大豆分离蛋白与壳聚糖复合材料的制备

蛋白质与多糖的静电作用是生物体内一个基本医学-化学现象,是实现自组装的主要驱动力,可利用这种非共价作用设计和构筑理想的微结构。 以大豆分离蛋白(Soybean Protein Isolates,SPI)和壳聚糖(Chitosan,CS)为原料,采用浊度法考察了配比、溶液pH值、离子强度和温度对SPI与CS在溶液中相互作用的影响。 结果显示,由于pH值影响静电作用强度,从而成为影响SPI与CS相互作用的主要因素,其中,当pH值为5.5~6.6时,SPI与CS可以实现有效结合。在较低的离子强度下,有利于形成具有紧凑结构的CS/SPI聚集体,较高离子强度下聚集体发生解离。 蛋白质受热发生变性,多肽链上的疏水氨基酸残基暴露在溶液中,导致与壳聚糖链的疏水作用增强。 DLS结果显示,CS与SPI自组装形成了分布均一的纳米粒子,变性后的SPI与CS形成的纳米粒子粒径有所增大,分布均一;经戊二醛交联,粒径有所减小。 SEM显示,壳聚糖单层膜表面存在龟裂现象,与SPI形成双层膜后龟裂消失;同时,单层膜厚度约为300 nm,双层膜厚度约为500 nm。     

双重响应性核交联星型聚合物的合成及其性能研究

通过"臂优先"的途径和可逆加成-断裂转移(RAFT)自由基聚合制备了以p H响应性聚(3-丙烯酰胺基苯硼酸-co-丙烯酰胺)(PAA-DMP)为线性外臂,温敏性聚(N-异丙基丙烯酰胺-co-苯乙烯-co-N,N-亚甲基双丙烯酰胺)(PNSB)为核的核交联星型聚合物(PNSB@PAA-DMP).采用傅里叶红外光谱(FTIR)、核磁氢谱(1H-NMR)和凝胶渗透色谱(GPC)对产物进行了表征.粒径和形貌也分别通过动态光散射(DLS)和透射电子显微镜(TEM)做了表征.采用紫外可见光谱(UV-Vis)和动态光散射(DLS)考察了聚合物在水中的相变行为.结果表明,所制备的核交联星型聚合物具有p H和温度双重响应,其低临界溶解温度(LCST)可以通过改变核内聚苯乙烯的量来进行调节.除此之外,在高浓度(20 mg/m L)下,还可以通过控制温度和p H实现聚合物溶液溶胶-凝胶(sol-gel)的转化.     

CS/TPP纳米微胶囊的制备及其载药性能

利用离子凝胶法, 以三聚磷酸钠(TPP)为交联剂, 由壳聚糖(CS)制备了CS/TPP纳米微胶囊. 用红外光谱仪、扫描电镜和粒径分析仪进行了表征, 并以牛血清蛋白(BSA)作为模型药物, 考察了所制备的CS/TPP纳米微胶囊的包载和缓释性能. 结果表明, CS/TPP纳米微胶囊的红外光谱相对于CS和TPP的红外光谱发生了很大变化, 说明CS和TPP通过正负电荷吸引聚合成囊; 粒径分析表明, 离子凝胶法可以得到粒径约430 nm的均匀分散的壳聚糖纳米微胶囊, 经冷冻干燥后粒径变为300 nm左右; 微胶囊包封率最高可达79.74%, 模型药物的持续释放时间可达7 d以上.     

壳聚糖复合纳米凝胶的聚合诱导自组装制备及生物应用

以生物大分子壳聚糖为主要组成基元,在壳聚糖的羟基碳上引发单体自由基共聚合。在聚合过程中疏水的合成高分子接枝链与亲水的壳聚糖分子自组装诱导形成纳米尺度的聚集体,通过引入具有肿瘤还原环境响应性的交联剂,得到了肿瘤环境响应的壳聚糖-合成高分子共聚物纳米凝胶。采用透射电镜、红外光谱等手段对纳米凝胶的粒径、结构、形貌和性能进行表征,探讨了聚合诱导自组装高效制备壳聚糖纳米凝胶的机理,证实了所得纳米凝胶粒径的可控性。进一步采用近红外荧光分子和磁共振显影(MRI)分子标记的方法制备了荧光/MRI多功能复合纳米凝胶,对凝胶显影性能进行了探讨,证实了其优异的细胞标记能力和良好的生物相容性。     

pH值响应性超支化多臂共聚物的合成及其自组装行为研究

以超支化双硫酯为链转移剂,偶氮二异丁腈(AIBN)为引发剂,采用可逆加成-断裂链转移(RAFT)活性自由基聚合方法,合成了以超支化聚酯(Boltorn H20)为核,聚丙烯酸为臂的两亲性超支化多臂共聚物(H20-star-PAA),并通过紫外分光光度计、动态光散射(DLS)和透射电子显微镜(TEM)对它在水溶液中的pH响应的自组装行为进行了研究.结果表明,在稀溶液条件下,H20-star-PAA始终以单分子胶束的形式存在,随着溶液pH的降低,胶束的PAA壳层会逐步塌缩,导致胶束尺寸减小;而在浓溶液条件下,当溶液的pH较低时,单分子胶束会进一步聚集形成多分子胶束.     

