Synthesis of a silica-bonded bovine serum albumin s-triazine chiral stationary phase for high-performance liquid chromatographic resolution of enantiomers

A novel method of synthesizing protein chiral stationary phase (protein-CSP) is proposed with 2,4,6-trichloro-1,3,5-triazine as the activator. The bovine serum albumin (BSA) based chiral columns (150 x 4.6 mm I.D.) were prepared successfully within 8 h. With tryptophan as the probe solute, it was observed that the BSA immobilized by this method had a better ability to distinguish enantiomers than that activated by glutaric dialdehyde. This may be due to the well-maintained BSA conformation and the larger amount of BSA immobilized on the silica gel. The BSA-CSP prepared by this method was relatively stable under experimental conditions, and the resolution of 13 chiral compounds was achieved. The coupling reaction in this method is mild, reliable and reproducible; it is also suitable for the immobilization of various biopolymers in the preparation of bioreactor, biosensor and affinity chromatography columns.     

Separation of basic, acidic and neutral compounds by capillary electrochromatography using uncharged monolithic capillary columns modified with anionic and cationic surfactants

A mode of capillary electrochromatography (CEC), based on the dynamical adsorption of surfactants on the uncharged monolithic stationary phases has been developed. The monolithic stationary phase, obtained by the in situ polymerization of butyl methacrylate with ethylene dimethacrylate, was dynamically modified with an ionic surfactant such as the long-chain quaternary ammonium salt of cetyltrimethylammonium bromide (CTAB) and long-chain sodium sulfate of sodium dodecyl sulfate (SDS). The ionic surfactant was adsorbed on the surface of polymeric monolith by hydrophobic interaction, and the ionic groups used to generate the electroosmotic flow (EOF). The electroosmotic mobility through these capillary columns increased with increasing the content of ionic surfactants in the mobile phase. In this way, the synthesis of the monolithic stationary phase with binary monomers can be controlled more easily than that with ternary monomers, one of which should be an ionic monomer to generate EOF. Furthermore, it is more convenient to change the direction and magnitude of EOF by changing the concentration of cationic or anionic surfactants in this system. An efficiency of monolithic capillary columns with more than 140000 plates per meter for neutral compounds has been obtained, and the relative standard deviations observed for to and retention factors of neutral solutes were about 0.22% and less than 0.56% for ten consecutive runs, respectively. Effects of mobile phase composition on the EOF of the column and the retention values of the neutral solutes were investigated. Simultaneous separation of basic, neutral and acidic compounds has been achieved.     

The molecular mechanism of stabilization of proteins by TMAO and its ability to counteract the effects of urea

Trimethylamine n-oxide (TMAO) is a naturally occurring osmolyte that stabilizes proteins and offsets the destabilizing effects of urea. To investigate the molecular mechanism of these effects, we have studied the thermodynamics of interaction between TMAO and protein functional groups. The solubilities of a homologous series of cyclic dipeptides were measured by differential refractive index and the dissolution heats were determined calorimetrically as a function of TMAO concentration at 25 degrees C. The transfer free energy of the amide unit (-CONH-) from water to 1 M TMAO is large and positive, indicating an unfavorable interaction between the TMAO solution and the amide unit. This unfavorable interaction is enthalpic in origin. The interaction between TMAO and apolar groups is slightly favorable. The transfer free energy of apolar groups from water to TMAO consists of favorable enthalpic and unfavorable entropic contributions. This is in contrast to the contributions for the interaction between urea and apolar groups. Molecular dynamics simulations were performed to provide a structural framework for the interpretation of these results. The simulations show enhancement of water structure by TMAO in the form of a slight increase in the number of hydrogen bonds per water molecule, stronger water hydrogen bonds, and long-range spatial ordering of the solvent. These findings suggest that TMAO stabilizes proteins via enhancement of water structure, such that interactions with the amide unit are discouraged.     

Synthesis of (+)-zeylenone from shikimic acid

Starting from shikimic acid, the total synthesis of zeylenone was studied. The product was proved to be the (+)antipode of zeylenone through analysis and comparison of their respective spectra (including NMR, MS, IR and CD) and optical data. The absolute configuration of the natural product was thus determined to be (1S,2S,3R).     

