碳纳米管负载钴/铁混合氧化物修饰电极碱性条件下测定葡萄糖

以碳纳米管为模板,采用电化学方法制备了碳纳米管负载的钴/铁混合氧化物修饰电极,并研究了该修饰电极在碱性介质中对葡萄糖的电催化活性。结果表明,该修饰电极对葡萄糖具有良好的电催化氧化活性。在优化条件下,安培法检测葡萄糖的线性范围为2.0×10-7~4.2×10-5mol·L-1和4.2×10-5~4.9×10-4mol·L-1,检出限(3sb,n=7)为5.0×10-8mol·L-1,灵敏度分别为242.7μA·(mmol·L-1)-1和114.8μA·(mmol·L-1)-1,响应时间小于5 s。     

碳纳米管修饰电极离子色谱电化学法测定盐酸麻黄碱

采用阴离子交换分离,碳纳米管修饰电极安培检测离子色谱电化学法测定盐酸麻黄碱.在优化条件下,用碳酸钠溶液和甲醇溶液混合溶液为淋洗液,用碳纳米管修饰玻碳电极,在0.8 V电位处进行直流安培检测.结果发现在碳纳米管修饰玻碳电极后盐酸麻黄碱的电流响应值比未修饰前大大增加,方法的灵敏度比未修饰电极提高了10倍,用未修饰电极测定的检出限为2.4 μg·L-1,用修饰电极测定的检出限为0.2 μg·L-1,样品加标回收率为103.6%..     

碳纳米管负载氢氧化镍修饰电极的制备及应用

采用表面滴涂结合循环伏安法制备了碳纳米管负载氢氧化镍修饰电极(Ni(OH)2/MWNT/CCE)。研究了该修饰电极对葡萄糖的电催化氧化性能。结果表明,该修饰电极对葡萄糖具有良好的电催化氧化活性。在优化条件下,安培法检测葡萄糖的线性范围为2.0×10-7～5.7×10-4 mol.L-1(r=0.999 9,s=2 786.5μA.(mmol.L-1)-1.cm-2)和5.7×10-4～2.7×10-3 mol.L-1(r=0.999 1,s=2 005.2μA.(mmol.L-1)-1.cm-2),检出限(3sb)为8.0×10-8 mol.L-1。该法已成功用于血清中葡萄糖含量的测定。     

高效毛细管电泳-电化学检测滴鼻液中盐酸麻黄碱和磺胺嘧啶

采用毛细管电泳-电化学检测法(CE-ED) 同时测定滴鼻液中盐酸麻黄碱和磺胺嘧啶的含量,考察了缓冲液酸度和浓度、氧化电位、分离电压和进样时间等试验参数对分离检测的影响.在最佳试验条件下,工作电极为直径 300 μm 的碳圆盘电极,检测电位为 0.95 V(vs.SCE),缓冲液为50 mmol·L-1 硼砂-硼酸溶液(pH 8.0),分离电压为 17 kV,上述两组分在 7 min 内即可实现分离.盐酸麻黄碱和磺胺嘧啶在三个数量级的范围内呈线性,检出限(S/N=3)分别为 7.0×10-5g·L-1和3.0×10-5g·L-1,回收率在 97.0%～98.0%之间.     

Nd_2O_3/多壁碳纳米管修饰电极检测亚硝酸根

制备了纳米Nd2O3/多壁碳纳米管修饰电极并用于亚硝酸盐的检测。采用原子力显微镜、X-粉末衍射仪表征制备的纳米材料。实验表明:修饰电极对亚硝酸根的氧化具有明显地电催化作用。利用示差脉冲伏安法测定亚硝酸盐,其氧化峰电流和其浓度在20μmol·L-1-20 mmol·L-1范围内呈现良好的线性关系,检测线为0.83μmol·L-1(S/N=3)。更重要的是,实验结果表明:与Nd2O3修饰电极相比,多壁碳纳米管能显著地提高电极的稳定性。此外,修饰电极具有良好的选择性,能用于样品的检测,结果令人满意。     

