Au纳米颗粒作用下的仿生纳米通道

在自然界的生物体系中,各种各样的离子通道对物质交换、能量输运等生理过程起着重要作用.用人工制备的仿生纳米器件模仿生物孔道的离子输运性质是一项非常具有挑战性的课题.通过在对称柱形聚对苯二甲酸乙二醇酯（PET）聚合物孔道中引入非对称结构,获得了一种具有高整流比的人工纳米孔道体系.通过带正电荷的2-十一烷基-1-二硫脲乙基咪唑啉季铵盐（SUDEI）在柱形纳米孔道的单面吸附,使体系具有了非对称的电荷分布和几何结构,从而具有非线性的离子输运性质,表现出较好的门控性能.Au纳米颗粒可以与SUDEI以Au-S键稳定结合,有效地减小柱孔一端的孔径,进一步提高体系的门控比,且该纳米通道体系非对称响应离子输运有很好的稳定性.     

简易制备高整流比的异质纳米通道

生命体内的离子通道在各种生物功能调节过程及生命活动中具有重要的意义.模仿生物孔道的离子输运性质,构筑人工纳米通道,并研究人工纳米通道的离子输运性质是一项具有重大意义的研究课题.本文通过双面阳极氧化和原位扩孔结合的方法制备了对称结构的沙漏形氧化铝纳米通道.通过在对称结构的沙漏形氧化铝（AAO）纳米通道一侧粘贴一层透明胶带,经过热处理后,获得了一种具有高整流比的有机-无机异质纳米通道.基于非对称的结构和电荷分布,氧化铝纳米通道与有机纳米通道在复合区域形成异质结构.由于多孔AAO纳米通道和有机纳米通道的协同效应,异质纳米通道表现出独特的纳米流体二极管特性,即在比较宽的pH范围内具有单一的整流方向.在该体系中,氧化铝纳米通道内壁的羟基和有机纳米通道内壁的羧基在不同pH值下所带电荷性质不同,使异质结构纳米通道内壁表面电荷的性质和电荷密度发生改变,可以通过调节体系的pH来调控通道内的离子传输.     

pH和钙离子协同控制的纳米流体门控器件

生命体内的钙离子通道在各种生物功能调节过程及生命活动中起着至关重要的作用. 模仿生物体中钙离子通道的各种功能性, 构建人工智能通道, 并研究通道中的钙离子输运性能成为一项非常重要的研究课题. 通过重粒子轰击技术及径迹刻蚀方法在高分子聚合物薄膜上设计并制备了一种非对称的锥形多孔纳米通道. 并且通过在锥形纳米通道内壁修饰功能分子O-磷酸基L-络氨酸(OPLT)使纳米通道具有pH与钙离子协同响应的功能. 此体系模仿了生物体中钙离子响应的离子通道的离子输运行为, 及类似二极管的离子整流特性, 并表现出了稳定的离子门控特性及可逆性. 当pH为5时, 通道内壁修饰的OPLT中的氨基使通道内壁显正电性, 通道表现为选择阴离子, 而排斥阳离子的离子选择输运性能, 加入钙离子后离子电流并无明显变化, 此时纳米通道不具有钙离子响应性质; 当pH为9时, OPLT中的磷酸根基团使通道内壁呈现负电性, 通道表现出选择阳离子, 而排斥阴离子的离子选择输运性能, 此时向纳米系统中加入钙离子, 钙离子与磷酸根离子络合, 离子电流改变. 即OPLT修饰的纳米通道具有pH与钙离子协同响应的性能.     

平行四面体纳米孔道中DNA超结构的组装和离子输运特性

<正>受生物膜离子通道结构和功能的启发,人工制备固体纳米孔道门控开关器件一直备受关注[1,2].基于仿生纳米孔道的非对称离子传输性质制备的离子二极管和场效应管装置对于构建离子电路和能量转换的纳米器件至关重要[3,4].然而,仿生制备的固体纳米孔道在离子传输过程中有漏电流的存在,严重影响了固体纳米孔道应用的灵敏度和信噪比[5].针对这一问题,研究者利用DNA分子的特殊识别和自组装的功能特性,相继构筑了基于DNA和纳米孔道的智能响应体系[6,7].但在之前的研究工作中,分[8]     

纳米多孔金的单分子层门控离子输运性质研究

生物离子通道能够对环境刺激作出响应,有效地调节细胞内外的物质平衡,保证体内的正常生命活动.研究具有生物离子通道功能的人工离子通道对发展离子开关具有重要的意义.本工作利用电化学去合金法制备了具有三维通道结构的纳米多孔金膜,并将其应用于离子通道,研究其离子输运性质.在电场作用下,纳米多孔金由于发生极化而使通道表现出离子整流性质.在纳米多孔金表面修饰十二烷基硫醇单分子层,利用其疏水效应,通道能够阻止离子的传输,使其处于“关闭”态.溶液中的化学刺激如表面活性剂能够增强电解质溶液在通道表面的浸润,有利于离子的传输,使通道处于“打开”态.这种单分子层修饰的纳米多孔金表现出表面活性剂响应的离子开关特性.     

