壳聚糖基可注射型温度敏感性水凝胶

壳聚糖基可注射型温度敏感性水凝胶是一种pH值中性的,在室温或低于室温时可保持液态,温度达到体温时可凝胶化的材料,有望被广泛应用于药物释放和组织工程领域,作为多肽和蛋白质等生物活性药物的可注射型释放载体或组织修复材料.本文介绍了壳聚糖基可注射型温敏性水凝胶的种类、特性、机制和应用等方面的研究进展.     

基于壳聚糖的纳米药物传递体系

壳聚糖作为天然高分子材料,不仅安全无毒、而且具有良好的生物相容性、可生物降解性等优点,在药物传递领域作为纳米载体倍受关注。壳聚糖基纳米载体材料制备条件简单温和,近年来,其相关研究也颇为新颖。本文以载体形成的驱动力作为切入点,从共价交联、离子相互作用、聚电解质络合物和疏水改性四个方面,总结不同种类壳聚糖基纳米载体的构筑方法,同时介绍该载体对药物传递中载药量、载药率、释放行为以及细胞毒性等方面的影响,在此基础上展望其未来的应用前景。     

壳聚糖基抗菌材料的制备研究新进展

壳聚糖及其衍生物的抗菌活性和优良加工性能,使其成为巨大潜力的抗菌材料,可用于食品保鲜、伤口敷料、纺织品功能化和组织工程等方面。本文综述了近年来壳聚糖基抗菌材料的制备研究新进展,并讨论了壳聚糖基材料的抗菌模型及影响抗菌活性的因素,希望对壳聚糖基抗菌材料的制备及抗菌活性的优化提供指导。     

壳聚糖基抗菌型创伤敷料的研究进展

近年来,随着再生医学的快速发展,组织工程技术再造人体组织器官被广泛的关注和研究。其中对加速创伤修复的敷料材料设计非常重要,其结构性质严重影响了再生组织的形态和效果。天然高分子壳聚糖具有广谱抗菌、强效止血作用,无毒性降解物,具有良好的生物相容性、生物活性和生物可降解性良好,能够有效地促进创面愈合和组织修复再生,在生物医用敷料领域具有广阔的应用前景。本文主要综述近年来壳聚糖基创伤敷料设计成型方法,并讨论不同的成型工艺及负载不同抗菌剂的敷料性能及用途差异。以期能够为设计和开发新型壳聚糖基抗菌型创伤敷料材料提供重要参考。     

壳聚糖基智能水凝胶的研究进展

壳聚糖是一种天然高分子,含有氨基和羟基等特征基团;水凝胶是一种高分子交联网络体系,具有亲水性,在水中能够溶胀并保持大量水分而不溶解;“智能化”是自发地对外界环境刺激产生响应的一种特性.壳聚糖基智能水凝胶具有良好的生物相容性和可降解性,正倍受广大研究学者的关注.文章综述了近年来关于pH敏感型、温度敏感型以及pH/温度双重敏感型壳聚糖基智能水凝胶的研究概况,介绍了壳聚糖基水凝胶在医学领域如组织工程、药物释放方面的应用并对其未来的发展方向进行了探讨.     

柱撑壳聚糖的氢键密堆积结构制备生物安全的高性能保润材料

保润剂材料内部含有大量亲水基团,能够增加或长期保持物质的含水量,在医疗保健、食品、化妆品和药品等领域应用广泛.壳聚糖分子具有可生物降解、无毒及抗菌等多种优点,是一种高性能的保润剂.然而,其链中存在多个氢键,这种氢键密堆积结构导致水分子无法储存在颗粒内部,严重削弱了材料的吸水和储水能力.本文采用共价偶联方法,使苯甲酸与壳聚糖发生脱水聚合反应.疏水性苯基结构单元能够将亲水性的柔性链进行柱撑,从而形成水分子的存储空间.基于这种独特的设计,制得材料的比表面积比原来的壳聚糖提高了9倍多,吸水能力也相应提高了3倍多.安全性测试结果表明,小鼠在口服壳聚糖基多孔保润剂后,蛋白质水平均无明显变化,证实了壳聚糖基多孔保润剂没有生物毒性.将壳聚糖多孔保润材料均匀分布在试纸上后,试纸的失水量比商用丙二醇分布的试纸减少了20%.     

壳聚糖基抗菌水凝胶的应用及研究进展

抗菌生物材料因其能够有效抑制细菌感染而被公认为是重要的抗生素替代品。其中抗菌水凝胶因制备工艺简单,结构多样,具有易负载和可控药物释放性、良好的生物相容性和抗菌性等多种特殊功能而受到越来越多的关注。壳聚糖及其衍生物具有高抗菌性、低毒性、生物相容性和降解性等优点被广泛用作抗菌水凝胶材料。本文根据壳聚糖基抗菌水凝胶的性能和抗菌机理,综述了近年来在固有抗菌水凝胶、光响应性抗菌水凝胶、荧光抗菌水凝胶、负载抗菌药物水凝胶和协同抗菌水凝胶等方面的研究进展,探讨了壳聚糖基抗菌水凝胶目前所面临的挑战,并对其未来发展作了展望。     

糖基阳离子表面活性剂的研究进展

由糖基开发出的各种阳离子表面活性剂既有糖基非离子表面活性剂的温和性、低毒性、低刺激性、与阴离子表面活性剂良好的配伍性能和协同增效作用,还有阳离子表面活性剂的杀菌性、抗静电性和柔软性等性能,在洗涤剂、医药、化妆品、农业、材料、皮革、造纸和食品等领域具有广阔的应用前景。本文综述了国内外糖基阳离子表面活性剂的合成路线、分子结构和应用领域,并对该领域的研究现状、存在的问题和未来的发展方向进行了讨论与展望。     

壳聚糖基聚电解质复合物在生物医学领域的应用

近年来,国内外对壳聚糖在生物医学领域的应用研究十分活跃。壳聚糖在低pH时带正电荷,在溶液中可与带负电荷的聚离子形成聚电解质复合物。壳聚糖基聚电解质复合物除了具有壳聚糖的生物相容性,还表现出良好的物理化学性质,在药物控制释放体系、蛋白质分离、生物酶以及细胞固定化等领域具有广泛应用。本文重点介绍壳聚糖与几种天然的或合成的聚阴离子形成的聚电解质复合物及其在生物医学领域的应用。     

胶原蛋白静电纺丝纳米纤维研究进展

由于胶原蛋白静电纺丝纳米纤维具有胶原蛋白的生物活性以及纳米结构材料的优异性能,其在生物医学领域的研究和应用开发取得了非常大的进展。本文首先综述了胶原蛋白静电纺丝纳米纤维的研究现状,讨论了胶原蛋白静电纺丝纳米纤维在组织工程、止血及伤口愈合、载药和防粘连等生物医学领域的应用,最后针对胶原蛋白静电纺丝纳米纤维存在的问题及其未来的发展方向进行了展望。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.