阿米卡星与碲化镉量子点和牛血清白蛋白所形成的复合物之间的相互作用

以3-巯基丙酸为稳定剂,聚乙烯吡咯烷酮为表面活性剂,采用水热法合成了具有优异光学性质的碲化镉量子点.量子点与牛血清白蛋白(BSA)结合使荧光强度明显增大.对BSA测定的线性范围为0.68～13.6 mg·L-1,检出限为0.26 mg·L-1.阿米卡星对碲化镉量子点-BSA复合物的荧光有明显猝灭作用,荧光猝灭程度与其浓度呈线性关系.结果表明为静态猝灭,阿米卡星与BSA按物质的量比1比1结合,结合常数为6.47×103L·mol-1.用圆二色光谱技术探讨了阿米卡星对BSA构象的影响.     

氮掺杂石墨烯量子点用于定量分析牛血清白蛋白的含量

合成了氮掺杂石墨烯量子点,并基于茜素红-氮掺杂石墨烯量子点之间的相互作用形成氢键复合物,茜素红可以对所合成的氮掺杂石墨烯量子点产生明显的荧光猝灭作用(荧光关),氮掺杂石墨烯量子点荧光强度的变化(F0/F)与茜素红浓度(2.78~23.59 nmol/L)具有良好的线性关系,检出限为1.24 nmol/L;继续向该溶液中加入牛血清白蛋白,会使原已发生荧光猝灭的氮掺杂石墨烯量子点溶液的荧光发射强度得以恢复(荧光开),且荧光发射强度的恢复与牛血清白蛋白浓度(0.1~0.375 g/L)之间具有良好的线性关系,检出限为0.011 g/L。此外,该"关-开"荧光检测体系被用来定量分析人尿液中的牛血清白蛋白含量,方法已用于实际尿液样品的定量分析。     

水热法合成CdTe量子点及其与蛋白质连接作为生物荧光探针的研究

以巯基丙酸为稳定剂,采用水热法合成了CdTe量子点.吸收光谱和荧光光谱表明,所合成的CdTe量子点具有优异的发光特性.透射电子显微境(TEM)表征了纳米微粒的结构和粒径分布.并以牛血清白蛋白(BSA)为代表,通过测定CdTe量子点与BSA偶联(QDs-BSA)后溶液的荧光强度确定CdTe量子点与蛋白质偶联的最佳反应条件为pH 9～10,反应温度37 ℃,反应时间2 h.通过荧光发射光谱研究了溶液pH和NaCl浓度对QDs-BSA溶液和QDs溶液荧光强度的影响.在优化的反应条件下,用制备的QDs-BSA荧光探针对BSA进行了定量测定,线性范围是0.06～0.48 μg/mL,对0.24 μg/mL QDs-BSA样品7次测定的相对标准偏差是2.2%.     

光谱法研究核壳量子点CdTe/CdS与牛血清白蛋白的相互作用

应用荧光光谱、圆二色光谱和紫外吸收光谱等技术研究核壳量子点CdTe/CdS与牛血清白蛋白(BSA)相互作用的结果表明,CdTe/CdS对BSA的荧光猝灭机理为静态猝灭。根据不同温度下量子点对BSA的荧光猝灭作用计算了结合常数、热力学参数,证明了量子点与BSA相互作用力主要是范德华力或氢键作用力。探讨了量子点对BSA构象的影响。     

伊文思蓝作荧光探针研究牛血清白蛋白与氨苄青霉素之间的竞争反应

用伊文思蓝(Evans blue, EB)作荧光探针研究了氨苄青霉素(Ampicillin, A)对牛血清白蛋白(Bovine serum albumin, BSA)的竞争反应. 伊文思蓝与牛血清白蛋白作用, 使牛血清白蛋白荧光发生猝灭, 根据Stern-Volmer方程及荧光寿命研究了荧光猝灭的类型及机理. 结果表明, 猝灭类型为静态猝灭, 即伊文思蓝和牛血清白蛋白形成了一种稳定的复合物. 伊文思蓝与牛血清白蛋白的结合常数KBSA-EB=1.122×106 L/mol, 结合点数n=0.9935, 并确定了EB和BSA之间的热力学常数及作用力类型. 当加入氨苄青霉素后, 牛血清白蛋白的相对荧光强度恢复. 这表明氨苄青霉素与伊文思蓝对牛血清白蛋白发生了竞争反应. 探讨了该竞争反应的相关机理, 求出了伊文思蓝与氨苄青霉素的结合常数为KEB-A=7.131×105 L/mol.     

