Novel ferrofluid based on water-based deep eutectic solvents: application in dispersive liquid-liquid microextraction of naphthalene-derived plant growth regulators in edible oil.

A new ferrofluid extractant (Fe3O4 @SiO2-WDES) was ingeniously prepared by coating magnetic Fe3O4 @SiO2 microspheres with water-based deep eutectic solvent (WDES) and used for dispersive liquid-liquid microextraction (DLLME) and HPLC determination of naphthalene-derived plant growth regulators (PGRs, i.e., 1-naphthylacetic acid, 2-naphthylacetic acid, 1-naphthoxy acetic acid, 2-naphthyloxyacetic acid and 1-naphthylacetamide) in edible oil. Herein, mass transfer of the analytes in DLLME was significantly enhanced via increasing the contact surface by employing the microspheres as the supporter and dispersant of WDES, and phase separation can be efficiently achieved using an external magnet rather than centrifugation in traditional DLLME. Response surface methodology (RSM) based on Box-Behnken design (BBD) was employed for the optimization of core experimental conditions, and Analytical Eco-Scale and Analytical GREEnness Metric Approaches were adopted to evaluate the degree of greenness of the procedure. Under the optimal conditions, satisfactory performances of linearity ranged from 5 to 100 µg/L (R2 ≥ 0.9982), limit of detection (0.58-0.91 µg/L), limit of quantitation (1.9-3.0 µg/L), precision (RSDs ≤ 5.5%), recovery (81.3%-108.1%) and negligible matrix effect were achieved, which introduced a promising alternative route for the determination of naphthalene-derived plant growth regulators in edible oil.

Molecular imprinting electrochemiluminescence sensor based on nitrogen-doped carbon quantum dots /Ru(bpy)3@SiO2 for the determination of citrinin.

An electrochemiluminescence (ECL) sensor based on molecular imprinting polymer and SiO2 nanoparticles loaded Ru(bpy)3 and nitrogen-doped carbon quantum dots (NCQDs) is constructed for citrinin detection. The Ru(bpy)3 acts as ECL emitter, and the NCQDs cooperate with tri-n-propylamine (TPA) in solution as a coreactant to facilitate the luminescence. The citrinin imprinted poly(p-aminothiophenol) film is deposited on the surface of the luminophore by electrochemical method, which can immobilize the luminophore besides recognizing the target. The obtained ECL sensor exhibits high sensitivity, stability, and reproducibility. The change of ECL intensity and the logarithm of citrinin concentration display a good linear relationship in the range 1.0 to 100 pg mL-1, and the detection limit is 5 fg mL-1. When it is applied to the detection of citrinin contents in food sample (i.e., rice and millet) solutions, the RSD is less than 6.1%, and the recoveries for spiked standards range from 95.5 to 102.0%. Hence, this work provides a promising alternative for citrinin detection.

A ratiometric electrochemical sensing platform based on multifunctional molecularly imprinted polymer with catalytic activity for the detection of psychoactive substances.

Molecularly imprinted polymers (MIPs) are widely used as artificial recognition element in sensing field, but their electrochemical sensing performances are generally affected by their poor catalytic activity and unruly condition change. In this work, an MIP film with catalysis (Fe-DMMIP) is constructed by electrodeposition of Fe-coordinated aminophenanthroline and 3,4-ethylenedioxythiophene on N, S doped C material, using cannabinoid (CBD) as template molecule. Due to the presence of Fe-N active sites, the obtained Fe-DMMIP possesses enzyme-like catalytic activity besides conventional recognition capability. Accordingly, the sensor exhibits high electrocatalytic activity and selectivity. Moreover, the Fe-DMMIP can produce a stable and well-defined signal as an internal reference around 0 V (vs. Ag/AgCl) for ratiometric sensing. Under the optimal conditions, the ratiometric signal is linear to CBD concentration in the range of 0.004-0.8 µmol L-1 (R2 = 0.9946) with a detection limit of 2.9 nmol L-1. The ratiometric sensor shows high reproducibility, stability and applicability. In addition, through replacing the template molecule, the resulting biomimetic sensor also exhibits good performance in sensing other psychoactive substances such as melatonin and 5-hydroxytryptophan, with LODs of 19 nmol L-1 and 8 nmol L-1for them, respectively. Therefore, the developed sensing platform has good prospects, and this work provides a new way for developing ratiometric electrochemical sensors with high sensitivity, reproducibility and anti-interference ability.

