溶胶凝胶固定化酶流动注射化学发光法测定人体血清中的胆固醇

采用溶胶凝胶技术分别固定了胆固醇脂酶和胆固醇氧化酶,制成固定化酶柱;人体血清中胆固醇脂在胆固醇脂酶的催化作用下生成胆固醇,胆固醇在胆固醇氧化酶的催化作用下被氧化产生H2O2,将其与鲁米诺发生耦合的化学发光反应,在模拟酶血红蛋白的催化作用下产生较强的化学发光。结合流动注射技术,建立了溶胶凝胶固定化酶流动注射化学发光法测定胆固醇的新方法。实验发现,发光强度与胆固醇的浓度在一定范围内呈良好的线性关系,总胆固醇的线性范围为1.01×10-6～2.02×10-4mol/L(r=0.9975);检出限为7.5×10-7mol/L;游离胆固醇的线性范围为5.0×10-8～2.18×10-5mol/L(r=0.9991);检出限为5.0×10-9mol/L。用生化分析仪(东芝TBA-120FR)与本方法进行对照,两种方法无显著性差异。本方法已应用于临床血清样品中胆固醇的检测。     

基于脱乙酰基魔芋葡甘聚糖固定酶的H2O2生物传感器

对魔芋葡甘聚糖进行了脱乙酰基改性处理,并用红外光谱表征了其脱乙酰基前后的结构变化.探讨了脱乙酰基魔芋葡甘聚糖溶胶-凝胶的制备条件对其成膜性能及酶固定化的影响.将脱乙酰基魔芋葡甘聚糖用于辣根过氧化物酶的固定,制备出了H2O2生物传感器.传感器在优化的工作条件下线性范围为1.0×10-6 ～6.0×10-4 mol/L,检出限为8×10-7 mol/L,稳定性良好.实验表明脱乙酰基魔芋葡甘聚糖是一种适用于生物传感器领域酶固定化的优良材料.     

SiO_2/Nafion杂化膜固定酶的过氧化氢生物传感器

通过溶胶-凝胶技术制备SiO2/Nafion杂化膜并固定辣根过氧化物酶,以杂化膜中Nafion固定的亚甲基蓝为辣根过氧化物酶和玻碳电极间的电子传递介体,制成了电流型过氧化氢生物传感器。探讨了杂化膜的制备条件、工作电位、pH值、温度、干扰物质等对生物传感器的影响。该生物传感器的线性响应范围为1.0×10-6～1.6×10-4mol/L,检出限(S/N=3)为6.0×10-7mol/L,达到95%稳态响应电流用时少于15s。固定化酶对过氧化氢催化反应的米氏常数为1.129 mmol/L。     

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%.     

溶胶-凝胶壳聚糖/二氧化硅杂化复合膜固定辣根过氧化酶的H2O2电化学生物传感器的研制

利用溶胶 凝胶法制备壳聚糖 二氧化硅有机无机复合杂化膜,用于对辣根过氧化酶进行固定,制得测定H2O2的电流型生物传感器。以1mmol/LK4Fe(CN)6作为电子媒介体。研究了各种因素如壳聚糖与二氧化硅的比率、pH、温度、工作电位等对传感器响应电流的影响。计时电流法测定H2O2的线性范围为2.0×10-6～6.8×10-4mol/L,检出限为8.0×10-7mol/L。测得酶催化动力学参数米氏常数Km=0 87mmol/L。用该法对实际样品进行了测定。     

基于碳纳米管体修饰的溶胶-凝胶葡萄糖生物传感器

采用多壁碳纳米管(MWNTs)体修饰石墨作为裸电极,结合正硅酸乙酯与聚乙二醇溶胶凝胶法包埋葡萄糖氧化酶制成直接电子传递型葡萄糖生物传感器。实验结果表明,当V(水):V(正硅酸乙酯):V(聚乙二醇)=1:3:6,V(凝胶):V(酶溶液)=2:1,在1mL聚乙二醇中加入6mg的MWNTs,溶胶老化时间为60h时,所制得的传感器在葡萄糖浓度为5.0×10-4～5.0×10-2mol/L范围内呈线性关系j(μA/cm-2)=0.9454c(mmol/L)+43.986,线性相关系数为0.9849,检出限为1×10-6mol/L。     

基于脱乙酰基魔芋葡甘聚糖固定酶的葡萄糖传感器

制备了脱乙酰基魔芋葡甘聚糖(d-KGM)的溶胶-凝胶,用红外光谱表征了其脱乙酰基前后的结构转化.探讨了d-KGM溶胶-凝胶的制备条件对其成膜性能及酶固定化的影响.在此基础上将d-KGM用于电极表面葡萄糖氧化酶的固定,制备了相应的葡萄糖传感器,并对传感器的工作条件进行了优化.所制备的传感器灵敏度为240 nA/mmol/L,线性范围为0.1～8 mmol/L,表观米氏常数KM为19.6 mmol/L,稳定性好,寿命长.实验结果表明d-KGM是一种可用于生物传感器中酶固定化的优良材料.     

溶胶-凝胶法修饰的硫氰酸根离子选择性电极(ISE)的研究

报道了一种基于溶胶-凝胶技术的新型硫氰酸根电极,讨论了电极性能的影响因素.该电极有良好的能斯特响应,斜率为63 mV/pC,线性范围为1.0×10-2～6.0×10-6mol/L,检出限为4.0×10-6 mol/L,适宜的pH范围为3.4～7.1.     

纳米碳管修饰铂结合溶胶-凝胶固定酶制备高性能胆碱生物传感器

为了提高胆碱传感器的灵敏度和抗干扰性,以纳米碳管修饰铂电极为基础电极,采用溶胶-凝胶法固定胆碱氧化酶(ChOx),构建了电流型胆碱检测生物传感器,对纳米碳管修饰电极的电化学特征进行分析,得知纳米碳管的引入不仅使电极对H2O2的催化电流增大,同时降低了电催化所需的恒定电位。讨论了缓冲液介质、pH值、酶负载量对传感器响应的影响。研究表明,所制备的传感器在pH 7.2、电位为0.15V条件下对氯化胆碱的线性响应范围为5.0×10-6~1.0×10-4mol/L;检出限为5.0×10-7mol/L;灵敏度为9.48μA/mmol/L。传感器的稳定性好,经过1个月,仍可保持初始电流的85%。抗干扰能力有很大提高。用于人体血清中的胆碱浓度测定,结果令人满意。     

溶胶-凝胶法固定胆固醇氧化酶偶联普鲁士蓝化学修饰电极的研究

用溶胶-凝胶法将胆固醇氧化酶固定在普鲁士蓝修饰的玻碳电极表面,制成了一种新型胆固醇传感器,实现了低电位下对胆固醇的间接测定,胆固醇的测定范围伏安法为5×10-7～8×10-5mol/L,安培法为5×10-6～5×10-4mol/L.伏安法检出限为1.2×10-7mol/L,是目前所见灵敏度最高的胆固醇传感器之一,该传感器对胆固醇的测定可避免常规电化学传感器测定中由于样品中大量存在的易氧化物质所带来的干扰,该传感器的寿命长,使用次数在300次以上.     

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.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.     

Copper-catalyzed multicomponent reactions of 2-iodoanilines,benzylamines, and elemental sulfur toward 2-arylbenzothiazoles

A relatively cheap copper salt-catalyzed, three-component approach providing 2-arylbenzothiazoles in good to excellent yields from readily available 2-iodoanilines, benzylamines, and sulfur powder is reported. This methodology allows preparation of various classes of 2-arylbenzothiazoles and provides a general, reliable approach.