电催化测定烟酰胺腺嘌呤二核苷酸——以聚亚甲基蓝一碳纳米管修饰电极作为工作电极

制备了聚亚甲蓝一碳纳米管修饰的玻碳电极(PMB-SWCNT's/GCE),并研究了烟酰胺腺嘌呤二核苷酸(NADH)在此电极上的电化学行为.结果表明:此修饰电极对NADH表现出协同电催化作用和较好的响应性能.在pH 7.0的磷酸盐缓冲溶液中可观察到NADH氧化峰电位的正移及其峰电流的增加,当NADH的浓度在5.0×10-6～7.0×10-4mol·L-1范围内,与相应的氧化峰电流值之间存在线性关系.方法的检出限(3S/N)为1.4×10-6mol·L-1,所提出的方法应用于生物材料样品中NADH的直接测定,测得方法的平均回收率为99.5%.     

苯酚及3种苯二酚异构体在多壁碳纳米管修饰玻碳电极上的电化学行为研究及循环伏安法测定水样中总酚含量

移取1.00×10-3 mol·L-1的苯酚、对苯二酚、邻苯二酚和间苯二酚标准溶液各5.00mL,分别置于4支比色管中,各加pH 5.0的柠檬酸-柠檬酸钠缓冲溶液3.00mL,用水定容至10mL,采用多壁碳纳米管修饰的玻碳电极为工作电极,以0.25V·s-1速率扫描获得循环伏安曲线。结果发现:0.225,0.333,0.727V处的氧化峰电流的加和与总酚浓度在0.5~2 000μmol·L-1内呈线性关系,检出限(3S/N)为0.15μmol·L-1。方法用于测定环境水样中总酚含量,加标回收率在95.0%~105%之间,测定值的相对标准偏差(n=6)小于6.0%。     

毛细管电泳安培法测定田基黄中的芦丁与槲皮素

建立了毛细管电泳电化学分离检测田基黄中生物活性成分芦丁和槲皮素的方法。考察了检测电极电位、缓冲液浓度、pH、运行电压和进样时间对分离的影响。以40 cm长,50μm内径的石英毛细管作为分离通道,运行缓冲液为25 mmol/L硼砂(pH 9.2)溶液,分离电压12 kV,0.3 mm直径的铂圆盘电极为检测电极,检测电位1.00 V(vs.Ag/AgCl),芦丁和槲皮素在10 min内得到良好分离。在上述实验条件下,芦丁和槲皮素分别在8.2×10-6~5.2×10-4mol/L与6.8×10-6~7.2×10-4mol/L范围内与峰面积呈良好线性关系,检出限分别为9.0×10-7mol/L(S/N=3)和4.7×10-7mol/L(S/N=3)。方法已应用于田基黄药材提取物成分分析。     

对乙酰氨基酚在多壁碳纳米管修饰电极上的电化学行为

制备了多壁碳纳米管修饰玻碳电极,研究了对乙酰氨基酚在多壁碳纳米管修饰电极上的循环伏安行为,并建立了测定对乙酰氨基酚含量的电化学分析方法。在pH为6.89的磷酸盐缓冲液中,多壁碳纳米管修饰电极对对乙酰氨基酚有明显的电催化作用,其氧化峰电流与对乙酰氨基酚浓度在1.0×10-6～1.0×10-4mol·L-1范围内呈良好的线性关系,检测限为2.0×10-7mol·L-1。     

