基于多边形金纳米颗粒的非标记型可卡因适体传感器的研制

实验合成了多边形金纳米颗粒,通过壳聚糖(CHIT)将合成的多边形金纳米颗粒固定在玻碳电极表面,然后通过自组装技术将带巯基的捕获DNA探针固定在修饰有多边形金纳米颗粒的电极表面,利用杂交反应使可卡因适体与DNA捕获探针结合,制成非标记型可卡因适体传感器。以六氨合钌作为电化学指示剂,通过测量传感器与目标物可卡因结合前后电流变化情况对可卡因进行测定。考察了缓冲溶液的pH、可卡因培育时间、扫描速度等对测定的影响。结果表明,在pH为7.40时该传感器的检测范围为1.0×10-10～1.0×10-3 mol/L,检测限为3.0×10-11 mol/L。该传感器制作简单,响应好,抗干扰能力强。     

硅溶胶/Nano-Au固定联吡啶钌电化学发光行为的研究

研究了舒必利在硅溶胶/纳米金/联吡啶钌修饰的金电极上的电化学发光行为,建立了电化学发光法检测舒必利的新方法。在最佳实验条件下,舒必利浓度在1.0×10-6～1.0×10-4mol/L范围内与发光强度呈良好的线性关系(r2=0.9954),检出限(S/N=3)为3.4×10-9mol/L。连续平行测定1.0×10-5mol/L的舒必利溶液8次,发光强度的相对标准偏差(RSDs)为1.5%。该电极用于样品测定,回收率为97.6%～102.1%。结果表明,纳米金表现出较好的电分析活性,对联吡啶钌具有较好的电催化作用,并可应用于舒必利药物的测定。     

多壁纳米碳管/二氧化硅复合膜中的联吡啶钌电化学发光法测定氧氟沙星的研究与应用

基于氧氟沙星对联吡啶钌(Ru(bpy)_3~(2+))电化学发光的增敏作用,建立了一种以多壁纳米碳管(MWCNTs)/二氧化硅-联吡啶钌复合物修饰的玻碳电极电化学发光检测氧氟沙星的新方法.利用溶胶-凝胶(sol-gel)固定化稳定的优点和纳米碳管的电催化作用,提高了传感器的电流响应.在最佳实验条件下,氧氟沙星浓度在4.0×10~(-6) ～1.0×10~(-4) mol/L范围内与相对发光强度呈线性关系(r~2=0.994 8),检出限(S/N=3)为2.0×10~(-6) mol/L.连续平行测定2.4×10~(-5) mol/L的氧氟沙星溶液 5次,发光强度的RSD为1.8%.     

纳米金放大计时库仑法的PML/RARα融合基因检测

应用恒电位在金基底表面电化学沉积纳米金,通过Au—S键将巯基修饰DNA探针固定在纳米金表面,与互补靶序列杂交,构建计时库仑电化学DNA传感器,并检测急性早幼粒细胞白血病(APL)PML/RARα融合基因.采用扫描电子显微术(SEM)与电化学交流阻抗技术(EIS)观察纳米金和表征DNA传感器的构筑过程.以氯化六氨合钌([Ru(NH3)6]Cl3,RuHex)作电化学杂交指示剂,由计时库仑法检测人工合成APL的PML/RARα融合基因.结果表明,纳米金能放大RuHex检测信号,杂交前后电量差值(ΔQ)与靶标链DNA浓度的对数(lgC)值在1.0×10-13～1.0×10-9mol.L-1范围内呈线性关系,检出下限3.7×10-14mol.L-1(S/N=3).该法操作简便、特异性好,有望用于实际样品的检测.     

墨鱼骨有机质与纳米金复合膜光学传感器的构建及其应用

利用纳米金种法制备墨鱼骨有机质纳米金复合膜(CDMS/AuNPs),构建一种有机质复合纳米材料的光学传感器。采用扫描电镜(SEM)和紫外-可见吸收光谱对复合膜的结构和光学性质进行表征。根据金纳米颗粒(AuNPs)的局域表面等离子体共振(LSPR)效应,利用亚硝酸盐还原氯金酸诱导纳米金种生长,进而应用于亚硝酸盐的检测。在优化实验条件下,CDMS/AuNPs传感器的吸光度与亚硝酸盐的浓度在2.5×10-6～5.0×10-5mol/L范围内呈良好的线性关系(R=0.9950),检出限为8.0×10-7 mol/L(S/N=3)。     

基于多壁碳纳米管和纳米金修饰电极测定特殊序列DNA的电化学生物传感器的制备

基于多壁碳纳米管和纳米金复合膜修饰电极制备了特殊序列的靶DNA的电化学生物传感器.该传感器以六氨基合钌为杂交指示剂,用差示脉冲伏安法进行检测DNA杂化,其响应信号与靶DNA浓度在1.0×10<'-12>～1.0×10<'-7>mol/L范围内呈线性关系,检测限达3.5×10<'-13>mol/L.该传感器能区分单碱基错配的靶DNA.     

