羟烷基壳聚糖制备及应用研究进展

壳聚糖是由甲壳素通过脱乙酰作用得到的一种天然高分子多糖,具有良好的生物相容性、抗菌性、无毒和可生物降解等优点,但壳聚糖水溶性差限制了其在很多方面的应用。为克服壳聚糖在水溶性上的不足,利用壳聚糖结构中氨基和羟基上的活泼氢进行化学改性以引进羟烷基等亲水性基团成为重要手段。本文主要对壳聚糖羟烷基化改性的方法及羟烷基壳聚糖在医药、水处理和组织工程材料等领域的研究和应用现状进行介绍,并对羟烷基壳聚糖未来的发展趋势进行了展望。     

One‐Step Labeling of Collagen Hydrogels with Polydopamine and Manganese Porphyrin for Non‐Invasive Scaffold Tracking on Magnetic Resonance Imaging

Biomaterial scaffolds are the cornerstone to supporting 3D tissue growth. Optimized scaffold design is critical to successful regeneration, and this optimization requires accurate knowledge of the scaffold's interaction with living tissue in the dynamic in vivo milieu. Unfortunately, non‐invasive methods that can probe scaffolds in the intact living subject are largely underexplored, with imaging‐based assessment relying on either imaging cells seeded on the scaffold or imaging scaffolds that have been chemically altered. In this work, the authors develop a broadly applicable magnetic resonance imaging (MRI) method to image scaffolds directly. A positive‐contrast “bright” manganese porphyrin (MnP) agent for labeling scaffolds is used to achieve high sensitivity and specificity, and polydopamine, a biologically derived universal adhesive, is employed for adhering the MnP. The technique was optimized in vitro on a prototypic collagen gel, and in vivo assessment was performed in rats. The results demonstrate superior in vivo scaffold visualization and the potential for quantitative tracking of degradation over time. Designed with ease of synthesis in mind and general applicability for the continuing expansion of available biomaterials, the proposed method will allow tissue engineers to assess and fine‐tune the in vivo behavior of their scaffolds for optimal regeneration.     

Molecular Mechanism Study on Effect of Biodegradable Amino Acid Ester–Substituted Polyphosphazenes in Stimulating Osteogenic Differentiation

Amino acid ester substituted polyphosphazenes are osteoactive benefiting from their phosphorus‐containing chemical structure, which highlights interests in bone tissue engineering. To correlate their chemical structures with cell activities, in this study, poly[(ethyl alanato)_0.3(ethyl glycinato)_0.7phosphazene] (PAGP) and poly[(ethyl phenylalanato)_0.3(ethyl glycinato)_0.7phosphazene] (PPGP) are synthesized to carry out studies on cell osteogenic differentiation. In the non‐contact culture manner, bone mesenchymal stromal cells (BMSCs) are cultured in transwell chambers containing PAGP or PPGP films, while the cells and the materials do not contact. In the contact culture manner, BMSCs are cultured on the PAGP or PPGP films. In the meantime, solutions containing PAGP or PPGP degradation products (i.e., phosphate, ammonium, and corresponding amino acids) are applied for cell culture using inorganic phosphate (Pi) ion as control. Thus, the influences from substrate surface and degradation products can be identified separately. The results reveal that both the phosphorus‐containing surface of PAGP and PPGP films and their degradation products play significant roles in regulating cell behaviors. In comparison with PAGP, PPGP seems able to provide relatively stable phosphorus‐containing surface to strengthen the cell‐scaffold interaction because of its slower degradation rate and higher Young's modulus, leading to greater promotion in osteogenic differentiation via contact effect.     

基于真实情境开展化学学科核心素养为本的教学案例

从《普通高中化学课程标准（2017年版）》的教学标准和考试大纲化学部分的考查标准出发,探讨素养为本的教学和学业评价中真实情境对教、学、考有机衔接的促进作用。通过基于真实情境的不同类型的主题教学实践案例,阐述认知台阶搭建、主题研究任务开发、教材内容整合、情境化单元课程建设与社会生活、生产实践、科技研究、实验探究的有效链接,为学生创设驱动性任务,在实际问题解决过程中构建联系性、发展性的知识框架和认知模型的教学设计策略,呈现素养为本的教学案例。     

英国CIE A-level化学教材与人教版高中化学教材中“有机化学”模块的比较研究

以中英2国高中化学教材中的有机化学模块为切入点，对英国CIE A-level化学教材与人教版高中《化学2（必修）》及《有机化学基础（选修5）》在该模块中的课程标准、结构体系、内容选取及组织呈现、栏目设计、典型知识点的编排等方面进行比较，分析英国CIE A-level化学教材的特色和优势。     

Total spontaneous resolution of chiral covalent networks from stereochemically labile metal complexes

Stereochemically labile copper and zinc complexes with the N,N'-dimethylethylenediamine ligand (dmeda) have been shown to be promising precursors for the total spontaneous resolution of chiral covalent networks. (N,N')-[Cu(NO3)2(dmeda)]infinity crystallises as a conglomerate and yields either enantiopure (R,R)-1 or enantiopure (S,S)-1. A mixed-valence copper(I/II) complex, [{Cu(II)Br2(dmeda)}3(Cu(I)Br)2]infinity (2), which crystallises as a pair of interpenetrating chiral (10,3)-a nets, is formed from CuBr, CuBr2 and dmeda. One net contains ligands with solely (R,R) configuration and exhibits helices with (P) configuration while the other has solely (S,S)-dmeda ligands and gives rise to a net in which the helices have (M) configuration. The whole crystalline arrangement is racemic, because the interpenetrating chiral nets are of opposite handedness. With zinc chloride (R,S)-[ZnCl(dmeda)2]2[ZnCl4] (3) is obtained, which is a network structure, although not chiral. Total spontaneous resolution of stereochemically labile metal complexes formed from achiral or racemic building blocks is suggested as a viable route for the preparation of covalent chiral networks. Once the absolute structure of the compound has been determined by X-ray crystallography, a quantitative determination of the enantiomeric excess of the bulk product can be undertaken by means of solid-state CD spectroscopy.     

Molecular recognition of l-leucyl-l-alanine: enantioselective inclusion of alkyl methyl sulfoxides

A simple aliphatic dipeptide, l-leucyl-l-alanine (Leu-Ala), includes several alkyl methyl sulfoxides enantioselectively to form inclusion crystals. From single-crystal X-ray analyses of three inclusion compounds of dimethyl sulfoxide (DMSO), isobutyl methyl sulfoxide, and benzyl methyl sulfoxide, it was elucidated that Leu-Ala molecules self-assemble to form layer structures and the sulfoxides are included via hydrogen bonding in a cavity between these layers. The inclusion cavity has methyl group and isobutyl group at its each side, and the guest sulfoxide is placed in such a manner that its methyl group faces toward the methyl of the Leu-Ala cavity. When the alkyl group of the sulfoxide is comparably large, it is located in the residual space of the cavity to attain effective crystal packing. Thus, the sulfoxides having a comparably large group such as isobutyl, butyl, and benzyl are included with a high (R)-enantioselectivity in Leu-Ala crystals.