An Unusual Dehydratase Acting on Glycerate and a Ketoreducatse Stereoselectively Reducing α‐Ketone in Polyketide Starter Unit Biosynthesis

Polyketide synthases (PKSs) usually employ a ketoreductase (KR) to catalyze the reduction of a β‐keto group, followed by a dehydratase (DH) that drives the dehydration to form a double bond between the α‐ and β‐carbon atoms. Herein, a DH*‐KR* involved in FR901464 biosynthesis was characterized: DH* acts on glyceryl‐S‐acyl carrier protein (ACP) to yield ACP‐linked pyruvate; subsequently KR* reduces α‐ketone that yields L ‐lactyl‐S‐ACP as starter unit for polyketide biosynthesis. Genetic and biochemical evidence was found to support a similar pathway that is involved in the biosynthesis of lankacidins. These results not only identified new PKS domains acting on different substrates, but also provided additional options for engineering the PKS starter pathway or biocatalysis.     

Auto‐Oxidative Coupling of Glycine Derivatives

The unprecedented title reaction between glycine derivatives and indoles, as well as the auto‐oxidative Povarov/aromatization tandem reaction of glycine derivatives with olefins are described. The reactions were performed in the absence of redox‐active catalysts and chemical oxidants under mild reaction conditions. Only simple organic solvents and air (or O₂) were required.     

Two‐Component Supramolecular Gels Derived from Amphiphilic Shape‐Persistent Cyclo[6]aramides for Specific Recognition of Native Arginine

A unique supramolecular two‐component gelation system was constructed from amphiphilic shape‐persistent cyclo[6]aramides and diethylammonium chloride (or triethylammonium chloride). This system has the ability to discriminate native arginine from 19 other amino acids in a specific fashion. Cyclo[6]aramides show preferential binding for the guanidinium residue over ammonium groups. This specificity was confirmed by both experimental results and theoretical simulations. These results demonstrated a new modular displacement strategy, exploring the use of species‐binding hydrogen‐bonded macrocyclic foldamers for the construction of two‐component gelation systems for selective recognition of native amino acids by competitive host–guest interactions. This strategy may be amenable to developing a variety of functional two‐component gelators for specific recognition of various targeted organic molecular species.     

Synthesis and self-assembly behavior of thermoresponsive triblock copolymer

Block copolymers comprising thermosensitive poly(N-isopropylacrylamide) (PNIPAM) and hydrophobic poly(n-butyl acrylate) (PBA) blocks, were synthesized using the reversible addition-fragmentation chain transfer polymerization (RAFT), their thermosensitive behavior was studied by ultraviolet spectrophotometer (UV) and dynamic light scattering (DLS). The lower critical solution temperature (LCST) was strongly correlated to the hydrophobic/hydrophilic ratio of the copolymers. Their micellization and self-assembly behavior in dilute aqueous solution were studied by surface tension (SFT), DLS and TEM. The resulting block copolymers reversibly formed or deformed micellar assemblies during their LCSTs. The critical micelle concentration (CMC) was controlled by the composition of PBA and PNIPAM, indicating the successful formation of the block copolymers.     

High‐expression β1 adrenergic receptor/cell membrane chromatography method based on a target receptor to screen active ingredients from traditional Chinese medicines

β‐Adrenergic receptors are important targets for drug discovery. We have developed a new β₁‐adrenergic receptor cell membrane chromatography (β₁AR‐CMC) with offline ultra‐performance LC (UPLC) and MS method for screening active ingredients from traditional Chinese medicines. In this study, Chinese hamster ovary‐S cells with high β₁AR expression levels were established and used to prepare a cell membrane stationary phase in a β₁AR‐CMC model. The retention fractions were separated and identified by the UPLC–MS system. The screening results found that isoimperatorin from Rhizoma et Radix Notopterygii was the targeted component that could act on β₁AR in similar manner of metoprolol as a control drug. In addition, the biological effects of active component were also investigated in order to search for a new type of β₁AR antagonist. It will be a useful method for drug discovery as a leading compound resource.     

Intrinsic Peroxidase‐like Activity of Porous CuO Micro‐/nanostructures with Clean Surface

Porous CuO micro‐/nanostructures with clean surface, prepared through Cu₂(OH)₂CO₃ precursor followed by calcination in air, were proven to be an effective peroxidase mimic. They can quickly catalyze oxidation of the peroxidase substrate 3,3′,5,5′‐tetramethylbenzidine (TMB) in the presence of H₂O₂, producing a blue color. The obtained porous CuO micro‐/nanostructure have potential application in wastewater treatment. The apparent steady‐state kinetic parameter was studied with TMB as the substrate. In addition, the potential application of the porous CuO in wastewater treatment was demonstrated with phenol‐containing water as an example. Such investigation not only confirms the intrinsic peroxidase‐like activity of micro‐/nanostructured CuO, but also suggests its potential application in wastewater treatment.     

A ladder conjugated polymer transducer for solid-contact Cu2+-selective electrodes

In recent years, there has been a pronounced interest in solid-contact ion-selective electrodes （SC-ISEs）, with emphasis on the use of conducting polymers as ion-to-electron transducer. In this work, a ladder conjugated polymer, thieno[3,2-b]thiophene （LCPT）, was investigated in fabricating Cu2＋-selective electrodes for the first time. The resulting electrodes were characterized by electrochemical impedance spectroscopy （EIS）, chronopotentiometry, and the water layer test. Results proved that the active LCPT facilitates the ion-to-electron transduction, and avoids the detrimental aqueous layer formed at the interface of SC-ISEs.     

Synthesis and properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/chitin nanocrystals composite scaffolds for tissue engineering

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/chitin nanocrystals (CNC) composite scaffolds were synthesized by the salt leaching and thermally induced phase separation (TIPS) technique. The scaffolds have porous structures with macro-pores (100-300 mm in diameters) and micro-pores (10 mm). The surface characteristics of the scaffolds were characterized by X-ray photoelectron spectroscopy (XPS) and static water contact angle measurement, and the mechanical properties were investigated by a compression test. Human adipose-derived stem cells (hADSCs) were seeded onto the PHBV/CNC scaffolds and in vitro cell culture results showed that the composite scaffolds enhanced the hADSCs adhesion, which implies that the material may have potential application in tissue engineering.     

Bromodimethylsulfonium bromide: A brominating reagent for the conversion of anthracene into 9,10-dibromoanthracene

Bromodimethylsulfonium bromide(BDMS) was used as an efficient brominating reagent for the synthesis of 9,10-dibromoanthracene in dichloromethane. The desired products were obtained in excellent yields.     

静电纺丝工艺制备纳米抗菌敷料的研究与应用进展

与传统敷料相比,静电纺丝纳米抗菌敷料具有极大的比表面积和孔隙率,既有益于细胞呼吸,又可阻止细菌感染伤口,并能有效增大抗菌药物与伤口中细菌的作用面积而高效杀菌。此外,纳米敷料还能最大程度仿生细胞外基质的结构,有利于加快细胞和组织的生长,促进受损皮肤的恢复,因而非常适合用做皮肤敷料。本文对静电纺丝纳米抗菌敷料的特点,各类基体材料、抗菌药物在静纺抗菌敷料制备中的应用,以及静纺敷料的抑菌效果做了介绍,并对静电纺丝纳米抗菌敷料的应用前景做了展望。