中性红掺杂SiO2纳米粒子修饰的酶阵列传感器同时测定葡萄糖、乳酸和L-谷氨酸的研究

本文以中性红为核，二氧化硅为壳，利用反相微乳液技术，通过正硅酸四乙酯的水解制备了掺杂有中性红的二氧化硅纳米粒子，并用TEM技术进行了表征。核中性红能够催化测定葡萄糖，乳酸和L-谷氨酸的反应，而壳二氧化硅不仅克服了电活性物质中性红易流失的缺点，且具有高的生物亲和性。分别与葡萄糖氧化酶、乳酸氧化酶以及L-谷氨酸氧化酶混合后，修饰在碳阵列电极表面。最后在该酶阵列电极表面滴加一层Nafion, 防止电活性物质抗坏血酸、尿酸等的干扰。该酶阵列传感器与流动注射分析技术(FIA)相结合，可应用于同时检测大鼠血样中的葡萄糖，乳酸和L-谷氨酸浓度。该方法无需通过传统的色谱柱的分离，大大简化了实验条件，为这一领域的研究提供了有效的分析方法。     

Biosensing Membrane Base on Ferulic Acid and Glucose Oxidase for an Amperometric Glucose Biosensor

A biosensing membrane base on ferulic acid and glucose oxidase is synthesized onto a carbon paste electrode by electropolymerization via cyclic voltammetry in aqueous media at neutral pH at a single step. The developed biosensors exhibit a linear response from 0.082 to 34 mM glucose concentration, with a coefficient of determination R² equal to 0.997. The biosensors display a sensitivity of 1.1 μAmM⁻¹ cm⁻², a detection limit of 0.025 mM, and 0.082 mM as glucose quantification limit. The studies reveal stable, repeatable, and reproducible biosensors response. The results indicate that the novel poly-ferulic acid membrane synthesized by electropolymerization is a promising method for glucose oxidase immobilization towards the development of glucose biosensors. The developed glucose biosensors exhibit a broader linear glucose response than other polymer-based glucose biosensors.     

Structure of an anthocyanin-anthocyanin dimer molecule in anthocyanin-producing cells of a carrot suspension culture

A novel anthocyanin, an anthocyanin-anthocyanin dimer, was isolated from the cells of an anthocyanin-producing carrot cell-line culture, and its structure was elucidated using spectroscopic methods. It consists of two molecules of the anthocyanin, cyanidin 3-[xylosyl-(sinapoyl-glucosyl)-galactoside], with a CH-CH₃ linkage at the 8-8 position. This is the first report of the identification and isolation of an anthocyanin-anthocyanin dimer with a CH-CH₃ linkage from intact plant cells.     

In situ proton NMR study of acetyl and formyl group migration in mono‐O‐acyl D‐glucose

Acetyl and formyl group migration, mutarotation, and hydrolysis of mono‐O‐acylated glucose are studied by in situ 1D and 2D ¹H NMR spectroscopy. α‐D ‐Glucosyl‐1‐acetate and α‐D ‐glucosyl‐1‐formate serve as sole starting materials. They are generated in situ by configuration retaining glucosyltransfer from α‐D ‐glucosyl‐1‐phosphate to formate and acetate, which is catalyzed by the Glu‐237 → Gln mutant of Leuconostoc mesenteroides sucrose phosphorylase. Temporary accumulated regio‐isomeric mono‐O‐acyl D ‐glucoses are identified, characterized, and quantified directly from the reaction mixture. Time courses of the transformations give insight into pH dependence of acyl group migration and mutarotation as well as into the stability of various regioisomers. Copyright © 2009 John Wiley & Sons, Ltd.     

2-Deoxyglucose as a selective agent for derepressed mutants of Pichia stipitis

The glucose analog 2-deoxyglucose (2-DOG) has been used to obtain mutants depressed for pentose metabolism. Some researchers have used 2-DOG alone whereas others have used it in the presence of a glucose-repressible carbon source. We examined both methods and screened mutant strains for improved use of xylose in the presence of glucose. Pichia stipitis mutants selected for growth on d-xylose in the presence of 2-DOG used xylose from a 1∶1 glucose:xylose mixture more rapidly than did their parents. One of these mutants, FPL-DX26, completely consumed xylose in the presence of glucose and produced 33g/L ethanol in 45h from 80 g/L of this sugar mixture. Mutants selected for growth on 2-DOG alone did not show significant improvement. Selection for growth on d-xylose in the presence of 2-DOG has been useful in developing parental strains for further genetic manipulation. The Forest Products Laboratory is maintained in cooperation with the University of Wisconsin-Madison. This article was prepared by U.S. Goverment employees on official time, and it is therefore in the public domain and not subject to copyright.     

Silica coated quantum dots: a new tool for electrochemical and optical glucose detection

The application of silica coated quantum dots (QDs@SiO₂) in glucose detection in combination with glucose oxidase is reported. The high specific surface area of such particles can be exploited to immobilise a greater amount of the enzyme on a modified electrode. In addition to this electrochemical method, we report here an indirect optical technique based on the photoluminescence quenching of QDs by hydrogen peroxide produced during glucose oxidation. The results obtained with these two different detection methodologies are compared. Correspondence: Sara Cavaliere-Jaricot, Freiburg Materials Research Centre (FMF), Albert-Ludwig University Freiburg, Stefan-Meier-Strasse 21, D-79104 Freiburg, Germany     

内源性n-3多不饱和脂肪酸对fat-1转基因小鼠血糖血脂的影响

利用fat-1转基因小鼠模型,研究内源性n-3多不饱和脂肪酸(n-3 PUFAs)的血糖血脂调节作用.采用fat-1转基因小鼠和C57BL/6野生型小鼠喂食高n-6、低n-3 PUFAs的标准配方饲料4周,然后2组小鼠给予高糖饮液自由饮用4周,每周测体重.第8周末,取血离心测血糖、胰岛素、甘油三脂(TG)、胆固醇(TC)、高密度脂蛋白(HDL-C)、低密度脂蛋白(LDL-C)水平.结果表明：fat-1转基因小鼠体重增加幅度、空腹血糖值、血清胰岛素、胰岛素抵抗指数、血清TC、TG、HDL-C、LDL-C水平明显低于野生型小鼠(P<0.05).认为n-3 PUFAs能抑制体重增长,降低小鼠血糖、血脂和胰岛素抵抗,起到调节血糖、血脂的作用.