A ratiometric electrochemical sensor based on Cu-coordinated molecularly imprinted polymer and porous carbon supported Ag nanoparticles for highly sensitive and selective detection of perphenazine.

In this work, a ratiometric electrochemical sensor was developed for the detection of perphenazine (PPZ). The sensor was constructed by electrodepositing Cu-coordinated molecularly imprinted polymer (Cu-MIP) on Ag nanoparticles (NPs) modified flexible porous carbon cloth. The Cu-MIP showed highly electrochemical response because of the enhanced adsorptive ability and electronic properties of Cu2+ chelation; Ag NPs could provide a stable and effective reference signal for ratiometric quantification. Thus the resulted sensor not only displayed high selectivity and sensitivity, but also exhibited satisfactory reproducibility and anti-interference ability. Under the optimum conditions, the quantitative detection of PPZ was performed with differential pulse voltammetry. It was found that the peak current ratio of PPZ and Ag NP was linear to the concentration of PPZ in the range of 1-700 nmol L-1 (R2 = 0.9968), and the limit of detection was 0.43 nmol L-1 (S/N = 3). The practicability of the sensor was examined by determining human serum and pharmaceutical samples, and satisfactory results and recoveries (ranging from 92.46% to 104.90%) were achieved.

Organic-Inorganic Hybrid Flower-Shaped Microspheres Applied in Photoelectrochemical Sensing.

Organic-inorganic hybrid materials are rarely applied in photoelectrochemical (PEC) sensing because of the serious charge-carrier recombination in organic conjugated polymers. In this work, a series of poly(3,4-ethylenedioxythiophene) (PEDOT)/ZnIn2S4 hybrid flower-shaped microspheres were synthesized using ionic liquids (ILs) as the supporting electrolyte for EDOT electropolymerization and as the regulating reagent for controlling ZnIn2S4 growth, respectively. It was found that the hybrid material [HOEMIM]NTf2-PEDOT/[HOEMIM]BF4-ZnIn2S4 ([HOEMIM]+: 1-hydroxyethyl-3-methylimidazolium cation; NTf2-: bis(trifluoromethanesulfonyl)amide) was the optimal one, with a smooth, transparent, and continuous polymer film covering the uniform and ordered cross-linked nanosheet arrays. The hybrid material could produce a high anodic photocurrent, which was about 78 times as high as that produced by the [HOEMIM]BF4-ZnIn2S4. The enhancement effect should be the highest among all the organic-inorganic hybrid materials reported so far. This was related to its unique micromorphology structure, p-n heterojunction, and the coexisting ILs, which restrained the charge-carrier recombination in PEDOT and enhanced PEDOT sensitization to ZnIn2S4. Then, a carcinoembryonic antigen PEC immunosensor was constructed based on the photoanodic sensing platform, and it exhibited good performance. Furthermore, the [HOEMIM]BF4-ZnIn2S4 was treated with NaClO solution to create the [HOEMIM]NTf2-PEDOT/[HOEMIM]BF4-S-ZnwInxSyOz general platform for both photoanodic and photocathodic sensing. As a proof of concept, L-cysteine and dissolved oxygen were used as models for photoanodic and photocathodic sensing, respectively. The results demonstrated that the general PEC platform was quite competent. This work opens up a window for the design of organic-inorganic hybrid PEC materials and will promote the application of such hybrid materials in PEC biosensing.

Water based-deep eutectic solvent for ultrasound-assisted liquid-liquid microextraction of parabens in edible oil.

A novel water-based deep eutectic solvent was synthesized and used for the ultrasound-assisted liquid-liquid microextraction of parabens in edible oil and for their determination by high performance liquid chromatography. Herein, the water-based deep eutectic solvent was formulated at room temperature by tetrabutylammonium chloride as hydrogen bond acceptor and water as hydrogen bond donor at the molar ratio of 1:5. As component, water has the effect on tailoring the physicochemical properties of water-based deep eutectic solvent and assisting tetrabutylammonium chloride (hydrogen bond acceptor) capturing parabens (hydrogen bond donor) through in-situ deep eutectic solvent formation. The developed method has satisfactory linearity (1.5-500 µg/L), limits of detections (0.2-0.4 µg/L), precisions (RSDs ≤ 5.8%), and was fruitfully applied to detect parabens in edible oil with excellent recoveries (85.1-106.8%). The feature of the procedure lies in simplicity, low cost and high sensitivity, and this can be extended for the efficient separation of other hydrophobic compounds.

