白藜芦醇-大麦醇溶蛋白复合纳米颗粒的光稳定性、缓释行为及抗氧化能力

采用液-液分散法自组装制备了白藜芦醇-大麦醇溶蛋白复合纳米颗粒,其平均粒径为(135.0±2.5)nm,白藜芦醇包封率为90.4%,负载率为18.8%;扫描电子显微镜表征结果显示纳米颗粒表面光滑,呈较规则的圆球状.考察了复合纳米颗粒载体形式对白藜芦醇光稳定性的影响,结果表明,在紫外光下暴露18 h,与游离白藜芦醇相比,纳米颗粒中的白藜芦醇稳定性提高了26%.通过模拟胃肠道环境考察了复合纳米颗粒的白藜芦醇缓释行为,结果表明,2 h内白藜芦醇在模拟胃液中的释放率为35%,随后释放速率减慢,6 h后的释放率为56%;在模拟肠液中2 h内白藜芦醇的释放率为42%,且在4 h内的释放行为遵循零级释放特征,6 h后的释放率为88%.对游离态白藜芦醇和复合纳米颗粒形式的白藜芦醇抗氧化能力进行了对比研究,1,1-二苯基-2-苦肼基(DPPH)实验结果表明,复合纳米颗粒形式的白藜芦醇比游离形式在清除氢过氧自由基方面能力稍强(IC50值分别为0.4182 mmol/L和0.4378 mmol/L);Hep G2细胞抗氧化模型实验进一步证实白藜芦醇在形成复合纳米颗粒后其抗氧化能力略有增强.     

聚肽-壳聚糖复合体系的自组装行为研究

以聚肽、壳聚糖为原料,制备复合纳米粒子,采用透射电镜、动态激光散射仪及Zeta电位分析仪、荧光光谱仪对制备成的聚肽-壳聚糖复合体系纳米粒子的形貌、粒径、Zeta电位及临界胶束浓度等自组装行为进行表征,结果表明:聚肽-壳聚糖复合体系纳米粒子是具有壳-核结构的球型粒子;纳米粒子平均粒径为240nm,粒径分布较均匀,稳定性较好;复合体系中聚肽的临界胶束浓度为4.55×10-4mg/mL.     

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.     

玉米蛋白/吐温-20复合纳米颗粒对姜黄素的包载作用

本文采用反溶剂沉淀法制备了玉米蛋白/吐温-20复合纳米颗粒。通过测定玉米蛋白/吐温-20复合纳米颗粒对姜黄素的包封率、稳定性及荧光光谱性质,考察了不同浓度吐温-20对玉米蛋白/吐温-20复合纳米颗粒包载姜黄素的影响规律。相比玉米蛋白纳米颗粒,玉米蛋白/吐温-20复合纳米颗粒能够显著提高姜黄素的包封率、稳定性、荧光发射光谱强度和各向异性。这些结果说明姜黄素通过疏水作用缔合于玉米蛋白/吐温-20复合纳米颗粒的疏水微区。吐温-20作为稳定剂不仅有助于生成粒径较小的玉米蛋白/吐温-20复合纳米颗粒,而且吐温-20与玉米蛋白的结合能够为姜黄素提供更适合的疏水缔合环境。     

阳离子修饰纳米Pt的合成及其在Nafion膜上的自组装行为研究

以季铵阳离子聚合物为修饰离子、乙醇为还原剂,在水溶液中合成了具有稳定电位的阳离子修饰纳米Pt颗粒,还原过程采用UV-vis光谱监控,粒子形貌采用TEM表征.结果表明,合成体系在45 min左右还原完毕,颗粒粒径约为4.5 nm,呈多晶态结构,粒径分布狭窄,具有良好的分散性.采用Zeta电位测定仪分析了不同pH条件下粒子的电位,选择了合适的组装pH值并运用静电自组装的方法把Pt颗粒成功地组装到Nafion膜表面.同时对该自组装体系的影响因素进行了一些理论分析,并以此对组装过程的动力学性质和组装膜电化学特性进行了解释.     

白芨多糖两亲性聚合物的合成及载药纳米体系

制备了硬脂酸改性白芨多糖两亲性聚合物(SA-BSPS)药物载体,采用红外光谱及核磁共振氢谱对SA-BSPS药物载体进行了表征,并以核磁共振氢谱峰面积计算取代度.以多西他赛(DTX)为模型药物,制备了多西他赛-硬脂酸改性白芨多糖聚合物(DTX-SA-BSPS)胶束,测定了DTX-SA-BSPS的粒径分布、Zeta电位、载药量及包封率.结果表明,硬脂酸已接枝到白芨多糖的羟基上,取代度为12.94%.DTX-SA-BSPS胶束的粒径为(97.01±3.17)nm,Zeta电位为(-19.56±0.22)m V,载药量为(9.13±0.17)%、包封率达(81.11±0.18)%.探讨了SA-BSPS胶束的细胞毒性及其被人肝癌细胞(Hep G2)株摄入的情况.细胞毒性实验表明,浓度为0.5μg/m L的SA-BSPS胶束孵育72 h时,肝癌细胞存活率为(78.82±3.25)%.荧光摄入实验表明,孵育4 h后细胞中包载罗丹明B的SA-BSPS胶束的荧光强度明显强于游离罗丹明B,且在孵育过程中,荧光强度随孵育时间的延长而增强.     