芯片毛细管电泳电化学发光法快速测定盐酸普鲁卡因的含量

建立了芯片毛细管电泳电化学发光法快速测定盐酸普鲁卡因含量的新方法。采用三联吡啶钌(Ru(bpy)2+3)为电化学发光试剂,三电极体系(直径300μm的铂圆盘电极为工作电极,集成在铂圆盘工作电极外的钛管为对电极,Ag/AgCl丝为参比电极)进行检测。分别考察了运行缓冲溶液pH值、检测缓冲溶液pH值、检测电位以及分离电压对分离和检测性能的影响。在优化条件下,即运行缓冲溶液为10mmol/L磷酸盐溶液(pH4.0),检测池缓冲溶液为含5mmol/LRu(bpy)2+3的50mmol/L磷酸盐缓冲溶液(pH7.0),检测电位为1.25V,分离电压为300V/cm时,盐酸普鲁卡因可在40s内实现较好的分离与检测,其线性范围为10~2000μg/mL(r2=0.9991),检出限(S/N=3)为3.0μg/mL,加标回收率为97%~99%,相对标准偏差为1.8%~2.2%。该方法简便、快速、准确,可用于盐酸普鲁卡因注射液的质量控制。     

新型吡虫啉类化合物的合成

以6-氯-3-氯甲基吡啶为原料,经水解和氧化制得6-氯-3-醛基吡啶(3);3与丙二腈反应制得关键中间体——2-(6-氯-3-亚甲基吡啶)丙二腈(4);4与杂环烯酮缩胺经加成-异构化-环化反应合成了5个新型的吡虫啉类化合物,其结构经1H NMR,13C NMR,IR,HR-EI-MS和MS表征。     

Synthesis of Nicotinamide Adenine Dinucleotide (NAD) Analogues with a Sugar Modified Nicotinamide Moiety

The synthesis of nicotinamide adenine dinucleotide (NAD) analogues in which the ribose unit of the nicotinamide moiety is replaced by a hexitol, altritol, and cyclohexenyl sugar mimic is described.     

烟酰胺极谱行为的研究

用单扫示波极谱法，烟酰胺在ＫＨ２ＰＯ４－Ｎａ３２Ｂ４Ｏｒ－ＮａＯＨ，底液中呈出现良好的二阶导数峰，Ｅｐ＝－１．８０±０．０１Ｖ，在５×１０＾－７－２×１０＾－５ｍｏｌ／Ｌ范围内，峰高与浓度成线性关系，检测限为２．２×１０＾－７ｍｏｌ／Ｌ。此法用于ＮＡ片剂含量的测定，其结果良好。     

Nicotinamide solvation state in aqueous dimethyl sulfoxide

The solvation state of biologically active compound vitamin B₃, viz., 3-pyridinecarboxamide, in an aqueous-dimethyl sulfoxide solvent of a variable composition was studied by ¹H and ¹³C NMR and IR spectroscopy. Below X _DMSO ?0.65 molar fraction, the solvation of the N heteroatom due to hydrogen bonds with water molecules weakens. At X _DMSO > 0.65 molar fraction, almost no changes are observed in the solvate state of the N heteroatom. The ¹H NMR spectra indicate that the degree of conjugation of the carbamide group with the heterocycle increases with an increase in the DMSO concentration. The structures of the dimethyl sulfoxide and mixed aqueous-dimethyl sulfoxide solvates of nicotinamide were optimized by the B3LYP/6311++(DP) method, and their ¹³C chemical shifts (GIAO) and IR spectra were obtained. According to the IR spectroscopic data, the number of hydrogen bonds involving the carbamide group decreases on going from H₂O to DMSO.     

Nicotinamide Prevents Ultraviolet Radiation-induced Cellular Energy Loss

UV radiation is carcinogenic by causing mutations in the skin and also by suppressing cutaneous antitumor immunity. We previously found nicotinamide (vitamin B3) to be highly effective at reducing UV-induced immunosuppression in human volunteers, with microarray studies on in vivo irradiated human skin suggesting that nicotinamide normalizes subsets of apoptosis, immune function and energy metabolism-related genes that are downregulated by UV exposure. Using human adult low calcium temperature keratinocytes, we further investigated nicotinamide’s effects on cellular energy metabolism. We found that nicotinamide prevented UV-induced cellular ATP loss and protected against UV-induced glycolytic blockade. To determine whether nicotinamide alters the effects of UV-induced oxidative stress posttranslationally, we also measured UV-induced reactive oxygen species (ROS). Nicotinamide had no effect on ROS formation, and at the low UV doses used in these studies, equivalent to ambient daily sun exposure, there was no evidence of apoptosis. Hence, nicotinamide appears to exert its UV protective effects on the skin via its role in cellular energy pathways.     

