin (SAR) residues from egg samples, and influences on their performance were investigated. Optimum synthesis of RAM-MIPs was achieved by combining a bi-functional monomer (4-vinylpyridine-co-methacrylic acid, 1:3) with an 8:1:32:8 ratio of a template molecule, cross-linker, and restricted-access functional monomer. The SAR imprinting factor of RAM-MIPs was 6.05 and the selectivity coefficient between SAR and other fluoroquinolones was 1.86-2.64. Compared with traditional MIPs, the RAM-MIPs showed better SAR enrichment and selectivity during extraction of a complex protein-containing solution. Empty SPE cartridges were filled with RAM-MIP microspheres as SPE adsorbents. The limit of quantitation for SAR was 4.23 ng g-1 (signal-to-noise ratio = 10) and the mean SAR recovery from spiked egg samples was 94.0-101.3%. Intra-day and inter-day relative standard deviations were 1.1-9% and 1.5-3.3%, respectively.

Highly selective enrichment and direct determination of imazethapyr residues from milk using magnetic solid-phase extraction based on restricted-access molecularly imprinted polymers.

Restricted access media magnetic molecularly imprinted polymers (RAM-MMIPs) were prepared as magnetic solid phase extraction (M-SPE) material by reversible addition fragmentation chain transfer (RAFT) technique. The resulting RAM-MMIPs had a uniform, imprinted, hydrophilic layer (63 nm), good binding capacity (34.85 mg g-1) and satisfactory selectivity. In addition, these RAM-MMIPs had a robust ability to eliminate the interference of protein macromolecules. These RAM-MMIPs were then coupled with HPLC/UV to identify imazethapyr (IM) residues in untreated milk samples. Several major factors would affect M-SPE extraction efficiency, such as the amount of RAM-MMIPs, pH, extraction time of the sample solution, and the volume ratio of the elution solvent. Under the optimal conditions, the developed method had good linearity (R2 > 0.9993), low detection limit (2.13 µg L-1), and low quantitative limit (7.15 µg L-1). These results indicated this proposed approach is an efficient method for direct enrichment and detection of IM herbicides in milk and other biological samples.

Synthesis of monodisperse magnetic restricted microspheres for recognition of thiamphenicol in milk.

Taking thiamphenicol as the research object, a new type of magnetic restricted access molecularly imprinted polymer (RAM-MMIP) with specific recognition was prepared by a one-step swelling method. The polymer microspheres were characterized and analyzed by scanning electron microscopy, X-ray diffraction, elemental analysis, contact angle measurement and vibrating sample magnetometry. When the ratio of template molecule, functional monomer and cross linking agent was 1 : 4 : 8, the adsorption capacity reached the maximum. Under these conditions, RAM-MIP magnetic solid phase extraction (M-SPE) was combined with HPLC to analyze thiamphenicol in milk samples. Satisfactory linear correlation (R 2 > 0.9977), good detection limit (LOD: 10.4 µg L-1), high recovery rate (96.5-101.1%), and relative standard deviation (RSD: 2.8-3.8%) were obtained. Therefore, our synthesized material can be used for the analysis of TAP in complex milk samples, and has broad application value.

Preparation of high-capacity magnetic polystyrene sulfonate sodium material based on SI-ATRP method and its adsorption property research for sulfonamide antibiotics.

A novel polystyrene sulfonate sodium (PSS) magnetic material was prepared by surface-initiated atom transfer radical polymerization (SI-ATRP). The starting materials were brominated magnetic material as the carrier and macroinitiator, sodium styrene sulfonate (NaSS) as the monomer, and cuprous bromide/2,2'-dipyridyl as the catalyst system. The PSS material was characterized by Fourier transform infrared spectroscopy (FT-IR), elemental analysis, transmission electron microscope (TEM), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and a vibrating sample magnetometer (VSM). The adsorption properties of the material were then investigated on sulfa antibiotics. The kinetic and thermodynamic parameters were determined in adsorption of sulfamethazine (the smallest molecular-weight sulfonamide). The adsorption amount of sulfamerazine free acid (SMR) was found to increase with the initial concentration and temperature of SMR in solution. The adsorption effect was maximized at an initial concentration of 0.6 mmol/L. The static saturation adsorption capacity of the material was 33.53 mg/g, Langmuir and Freundlich equations exhibited good fit. The thermodynamic equilibrium equation is calculated as ΔG < 0, ΔH = 38.29 kJ/mol, ΔS > 0, which proves that the adsorption process is a process of spontaneous, endothermic and entropy increase. Kinetic studies show that the quasi-second-order kinetic equation can better fit the kinetic experimental results, which is consistent with the quasi-second-order kinetic model. The experimental results of kinetic studies were well fitted to a quasi-second-order kinetic equation. High performance liquid chromatography (HPLC) of an actual milk sample treated by the PSS magnetic material confirmed the strong adsorption of SMR from milk.

