Au纳米簇-WS_2纳米片复合材料的合成及类过氧化物酶活性研究

通过静电组装技术制备了金纳米簇-硫化钨片纳米复合材料(Au-WS_2NCs),此Au-WS_2NCs具有优良的过氧化物酶催化活性,能有效催化H_2O_2氧化3,3',5,5'-四甲基联苯胺盐酸盐(TMB)发生显色反应。考察了Au-WS_2催化NCs/TMB/H_2O_2显色反应条件对此纳米复合材料类过氧化物酶活性的影响,并进行了稳态动力学分析。实验结果表明,Au-WS_2NCs的酶催化反应遵循典型的Michaelis-Menten动力学模型。基于Au-WS_2NCs在H_2O_2存在下对TMB的催化显色反应及葡萄糖在葡萄糖氧化酶作用下可产生H_2O_2的催化氧化反应,在最优实验条件下,实现了比色法测定H_2O_2和葡萄糖,检出限分别为6.0×10~(-7)mol/L和3.1×10~(-6)mol/L,并成功用于血糖的检测。     

Ti3C2Tx/Au@Pt纳米花复合膜的制备及其无酶H2O2传感器的应用

基于二维过渡金属碳化物(MXene)-Ti_3C_2T_x材料的导电性与Au@Pt纳米花的催化活性,组装了一种用于超灵敏和快速检测H_2O_2含量的Ti_3C_2T_x/Au@Pt纳米花无酶传感器。通过发射扫描电镜和X-射线衍射对制备的Ti_3C_2T_x进行表征。结果表明Ti_3C_2T_x材料表现出特有的手风琴结构,Ti_3C_2T_x/Au@Pt为以Au粒子为中心,Pt粒子环绕周围组成蒲公英状纳米球。研究了H_2O_2在Ti_3C_2T_x/Au@Pt纳米花修饰玻碳电极上的循环伏安曲线和时间电流曲线,结果显示该修饰电极检测H_2O_2具有线性范围良好(0.03～1 100μmol/L)、灵敏度高(检出限可达0.02μmol/L)、抗干扰性和再现性好等优点。与传统滴定法相比,该新型无酶传感器能在复杂环境下快速准确检出H_2O_2含量。     

基于PAC修饰的氧化石墨烯负载纳米Pt构建新型三维过氧化氢电化学传感器

为构建一种新的无酶电化学生物传感器并将其用于细胞中释放的H_2O_2的有效检测,将聚二烯丙基二甲基氯化铵(PAC)修饰的氧化石墨烯(GO)和纳米Pt通过物理吸附和电化学沉积H_2PtCl_6共同负载于玻碳电极上,成功制备了Pt/PAC-GO/GCE生物传感器。扫描电镜表明纳米Pt能很好地负载于PAC-GO表面。Pt/PAC-GO/GCE生物传感器对H_2O_2具有较宽的线性范围(0.04～3.6μmol/L及4.4～28.6μmol/L)及较高的电流响应(检出限为0.01μmol/L)。此外,该生物传感器具有较强的抗干扰能力,已成功用于活细胞H_2O_2的检测,有望用于医学诊断。     

核壳Au@MnO2纳米粒子比色法检测硫离子

核壳Au@MnO_2纳米粒子催化3,3',5,5'-四甲基联苯胺(TMB)和过氧化氢(H_2O_2)反应,生成黄色的氧化产物oxTMB,S~(2-)的引入使得S~(2-)和oxTMB反应生成TMB,导致黄色变浅。基于此原理,建立了比色法检测S~(2-)的传感器。在最佳实验条件下,溶液吸光度与S~(2-)浓度分别在0.1～10μmol/L和0.05～10 mmol/L范围内具有良好的线性关系,检出限为58 nmol/L。该方法用于自来水中S~(2-)的检测,回收率为95.1%～102.7%,相对标准偏差(RSD)小于3.1%。     

以碳量子点为过氧化物模拟酶的葡萄糖测定方法

以烟炱为原料制备水溶性碳量子点(CQDs),此碳量子点具有过氧化物模拟酶活性,可催化H_2O_2氧化3,3',5,5'-四甲基联苯胺(TMB)产生显色反应,而葡萄糖氧化酶(GOx)可催化葡萄糖氧化产生H_2O_2,基于上述原理,建立了一种以CQDs为过氧化物模拟酶的葡萄糖测定方法。以TMB为底物,研究了温度、p H值等条件对催化性能的影响。结果表明,pH 3.5、35℃、0.5 mmol/L TMB、1μg/mL CQDs时,此方法检测葡萄糖的线性范围为0.025~0.40 mmol/L,检出限为5.10μmol/L(S/N=3),尿液中的常见干扰物不干扰测定。实际尿液中的加标回收率为95.0%~105.1%。     