New Crystalline Salts of Nicotinamide Riboside as Food Additives

NR⁺ is a highly effective vitamin B₃ type supplement due to its unique ability to replenish NAD⁺ levels. While NR⁺ chloride is already on the market as a nutritional supplement, its synthesis is challenging, expensive, and low yielding, making it cumbersome for large-scale industrial production. Here we report the novel crystalline NR⁺ salts, d/l/dl-hydrogen tartrate and d/l/dl-hydrogen malate. Their high-yielding, one-pot manufacture does not require specific equipment and is suitable for multi-ton scale production. These new NR⁺ salts seem ideal for nutritional applications due to their bio-equivalence compared to the approved NR⁺ chloride. In addition, the crystal structures of all stereoisomers of NR⁺ hydrogen tartrate and NR⁺ hydrogen malate and a comparison to the known NR⁺ halogenides are presented.     

烟酰胺碳核苷类似物的模块化合成

以核糖异头羧酸制备为起始,以可见光/金属镍双重催化脱羧偶联反应为核心,与氰基水解反应相结合,开发了一条新的模块化合成路线,实现了一系列苄基保护烟酰胺碳核苷类似物的高效合成,其结构经¹H NMR, ¹³C NMR和HR-MS( ESI)表征。      

烟酰胺腺嘌呤二核苷酸磷酸与生物光化学

生物光化学的核心内容是光合作用。在光合作用这个生物光化学的核心领域，烟酰胺腺嘌呤二核苷酸磷酸(NADPH)始终起着极其重要的作用，NADPH就是一个传递电子和能量的最关键活性生物分子。本文对海洋里的光合作用、细菌与光合作用以及光合作用的模拟等作了介绍。     

Nicotinamide adenine dinucleotide: beyond a redox coenzyme

ADP-ribosylation using nicotinamide adenine dinucleotide (NAD+) is an important type of enzymatic reaction that affects many biological processes. A brief introductory review is given here to various ADP-ribosyltransferases, including poly(ADP-ribose) polymerase (PARPs), mono(ADP-ribosyl)-transferases (ARTs), NAD(+)-dependent deacetylases (sirtuins), tRNA 2'-phosphotransferases, and ADP-ribosyl cyclases (CD38 and CD157). Focus is given to the enzymatic reactions, mechanisms, structures, and biological functions.     

Fluorescence Properties of Carba Nicotinamide Adenine Dinucleotide for Glucose Sensing

Carba nicotinamide adenine dinucleotide (cNAD) may serve as a stable cofactor for the enzyme‐based detection of glucose. Many characteristics of cNAD and its reduced form cNADH resemble those of NAD and NADH, respectively. The fluorescence lifetimes of cNADH are determined to be 0.32(2) ns and 0.66(3) ns compared to 0.28(2) ns and 0.60(3) ns for NADH, and the temperature dependence of these lifetimes hints towards identical processes for quenching. The maximum emission occurs at 464 nm for both cNADH and NADH and absorbance maxima are found at 360 nm and 340 nm, respectively. In contrast to previous suggestions the respective maximum extinction coefficient of cNADH equals that of NADH and amounts to 6.2(2) mM ^?1 cm^?1. When changing from NADH to cNADH we observe a ～50 % increase in quantum efficiency, which—together with the larger excitation wavelength and the higher stability—should make cNAD a well suited alternative as coenzyme for robust glucose detection.