Activation of autophagy promotes the inhibitory effect of curcumin analog EF-24 against MDA-MB-231 cancer cells.

Breast cancer is the leading cause of cancer deaths in women worldwide. EF-24, an analog of curcumin, has been shown to possess promising anticancer effects. However, the underlying mechanism remains elusive. In the present study, the inhibitory effect of EF-24 against one breast cancer cell line, MDA-MB-231, and its anti-migration ability were assessed by MTT, wound healing, and Transwell assay. Furthermore, we found that EF-24 could induce initiation of autophagy as evidenced by fluorescence and electron microscope observation. EF-24 also induced mitochondrial apoptosis in MDA-MB-231 cells as detected by Hoechst 33342 staining, flow cytometry analysis, and western blot analysis. In addition, the early autophagy inhibitor 3-MA could reduce the cleavage of PARP protein and protect cells from EF-24-induced apoptosis, while the autophagy inducer (rapamycin) could enhance the anticancer effect of EF-24 in MDA-MB-231 cells, which suggest that EF-24 induces crosstalk between autophagy and apoptosis, which herein participate in the antiproliferative effect of EF-24 in breast cancer cells. Moreover, removal of EF-24-activated ROS with NAC significantly reversed migration ability of MDA-MB-231 cells, indicating that EF-24 exerted an inhibitory effect through a ROS-mediating pathway. These results will help to elucidate the antitumor mechanism of curcumin analogs and to explore future potential clinical applications.

Magnetic solid phase extraction coupled with desorption corona beam ionization-mass spectrometry for rapid analysis of antidepressants in human body fluids.

Ambient ionization techniques show good potential in rapid analysis of target compounds. However, a direct application of these ambient ionization techniques for the determination of analytes in a complex matrix is difficult due to the matrix interference and ion suppression. To resolve this problem, here we developed a strategy by coupling magnetic solid phase extraction (MSPE) with desorption corona beam ionization (DCBI)-mass spectrometry (MS). As a proof of concept, the pyrrole-coated Fe3O4 magnetic nanoparticles (Fe3O4@Ppy) were prepared and used for the extraction of antidepressants. After extraction, the Fe3O4@Ppy with trapped antidepressants was then directly subjected to DCBI-MS analysis with the aid of a homemade magnetic glass capillary. As the MSPE process is rapid and the direct DCBI-MS analysis does not need solvent desorption or chromatographic separation processes, the overall analysis can be completed within 3 min. The proposed MSPE-DCBI-MS method was then successfully used to determine antidepressants in human urine and plasma. The calibration curves were obtained in the range of 0.005-0.5 µg mL(-1) for urine and 0.02-1 µg mL(-1) for plasma with reasonable linearity (R(2) > 0.951). The limits of detection of three antidepressants were in the range of 0.2-1 ng mL(-1) for urine and 2-5 ng mL(-1) for plasma. Acceptable reproducibility for rapid analysis was achieved with relative standard deviations less than 19.1% and the relative recoveries were 85.2-118.7%. Taken together, the developed MSPE-DCBI-MS strategy offers a powerful capacity for rapid analysis of target compounds in a complex matrix, which would greatly expand the applications of ambient ionization techniques with plentiful magnetic sorbents.

Facile synthesis of magnetic molybdenum disulfide@graphene nanocomposite with amphiphilic properties and its application in solid-phase extraction for a wide polarity of insecticides in wolfberry samples.

A novel magnetic molybdenum disulfide@graphene (Fe3O4/MoS2@G) nanocomposite with amphiphilic properties was prepared via a co-mixing solvothermal method. To demonstrate the feasibility of Fe3O4/MoS2@G as a sorbent during sample preparation, it was employed for the magnetic solid phase extraction (MSPE) of ten pyrethroids, three triazoles and two acaricide pyridaben and picoxystrobin in an emulsified aqueous solution. Dichloromethane was used as the extractant to form an emulsified aqueous solution. Subsequently, the Fe3O4/MoS2@G sorbent with amphiphilic properties was used to retrieve 15 wide polarity insecticides from dichloromethane via MSPE. The proposed method has the advantage of being applicable to different polar pesticides, strengthening the capacity of enrichment and purification of target analytes. The π-π interaction between the hydrophilic and hydrophobic moieties of Fe3O4/MoS2@G and the aromatic rings of target analytes were responsible for the efficient sorption. Thus, a reliable, convenient, and efficient method for the analysis of 15 insecticides with wide polarity in wolfberry samples was established by coupling Fe3O4/MoS2@G nanocomposite MSPE with gas chromatography-mass spectrometry (GC-MS) analysis. The obtained linearity of this method was in the range from 1 to 5000 ng mL-1 for 15 analytes, with determination coefficients (R2) ≥0.9907. The limit of detection (LOD) for 15 insecticides was in the range from 0.1 to 5.0 ng g-1. The recoveries of 15 insecticides from spiked wolfberry samples were in the range from 71.41% to 110.53%, and RSD was less than 14.8%.