消旋反式菊酸α—氰基—4—氟—3—苯氧基苄酯的合成

含氟拟除虫菊酯的合成是近年来新型高效拟除虫菊酯研究工作的方向之一。该类化合物由于具有高效、低毒、广谱、低残留、无致癌、致畸作用,有的还具有低鱼毒,杀螨的特性,因此倍受注目。西德拜尔公司开发的百治菊酯(Baythroid)(1)便是其中一种高效杀虫剂。     

反相键合相高效液相色谱法分离测定萘普生

 建立了分离测定萘普生和溴代萘普生的反相键合相高效液相色谱法。采用ＯＤＳ柱，以添加５０ｍｍｏｌ／Ｌ乳酸并用高氯酸调节ｐＨ为２．５的８０％甲醇－水溶液作为流动相，以苯甲酸为内标物，测定了不对称合成工艺产物中萘普生和溴代萘普生的含量。方法的准确度分别为９９．８３％～１０２．０７％（萘普生）和９９．０％～１００．８３％（溴代萘普生），相对标准偏差分别小于２．５８％（萘普生）和３．６４％（溴代萘普生）。方法可用于工艺条件的选择和质量检测。     

Crystal structure and strong antiferromagnetic interaction of a terephthalate-bridged binuclear copper(II) Complex, [{Cu(dipn)}2(μ-TPHA)](ClO4)2 (dipn = N-(3-aminopropyl)-1,3-propanediamine)

Three binuclear copper(II) complexes bridged by three different bridging ligands: μ-TPHA (terephthalato), μ-PHTA (phthalato) and μ-TCB (tetracarboxylatobenzene) have been synthesized. The crystal structure of [{Cu(dipn)}₂(μ-TPHA)](ClO₄)₂ where dipn = N-(3-aminopropyl)-1,3-propanediamine was solved at room temperature. The [{Cudipn}₂(μ-TPHA)](ClO₄)₂ complex consists of a μ-terephthalato bridging binuclear copper(II) cationic unit and two non-coordinated perchlorate anions. The TPHA ligand bridges in a bismonodentate fashion. The environment of the copper(II) ion is a distorted plane-square-planar coordination sphere. The magnetic properties of the three complexes have been investigated in the 75–300 K range, and show that the geometry of the Cu^II atom is the important factor for magnetic interactions in the terephthalato bridging binuclear copper(II) complexes. This revised version was published online in June 2006 with corrections to the Cover Date.     

Color-tunable photoluminescence of alloyed CdS(x)Se(1-x) nanobelts

High-quality CdSxSe1-x nanobelts of variable composition (0 相似文献   

“双一流”背景下高等农业院校有机化学基础课程教学新模式的构建及实践

The crop science of Sichuan Agricultural University is an authorized first-class discipline. As the strategic supporting department for innovative talent cultivation in agriculture and forestry major, we are facing a long-term challenge in reforming the teaching mode for basic course-organic chemistry and cultivating talented students with solid basic knowledge and strong sense of innovation. Herein a thorough survey was performing to establish the executable teaching programs for this course during the "Double-First Class Universities Plan" period. A multidimensional teaching resource library for organic chemistry course was also constructed. The new classroom teaching mode "Interest cultivation-Creative thought development-Autonomous and Cooperative learning", along with a stepwise practice teaching mode "Foundation skills-Integrated application-Innovative trial" was proposed and practiced among thirty-five majors including agriculture, forestry and veterinary, to improve the quality for innovative talent cultivation and support our first-class discipline construction. This research could probably serve as a reference for congeneric agricultural university.     

Regulation of redox balance using a biocompatible nanoplatform enhances phototherapy efficacy and suppresses tumor metastasis

Many cancer treatments including photodynamic therapy (PDT) utilize reactive oxygen species (ROS) to kill tumor cells. However, elevated antioxidant defense systems in cancer cells result in resistance to the therapy involving ROS. Here we describe a highly effective phototherapy through regulation of redox homeostasis with a biocompatible and versatile nanotherapeutic to inhibit tumor growth and metastasis. We systematically explore and exploit methylene blue adsorbed polydopamine nanoparticles as a targeted and precise nanocarrier, oxidative stress amplifier, photodynamic/photothermal agent, and multimodal probe for fluorescence, photothermal and photoacoustic imaging to enhance anti-tumor efficacy. Remarkably, following the glutathione-stimulated photosensitizer release to generate exogenous ROS, polydopamine eliminates the endogenous ROS scavenging system through depleting the primary antioxidant, thus amplifying the phototherapy and effectively suppressing tumor growth in vitro and in vivo. Furthermore, this approach enables a robust inhibition against breast cancer metastasis, as oxidative stress is a vital impediment to distant metastasis in tumor cells. Innovative, safe and effective nanotherapeutics via regulation of redox balance may provide a clinically relevant approach for cancer treatment.

Amplified oxidative stress achieved by modulating redox homeostasis with PDA–MB for highly effective synergistic phototherapy to inhibit primary tumors and metastases.