Search

Medicine food homologous (MFH) plants provide therapeutic and health care effects through diet. Thus, a risk assessment system for hazardous ingredient residues is urgently required to ensure their safe use. In this study, the pesticide contamination of six root and rhizome Chinese herbs, Ginseng Radix et Rhizoma, Panacis Quinquefolii Radix, Pseudostellariae Radix, Salviae Miltiorrhizae Radix et Rhizoma, Codonopsis Radix, and Glehniae Radix, and the risks associated with their intake were investigated. A total of 420 MFH plant samples collected from 22 provinces in China were tested, and 61 pesticides were detected in 413 samples. Multiple pesticide residues were detected in each MFH sample, with contents ranging from 0.0002 to 3.010 mg/kg dry weight. Carbendazim (≥47.14%) and propham (≥40%) were the most frequently detected pesticides. Risk assessment determined by hazard quotients indicated that the risks were acceptable, with no short- or long-term adverse health effects. However, considering the high incidence of residues and the detection of unregistered or even prohibited pesticides, strict supervision of soil quality and pesticide application (particularly cadusafos) in MFH plant cultivation are recommended to aid in monitoring MFH plant quality and ensuring diet and drug safety. PRACTICAL APPLICATION: Ensure the diet and drug safety of Chinese herbs.

A 2D Z-scheme BiVO4/g-C3N4 photocatalyst was successfully synthesized by a two-step hydrothermal/calcination method for overall water splitting. Morphology design to restrain the growth of BiVO4 nanoplates with thickness around 20 nm was achieved by adjusting the pH value and introducing graphene sheets. Then, the BiVO4/g-C3N4 (BVO-CN) hybrid photocatalysts were fabricated with different mass ratios of two components. The structures and optical properties of the BVO-CN photocatalysts were characterized by transmission electron microscope, scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, and photoluminescence spectroscopy. In application, the BVO-CN photocatalysts exhibited the catalytic overall water splitting activity up to 15.6 μmol h−1 for H2 production and 7.3 μmol h−1 for O2 evolution under visible light irradiation. A possible Z-scheme mechanism is proposed for the enhanced photocatalytic activity and was further confirmed by electron spin resonance spectroscopy. This study demonstrated enhanced overall water splitting photocatalytic performance of BiVO4/g-C3N4 photocatalyst by constructing a 2D nanoplates morphology and shed light on the morphology design of Z-scheme semiconductor materials.

We have determined the interaction strengths of the common naturally occurring amino acids using a complete binding affinity matrix of 20 × 20 pairs of homo-octapeptides consisting of the 20 common amino acids between stationary and mobile states. We used a bead-based fluorescence assay for these measurements. The results provide a basis for analyzing specificity, polymorphisms, and selectivity of inter-amino-acid interactions. Comparative analyses of the binding energies, i.e., the free energies of association (ΔGA), reveal contributions assignable to both main-chain-related and side-chain-related interactions originating from the chemical structures of these 20 common amino acids. Side-chain–side-chain and side-chain–main-chain interactions are found to be pronounced in an identified set of amino acid pairs that determine the basis of inter-amino-acid recognition., Interaction strengths between common amino acids were measured with a bead-based fluorescence assay. The results provide a basis for analyzing specificity and selectivity of inter-amino-acid recognition.

The size and distribution of matrix crystals deposited on the surface of a tissue section play a key role in the performance of MALDI mass spectrometry imaging (MALDI-MSI). In this study, uniform distribution and a restricted size of matrix crystals were achieved via a homemade matrix sublimation device with controllable crystallization temperature. The crystallization temperature was stably controlled at a subzero temperature, and homogeneous matrix crystals with diameters

Covalent organic nanospheres (CONs) were explored as a fiber coating for solid-phase microextraction of genotoxic impurities (GTIs) from active ingredients (AIs). CONs were synthesized by an easy solution-phase procedure at 25 °C. The obtained nanospheres exhibited a high specific surface area, good thermostability, high acid and alkali resistance, and favorable crystallinity and porosity. Two types of GTIs, alkyl halides (1-iodooctane, 1-chlorobenzene, 1-bromododecane, 1,2-dichlorobenzene, 1-bromooctane, 1-chlorohexane, and 1,8-dibromooctane) and sulfonate esters (methyl

The design and synthesis of effective photocatalysts for photodegradation of persistent organic pollutants is of significant importance. Novel CuFe2O4 microspheres were successfully synthesized through a facile one-pot hydrothermal route. The composite CuFe2O4–TiO2 photocatalysts with a heterojunction were then fabricated through a simple mixing and heating method. The transmission electron microscopy (TEM) images revealed the clear hollow structure of the catalyst, and the TiO2 nanoparticles were attached tightly on the surface of the microspheres. Crystal structures and surface chemical composition of the photocatalysts were confirmed by powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements. The band structure of the CuFe2O4–TiO2 photocatalyst was confirmed using Mott–Schottky measurements and UV–Vis absorption results. As expected, the CuFe2O4–TiO2 photocatalysts exhibited an enhanced photodegradation activity of methylene blue compared to bare CuFe2O4 and TiO2. A Z-scheme system was proposed and the efficient separation of photogenerated electron-hole pairs through the heterojunction resulted in the enhanced performance. This study provides an effective noble-metal-free and low-cost photocatalyst, and opens up a new synthesis strategy to construct other types of photocatalysts with morphology design.

