三氧化二铝溶胶-凝胶固定过氧化氢生物传感器

三氧化二铝溶胶凝胶将辣根过氧化物酶和硫堇同时固定在玻碳电极上,紫外-可见光谱结果表明酶在固定过程中生物活性保持得较好.传感器在pH 7.0外加电压为-0.22 V条件下,对过氧化氢浓度为1.76×10-3～5.5×10-2 mol/L的范围内呈线性响应,检出限为1.1×10-4 mol/L.传感器的选择性和稳定性较好,使用3个星期后,仍能保持其初始活性的80%.     

新型多壁碳纳米管/白藜芦醇印迹溶胶-凝胶层层组装电化学传感器研究

采用电化学沉积方法将印迹溶胶-凝胶膜沉积到功能化碳纳米管(MWNT-COOH)修饰的碳电极表面,成功研制一种新型多壁碳纳米管/白藜芦醇印迹溶胶-凝胶电化学传感器.采用扫描电镜(SEM),循环伏安法(CV),方波伏安法(SWV)和计时电流法(i-t)详细考察该印迹溶胶-凝胶膜的形态和电化学性能.结果表明该传感器对白藜芦醇具有较高的选择性和亲和性.与无多壁碳纳米管修饰的印迹传感器比较,MWNT层修饰的印迹传感器电流响应信号明显提高.白藜芦醇与印迹溶胶-凝胶膜的特异性结合使该传感器的电流发生变化,电流变化与白藜芦醇浓度在5.0×10-7～8.0×10-5mol?L-1范围内呈良好线性关系,检测限为5.1×10-8mol?L-1,该传感器成功应用于葡萄酒中白藜芦醇含量的检测.     

普鲁士蓝/壳聚糖杂化膜修饰氧化锌球腔阵列/氧化铟锡电极制备及应用

用Langmuir-Blodgett技术制成了附着聚苯乙烯小球的氧化铟锡(InSnO)模板。将此模板水平置于由硝酸锌及柠檬酸组成的前驱体溶胶中,用溶胶-凝胶法制得氧化锌球腔阵列/氧化铟锡电极。采用电沉积法得到普鲁士蓝/壳聚糖杂化膜修饰的氧化锌球腔阵列/氧化铟锡电极。该电极在pH 7.0～8.0的溶液中具有良好的电化学活性,过氧化氢浓度在7.67×10-7～4.72×10-4mol.L-1范围内与相应的电流响应值呈线性关系,检出限(3S/N)为2.4×10-7mol.L-1。测定2.0×10-5mol.L-1过氧化氢溶液时,其相对标准偏差(n=10)为3.8%。     

溶胶-凝胶包埋法制备银离子选择电极的研究

研制了一种用溶胶 凝胶技术包埋电活性物质的银离子选择电极。研究了包埋过程的变量参数及电极的响应机理。电极Nernst响应范围为 1.0× 10 - 1～ 1.0× 10 - 5mol·L- 1,斜率为5 5 .5mV·pc- 1,检出限为 3.1× 10 - 6mol·L- 1。该电极响应快 ,体积小 ,制作简单 ,使用方便 ,具有坚固耐磨 ,可在严酷条件下使用的特点。此研究对进一步研制溶胶 凝胶ISFET化学传感器和生物传感器具有探索意义     

电致化学发光-分子印迹传感器测定L-苯丙氨酸

在三联吡啶钌固相电极上,采用溶胶-凝胶法电沉积分子印迹聚合物,制得电致化学发光-分子印迹传感器。研究了该传感器的电化学和电致化学发光性能。结果表明,此传感器对L-苯丙氨酸具有很高的检测灵敏度和良好的选择性。在优化的条件下,测定L-苯丙氨酸的线性范围为1.0×10#11~1.0×10#8mol/L,检出限为3.1×10#12mol/L。此传感器可应用于尿样中L-苯丙氨酸的测定,回收率为94.8%~110.6%。     