大麻二酚纳米结构脂质载体的制备及其性质研究

通过高压均质法制备包载大麻二酚(CBD)的纳米结构脂质载体(CBD-NLC),并考察其载药量、包封率、平均粒径、Zeta电位、长期储存稳定性等物理化学性质,筛选获得CBD-NLC最佳配方。在优化条件下制备的CBD-NLC平均粒径为163.7±1.3nm,多分散性指数(PDI)为0.14±0.02,包封率和载药量分别为95.5±1.0%和9.8±0.1%。通过透射电镜、傅里叶变换红外光谱、差示量热扫描、X射线衍射对CBD-NLC进行表征,结果表明,CBD被很好地负载在NLC中,CBD-NLC主要为球形结构。与文献报道相比,纳米结构脂质载体能够包载CBD,具有较好的载药量和包封率,可解决CBD的溶解性及稳定性问题,提高CBD的有效利用度。制备的CBD-NLC可用去离子水以任意比例稀释,具有良好的稳定性,便于其在医药产品中的应用。     

适配子修饰靶向PLGA纳米基因载体的构建

化学合成了功能性三嵌段复合物乳酸乙醇酸共聚物-聚乙二醇-适配子(PLGA-PEG-Apt)。使用双乳化挥发法制备包裹DNA片段的PLGA-PEG-Apt新型纳米基因药物载体,表征检测显示:制备的纳米基因载体粒径为(225.2±8.1)nm,Zeta电位约(-35.5±-3.3)mV。扫描电子显微镜下纳米颗粒形态呈圆形,表面光滑,粒径分布较均匀。纳米粒子对TFO的包封率为(25.4±3.1)%(n=3),载药量为(1.34±0.16)μg/mg。体外释放实验研究结果显示持续释放过程达23 d,且PLGA-PEG-Apt纳米粒子呈突释之后的持续缓释过程。细胞水平实验结果显示,A10适配子修饰的纳米基因载体能更多进入靶向的前列腺癌细胞株,进而发挥其抗前列腺癌增殖的作用。该研究成功制备了靶向PLGA纳米基因载体,结果满意。     

生物亲和性壳聚糖-二氧化硅复合纳米粒子的合成及其吸附DNA特性研究

采用反相微乳液法制备了壳聚糖-二氧化硅复合纳米粒子,通过透射电镜（TEM）、红外光谱方法、Zeta电位实验等对所合成的复合纳米粒子的结构和性质等进行了表征.结果显示,基于壳聚糖与silica之间超分子作用所形成的复合纳米粒子呈规则的球形,粒径为50 nm左右,具有良好的单分散性和微孔结构,Zeta电位测定结果表明复合纳...     

聚乙二醇接枝聚乳酸的自组装纳米微球的制备及性能

对制备的新型聚乙二醇(PEG)接枝聚乳酸(PLA)在水中的自组装性能进行研究, 探讨其作为纳米药物载体的可行性和稳定性. 目测法得到其溶解度为(2.16～4.32)×10^－2 mg•mL^－1; 荧光法得到聚合物的临界胶束浓度为1.12×10^－3 mg•mL^－1; 透射电子显微镜观察显示该聚合物在水中的自组装聚集体为纳米级球形; 动态激光光散射测试微球的粒径和Zeta电位发现, 在微球的制备过程中, 聚合物的亲/疏水性比例、水相介质及水溶液的pH值对它影响显著; 而制备后, 稀释和冷冻对它无显著影响, 改变微球的环境pH值至酸性, 出现聚集, 至碱性无影响. 研究结果显示, 该聚合物在水和磷酸钠盐缓冲液中可形成稳定的纳米微球, 通过微球的制备条件和存在环境可控制其粒径和Zeta电位, 因此根据应用需要, 通过控制其粒径和Zeta电位, 可能提高微球的在体血液循环时间并实现靶向缓释.     

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.     

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.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.     

Studies of Photoionization of CF3 I by Femtosecond Time-resolved Mass Spectrometry

The multi-photon dissociative photoionization dynamics of CF3I has been studied with femtosecond two-color pump-probe time of flight mass spectra at a pump pulse of 265 nm and a probe pulse of 398 nm. The life constants of CF3I+ and its fragment ions CF3+ and I+ are obtained as (96±7), (198±130) and (167±6)fs, respectively. The multi-photon dynamics leading to these ions differ. CF3I+ corresponds to a (1+2′) transition with one-photon pump excitation to the A band of CF3I. CF3+ are mainly formed by a tow-photon probe excitation to the CF3+ with subsequent dissociation of parent ions. I+ are produced in (2+2′) combined with (1+1′+2′) process. The results provide information on the multi-photon pathways involved.