Abnormal aggregation of β-amyloid (Aβ) peptide plays an important role in the onset and progress of Alzheimer's disease (AD); hence, targeting Aβ aggregation is considered as an effective therapeutic strategy. Here, we studied the aromatic-interaction-mediated inhibitory effect of oligomeric polypeptides (K8Y8, K4Y8, K8W8) on Aβ42 fibrillization process. The polypeptides containing lysine as well as representative aromatic amino acids of tryptophan or tyrosine were found to greatly suppress the aggregation as evaluated by thioflavin T assay. Circular dichroism spectra showed that the β-sheet formation of Aβ42 peptides decreased with the polypeptide additives. Molecular docking studies revealed that the oligomeric polypeptides could preferentially bind to Aβ42 through π–π stacking between aromatic amino acids and Phe19, together with hydrogen bonding. The cell viability assay confirmed that the toxicity of Aβ42 to SH-SY5Y cells was markedly reduced in the presence of polypeptides. This study could be beneficial for developing peptide-based inhibitory agents for amyloidoses. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.

A set of the homogeneous and heterogeneous octapeptides have been studied for the composition and sequence effects on surface-mediated assemblies at liquid–solid interfaces by using scanning tunneling microscopy. The observed assembly structures on graphite surface reveal that all these peptides can form homogeneous lamella characteristics. By analyzing the distributions of lamella width and intralamella peptide strand length, it is suggested that the composition and sequence of the octapeptides consisting of tryptophan and glycine in the present experiments do not have a significant impact on the observed assembling characteristics. These results indicate that the observed assembling stability on the highly oriented pyrolytic graphite (HOPG) surface is dominated by the main chains of the octapeptides containing tryptophan and glycine, and independent of the bulky moieties of tryptophan in the sequence.

The chemokine CXCL12, and its receptor CXCR4, have been recognized to be involved in various instances of cancer metastasis. The CXCL12/CXCR4 axis has emerged as a potential target for cancer therapy. Here, we demonstrate a designed peptide (W4) targeting CXCL12 with high binding affinity, and describe its significant inhibitory effect on the CXCL12/CXCR4 axis. We show that W4 has comparable binding affinity (KD = 5.7 × 10−8 M) to that of the antibody of CXCL12 (KD = 3.0 × 10−9 M) using the surface plasma resonance (SPR) technique. Upon introduction of W4, the circular dichroism (CD) spectra show that the α-helical structure of CXCL12 gradually transformed into a β-sheet and random coil. These effects lead to the significant inhibitory effects on the CXCL12/CXCR4 axis using the CXCR4-positive breast cancer cell lines MCF-7 and MDA-MB-231 and the leukemia cell lines HL-60 and U937 as models. The results show that W4 significantly inhibits CXCL12-induced cell migration of MCF-7, MDA-MB-231, HL-60 and U937 even to 20.0% when the mole ratio is 1 : 1, completely abolishing the effect of CXCL12. These effects may provide evidence of the modulating ligand–receptor interactions of peptides as anti-ligand molecules that differ from the traditional receptor antagonists leading to therapeutic agents.

Mesoporous carbon hollow spheres coated with MoS2 (C@MoS2) were synthesized to obtain a material with large specific surface area, fast electron transfer efficiency and good water dispersibility. The composite material was applied as a matrix for the analysis of small molecules by surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS). The use of a core-shell C@MoS2 matrix strongly reduces matrix background interferences and increases signal intensity in the analysis of sulfonamides antibiotics (SAs), cationic dyes, emodin, as well as estrogen and amino acids. The composite material was applied to the SALDI-TOF MS analysis of selected molecules in (spiked) real samples. The ionization mechanism of the core-shell C@MoS2 as a matrix is discussed. The method exhibits low fragmentation interference, excellent ionization efficiency, high reproducibility and satisfactory salt tolerance.