纳米金/三聚氰胺修饰电极检测亚硝酸盐

采用电聚合方法制备三聚氰胺(MA)膜修饰玻碳电极(GCE),然后采用原位恒电位沉积法制备金纳米颗粒(Au),并将其修饰于膜电极表面,制得纳米金/三聚氰胺修饰玻碳电极(Au/MA/GCE)。用扫描电子显微镜(SEM)对修饰电极进行表面形貌和元素成分分析。用循环伏安法研究亚硝酸根(NO2-)在该修饰电极上的电化学行为发现,NO2-在0.85 V出现一灵敏的氧化峰。在优化的实验条件下,NO2-在1.0×10-5～1.0×10-3mol/L浓度范围内与其氧化峰电流成线性关系,检测下限为8.9×10-7mol/L。将修饰电极用于实际样品中NO2-的检测,效果良好。     

L-丝氨酸/壳聚糖/石墨烯/纳米金修饰电极的制备及应用

将L-丝氨酸(L-Serine)电聚合到裸金电极表面,再将壳聚糖(CS)、纳米金(Nano-Au)、石墨烯(GO)混合液滴涂在L-丝氨酸修饰的金电极上,制成L-Serine/GO/Nano-Au/CS/Au/CME电化学传感器.考察了胞嘧啶在该传感器上的电化学行为,优化了实验条件.结果表明,该传感器对胞嘧啶有良好的选择性和灵敏度,胞嘧啶的浓度在1.0×10~(-7)~1.0×10~(-3)mol/L范围内与峰电流的减小量呈现良好的线性关系,检出限为3.2×10~(-8)mol/L(S/N=3).将该传感器应用于实际样品中测定胞嘧啶,结果令人满意.     

Nano-Au/Silica sol/PVP修饰金电极上电化学发光测定盐酸硫必利

采用溶胶-凝胶法制备了Nano-Au/Silica sol/PVP修饰金电极,并基于盐酸硫必利对联吡啶钌(Ru(bpy)2+3)在该修饰电极上弱电化学发光具有较强的增敏作用,建立了电化学发光检测盐酸硫必利的新方法。在最佳实验条件下,盐酸硫必利浓度在1.0×10-7~1.0×0-4 mol/L范围内与相对发光强度呈线性关系(r2=0.9978),检出限(S/N=3)为6.7×10-10 mol/L。连续平行测定1.0×10-5 mol/L盐酸硫必利溶液10次,发光强度的相对标准偏差(RSD)为1.78%。对样品进行回收率试验,其回收率在97.7%~103.9%之间,RSD为2.62%。该方法具有较高的选择性和灵敏度,样品处理简单快速,用于盐酸硫必利的测定,结果满意。     

纳米二氧化钛-氧化锌/硅溶胶/导电胶复合材料固定联吡啶钌制备磷酸可待因电化学发光传感器

利用硅溶胶的成膜性、纳米二氧化钛-氧化锌大的比表面积及导电胶的粘结性,制备了纳米二氧化钛-氧化锌/硅溶胶/导电胶复合材料,基于此复合材料将联吡啶钌固定到金电极表面,制备了磷酸可待因电化学发光(ECL)传感器.在优化的实验条件(800 V负高压、扫描速度100 mV/s,磷酸盐缓冲体系(pH 6.5))下,可待因浓度在1.0×10-7～1.0×10-4 mol/L范围内与电化学发光强度呈良好的线性关系(r2=0.9973),检出限为2.56×10-8 mol/L (S/N=3).传感器表现出良好的重现性与稳定性,连续平行测定1.28×10-5 mol/L可待因溶液10次,发光强度的相对标准偏差(RSD)为2.7％;室温下保存10天后,发光强度为初始值的92％以上.测定可待因药物实际样品的加标回收率在99.3％ ～ 102.5％之间.     

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.     

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.     

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.