Novel metal-organic framework combining with restricted access molecularly imprinted nanomaterials for solid-phase extraction of gatifloxacin from bovine serum.

Novel restricted access molecularly imprinted nanomaterials (RAMIPs) were successfully prepared on the surface of metal-organic frameworks (NH2-MIL-125) by surface-initiated atom transfer radical polymerization (SI-ATRP) technology. Then it was applied as a solid phase extraction (SPE) material in analysis of quinolones in bovine serum by HPLC detection. NH2-MIL-125@RAMIPs was empolyed as a sorbent for gatifloxacin (GTFX) and the resulted material has a good binding amounts (86.1 mg g-1), rapid binding kinetic (36 min). The results indicated that the prepared NH2-MIL-125@RAMIPs possess excellent specific recognition for GTFX. Combined with high-performance liquid chromatography (HPLC), the SPE column filled with NH2-MIL-125@RAMIPs was applied to selectively enrich GTFX antibiotic from bovine serum. The recovery of GTFX is between 96.8% and 105.6%, with relative standard deviations of 1.7-3.2% (n = 3). The research results illustrate that the method is successfully applied to the selective enrichment of GTFX in bovine serum. It provides a simple and efficient method for the direct detection of GTFX in bovine serum.

Restricted access magnetic imprinted microspheres for directly selective extraction of tetracycline veterinary drugs from complex samples.

A novel restricted access media-magnetic molecularly imprinted polymers (RAM-MMIPs) was prepared as magnetic-solid phase extraction (M-SPE) material for tetracyclines (TCs). The RAM-MMIPs can not only specifically adsorb target molecules in samples, but also effectively eliminate the interference of protein macromolecules. The protein exclusion rate is 99.4%. Besides, RAM-MMIPs have a uniform imprinted and hydrophilic layer (600 nm), rapid binding kinetic (35 min), high selectivity and larger adsorption capacity. The M-SPE was coupled with HPLC/UV to extract TCs from untreated milk and egg samples, and several major factors affecting M-SPE efficiency were optimized. Under optimized conditions, the developed method achieved good linearity (R2>0.9989), lower limits of detection (LOD) and higher recoveries of TCs. For milk samples, the LOD is 1.03-1.31 µg L-1 and the recovery is 86.7% to 98.6% with relative standard deviation (RSD) of 1.4-5.7%. For the egg samples, the LOD, recovery and RSD are 2.21-2.67 µg L-1, 84.2-96.5% and 1.7-5.9%, respectively. Consequently, this work provides an improved strategy for the selective extraction and detection of target molecules directly from complex samples with proteins.

Restricted access media-imprinted nanomaterials based on a metal-organic framework for highly selective extraction of fluoroquinolones in milk and river water.

A new type of restricted access media-imprinted nanomaterials (RAM-MIPs) were successfully prepared on the surface of metal-organic framework by reversible addition fragmentation chain transfer polymerization technology. Then it was applied as a dispersed solid phase extraction (DSPE) material in analysis of fluoroquinolones (ofloxacin, pefloxacin, norfloxacin, enrofloxacin and gatifloxacin) in untreated milk and river water by HPLC-UV detection. The resulted material has a good binding amounts (60.81 mg g-1), rapid binding kinetic (15 min) and satisfactory selectivity as well as has a good ability to eliminate matrix interference. Several major factors affecting DSPE efficiency, pH of sample solution, dosage of RAM-MIPs, adsorption time and volume ratios of elution solvent were primarily optimized. In optimization conditions, RAM-MIPs-DSPE was combined with HPLC-UV to enrich fluoroquinolones in untreated milk and river water, achieving satisfactory linear correlation (R2 > 0.9988), good limits of detection (LOD, 1.02-3.15 µg L-1 for milk and 0.93-2.87 µg L-1 for river water) and better recoveries (80.7-103.5% and 85.1-105.9% with relative standard deviation (RSD) of not higher than 5.3% and 4.7% for milk and river water samples, respectively). The research results illustrate that it provides a simple and efficient method for the direct detection of FQs in complex samples.

Preparation of Monodisperse Enrofloxacin Molecularly Imprinted Polymer Microspheres and Their Recognition Characteristics.