掺杂固定化酶柱的次黄嘌呤液滴光化学传感器研究

研制了一种基于掺杂的溶胶-凝胶固定化酶柱的次黄嘌呤液滴光化学传感器。在凝胶形成过程中添加肌氨酸和山梨醇,由于两种添加剂的模板作用,可形成大而有序的凝胶网格,使得酶与底物能充分接触,从而达到提高传感器响应速度和灵敏度的目的。基于这一方法固定了黄嘌呤氧化酶,并结合液滴光化学传感装置,用于次黄嘌呤的测定。在pH值为8.74的Tris-HC l缓冲液中,该传感器对2.0×10-7~8.0×10-6mol/L的次黄嘌呤呈线性响应,检出限为5.0×10-8mol/L。本实验固定化黄嘌呤氧化酶的催化效率是普通溶胶-凝胶法固定化酶的2.54倍。     

测定盐酸西布曲明的电位传感器的研制与应用

以四苯硼酸钠与盐酸西布曲明生成的离子缔合物为电活性物质,研制了盐酸西布曲明传感器。试验表明:盐酸西布曲明聚氯乙烯(PVC)膜传感器对盐酸西布曲明具有良好的选择性和电位响应特性。在pH 5的溶液中,电极电位呈现近能斯特响应,线性范围为1.0×10-6～1.0×10-1mol.L-1,斜率为50 mV.pc-1(26℃),检出限(3S/N)为5.62×10-7mol.L-1。将电极用于药物中盐酸西布曲明含量的测定,测得回收率为97.3%～100.2%,测定值的相对标准偏差(n=5)均小于2%。     

壳聚糖固定双酶的丝网印刷胆固醇传感器的制备及应用

以亚甲基蓝为电子媒介,通过壳聚糖固定胆固醇氧化酶和辣根过氧化酶在丝网印刷电极表面,制成了一种新型胆固醇生物传感器,实现了低电位下对胆固醇的间接测定.循环伏安法和恒电位法用于研究修饰电极的电化学特性,在优化的试验条件下,安培法对胆固醇响应的线性范围为2.0×10-5～3.0×10-3mol·L-1,检出限(3S/N)为5.0×10-6mol·L-1.用同一支电极对6.0×10-4mol·L-1胆固醇溶液进行10次连续测定,测定值的相对标准偏差为4.6%,用3支电极做相同试验,测得相对标准偏差为6.2%.应用此传感器测定了血清样品中胆固醇含量,测定值的相对标准偏差(n=5)以及回收率试验结果依次在2.3%～6.1%之间及94.3%～105.2%之间.     

以高氯酸·三-2,2′-联吡啶合钴(Ⅲ)作为电子媒介体金纳米颗粒增强的葡萄糖生物传感器

用纳米金溶胶与聚乙烯醇缩丁醛(PVB)构成复合固酶基质,采用溶胶-凝胶法固定葡萄糖氧化酶(GOx)于铂电极表面,并在葡萄糖溶液中加入高氯酸·三-2,2′-联吡啶合钴(Ⅲ)作为电子媒介体,制成了高灵敏的葡萄糖生物传感器.葡萄糖氧化酶吸附在纳米金颗粒表面上稳定且保持其生物活性;而电子媒介体的存在,显著提高了传感器的响应灵敏度.该传感器对葡萄糖响应的线性范围为1.2×10-8～6.2×10-6 mol/L,检出限6.2×10-9 mol/L(S/N=3).该生物传感器有效消除了抗坏血酸、尿酸的干扰,可用于人体血清中葡萄糖的测定.     

基于胱胺/壳聚糖/酶标纳米金自组装的的酪氨酶传感器的研制

通过自组装技术构制了一种简单有效的酪氨酸酶传感器。该法先通过戊二醛交联将壳聚糖固定在胱胺修饰的金丝电极上,进而通过氨基与纳米金的强力相互作用将酶标纳米金固定在壳聚糖层上。结果表明,酪氨酸酶能很好地保持其生物活性,所构制的传感器达到95%稳定状态电极的时间在15s以内。酚类化合物是通过酶催化产生的醌在-100mV(相对饱和甘汞电极)直接还原而测定的,传感器对邻苯二酚、苯酚、对甲基苯酚测定的灵敏度依次为2.216,4.828,4.885μA·μmol-1L.cm-2,检测限依次为0.32,0.60,0.18μmolL-1。二周后活性仍保持原有活性的75%。     

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.     

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.     

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.     

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.     

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.     

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.     

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.