水诱导N,N′,N″-三(4-吡啶基)-均三苯甲酰胺形成超分子凝胶研究

以均三苯甲酸为母体分子,用4-氨基吡啶对其进行化学修饰,合成了N,N′,N″-三(4-吡啶基)-均三苯甲酰胺(4-btapa)并考察其在不同溶剂及酸碱度中的胶凝性能.实验结果表明,4-btapa不溶于水,但可溶于一些极性溶剂中.室温条件下,在4-btapa的DMSO溶液中加入适量的水,可直接形成稳定凝胶.而在DMF,THF等溶剂形成的溶液中室温条件下加入适量的水得到只能得到粘度较大具有流动性的混浊液,但将得到的混浊液加热溶解后室温冷却均能形成稳定凝胶.扫描电子显微镜观察到4-btapa在不同含水有机溶剂中都能形成纤维状自组装聚集体,而4-btapa在p H=3.0的水-乙醇体系中呈明显的纤维团簇结构,与p H=7.0时的规则的纤维结构相比存在较大的差异,说明p H值会影响凝胶因子聚集形貌.核磁共振和红外光谱结果表明凝胶中存在N—H…Py的分子间氢键和芳香环的π-π堆积作用.根据FT-IR,1H NMR结果并比对干凝胶与晶体XRD曲线得到了凝胶因子4-btapa在凝胶(p H=7.0)中的自组装排列方式.     

SiO2-HA/PNIPAm核壳温敏微凝胶的合成及其溶胀性能

以SiO₂纳米颗粒为核,以透明质酸（HA）和聚异丙基丙烯酰胺（PNIPAm）的杂化凝胶（HA/PNIPAm）为壳制备了一系列无机-有机杂化核壳结构单分散微凝胶.该微凝胶具有很好的温度敏感性,其最低临界转变温度（LCST）在34 ℃附近;该微凝胶具有负触变性,且温度高于LCST时负触变性更明显.用动态光散射（DLS）测定了微凝胶颗粒的水动力学粒径随温度的变化关系,实验数据可以用我们早前建立的硬核高分子凝胶分子热力学模型进行关联计算,结果表明只需较少的模型参数就可较好地描述温度响应的核壳结构高分子凝胶的溶胀行为.     

自组装法制备pH响应性马来酰化壳聚糖纳米粒子的研究

采用碳酸钠为催化剂,室温下制备了水溶性的马来酰化壳聚糖,研究了反应物投料比对酰化取代度以及产物水溶性的影响。红外光谱结果说明马来酸酐成功接枝到壳聚糖分子上;XRD结果说明马来酸酐酰化破坏了壳聚糖分子内和分子间的氢键作用,使水溶性大大提高。用Nano-ZS90Malvern仪器对不同pH值下的粒子粒径和Zeta电位进行测定,发现存在1个等电点:pH=3.01。文章首次采用自组装方法分别在醋酸、甲酸、乳酸溶液中制备得到三种不同的马来酰化壳聚糖纳米粒子并用SEM做了表征;DLS测试表明,当pH值增大后,三种纳米粒子粒径均由几十纳米溶胀到几百纳米,显示具有pH响应性。     

一种新型季胺盐壳聚糖纳米载药体系的制备与性能

在制备壳聚糖衍生物N,N,N-三甲基壳聚糖盐酸盐(TMC)的基础上,通过将两种性质相反的电解质溶液进行共混,制备了一种新型的 TMC/CMC(羧甲基壳聚糖)纳米载药颗粒体系.用激光散射仪和透射电镜表征了空白颗粒和载药颗粒的粒径、粒径分布、Zeta 电位和形态结构.栽药体系纳米颗粒的粒径在 200～600 nm 范围,表面可带正或负电荷,且 Zeta 电位具有可调性.研究表明:牛血清蛋白(BSA)的包封率与起始的 TMC、BSA 浓度相关;纳米载药颗粒对 BSA 的释放表现为,先爆释而后缓释并可保持 40 h 以上的释放.     

光学活性偶氮苯自组装膜的制备及其蛋白吸附行为

研究了在紫外光作用下, 牛血清白蛋白(BSA)在偶氮苯自组装膜上光控可逆的吸附行为. 首先合成羧基偶氮苯衍生物, 并在金膜表面制备偶氮苯自组装膜, 采用紫外吸收光谱(UV)、原子力显微镜(AFM)观察偶氮苯衍生物的光学顺反异构现象以及偶氮苯自组装膜表面形貌的变化. 同时利用等离子体表面谐振仪(SPR)考察偶氮苯光学异构对牛血清白蛋白(BSA)在自组装膜表面上的吸附行为的影响. 结果表明, BSA在偶氮苯自组装膜表面的吸附作用主要来自于BSA分子与自组装膜之间的静电作用及亲疏水作用. 在紫外光作用下, 偶氮苯自组装膜可以实现光控可逆的牛血清白蛋白分子吸附行为.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.