This study presents a new strategy for the detection of enrofloxacin (ENR) in food samples by the use of monodisperse ENR molecularly imprinted polymers (MIPs). Using enrofloxacin as template molecule, methacrylic acid as functional monomer, and ethylene diglycidyl ether as cross-linker, surface molecularly imprinted polymers (MIPs) were prepared on the surface of polymeric glycidyl methacrylate-ethylene glycol dimethacrylate (PGMA-EDMA) microspheres. The surface morphology and imprinting behavior of PGMA-EDMA@MIPs were investigated and optimized. Synthesized PGMA-EDMA@MIPs showed good physical and chemical stability and specific recognition toward fluoroquinolones. The introduction of PGMA-EDMA microspheres greatly increased the adsorption area of PGMA-EDMA@MIPs and increased the adsorption capacity of target molecules. The core shell structure increased the adsorption rate, and adsorption equilibrium was achieved within 6 min, much higher than that of MIPs synthesized by traditional methods. Enrofloxacin in milk samples was detected by molecular imprinting solid phase extraction (MISPE) combined with high performance liquid chromatography (HPLC). Implementing this method resulted in a recovery rate of 94.6~109.6% with a relative standard deviation (RSD) of less than 3.2%. The limit of detection (LOD) of this method was identified as three times the signal-to-noise ratio (10 µg/L). In summary, this work proposed a sensitive, rapid, and convenient method for the determination of trace ENR in food samples.

A restricted access molecularly imprinted polymer coating on metal-organic frameworks for solid-phase extraction of ofloxacin and enrofloxacin from bovine serum.

A restricted access molecularly imprinted polymer (RAMIP) crosslinked with bovine serum albumin (BSA) was prepared on the surface of the mesoporous UiO-66-NH2 metal-organic framework (MOF). The surface morphology, imprinting behavior, and protein exclusion properties of UiO-66-NH2@RAMIP@BSA were investigated. The maximum adsorption capacity was 50.55 mg g-1 for ofloxacin, with a 99.4% protein exclusion rate. Adsorption equilibrium was reached in 9 min. Combined with RP-HPLC, a solid-phase extraction column filled with UiO-66-NH2@RAMIP@BSA was used to selectively enrich and analyze ofloxacin and enrofloxacin antibiotics from bovine serum with recoveries of 93.7-104.2% with relative standard deviations of 2.0-4.5% (n = 3). The linear range and the limit of detection were 0.1-100 µg mL-1 and 15.6 ng mL-1, respectively. These results suggest that UiO-66-NH2@RAMIP@BSA is an efficient pretreatment adsorbent for biological sample analysis.

Preparation of Restricted Access Media-Molecularly Imprinted Polymers for the Detection of Chloramphenicol in Bovine Serum.

Chloramphenicol- (CAP-) restricted access media-molecularly imprinted polymers (CAP-RAM-MIPs) were prepared by precipitation polymerization using CAP as a template molecule, 2-diethylaminoethyl methacrylate (DEAEM) as a functional monomer, ethylene glycol dimethyl acrylate (EDMA) as a crosslinking agent, glycidyl methacrylate (GMA) as an outer hydrophilic functional monomer, and acetonitrile as a pore former and solvent. The CAP-RAM-MIPs were successfully characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The adsorption performance was investigated in detail using static, dynamic, and selective adsorption experiments. Adsorption equilibrium could be reached within 11 min. The CAP-RAM-MIPs had a high adsorption rate and good specific adsorption properties. Scatchard fitting curves indicated there were two binding sites for CAP-RAM-MIPs. Adsorption was Freundlich multilayer adsorption and consistent with the quasi-second kinetic model. Using CAP-RAM-MIPs for selective separation and enrichment CAP in bovine serum in combination with high-performance liquid chromatography (HPLC), CAP recovery ranged from 94.1 to 97.9% with relative standard deviations of 0.7-1.5%. This material has broad application prospects in enrichment and separation.

[Preparation of magnetic surface molecularly imprinted polymers for melamine and its application in milk samples].

By using melamine (MEL) as the template molecule, magnetic surface molecularly imprinted polymers (MMIPs) were prepared. Methacrylic acid (MAA) was chosen as the functional monomer, and ethyleneglycol dimethacrylate (EGDMA) was chosen as the cross-linker, and Fe3O4@SiO2 was used as the magnetic supporter. Transmission electron microscope (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) analysis and a vibrating sample magnetometer (VSM) were used to characterize the polymers. An imprinted polymer layer was found on the surface of the Fe3O4@SiO2 nanomaterials. MMIPs were applied to extract and enrich melamine in milk samples. The specific recognition capability of the material was confirmed by high performance liquid chromatographic (HPLC) analysis. Thus, a simple and selective method was successfully established using MMIPs as sorbents to detect melamine in milk with satisfactory results.

Preparation of Imazethapyr Surface Molecularly Imprinted Polymers for Its Selective Recognition of Imazethapyr in Soil Samples.

