葡萄糖对溶胶凝胶法制备Li1.2Ni0.13Co0.13Mn0.54O2正极材料性能的影响

利用XRD、SEM、EDS、BET、激光粒度、循环伏安、恒流充放电、交流阻抗方法研究了葡萄糖为碳源对溶胶凝胶法制备Li_1.2Ni_0.13Co_0.13Mn_0.54O₂正极材料的结构、形貌以及电化学性能的影响.结果表明：与前驱体中未加入葡萄糖所制备的材料相比,掺葡萄糖后样品颗粒分布相对均匀,粒径变小,D₅₀从11.56减小至9.94 μm,比表面积增加近1倍.经0.05C充放电活化后,未掺葡萄糖和掺葡萄糖样品0.2C放电比容量分别为183.4、211.6 mAh·g^-1,2C容量分别为其0.2C的62.2%、77.6%.1C循环50次后放电比容量分别为133.3、173.6 mAh·g^-1,容量保持率分别为95.1%、100%.掺葡萄糖可降低首次不可逆容量损失,提高材料的倍率性能与循环稳定性,减少电荷传递阻抗、Warburg阻抗以及双电层弥散效应,但不改变材料的晶型结构.     

Ferrocene and Ferricenium Ion as Versatile Photometric Titrants of H2O2 and D-Glucose in the Presence of Peroxidase and Glucose Oxidase. A Ferrocene-Peroxidase Stairway #

Abstract

Hydrogen peroxide can routinely be determined in the presence of ferrocene (FcH) and horseradish peroxidase by monitoring at 617 nm the enzymatically produced ferricenium dye. In contrast, D-glucose can be assayed by following the fading of the ferricenium dye FcH⁺PF₆ ^? in the presence of glucose oxidase. The change in absorbance in both cases corresponds to the amount of analyte. viz. H₂O₂ or D-glucose, in solution. The routine is very simple, invariant to the concentrations of both ferrocenes/ferricenium salt and enzyme and allows numerous “one pot” measuremeats with the detection limit of 10^?4 M for both the analytes. It takes 2–4 and 5–10 min to accomplish one analysis of H₂O₂ and D-glucose in the presence of peroxidase and glucose oxidase, respectively.

     

离子色谱脉冲安培法测定蜂蜜中的葡萄糖、果糖、蔗糖

利用离子色谱脉冲安培检测器对蜂蜜中葡萄糖、果糖、蔗糖的测定方法进行了研究。采用CARBOPAC^TM PAl分离柱和脉冲安培检测器,对淋洗分离条件进行了实验,选择50mmol/L NaOH作淋洗液,可使蜂蜜中的葡萄糖、果糖、蔗糖很好地分离。检出限分别为：葡萄糖2μg/kg,果糖2μg/kg,蔗糖5μg/kg。加标回收率为90％－108％。该方法只需简单的前处理、无基体干扰,分离效果好,测定准确率高,适用于蜂蜜中葡萄糖、果糖、蔗糖的测定。     

基于普鲁士蓝(PB)膜修饰铂电极的葡萄糖传感器的研究

在制备PB膜修饰铂盘电极的基础上,利用修饰电极对过氧化氢的电催化还原特性,得到了性能优良的葡萄糖传感器。作者系统地考察了有关修饰膜制备和测试实验条件对传感器性能的影响,结果表明传感器的最佳工作电位是0．05V,测试溶液的最适PH值为6．5,在选定的工作条件下,传感器的检测灵敏度为80nA/mmol.L^-1,线性范围为0．1－5mmol.L^-1,响应时间为1．5min,寿命在1个月以上,表观米氏常数为21mmol.L^-1。本方法制得的传感器能有效消除抗坏血酸,尿酸的干扰,有望用于血液中葡萄糖的直接测定。     

GpdA-promoter-controlled production of glucose oxidase by recombinant aspergillus niger using nonglucose carbon sources

The gpdA-promoter-controlled exocellular production of glucose oxidase (GOD) by recombinant Aspergillus niger NRRL-3 (GOD3-18) during growth on glucose and nonglucose carbon sources was investigated. Screening of various carbon substrates in shake-flask cultures revealed that exocellular GOD activities were not only obtained on glucose but also during growth on mannose, fructose, and xylose. The performance of A. niger NRRL-3 (GOD3-18) using glucose, fructose, or xylose as carbon substrate was compared in more detail in bioreactor cultures. These studies revealed that gpdA-promoter-controlled GOD synthesis was strictly coupled to cell growth. The gpdA-promoter was most active during growth on glucose. However, the unfavorable rapid GOD-catalyzed transformation of glucose into gluconic acid, a carbon source not supporting further cell growth and GOD production, resulted in low biomass yields and, therefore, reduced the advantageous properties of glucose. The total (endo- and exocellular) specific GOD activities were lowest when growth occurred on fructose (only a third of the activity that was obtained on glucose), whereas utilization of xylose resulted in total specific GOD activities nearly as high as reached during growth on glucose. Also, the portion of GOD excreted into the culture fluid reached similar high levels (≅ 90%) by using either glucose or xylose as substrate, whereas growth on fructose resulted in a more pelleted morphology with more than half the total GOD activity retained in the fungal biomass. Finally, growth on xylose resulted in the highest biomass yield and, consequently, the highest total volumetric GOD activity. These results show that xylose is the most favorable carbon substrate for gpdA-promoter-controlled production of exocellular GOD.     