Discovery of Natural Product-Based Fungicides (III): Semisynthesis and Biological Activity of N-Phenylpyrazole Sarisan Hybrids as Antifungal Agents.

Many phytopathogenic fungi can easily infect crops, resulting in crop yield reductions. In continuation of our efforts to develop natural product (NP)-based antifungal agents, a series of N-phenylpyrazole sarisan hybrids 6a-v were prepared via I2 -mediated oxidative cyclization, and their structures were determined by various spectral analyses including IR, 1 H-NMR and ESI-MS. Among all N-phenylpyrazole sarisan hybrids, compounds 6a, 6b, 6e, 6i, 6j and 6r exhibited more encouraging antifungal action against at least two phytopathogenic fungi than the reference fungicide hymexazol. Especially, 6a displayed really encouraging and broad-spectrum antifungal activity against F. graminearum, V. mali, and F. oxysporum f.sp.niveum with the EC50 values of 12.6±0.9, 18.5±0.2, and 37.4±1.8 µg/mL, respectively. Moreover, the structure-activity relationships (SARs) were also observed. Additionally, compounds 6a and 6e also exhibited relative low toxicity on normal LO2 cells. This study indicates that these N-phenylpyrazole sarisan hybrids would shed light on developing novel NP-based antifungal agents.

Deep eutectic solvent-based liquid-phase microextraction coupled with reversed-phase high-performance liquid chromatography for determination of α-, ß-, γ-, and δ-tocopherol in edible oils.

For simultaneous analysis of four fat-soluble tocopherols (α-, ß-, γ-, and δ-) in edible oils, an efficient and green method using deep eutectic solvent-based liquid-phase microextraction (DES-LPME) coupled with reversed-phase high-performance liquid chromatography (RP-HPLC) was developed. The DESs formed by different quaternary ammonium salts and ethanol were used as the extractants. Tetrabutylammonium chloride (TBAC)-ethanol DES at a molar ratio of 1:2 achieved the best extraction efficiency. Under the optimized conditions, the detection limits were in the range of 2.1-3.0 ng mL-1. The intra-day and inter-day repeatability were in the ranges of 3.9-5.3% and 4.8-7.1%, respectively, and the recoveries for the real samples varied from 80.7% to 105.4%. The developed method was successfully employed for the determination of all four tocopherol homologues with an RP-HPLC system containing a COSMOSIL π-NAP column in five edible oils collected locally. Graphical abstract.

Discovery of Natural Product-Based Fungicides (II): Semisynthesis and Biological Activity of Sarisan Attached 3-Phenylisoxazolines as Antifungal Agents.

Many phytopathogenic fungi cause severe damage to crop yields. In continuation of our research aimed at the discovery and development of natural products-based fungicides, a series of thirty-one sarisan attached 3-phenylisoxazolines were synthesized and evaluated for their antifungal activities against five phytopathogenic fungi (B. cinerea, C. lagenarium, A. solani, F. solani, and F. graminearum). Among all title sarisan derivatives, compounds IV2, IV14 and IV23 showed potent antifungal activity against some phytopathogenic fungi. In particular, compound IV2 exhibited a broad-spectrum and more potent antifungal activity against A. solani, F. solani, and F. graminearum than the commercial fungicide Hymexazol. In addition, compounds IV2, IV14 and IV23 also displayed relative low toxicity on normal NRK-52E cells. This work will give some insights into the development of sarisan derivatives as new fungicide candidates in plant protection.

National Alveolar Echinococcosis Distribution - China, 2012-2016.

What is already known about this topic? Both alveolar echinococcosis (AE) and cystic echinococcosis are endemic in China, among which alveolar echinococcosis has a very high mortality rate. What is added by this report? The survey results showed the prevalence and scope of AE in China and identified high-risk groups including children, monks, herdsmen and illiterate people. At the same time, all the cases found in the survey (more than 90% of the patients did not go to the hospital for diagnosis and treatment before survey) were promptly diagnosed and treated. What are the implications for public health practice? This study provides information for the development of a plan for AE prevention and control and for the implementation of interventions targeted to high-risk populations.

[Construction a lentiviral vector for RNA interference of glutathione peroxidase 2 gene and its effect on HepG2 cell apoptosis].