A novel strategy based on imazethapyr (IM) molecular-imprinting polymers (MIPs) grafted onto the surface of chloromethylation polystyrene resin via surface-initiated atom transfer radical polymerization (SI-ATRP) for specific recognition and sensitive determination of trace imazethapyr in soil samples was developed. The SI-ATRP was performed by using methanol-water (4 : 1, v/v) as the solvent, acrylamide as the functional monomer, trimethylolpropane trimethacrylate (TRIM) as the cross-linker, imazethapyr as the template, and CuBr/2,2'-bipyridine as the catalyst. The resulting MIPs were characterized by elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Then, the binding selectivity, adsorption capacity, and reusability of the MIPs were evaluated. The results indicated that the prepared MIPs exhibited specific recognition and high selectivity for imazethapyr. The MIPs were further used as solid-phase extraction (SPE) materials coupled with high-performance liquid chromatography (HPLC) for selective extraction and detection of trace imazethapyr from soil samples. The results showed that good linearity was observed in the range of 0.10-5.00 µg/mL, with a correlation coefficient of 0.9995. The limit of detection (LOD) of this method was 15 ng/g, and the extraction recoveries of imazethapyr from real samples were in the range of 91.1-97.5%, which proved applicable for analysis of trace imazethapyr in soils. This work proposed a sensitive, rapid, and convenient approach for determination of trace imazethapyr in soil samples.

Hyperoside Suppresses Lipopolysaccharide-induced Inflammation and Apoptosis in Human Umbilical Vein Endothelial Cells.

Finding the novel drug from the effective components of traditional Chinese herbal medicine is a hotspot of the modern pharmacological research. Hyperoside (HYP) belongs to flavonoid glycosides, and it has various properties, such as anti-inflammation, anti-spasm, anti-diuretic, antitussive, lowering blood pressure, and lowering cholesterol effects as well as protective effects for the cardiac and cerebral blood vessels. The purpose of this study was to investigate the effects of HYP on inflammatory and apoptotic responses in vascular endothelial cells stimulated by lipopolysaccharide (LPS) and further to identify the possible mechanisms underlying these effects. In our study, human umbilical vein endothelial cells (HUVECs) were stimulated with 1 µg/mL LPS in the presence or absence of HYP (10, 20 and 50 µmol/L). Our results indicated that HYP alone exerted no cytotoxicity on HUVECs, while it had an up-regulatory effect on the viability of HUVECs induced by LPS in a dose-dependent manner; increased mRNA expression of IL-1ß, IL-6, TNFα and iNOS induced by LPS was attenuated after treatment with HYP both in a dose-and time-dependent manner; LPS-induced HUVECs apoptosis and cleaved-caspase 8, 9, 3 were all significantly reduced by HYP. Furthermore, the possible pathway involved in apoptosis and inflammation by HYP was detected, and the results showed that when treated with HYP, LPS-induced mitochondrial membrane instability was significantly inhibited through up-regulation of Bcl-2 and down-regulation of Bax. Furthermore, the expression of TLR4 and the phosphorylation of IκBα and p65 in LPS-treated cells were blocked by HYP. Our results suggested that HYP treatment prevented HUVECs from LPSinduced inflammation and apoptosis responses, which might be mediated by inhibiting TLR4/NFκB pathway.

Concentration­dependent effects of paeoniflorin on proliferation and apoptosis of vascular smooth muscle cells.

Vascular smooth muscle cells (VSMCs) are an important component of arterial walls, and their dysfunction may serve an important role in the development of cardiovascular diseases, including atherosclerosis and restenosis. Paeoniflorin (PF) is a principal component of the commonly used traditional Chinese medicine, peonies. To the best of our knowledge, the effects of PF on apoptosis and proliferation of VSMCs and its underlying molecular mechanisms have not been widely reported. Therefore, the present study was designed to investigated this phenomenon. VSMCs were treated with different concentrations of PF (25, 50 and 100 µg/ml) for 12, 24 or 48 h. The data demonstrated that PF treatment not only significantly decreased cell viability and DNA synthesis but also blocked G0/G1 cell cycle progression. This effect was associated with a decreased expression of cyclin D1, cyclin E, cyclin­dependent kinase (CDK)4 and CDK2 as well as an upregulation of p21. Notably, a significant concentration­dependent decrease in the phosphorylation of p65 and nuclear factor of κ light polypeptide gene enhancer in B­cells inhibitor­α (IκBα) was observed. In addition, it was demonstrated that PF promoted the apoptosis of VSMCs, which was associated with the increased expression of caspases. In conclusion, PF inhibited the proliferation of VSMCs by downregulating proteins associated with the nuclear factor­κB signaling pathway. Furthermore, it promoted the apoptosis of VSMCs by upregulating the expression of caspases. These results may be useful in improving the understanding of the molecular mechanisms underlying the apoptotic and anti­proliferative effects of PF on VSMCs, and facilitate the development of novel treatments for cardiovascular diseases.