刺激响应型生物医用聚合物纳米粒子研究进展

近十几年来, 纳米科学的发展极大地推动了纳米材料在生物医用领域的应用. 聚合物纳米粒子由于其独特的性能在药物传递、医学成像等医用领域备受关注. 其中, 刺激响应型聚合物纳米粒子是一类可以在外界信号刺激下(包括pH、温度、磁场、光等)发生结构、形状、性能改变的纳米粒子. 利用这种刺激响应性可调节纳米粒子的某种宏观行为, 故而刺激响应型聚合物纳米粒子也被称为智能纳米粒子. 因为其特有的“智能性”, 刺激响应型聚合物纳米粒子的研究已成为当前生物材料领域的研究热点. 本文综述了几类重要的生物医用刺激响应型聚合物纳米粒子, 侧重介绍双重及多重刺激响应型聚合物纳米粒子的制备及其生物医学应用.     

溶胶-凝胶多孔性硅胶薄膜的制备及吸附特性研究

研究了纳米硅溶胶和多孔性硅胶薄膜的制备与性能.一定条件下Na2SiO3溶液经过阳离子交挟树脂除去Na+离子后形成纳米硅溶胶,再经过调节pH值和添加化学添加剂如丙三醇、聚乙烯醇(PVA)形成硅溶胶前体.用甩膜法制备的凝胶二氧化硅薄膜在约550℃下热处理30min后,薄膜孔径分布在55～310nm之间.对硅溶胶的粒度分布、粘度和多孔性硅胶薄膜的形貌、孔率分布和吸附性能及相关参数进行了表征,从中得知,通过化学添加剂、调节硅溶胶pH值可控制硅溶胶粒度分布,从而达到控制多孔性硅胶薄膜的徼结构;硅胶薄膜热处理温度在很大程度上影响着硅胶薄膜孔径、孔率分布和吸附量.考虑到硅胶薄膜微结构和吸附特性以及高温下多孔硅胶薄膜会出现熔结现象等因素,二氧化硅溶胶pH为7.5时,凝胶薄膜热处理温度550℃最佳.     

基于AIE效应的多重刺激响应性聚合物纳米微球的制备及其细胞示踪应用

基于AIE分子和智能响应性聚合物构筑的纳米材料,具有优良的AIE发光性能、环境刺激响应性和生物相容性,已在生命科学领域展现出诱人的应用前景. 本研究通过ATRP活性聚合方法, 以合成的TPE-BIB为引发剂, 引发具有多刺激响应特性的N-[2-(二乙氨基)-乙基]丙烯酰胺单体聚合, 成功制备具有温度/pH/CO₂三重响应性的两亲性聚合物: TPE-g-PDEAEAM, 并自组装形成约200 nm的纳米微球. 研究表明: 这种聚合物纳米粒子具有优良的水溶性、单分散性、稳定性及优异的AIE发光特性. 其相转变温度为60 ℃, 溶液荧光对环境温度、pH及CO₂均表现出快速敏感响应性能. 同时, 该纳米粒子表现出低细胞毒性, 能够有效示踪HeLa细胞增殖至11代以上, 有望作为一种活细胞荧光示踪探针材料.     

电致发光聚合物/纳米半导体材料及其双功能器件

电致发光材料在大屏幕平板显示和移动通讯器件方面有着极大的优越性。Ⅱ-Ⅵ族无机半导体、金属有机化合物及共轭聚合物等都是电致发光材料。由半导体纳米晶体和电致发光聚合物组成的双发光器件中,纳米半导体的发光不仅可以通过掺杂及形成核壳结构来加以调节,而且受到其复合体系类型、纳晶含量、外加电压等因素制约;而无机半导体的高电荷输运特性也将影响聚合物发光层的效率。同时,利用无机纳米半导体的光导特性,这种复合体系也可以制成光导与电致发光双功能器件,且其发光效率可有较大幅度提高。     

水下超疏油聚(3,4-乙烯基二氧)噻吩薄膜的制备简

以离子液体溴化(1-己基-3-甲基咪唑盐)作为电解质和掺杂剂采用电化学一步法制备了微纳米复合结构的聚(3,4-乙烯基二氧噻吩)薄膜,薄膜由槽内排布着纳米珠链的棒状结构组成. 研究表明,通过控制电流密度的大小,可以调节棒状结构和珠状结构的平均直径. 离子液体中的咪唑阳离子和对阴离子均掺杂到聚合物中,该薄膜具有可逆的电化学活性及水下超疏油特性.     

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%.     

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.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

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.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.