Motion‐Induced Changes in Emission as an Effective Strategy for the Ratiometric Probing of Human Serum Albumin and Trypsin in Biological Fluids

Herein, we report the formation of a highly luminescent, pH‐sensitive, thermoreversible nanoaggregate in pure aqueous medium through the self‐agglomeration of carbazole‐based amphiphiles. The self‐assembly process restricted the intramolecular motion of the molecules and induced a change in its emission signal from blue to cyan, owing to an aggregation‐induced emission (AIE) effect. A similar type of ratiometric response was also observed in the presence of human serum albumin (HSA). However, in this case, the molecular motion of the flexible fluorescent probe was restricted by its embedded microenvironment, owing to a motion‐induced change in emission (MICE) effect, not by aggregation. Moreover, the probe showed quite high selectivity for HSA over other serum albumin proteins. Our carbazole‐based fluorescent probes are a unique example of the ratiometric sensing of HSA through the sole involvement of reversible noncovalent interactions. Considering the important of HSA in clinical diagnosis, a wide range of biological fluids, such as human urine, saliva, and plasma, were screened to analyze their HSA content. In addition, this system was also employed for the detection of trypsin at subnanomolar concentrations through the digestion of HSA.     

Proliferative and antioxidant activity of Symphytum officinale root extract

The root of Symphytum officinale L. is commonly used in folk medicine to promote the wound healing, reduce the inflammation and in the treatment of broken bones. The objective of our investigation was to analyse the extract from S. officinale in term of its antioxidant activity and the effect on cell viability and proliferation of human skin fibroblast (HSF). Moreover, the quantification of main phenolics and allantoin was conducted using HPLC–DAD method. Five compounds were found: rosmarinic, p-hydroxybenzoic, caffeic, chlorogenic and p-coumaric acid. DPPH, FRAP and TPC assay showed the high antioxidant activity of the extract. MTT test proved the stimulatory effect on cell metabolism and viability of HSF cells. Moreover, no changes in cytoskeleton structure and cells shape were observed. The obtained results indicate that non-toxic extract from S. officinale root has strong antioxidant potential and a beneficial effect on human skin fibroblasts.     

Polyphenolic characterisation and bioactivity of an Oxalis pes-caprae L. leaf extract

The present work is focused on the characterisation of the polyphenolic content of an Oxalis pes-caprae L. leaf extract and on the evaluation of its bioactivity with particular interest on its vascular activity and antioxidant potential. The polyphenolic content was characterised by HPLC-DAD and LC-MS/MS. The vascular activity was evaluated according to the influence on the serotonergic and adrenergic systems of the human internal mammary artery (HIMA). Antioxidant and neuroprotective studies were also conducted. Several luteolin and apigenin derivatives were identified as main constituents of the extract, which did not present any contractile effect nor had any effect on the serotonergic system of HIMA. However, it showed antagonistic effect on the adrenergic system, inhibiting the contraction to noradrenaline (reduction of 58.44% of maximum contraction). The extract showed antioxidant activity and standardised luteolin and apigenin derivatives showed neuroprotective potential, particularly homoorientin.     

Determination of Pesticides in Organic Carrots by High-Performance Liquid Chromatography/High-Resolution Mass Spectrometry

Food contamination by pesticide residues, which may cause serious human health problems, is an ongoing challenge. Safer organically grown food is therefore needed. However, best practices are not always followed for farming organic foods, necessitating analytical testing. To this end, this report describes an analytical method for the evaluation of 82 pesticides by high-performance liquid chromatography–high-resolution mass spectrometry in organically grown carrots. The method was validated in terms of linearity, precision, and limits of detection and quantification that ranged from 0.3 to 5 and 5–40?µg?kg^?1, respectively. From the 82 pesticides evaluated in this multiresidue method, three were detected in real samples, with bendiocarb detected at the highest concentration (199.11?µg?kg^?1), which was above the maximum residue limit. Chlorpyriphos (43.20?µg?kg^?1) and amitraz (11.22?µg?kg^?1) were also detected. Measurement of contaminants in organic foods should be a standard practice, which would contribute to improved food safety. It is observed that even organic foods can be contaminated by pesticides, intentionally or unintentionally, perhaps by cross-contamination. Pesticides in organic foods are a public health problem because consumers expect organic foods to be free of pesticide contamination, but this is not necessarily the case.     

An electromembrane extraction–HPLC‐UV analysis for the determination of valproic acid in human plasma

In this study, an electromembrane extraction (EME) method combined with a simple HPLC‐UV analysis was developed and validated for the determination of valproic acid in human plasma samples. The major parameters influencing EME procedure, namely the solvent composition, voltage, pH of acceptor and donor solutions, salt effect, and time of extraction, were evaluated and optimized. The drug was extracted from the donor aqueous sample solution (pH 5) to the acceptor aqueous solution (pH 13). The donor and acceptor phases were separated by a hollow fiber dipped in 1‐octanol as a supported liquid membrane. A voltage of 60 V during 25 min was applied as the driving force. The drug concentration enrichment factor obtained was >125, which enhanced the sensitivity of the method. The limit of detection and the limit of quantitation were 0.2 and 0.5 μg/mL, respectively. The proposed method was successfully applied to a human plasma sample, with a relative recovery of 75%. The method was linear over the range 0.5–10 μg/mL for valproic acid (R² > 0.9996) with a repeatability (%RSD) between 0.9 and 3.3% (n = 3). Valproic acid is an anticonvulsant drug with poor UV absorption, and EME can improve the sensitivity of HPLC‐UV for the determination of valproic acid in plasma samples.     