基于中空多孔金纳米/石墨烯复合纳米材料的葡萄糖氧化酶直接电化学及其生物传感研究

采用溶液相牺牲模板法制备中空多孔金纳米粒子（HPAuNPs）,并将该材料与还原氧化石墨烯（rGO）复合,用于葡萄糖氧化酶（GOx）在玻碳电极（GCE）表面的有效固定,构建GOx/HPAuNPs/rGO/GCE传感界面。利用扫描和透射电镜、X射线光电子能谱、X射线衍射谱、红外光谱及电化学等方法对材料的形貌与结构,GOx的固定化过程,以及传感器的直接电化学和电催化性能进行表征。结果表明,HPAuNPs和rGO的协同作用能有效促进GOx与电极之间的直接电子转移（DET）。基于GOx/HPAuNPs/rGO/GCE对葡萄糖的良好电催化性能,该方法有效实现了对葡萄糖的高灵敏度检测,其电流响应的线性范围为0.05～7.0 mmol/L,检出限（S/N=3）为16μmol/L。该传感器具有良好的选择性、重现性及稳定性,对实际样品血清中血糖的测定结果令人满意,回收率为98.0%～103%,相对标准偏差不大于5.0%。     

基于芬顿反应和硫磺素T构建免标记荧光传感器用于葡萄糖的检测

基于芬顿反应和硫磺素T(ThT)构建新奇的免标记荧光传感器用于葡萄糖的检测。当无葡萄糖存在时,ThT诱导富G-DNA探针形成G-四链体/ThT复合物,ThT的荧光强度显著增强;当葡萄糖存在时,葡萄糖氧化酶催化葡萄糖产生H2 O2,在Fe^2+催化的芬顿反应作用下,H2 O2转化为羟基自由基(·OH),·OH引发DNA的氧化损伤导致富G-DNA探针裂解为短寡核苷酸片段而丧失形成G-四链体/ThT的能力,ThT的荧光强度显著降低,从而实现对葡萄糖的检测。在优化的检测条件下,G-四链体/ThT荧光强度变化和葡萄糖浓度在0.5~45μmol/L的范围内呈现较好的线性关系(R^2=0.99268),检出限为0.1μmol/L。利用本法对葡萄糖加标的血液样品进行分析,葡萄糖的回收率为90.7%~118.3%,相对标准偏差为1.7%~5.8%,方法可用于血糖检测。     

Carnation‐like CuO Hierarchical Nanostructures Assembled by Porous Nanosheets for Nonenzymatic Glucose Sensing

Carnation‐like CuO hierarchical nanostructures assembled by ultrathin porous nanosheets were successfully fabricated via a facile solvothermal route followed with heat treatment. As‐prepared CuO nanostructures exhibited excellent catalytic activity toward glucose oxidation in the absence of any enzymes. Under the optimized conditions, the CuO‐based enzymeless glucose sensor showed high sensitivity of 3.15 mA mM^?1 cm^?2, low limit of detection (98 nM, S/N=3), good reproducibility, excellent selectivity and long‐time stability. The superb nonenzymatic glucose sensing performance of the CuO hierarchical nanostructures was attributed to the highly catalytically active sites at the edges and basal planes of the CuO nanosheets, facile transportation of analytes through the abundant mesopores and macropores, robust and stable hierarchical structure. Moreover, the CuO‐based enzymeless glucose sensor showed high accuracy and reliability in comparison with clinical glucometer for quantitative determination of glucose in human blood serum samples.     

Glucose-Responsive Monoolein Cubic Phase Containing Glucose Oxidase

Glucose-responsive monoolein (MO) cubic phase was prepared by immobilizing proteinoid composed of Asp and Leu (PAL) and hydrophobically modified glucose oxidase (HmGOD) onto the MO bilayers. The hydrodynamic mean diameter of PAL aggregate in aqueous solution decreased with increasing the pH value. The number of pamitic acid residue per one molecule of HmGOD was determined to be 6.3 by a calorimetric method. HmGOD could acidify glucose solution in a few hours, possibly because it converted glucose to gluconic acid. PAL- and HmGOD-immobilized MO cubic phase was prepared by hydrating MO melt with the mixture aqueous solution of PAL and HmGOD. The cubic phase exhibited its phase transition around 62.5°C, determined by polarizing microscopy. The release of carboxylic fluorescein (CF) from the cubic phase was suppressed when the pH value of release medium decreased, possibly because PAL can aggregate more at a lower pH value. The release was suppressed when glucose concentration increased, possibly because the release medium can be more acidified and PAL will be more aggregated at a higher glucose concentration. The cubic phase could be used as a drug carrier which releases its content in a sustained manner when the glucose concentration is abnormally high.     

Molecularly engineered graphene surfaces for sensing applications: A review

Graphene is scientifically and commercially important because of its unique molecular structure which is monoatomic in thickness, rigorously two-dimensional and highly conjugated. Consequently, graphene exhibits exceptional electrical, optical, thermal and mechanical properties. Herein, we critically discuss the surface modification of graphene, the specific advantages that graphene-based materials can provide over other materials in sensor research and their related chemical and electrochemical properties. Furthermore, we describe the latest developments in the use of these materials for sensing technology, including chemical sensors and biosensors and their applications in security, environmental safety and diseases detection and diagnosis.