Facile dispersive solid-phase extraction based on humic acid for the determination of aflatoxins in various edible oils.

Aflatoxins (AFs), as the secondary metabolites of the toxigenic fungi Aspergillus flavus and Aspergillus parasiticus, are well known to be extremely harmful to humans and animals because of their high toxicity, mutagenicity, carcinogenicity, and teratogenicity. Recurring and increasing studies on AF ingestion incidents indicate that AF contamination is a serious food safety issue worldwide. Currently, immunoaffinity chromatography (IAC) has become the most conventional sample clean-up method for determining AFs in foodstuffs. However, the IAC method may be limited to some laboratories because it requires the use of expensive disposable cartridges and the IA procedure is time-consuming. Herein, to achieve the cost-effective determination of AFs in edible oils, we developed a dispersive solid-phase extraction (DSPE) clean-up method based on humic acids (HAs), which is followed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis. HAs could be directly used as a DSPE sorbent after simple treatment without any chemical modification. In the HA-DSPE, AFs could remain on the HA sorbent by both hydrophobic and hydrophilic interactions, whereas the oil matrix was retained on HA via only hydrophobic interactions. The oil matrix could be sufficiently washed off by n-hexane, whereas the AFs could still be retained on HA; thus, the selective extraction of AFs and clean-up of oil matrices were achieved. Under the optimal conditions of HA-DSPE, satisfactory recoveries ranging from 81.3% to 106.2% for four AFs (B1, B2, G1, and G2) were achieved in various oil matrices i.e. blended oil, mixed olive oil, tea oil, sunflower seed oil, rapeseed oil, sesame oil, soybean oil, rice oil, corn oil, and peanut oil. Minor matrix effects ranging from 89.3% to 112.9% were obtained for the four AFs, which were acceptable. Moreover, the LODs of AFs between 0.063 and 0.102 µg kg-1 completely meet the regulatory levels fixed by the Food and Drug Administration (FDA), the European Union (EU), China, or other countries. The proposed methodology was further validated using a naturally contaminated peanut oil, and the results indicated that the accuracy of the HA-DSPE could match the accuracy of the referenced IAC. In addition, HA-DSPE can be used to directly treat diluted edible oil without liquid-liquid extraction and HA is cheap and can be easily obtained from the market worldwide; these advantages make the proposed methodology simple, low-cost, and accessible for the determination of AFs in edible oils.

Tuning the Catalytic Activity of Ir@Pt Nanoparticles Through Controlling Ir Core Size on Cathode Performance for PEM Fuel Cell Application.

Pulse electrochemically synthesis of a series of core-shell structured Ir@Pt/C catalysts in cathode catalysts layer are achieved to fabricate membrane electrode assemblies (MEA) with cathode ultra-low Pt loading. The single cell performance of the MEAs in a H2/air PEMFC greatly rely on the sizes of the Ir core nanoparticle, and the optimum activity occurs with Ir core size of 4.1 nm. The cathode MEA with core-shell structured catalysts with optimal Ir core size exhibited excellent performance in a H2/air single fuel cell, comparable to that of a commercial Pt/C MEA (Johnson Matthey 40% Pt), even though the Pt loading in Ir@Pt was only 40% that of the commercial Pt cathode (0.04 vs. 0.1 mg cm-2). The catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy. Based on the characterization results, especially from XPS, we suggest that the effect of Ir core particle size on MEA performance may arise from the interactions between the Pt shell and the Ir core. The XPS results showed that the Ir@Pt/C-300 catalyst has the highest Pt0 fraction among the four tested samples. This work demonstrates the alternative to enhance the cathode performance in single cell of Pt-based core-shell structured catalysts by varying size of the core metal under the Pt shell.

Facile synthesis of magnetic carbon nitride nanosheets and its application in magnetic solid phase extraction for polycyclic aromatic hydrocarbons in edible oil samples.