基于谷胱甘肽抑制纳米金催化3,3’,5,5’-四甲基联苯胺与过氧化氢反应比色检测谷胱甘肽

采用具有类似过氧化物酶活性的金纳米粒子(AuNPs)催化四甲基联苯胺(TMB)-H2O2反应,氧化产物(oxTMB)被谷胱甘肽(GSH)还原成TMB,导致吸光度下降,颜色由蓝色变为无色。利用上述现象,设计了一种超灵敏检测谷胱甘肽的比色传感器。在10 pmol/L~10μmol/L范围内,吸光度随GSH浓度呈良好的线性降低关系,检出限为7.5 pmol/L。该方法可以定量检测人血清中的谷胱甘肽。     

复合铂纳米电极制备及其对H_2O_2的测定

基于丁烷高温裂解析碳的原理,采用气相裂解沉积法将碳纳米颗粒沉积到石英纳米管尖端,制备出碳纳米电极,采用循环伏安法将邻苯二酚聚合膜与铂纳米颗粒沉积至该碳纳米电极上,制备出了复合铂纳米电极。探究了不同制备条件的影响,确定了最佳制备条件,研究了该电极对痕量H_2O_2的检测,结果表明,在20～1000μmol/L浓度范围内,该电极对H_2O_2具有良好的线性关系,检出限为0.471μmol/L。该电极同时具备纳米电极和纳米孔道,为多功能一体化微纳集成系统的制作提供了一种新思路。同时由于该电极的纳米级尺寸(50～90 nm),可对活体生物组织/细胞进行微创无痕的实时在线检测,为直接测定活体组织体液及组织环境中H_2O_2含量提供了新方法。     

金纳米簇增强的化学发光反应及在葡萄糖检测中的应用

金纳米簇(Au NCs)具有拟过氧化物酶活性,能催化鲁米诺(Luminol)与H_2O_2反应,产生增强的化学发光信号。不同于其它纳米微粒催化的Luminol-H_2O_2化学发光反应,Au NCs催化得到的是慢化学发光信号,且其信号能在10min内保持稳定。基于此反应,本文发展了简单、方便的化学发光测定H_2O_2的新方法。在优化的实验条件下,测定H_2O_2的检测限为10μmol/L。将此方法应用于葡萄糖的检测,其线性范围为10~1 000μmol/L,检测限为10μmol/L。目前一些重要的生物分子,如尿酸和乳酸等均能与相关酶反应生成H_2O_2,本方法也能进一步拓宽至这些生物分子的检测。     

基于贵金属纳米颗粒构建无酶过氧化氢电化学传感器的研究

采用一步电化学沉积方法分别将三种常用贵金属纳米颗粒(Au,Ag,Pt)负载于工作电极上,构建了基于纳米薄膜的过氧化氢(H_2O_2)无酶电化学传感器。通过扫描电子显微镜(SEM)表征证明三种金属纳米颗粒成功修饰在玻碳电极(GCE)表面。通过比较三种金属纳米颗粒检测H_2O_2的能力,发现Ag纳米粒子具有更优异的催化活性。进一步研究扫描速率和检测电压对Ag/GCE催化性能的影响。电化学实验结果表明,该修饰电极显示出优异的H_2O_2催化活性以及在优化条件下可以达到0.01～23mmol·L~(-1)的线性范围,检出限为3.3μmol·L~(-1),并将该传感器用于检测吐温80中残留H_2O_2,为吐温80的质量检查提供了一种简单快捷的方法。     

基于增强的明胶-金纳米粒子类过氧化物酶活性检测汞离子

基于Hg²⁺对明胶-金纳米粒子(G-AuNPs)类过氧化物酶活性的增强作用，构筑了一种新型的Hg²⁺传感器。G-AuNPs具有类氧化物酶活性和类过氧化物酶活性，能够催化O₂或H₂O₂氧化3,3,5,5’-四甲基联苯胺(TMB)生成氧化TMB(oxTMB)的反应，在652 nm处出现紫外可见吸收特征峰。优化条件下，Hg²⁺能够增强G-AuNPs的类过氧化物酶活性，使吸收信号升高，且升高幅度与Hg²⁺浓度呈线性关系，在0～15μmol/L和15～35μmol/L范围内的线性方程分别为y=1.314+0.0135x和y=0.704+0.055x，检出限为1.65μmol/L。该传感体系对Hg²⁺具有良好的选择性，其他常见金属离子不干扰对Hg²⁺的检测。所设计传感器具有无需修饰、检测时间短、选择性好的优点，有望用于污染水现场Hg²⁺的检测。     

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.