OBJECTIVE: To construct a RNA interference lentiviral vector for human glutathione peroxidase 2 (GPX2) gene and observe the effect of GPX2 knockdown on cell apoptosis. METHODS: The sequence of the small interfering RNA (siRNA) for GPX2 interference was inserted into the pSicoR vector. HepG2 cells were infected by the packaged si-GPX2 lentivirus and the expression of GPX2 in the infected cells was detected by both RT-PCR and Western blotting. Changes of cell apoptosis following the infection were analyzed by flow cytometry. RESULTS: The lentiviral particles pSicoR-GPX2 were successfully packaged. The expression of GPX2 in the infected cells was obviously down-regulated at both RNA and protein levels. GPX2 knockdown caused increased apoptosis rate, increased Bax expression and lowered Bcl-2 expression in HepG2 cells. CONCLUSION: We have successfully constructed the lentiviral vector for RNA interference of human GPX2 gene.

[Simultaneous determination of the migrations of bisphenol A and phenol in polycarbonate bottles based on subcritical water extraction and high performance liquid chromatography].

A new method was established for the simultaneous determination of the migration amounts of bisphenol A (BPA) and phenol from polycarbonate (PC) bottles based on subcritical water extraction (SWE) and high performance liquid chromatography. The optimum extraction conditions included an extraction temperature of 120 degree C, a pressure of 6.89 MPa (1000 psi), a static extraction time of 1 h and one cycle. Under the conditions, the migration amounts of the BPA ranged from 6.81 to 1116 micro g/g in 11 samples. Phenol was not detectable in 5 samples, and in other ones the migration amounts of phenol varied in the range of 3.25 -6. 08 micro g/g. The traditional soaking extraction experiments showed that PC was subjected to weak hydrolysis after long-time leaching. The BPA and phenol were separated in 8 min. Good linearities were obtained in the range of 0. 05 - 20 mg/L for BPA and 0.02 - 20 mg/L for phenol ( r > 0.999 7). The limits of detection were 7.6 micro g/L for BPA and 2.0 micro g/L for phenol. Intra-day and inter-day repeatabilities (expressed as RSD) were less than 5.21% and 11.63%, respectively. Compared with traditional water soaking extraction, the extraction efficiencies increased 49 - 106 times using this developed SWE method. The procedure is simple, rapid and environment friendly, and can be utilized to determine the migration amounts of BPA and phenol in PC bottles.

Rapid determination of α-tocopherol in cereal grains using dispersive liquid-liquid microextraction followed by HPLC.

The traditional for the determination of α-tocopherol in cereal grains includes saponification of a sample followed by liquid-liquid extraction, and it is time- and solvent consuming. In this study, a dispersive liquid-liquid microextraction (DLLME) method was developed to extract α-tocopherol in situ from the saponified grain sample solution. The DLLME experimental parameters including the type and volume of extractants, the volume of dispersers, the addition of salt and the extraction/centrifuging time were examined and optimized. The recommended analytical procedure showed excellent precision (relative SDs of the α-tocopherol amount of 3.1% over intraday and 7.2% over interday), high sensitivity (the detection limit of 1.9 ng/mL), and strong recovery values (88.9-102.5%). In addition, statistical analyses showed no significant difference between the detected amounts of α-tocopherol found by the standardized method and this new procedure. The method was successfully applied to determining the amounts and distribution of α-tocopherol in 14 cereal grain samples.

Formation of higher-order nuclear Rad51 structures is functionally linked to p21 expression and protection from DNA damage-induced apoptosis.

After exposure of mammalian cells to DNA damage, the endogenous Rad51 recombination protein is concentrated in multiple discrete foci, which are thought to represent nuclear domains for recombinational DNA repair. Overexpressed Rad51 protein forms foci and higher-order nuclear structures, even in the absence of DNA damage, in cells that do not undergo DNA replication synthesis. This correlates with increased expression of the cyclin-dependent kinase (Cdk) inhibitor p21. Following DNA damage, constitutively Rad51-overexpressing cells show reduced numbers of DNA breaks and chromatid-type chromosome aberrations and a greater resistance to apoptosis. In contrast, Rad51 antisense inhibition reduces p21 protein levels and sensitizes cells to etoposide treatment. Downregulation of p21 inhibits Rad51 foci formation in both normal and Rad51-overexpressing cells. Collectively, our results show that Rad51 expression, Rad51 foci formation and p21 expression are interrelated, suggesting a functional link between mammalian Rad51 protein and p21-mediated cell cycle regulation. This mechanism may contribute to a highly effective recombinational DNA repair in cell cycle-arrested cells and protection against DNA damage-induced apoptosis.