Dietary intake is the major route for the exposure of residents to short-chain chlorinated paraffins (SCCPs). SCCPs are classified as persistent organic pollutants (POPs) by the Stockholm Convention since May 2017. This study assessed the general population’s dietary exposure to SCCPs through supermarket products. Five food categories, which included 40 food species, were collected from five supermarkets in April 2019. The SCCP concentrations in all food matrices varied between 58.6 and 1977 ng g−1 dry weight (dw), with the average and standard deviation (SD) value of 301 ± 379 ng g−1 dw. Generally, the SCCP concentrations in animal-origin food matrices were higher than those in plant-origin food matrices. The C10Cl7 congeners were predominant among the congener groups of SCCPs. The proportion of C10 congeners in the animal-origin food samples (29.8%) was lower than that in the plant-origin food samples (39.7%), and the C13 congeners showed a contrasting result. The estimated daily intake (EDI) of SCCPs through dietary intake for the residents was 3109 ng kg−1 day−1, which is much lower than the standards of European Food Safety Authority (10 mg kg−1 day−1) for SCCPs. Risk assessment based on the supermarket foods indicated that SCCP exposure through dietary intake does not cause adverse effects to human health according to the margin of exposure (MOE).

Lambda-cyhalothrin is a pyrethroid widely used in crop, fruit and vegetable production, but has potential health threats to human. Immunoassay is a cheap, rapid and facile method to detect lambda-cyhalothrin, yet wide application of this method still requires improvement in the construction of antigen. In this study, we developed a one-step lambda-cyhalothrin hapten synthesis that transformed the cyanide group in lambda-cyhalothrin to amide. Complete antigen was assembled by coupling the amide with succinic-anhydride-activated carrier proteins, and corresponding polyclonal antibodies were generated using Balb/c mice. Using antibody generated by the method in this paper, the competitive ELISA demonstrated the lowest detection limit of 3.772 μg/L for lambda-cyhalothrin, and no significant cross-reactivity for other pyrethroid pesticides was observed. All the results suggested we have established a more efficient technique of generating lambda-cyhalothrin antibody. Furthermore, since the activated proteins used in this study are highly controllable, we believe these proteins could potentially be the prototype of a series of standardized carrier proteins for the synthesis of complete antigens.

Rationale A thorough understanding of the content and distribution of active ingredients in pharmaceuticals is essential for drug efficacy and safety. Technological advancements in mass spectrometry imaging present an opportunity for methodological innovation by providing qualification and quantification analysis, as well as spatial information, in the same assay, which has great potential for applications in the rapid analysis and quality control of drugs. Methods Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) was employed to directly analyze oxytetracycline tablets in order to map the distribution of the active constituent within the whole tablet. Quantitative analysis was capable of differentiating tablets containing various doses of the active pharmaceutical ingredient. Results To establish the methodology, detailed factors that influence matrix spraying and spatial resolution during sample preparation and the data acquisition process were optimized systematically. Quantitative analysis could differentiate the tablets containing various doses of the active compound. The proposed method was successfully applied to analyze real commercial tablets. Conclusions The developed method could successfully achieve the spatial location of oxytetracycline in actual tablet samples. These results could contribute to pharmaceutical tracing technology, especially the formulation process of tablets, which is helpful for monitoring the quality of pharmaceutical products and guaranteeing drug security.

Monitoring the levels of perfluorinated compounds (PFCs) in the environment is of vital importance, owing to their sustained environmental presence, extensive distribution, and associated health risks. The development of cost-effective and efficient sorbents for the establishment of sensitive analytical methods is critical for achieving trace-level detection. In this study, a graphitic carbon nitride (g-C3N4)-based sorbent is synthesized by a facile sonication-assisted method exfoliated by zeolitic imidazolate framework-67 (ZIF-67) in situ. The novel ZIF-67/g-C3N4 composites were systematically characterized by transmission electron microscopy, scanning electron microscopy, atomic force microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and N2 adsorption–desorption analysis, exhibiting good dispersity and a large surface area. Moreover, molecular dynamics simulations indicated that g-C3N4 structures can be effectively exfoliated by the introduced ZIF-67 molecules. The hybrid material was successfully utilized as a dispersive solid-phase extraction sorbent, and the extraction factors were systematically optimized by response surface methodology. Under optimal conditions, the synthesized sorbent exhibited desirable linear correlations (R2 > 0.99), a low detection limit (0.3–2 ng L−1), and good repeatability (relative standard deviation

Far-red to near-infrared (NIR) fluorescent probes with absorption and emission in the spectral region of 600–900 nm are of high interest because of their low autofluorescence interference, deep-tissue penetration, and minimal photodamage to biological samples. In recent years, the Si-substituted xanthenes have attracted considerable attention owing to their remarkable far-red to NIR photophysical properties and biocompatible characteristics. This paper reviews the synthetic methods of silicon-substituted xanthene dyes and the progress in the development of far-red to NIR fluorescent probes based on these dyes, and introduces representative chemosensors along with their fluorescent behavior toward specific analytes. The fluorescent probes in sensing various biological species, including metal ions and anions, intracellular pH changes, reactive oxygen species (ROS) and reactive nitrogen species (RNS), as well as enzymes and other related species, were summarized. The sensing mechanisms and applications of corresponding sensors are also discussed.