In this study, we proposed a method to fabricate magnetic carbon nitride (CN) nanosheets by simple physical blending. Low-cost CN nanosheets prepared by urea possessed a highly π-conjugated structure; therefore the obtained composites were employed as magnetic solid-phase extraction (MSPE) sorbent for extraction of polycyclic aromatic hydrocarbons (PAHs) in edible oil samples. Moreover, sample pre-treatment time could be carried out within 10 min. Thus, a simple and cheap method for the analysis of PAHs in edible oil samples was established by coupling magnetic CN nanosheets-based MSPE with gas chromatography-mass spectrometry (GC/MS) analysis. Limits of quantitation (LOQs) for eight PAHs ranged from 0.4 to 0.9 ng/g. The intra- and inter-day relative standard deviations (RSDs) were less than 15.0%. The recoveries of PAHs for spiked soybean oil samples ranged from 91.0% to 124.1%, with RSDs of less than 10.2%. Taken together, the proposed method offers a simple and cost-effective option for the convenient analysis of PAHs in oil samples.

Magnetic "one-step" quick, easy, cheap, effective, rugged and safe method for the fast determination of pesticide residues in freshly squeezed juice.

A "one-step" quick, easy, cheap, effective, rugged and safe (QuEChERS) method was proposed for pesticide residue analysis in freshly squeezed juice of fruits and vegetables. In this method, a new magnetic adsorbent prepared by simple physical blending was adopt, which could endow the sample mixture with magnetic separability. To achieve the best performance of the modified QuEChERS towards target analytes, the amounts of adsorbents were investigated. Under the optimized conditions, a simple, rapid and sensitive method for the determination of 11 pesticide residues in freshly squeezed juice was established by coupling modified QuEChERS to gas chromatography/mass spectrometry analysis. The limits of quantification of the proposed method for 11 pesticides ranged from 2.0 to 49.6ng/g. Good linearities (R value ≥0.9993) were achieved at different concentration ranges, and acceptable method reproducibility was obtained by evaluating intra- and inter-day precisions with the relative standard deviations being less than 8.5% and 13.5%, respectively. The recoveries were in the range of 70.3-114.1% at different concentrations for real samples. Compared with the traditional QuEChERS methods, extraction/partitioning and purification were integrated into one step in the proposed method, which thus was time-saving (within 3.5min) with keeping good clean-up performance.

Facile synthesis of polyaniline-coated SiO2 nanofiber and its application in enrichment of fluoroquinolones from honey samples.

In this study, polyaniline coated SiO2 nanofibers (PANI/SiO2) was prepared by combining electrospinning technique with in-situ polymerization. The proposed strategy for the preparation of PANI/SiO2 can eliminate the aggregation of PANI and the yield of PANI/SiO2 was high. Scanning electron microscopy (SEM) images showed that PANI nanoparticles were uniformly coated on the surface of SiO2 nanofibers. The as-prepared PANI/SiO2 nanofibers were then applied as the sorbent for in-syringe dispersive solid-phase extraction (dSPE) for the extraction of fluoroquinolones (FQs) from honey samples. The influence of SiO2 amount on the formation of PANI/SiO2 and several parameters that affect the extraction efficiency were investigated. Under optimized conditions, a rapid, simple and effective method for the determination of FQs in honey sample was developed by coupling with liquid chromatography-fluorescence detector (LC-FLD) analysis. Due to the fast extraction equilibrium, the whole sample pretreatment process could be accomplished within 4 min. The limits of detection (LODs) for the target FQs were found to be 0.1-1.3 ng/g. The recoveries in honey sample were in the range of 81.4-118.1% with the RSDs of 0.8-14.4% (intra-day) and 1.4-14.9% (inter-day). This study offers a new strategy for the preparation of functional SiO2 nanofibers using post-electrospinning modification by in-situ polymerization, which could be generally applied in the preparation of various separation materials with electrospun nanofibers.

Facile synthesis of magnetic molecularly imprinted polymers and its application in magnetic solid phase extraction for fluoroquinolones in milk samples.