乡村振兴战略下农村人居环境整治PPP模式合作行为演化博弈分析

农村人居环境整治是乡村振兴战略的重要内容,基于有限理性的演化博弈理论,构建了以地方政府、社会资本和农村居民为博弈主体的农村人居环境整治PPP模式合作行为演化博弈模型,运用Matlab软件分析了三方主体的初始意愿和政府规制对三方主体行为策略演化的影响。研究发现:(1)政府规制对农村人居环境整治PPP模式合作博弈系统演化的影响从大到小依次是:政府对社会资本的补贴资助、投机罚金、合作奖励和政府对农村居民的参与奖励。(2)与提高地方政府对社会资本的补贴资助力度和惩罚力度相比,提高地方政府的激励规制初始意愿更能促进农村人居环境整治PPP项目的顺利落地实施。(3)农村居民参与PPP项目的初始意愿的提升关键在于提高农村居民参与收益。最后,为促进PPP模式在农村环境治理领域的应用与发展和推动农村人居环境整治的可持续改善提出相应建议。     

网络结构、资本缓冲与银行系统性风险传染效应——来自2007~2017年中国14个上市商业银行数据

银行体系稳健运行对国民经济健康发展具有重要意义。选取2007~2017年中国14个上市商业银行数据,利用债务矩阵构建银行网络,运用无残差完全分解模型将其分解为网络结构和资本缓冲两个因素,对我国银行系统性风险传染效应研究。结果表明:网络结构与银行系统性风险存在复杂的关联性,而资本缓冲与银行系统性风险有显著负相关关系;在金融危机期间,网络结构是诱导银行系统性风险波动的决定性因素,资本缓冲对降低银行系统性风险有重要作用。此外国有商业银行与其他银行债务关系更为紧密,对系统性金融风险贡献较大,中国银行处于网络结构中重要位置,中国工商银行和中国建设银行处于次重要位置。该结果为资本监管政策和宏观审慎政策有效实施提供了理论依据。     

Synthetic peptides for study of human immunodeficiency virus infection

The formation of a complex among gp120, CD4, and CCR5/CXCR4 represents a key step in human immunodeficiency virus (HIV) infection. The use of synthetic peptides reproducing sequences of these surface proteins has increased knowledge about the interactions that determine the penetration of HIV viruses into target cells. The final aim of such investigations is the design of molecules able to inhibit the initial step of infection and the development of high-sensitivity in vitro assays for detection of HIV. In particular, the studies presented herein concern the role of the gp120 V3 loop in the CD4 binding, the importance of the N-terminal sequence of HIV-coreceptor CCR5, the sequences patterned on CXCR4 natural ligand (stromal-derived factor 1 [SDF-1]) as inhibitory peptides, and the importance of substrate secondary structure in determining the enzymatic processing of gp120 precursor (gp160).     

Study of interactions between actinomycin D and oligonucleotides by microchip electrophoresis and ESI-MS

In the present study, the interactions between actinomycin D (ActD) and single stranded DNA (ssDNA) 5′-CGTAACCAACTGCAACGT-3′ and a duplex stranded DNA (dsDNA) with this sequence were investigated by microchip-based non-gel sieving electrophoresis and electrospray ionization mass spectrometry (ESI-MS). The ssDNA was designed according to the conserved regions of open reading frame 1b (replicase 1B) following the Tor 2 SARS genome sequence of 15611-15593. The binding constants of the interactions between ActD and ssDNA/dsDNA were (8.3 ± 0.32) × 10⁶ M⁻¹ (ssDNA) and (2.8 ± 0.02) × 10⁵ M⁻¹ (dsDNA), respectively, calculated from microchip electrophoresis via Scatchard plot. The binding stoichiometries were 1:1 (single/1ActD molecule) and 1:2 (duplex/2ActD molecules) calculated from microchip electrophoresis, and the results were further verified by ESI-MS. The results obtained by these two methods indicated that ActD bound much more tightly to ssDNA used in this work than dsDNA. Furthermore, this is shown that the microchip-based non-gel sieving electrophoresis method is a rapid, highly sensitive and convenient method for the studies of interactions between DNA and small molecule drugs.     

结合电生孔技术的抗体-纳米TiO2靶向光敏杀癌细胞

报道了用免疫、电生孔和纳米TiO₂光催化组合技术进行杀伤结肠癌LoVo细胞的研究. 先把结合LoVo细胞表面CEA抗原的单克隆抗CEA抗体吸附在纳米TiO₂微粒表面, 抗体-纳米TiO₂复合微粒就会自动吸附到LoVo细胞的表面, 然后用电脉冲法使LoVo癌细胞的细胞膜上产生小孔, 促使纳米TiO₂微粒进入癌细胞内部. 最后在紫外光照射下使TiO₂纳米粒子在癌细胞内部发生光催化氧化作用, 杀伤癌细胞. 结果表明, 这种组合技术具有很高的杀癌细胞能力. 在仅含3.12 μg/mL抗体-纳米TiO₂的细胞培养液内和强度为4 mW/cm²的紫外光照射下, 可在30 min内将所有LoVo癌细胞杀死. 这种技术对LoVo癌细胞的杀伤力远高于对不表达CEA抗原的人正常TE353.sk细胞的杀伤力, 显示了组合技术杀癌细胞的高选择性. 因此, 这种组合技术有望成为治疗癌症的新方法, 值得进一步探索.