The β-amyloid (Aβ) peptide plays an important role in the onset and progress of Alzheimer's disease (AD). Therefore, studies on inhibiting fibril formation and thus neurotoxicity of Aβ could be beneficial for the prevention and treatment of AD. We report a convenient synthetic approach for one-pot preparation of poly-(β-amino ester) copolymerized with the GGLVFF peptide, which is based on the frequently used inhibitor LVFF. The copolymer was found to efficiently inhibit the aggregation and fibrillation of Aβ42 by using fluorescence assay and atomic force microscopy. Reduced β-sheet formation of Aβ42 peptide after addition of copolymer was observed by circular dichroism. Furthermore, the cell viability assay confirmed that the toxicity of Aβ42 for SH-SY5Y cells was markedly reduced in the presence of copolymer. This could be beneficial for AD prevention and treatment and also for the molecular design of inhibitory agents for other amyloidoses. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.

Cancer is the leading cause of death worldwide, and metastasis is the main attribute to cancer death. CXCR4 and its natural ligand CXCL12 have been known to play a critical role in tumorigenesis, angiogenesis and metastasis. Therefore, designing a new CXCR4 antagonist to prevent tumor metastasis will be of great significance. Herein, a novel chemically synthesized peptide (E5) that has an ability to target CXCR4/CXCL12 axis was loaded in micelle glycol-phosphatidylethanolamine (PEG-PE) block copolymer to form micelle-encapsulated E5 (M-E5). We demonstrated that M-E5 exhibited higher affinity for CXCR4-overexpressing MCF-7 and HepG2 tumor cells as compared to free E5, and efficiently inhibited the tumor cells migration. Mechanistic studies implied that PEG-PE micelle can encapsulate E5 and improve E5 targeting efficiency for CXCR4 by accumulating E5 on the tumor cell membrane. Furthermore, through encapsulation of chemotherapeutic drug doxorubicin (Dox) in PEG-PE micelle, we proved that PEG-PE micelle could serve as a co-carrier for both E5 and Dox (M-E5-Dox). M-E5 enhanced the efficiency of Dox by down-regulating the phosphorylation level of Akt, Erk and p38/MAPK proteins. In conclusion, PEG-PE micelle demonstrated a promising delivery system for E5, and M-E5 is expected to be a potential therapeutic agent that will help to improve the clinical benefits in current therapies used for solid tumors.

Abnormal aggregation of β-amyloid (Aβ) peptide plays an important role in the onset and progress of Alzheimer's disease (AD); hence, targeting Aβ aggregation is considered as an effective therapeutic strategy. Here, we studied the aromatic-interaction-mediated inhibitory effect of oligomeric polypeptides (K8Y8, K4Y8, K8W8) on Aβ42 fibrillization process. The polypeptides containing lysine as well as representative aromatic amino acids of tryptophan or tyrosine were found to greatly suppress the aggregation as evaluated by thioflavin T assay. Circular dichroism spectra showed that the β-sheet formation of Aβ42 peptides decreased with the polypeptide additives. Molecular docking studies revealed that the oligomeric polypeptides could preferentially bind to Aβ42 through π-π stacking between aromatic amino acids and Phe19, together with hydrogen bonding. The cell viability assay confirmed that the toxicity of Aβ42 to SH-SY5Y cells was markedly reduced in the presence of polypeptides. This study could be beneficial for developing peptide-based inhibitory agents for amyloidoses. Copyright © 2017 European Peptide Society and John WileySons, Ltd.

We present for the first time an enhanced interaction affinity between an abundant soluble protein (human serum albumin) and a membrane protein (chemokine receptor 4) mediated by a dual-affinity peptide E5.

The β-amyloid (Aβ) peptide plays an important role in the onset and progress of Alzheimer's disease (AD). Therefore, studies on inhibiting fibril formation and thus neurotoxicity of Aβ could be beneficial for the prevention and treatment of AD. We report a convenient synthetic approach for one-pot preparation of poly-(β-amino ester) copolymerized with the GGLVFF peptide, which is based on the frequently used inhibitor LVFF. The copolymer was found to efficiently inhibit the aggregation and fibrillation of Aβ42 by using fluorescence assay and atomic force microscopy. Reduced β-sheet formation of Aβ42 peptide after addition of copolymer was observed by circular dichroism. Furthermore, the cell viability assay confirmed that the toxicity of Aβ42 for SH-SY5Y cells was markedly reduced in the presence of copolymer. This could be beneficial for AD prevention and treatment and also for the molecular design of inhibitory agents for other amyloidoses.