荧光光谱法研究托拉塞米与牛血清白蛋白的相互作用及其分析应用

在pH 7.40和离子强度0.15 mol/L的模拟生理条件下, 托拉塞米(TOR)对牛血清白蛋白(BSA)的内源荧光产生较强的猝灭作用. 从吸收光谱的变化、温度对猝灭作用的影响及猝灭常数判断该猝灭作用是TOR与BSA形成基态配合物而导致的静态猝灭过程. 文中计算了TOR与BSA的结合常数K、结合位点数n和相关的热力学函数. 在最大猝灭波长342 nm处, 荧光猝灭程度(ΔF)与托拉塞米的浓度成正比, 线性范围和检出限分别为0.02～5.0 mg/mL和6.3 ng/mL. 本文还研究了适宜的反应条件, 考察了共存物质的影响, 表明方法具有较好的选择性, 据此提出了以BSA为探针快速测定痕量TOR的荧光光谱新方法, 适用于服用TOR后尿样和片剂中托拉塞米的测定.     

头孢美唑钠与BSA及纳米银-BSA体系相互作用的研究

纳米银与牛血清白蛋白(BSA)均匀混合形成纳米银-BSA体系,运用荧光光谱,紫外吸收光谱,同步荧光光谱研究了注射用头孢美唑钠(Cefmetazole Sodium for Injection,CS)与BSA及纳米银-BSA体系的相互作用.头孢美唑钠对BSA具有荧光猝灭作用,其猝灭方式为静态猝灭,求出了猝灭常数,结合常数...     

铜、锌离子对齐墩果酸与蛋白质相互作用的影响

使用荧光光谱和紫外吸收光谱研究金属离子存在下对齐墩果酸(OA)与牛血清白蛋白(BSA)相互作用的影响.实验结果表明,生理pH值条件下齐墩果酸对牛血清白蛋白的荧光猝灭可能是一个单一的静态猝灭过程.求得了OA与BSA相互作用的结合常数为6.16×103 L·mol-1.Zn2+或Gu2+存在下,OA对BSA的荧光猝灭类型没...     

阿替洛尔的电化学行为及与牛血清白蛋白的相互作用

建立了石墨烯修饰玻碳电极测定阿替洛尔的电化学分析新方法。采用电化学方法结合紫外、荧光光谱分析,研究了阿替洛尔(ATN)与牛血清白蛋白(BSA)的相互作用。实验发现,在pH 10.0的Na2CO3-NaHCO3缓冲溶液中,ATN在0.78 V处有一灵敏的氧化峰,氧化峰电流Ip与ATN的浓度在4.8～30.0μmol/L范围内呈良好的线性关系(r=0.9926,n=11),方法检出限为3μmol/L。当BSA加入ATN溶液后,ATN氧化峰电流降低,氧化峰电流的降低值ΔIp与BSA的浓度在2.6～31.0μmol/L范围内呈良好线性关系。紫外光谱表明ATN的加入使BSA的吸收峰发生蓝移。荧光光谱表明,ATN对BSA的内源荧光有显著的猝灭作用,猝灭机制为静态猝灭。     

CdTe量子点与蛋白质相互作用的荧光猝灭效应

本文在水热法合成水溶性CdTe及核壳结构CdTe/CdS量子点的基础上,分别研究了细胞色素c对CdTe量子点及CdTe/CdS核壳量子点荧光的猝灭效应和CdTe量子点对牛血清白蛋白荧光的猝灭效应,并阐述了猝灭机理。结果显示,细胞色素c对CdTe量子点的荧光猝灭效应具有一定的粒径依赖性,粒径越小,猝灭效应越强;细胞色素c对CdTe/CdS核壳量子点的猝灭效应比对CdTe量子点的更强,揭示了受激电子的表面传递机理。CdTe量子点通过松散牛血清白蛋白的螺旋结构而猝灭其荧光。     

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%.     

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.     

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.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.