Amino-acid containing metallomonomers copolymerized into porous organic polymers: applicability to allylic alkylation catalysis

This paper reports the synthesis of a polymerizable dppe-derivative with eight pendent styrenyl units linked to the dppe core through four tyrosine residues. This diphosphine ligand was utilized in the synthesis of a series of P₂PdX₂ complexes (X₂=(R)-BINOL, (S)-BINOL, Cl₂ and π-1,3-Ph₂-allyl⁺). The compounds were used as comonomers for the synthesis of porous organic polymers (poly EDMA). Molecular imprinting effects on X₂-ligand removal were investigated. Overall, the presence of a cavity of significant size was found to be beneficial to the rate of the allylic alkylation reaction, however, chiral BINOL shaped cavities did not influence the enantio-selectivity of the reaction.     

Glycans of higher plant peroxidases: recent observations and future speculations

Plant peroxidases are composed of a peptide and associated heme, calcium and glycans. The 3D structure of the major cationic peanut peroxidase has revealed the sites of the heme and calcium. But the diffraction of the glycans was not sufficient to show their structure. This review presents research that has been executed to obtain putative glycans and their binding sites, and to gain an indirect insight into these glycans. It also offers approaches that will be used to determine the function of the glycans on the peanut peroxidase. Some comparisons are made with other plant glycoproteins including peroxidases from plants other than peanut.     

Positively charged acyl derivatives of carbohydrates as promising transfection agents

A convenient approach to the synthesis of mono-and polycationic glycolipid amphiphiles is suggested. The compounds obtained can be used for studying the structure-activity relationship and determination of the effect of hydrophobic and cationic domains on the transfection efficiency.     

Production of polyhydroxyalkanoates (PHAs) from waste materials and by-products by submerged and solid-state fermentation

Polyhydroxyalkanoates are biodegradable polymers produced by prokaryotic organisms from renewable resources. The production of PHAs by submerged fermentation processes has been intensively studied over the last 30 years. In recent years, alternative strategies have been proposed, such as the use of solid-state fermentation or the production of PHAs in transgenic plants. This paper gives an overview of submerged and solid-state fermentation processes used to produce PHAs from waste materials and by-products. The use of these low-cost raw materials has the potential to reduce PHA production costs, because the raw material costs contribute a significant part of production costs in traditional PHA production processes.     

Fluorescence cross-correlation spectroscopy as a valuable tool to characterize cationic liposome-DNA nanoparticle assembly

The development of nonviral gene delivery vehicles for therapeutic applications requires methods capable of quantifying the association between the genes and their carrier counterparts. Here we investigate the potential of fluorescence cross-correlation spectroscopy (FCCS) to characterize and optimize the assembly of nonviral cationic liposome (CL)-DNA complexes based on a CL formulation consisting of the cationic lipid DOTAP and zwitterionic lipid DOPC. We use a DNA plasmid for lipoplex loading encoding the Oct4 gene, critically involved in reprogramming somatic cells into induced pluripotent stem cells. We demonstrate that FCCS is able to quantitatively determine the extent of the association between DNA and the liposomes and assess its loading capacity. We also establish that the cationic lipid fraction, being proportional to the liposome membrane charge density, as well as charge ratio between the CLs and anionic DNA play an important role in the degree of interaction between the liposomes and DNA.     

Modification of the Benoit model for β1-4 glucans

The Benoit model for β1-4 glucans is considered taking into account intrachain hydrogen bonds. This model is basis for calculation of equilibrium rigidity of chains with completely free rotation. Analysis of the experimental value of equilibrium rigidity is carried out and the fraction of hinge C(1)OC(4) bonds about which rotation is free is evaluated.     

Mechanisms of amino acid partitioning in cationic reversed micelles

The aim of this work is to discuss the mechanisms involved in amino acidsolubilization in cationic reversed micelles. A simple mechanism was assumedin which the amino acid solubilization is mediated by an ion-exchangeprocess between the amino acid and the surfactant counter ion neglecting theeffect of the reversed micellar structure. Based on this mechanism a simplemodel to predict equilibrium was developed and applied to the solubilizationof amino acids with different structures. It was found that solubilizationof hydrophilic and slightly hydrophobic amino acids can be described by anion-exchange mechanism and the amino acid equilibrium concentration can bedetermined for different experimental conditions using this model. However,solubilization of hydrophobic amino acids can not be described by a simpleion-exchange model. In this case hydrophobic contributions play an importantrole in amino acid solubilization and must be considered in the overallsolubilization process. This hydrophobic contribution was evaluated bydetermination of an interfacial partition coefficient. The overall aminoacid extraction was determined using distribution coefficients of all theamino acid forms and considering their dependence on ionic strength.     

Synthesis and characterization of 3-thiophene carboxamides containing a pyridine ring: structure, electrochemistry, and complexation

A series of new thiophene amides containing a pyridine ring has been synthesized and characterized. Single crystal X-ray structures have been determined for four of the new substances which show two distinct patterns of hydrogen-bonding. The crystal structure of the copper (II) complex of one of the ligands shows that the bonding is O,N in a square planar geometry with perchlorate ions in the axial positions. The new compounds do not undergo electropolymerization due to primary oxidation of the amide function but tuning of the amide group by introduction of an electron-withdrawing group on the pyridine ring allows electropolymerization to occur.     

酶促聚合：绿色的高分子材料合成技术

以酶促聚合为代表的绿色高分子合成途径，以其反应条件温和、产物多分散性低、无金属催化剂残留、高度立体和区位选择性等优势，成为医用高分子材料合成领域中的研究热点。目前，氧化还原酶、水解酶、转移酶均成功应用于聚合反应，其中脂肪酶催化的缩聚反应及开环聚合反应研究最为广泛，同时，以可逆加成-断裂链转移聚合和原子转移自由基聚合为代表的酶促可逆失活自由基聚合得到了快速发展。针对酶促聚合中单体及合成产物结构与性能单一、应用范围有限等缺陷，基于酶促聚合与原子转移自由基聚合、开环易位聚合等反应的偶联，制备了多种不同结构与性能的聚合物材料，推动了上述材料在药物与基因递送领域中的应用。本文综述了脂肪酶催化聚合、酶促可逆失活自由基聚合、酶促化学偶联催化等方面的研究进展，并探讨了目前研究的局限性和未来研究方向。