In this work, we proposed a simple co-mixing method to fabricate magnetic molecularly imprinted polymers (magnetic MIPs). MIPs were commercial products while magnetic nanoparticles (MNPs) were prepared by chemical oxidation and solvothermal methods. When MNPs and MIPs (with mass ratio 1:1) were co-mixed and vortexed evenly in methanol, they could assemble into magnetic composites spontaneously and thus be magnetically separable. To testify the feasibility of the magnetic composites in sample preparation, the resultant magnetic MIPs were applied as sorbents for magnetic solid-phase extraction (MSPE) of fluoroquinolones (FQs) in milk samples. Under optimized conditions, a rapid, convenient, and efficient method for the determination of three FQs in milk samples was established by magnetic MIPs based MSPE coupling with high performance liquid chromatography with ultraviolet detector (HPLC-UV). The limits of detection (LODs) for three FQs were found to be 1.8-3.2ng/g. The intra- and inter-day relative standard deviations (RSDs) were less than 9.5% and 12.5%, respectively. The recoveries of FQs for two spiked milk samples were in the range from 94.0% to 124.4% with the RSDs less than 11.6%.

Quick, easy, cheap, effective, rugged and safe method with magnetic graphitized carbon black and primary secondary amine as adsorbent and its application in pesticide residue analysis.

By using magnetic graphitized carbon black and primary secondary amine (GCB/PSA/MNPs) as adsorbent, a modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method was proposed for pesticide residue analysis in vegetables. The magnetic adsorbent was fabricated via simple co-mixing method based on an "aggregate warp" mechanism. To achieve the optimum conditions of modified QuEChERS toward target analytes, several parameters, including the composition of analyte protectants and the amount of the adsorbents were investigated. Under the optimized conditions, a simple, rapid and effective method for the determination of 10 pesticide residues in vegetables was established by coupling modified QuEChERS to gas chromatography/mass spectrometry analysis. The detection limits of the proposed method for 10 pesticides ranged from 0.39 to 8.6ng/g. Good linearity (R value≥0.990) was achieved at concentration levels of 10-200ng/g, and acceptable method reproducibility was found as intra- and inter-day precisions, yielding the relative standard deviations less than 10.7% and 13.4%, respectively. The recoveries were in the range of 69.9-125.0% at different concentrations for real samples. Compared with the reported methods for the determination of a large number of samples, the proposed method has the advantage of less time-consuming in clean-up procedure.

Facile synthesis of magnetic one-dimensional polyaniline and its application in magnetic solid phase extraction for fluoroquinolones in honey samples.

In this work, we proposed a simple co-mixing method to fabricate magnetic one-dimensional polyaniline (denoted as 1D-PANIs/MNPs). One-dimensional polyanilines (1D-PANIs) and magnetic nanoparticles (MNPs) were prepared by chemical oxidation and solvothermal methods, respectively. When MNPs and 1D-PANIs (with mass ratio 4:1) were co-mixed and vortexed evenly in a solvent (e.g., ethanol, water, acetonitrile), they could assemble into 1D-PANIs/MNPs spontaneously and thus be magnetically separable. To testify the feasibility of 1D-PANIs/MNPs in sample preparation, it was applied as the sorbent for magnetic solid phase extraction (MSPE) of fluoroquinolones (FQs) in honey samples. Under optimized conditions, a rapid, convenient, and efficient method for the determination of four FQs in honey samples by 1D-PANIs/MNPs-based MSPE coupling with high performance liquid chromatography with fluorescence detection (HPLC-FLD) was established. The limits of detection (LODs) for four FQs ranged from 0.4 to 1.4 ng g(-1). The intra- and interday relative standard deviations (RSDs) were less than 17.6%. The recoveries of FQs for three spiked honey samples ranged from 86.3 to 121.3%, with RSDs of less than 16.3%.

An anionic exchange stir rod sorptive extraction based on monolithic material for the extraction of non-steroidal anti-inflammatory drugs in environmental aqueous samples.

In this study, a stir rod sorptive extraction (SRSE) adsorbent material was prepared by coating poly(4-vinylpyridine-co-ethylene glycol dimethacrylate) [poly(VP-co-EDMA)] monolithic polymer on stir rod, and then applied to the extraction of three non-steroidal anti-inflammatory drugs (NSAIDs) in environmental aqueous samples. The preparation conditions of monolithic material such as the amount of porogen and the ratio of functional monomer to cross-linker were investigated. To achieve the best extraction efficiency, several parameters, including pH value of sample solution, salt concentration in sample matrix, desorption solvent, extraction time, and desorption time, were optimized. By combining SRSE and high performance liquid chromatography with ultraviolet detector, a SRSE-HPLC/UV method for the determination of NSAIDs in environmental aqueous samples was proposed successfully. The limits of detection (LODs) of the developed method for three NSAIDs ranged between 0.09 and 0.25 ng/mL. Good method reproducibility presented as intra- and inter-day precisions were also obtained with the relative standard deviations (RSDs) less than 8.7% and 9.8%, respectively.