Biological Glucose Metabolism Regulated Peptide Self‐Assembly as a Simple Visual Biosensor for Glucose Detection

A glucose oxidase (GOx)‐mediated glucose metabolism was in vitro mimicked and employed to regulate the self‐assembly of peptide‐based building blocks. In this new stimuli‐responsive self‐assembly system, two peptide‐based building blocks, respectively, having aspartic acid (gelator 1 ) and lysine (gelator 2 ) residues were designed and prepared. When adding glucose and GOx to the aqueous solution of gelator 1 or the self‐assembled fibrillar hydrogel of gelator 2 to construct glucose metabolism system, the metabolic product (gluconic acid) can trigger the protonation of the peptide molecules and induce the phase transitions of gelators 1 (sol‐gel) and 2 (gel‐sol). Because this glucose metabolism regulated peptide self‐assembly is built on the oxidation of glucose, it can be used as a simple visual biosensor for glucose detection.     

Study On The Catalytic Reaction Of β-Cd-Hemin Using 2, 3, 4-Trichlorophenol As Substrate And Analytic Application

ABSTRACT|The catalytic activity of various mimetic enzymes instead of the peroxidase have been investigated by 4-aminoantipyrine (4-AAP) and 2, 3, 4-trichlorophenol (TCP) to form a dye utilizing hydrogen peroxide as hydrogen acceptor. The different Chlorophenolic derivatives, which act as a substrate in β-CD-hemin-H₂O₂-4-AAP catalytic reaction, have been systematically studied.|Meanwhile, the relationship of structure-effect for the β-CD-hemin as catalyst, and chlorphenols as substrate has been respectively discussed. The mechanism of catalytic reaction has been investigated. The results showed that β-CD-hemin was the best mimetic enzyme for peroxidase among those tested and TCP was a good substrate for the determination of hydrogen peroxide with β-CD-hemin. The method for the determination of hydrogen peroxide was proposed using 4-AAP-TCP system with β-CD-hemin as catalyst. A linear calibration graph was obtained over the H₂O₂ concentration of 4.8×10-^?8-7.7×10-^?5M, and the relative standard deviation at a H₂O₂ concentration of 2.8×10-^?5M was 2.5%. The apparent molar absorptivity of the chromogenic reaction for H₂O₂ was 1.54× 10⁴ L.mol-^?1.cm^?1. Satisfactory results were obtained in the determination of H₂O₂ in synthetic samples by this method.

Also, the method was coupled with the glucose oxidation reaction to determination glucose in human serum.     

Catalyzed Determination of Glucose with a Mimic Enzyme Constructed of Bis‐[‐6‐O‐(‐β‐ethyloic‐butanedioic Acid‐1,4‐ester‐4‐)]β‐Cyclodextrin · Fe3+

Abstract

Catalyzed determination of glucose with mimic glucose oxidase is constructed by the reaction of β‐cyclodextrin, maleic anhydride, and chloroacetic acid with iron trichloride in hydrogen peroxide. The method is simple and convenient, and sensitivity and repeatability are ideal. Beer's law is obeyed in a concentration range of 30–197 µg · ml^?1 glucose with an excellent correlation coefficient (r=0.9994), while the detection limit is 4.10 µg · ml^?1, the RSD is 0.98% (n=8). The recovery of sample is 95.8–103.1%.     

Rapid Amperometric Determination of Magnesium(II) Ions

Abstract

An amperometric procedure for the measurement of magnesium(II) has been developed using the enzyme hexokinase in solution and glucose oxidase immobilized onto a preactivated polymeric support. The reaction of hexokinase was monitored following the decrease in current due to the glucose consumption by the enzyme in the presence of the ATP-Mg²⁺ complex. The reaction rate was dependent on the concentration of magnesium(II) in solution. Concentrations of hexokinase and ATP were optimised. Measuring the current change in the 1-3 min interval after the start of the reaction magnesium(II) can be determined in the 4 × 10^?5 to 10^?3 M range. Other divalent cations tested showed no interference. The magnesium(II) content of 5 pharmaceutical products was measured with the amperometric and compared to a spectrophotometric procedure. The results correlated well.     

Fast Spectrometric Method of Determining the Activity of Glucose Oxidase

Abstract

A method is described of fast spectrometric determination of glucose oxidase activity based on enzymatic reduction of benzoquinone to hydroquinone and on the measurement of the rate of increase of hydroquinene absorbance at 290 nm. The enzymatic activity is deduced from the initial rate. The method is rapid and sensitive.     

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.

     

The Application of Engineered Glucose Dehydrogenase to a Direct Electron–Transfer‐Type Continuous Glucose Monitoring System and a Compartmentless Biofuel Cell

Abstract

Continuous glucose monitoring (CGM) is expected to become an ideal way to monitor glycemic levels in diabetic patients. On the other hand, biofuel cells can be used as an alternative energy source in future implantable devices, such as implantable glucose sensors in the artificial pancreas. Glucose dehydrogenase from Acinetobacter calcoaceticus, which harbors pyrroloquinoline quinone as the prosthetic group (PQQGDH), is one of the enzymes most attractive as a glucose sensor constituent and as the anode enzyme in biofuel cells, due to its high catalytic activity and insensitivity to oxygen. However, the application of PQQGDH for these purposes is inherently limited because an electron mediator is required for the electron transfer to the electrode.

We have recently reported on the development of an engineered enzyme, quinohemoprotein glucose dehydrogenase (QH‐GDH), in which the cytochrome c domain of the quinohemoprotein ethanol dehydrogenase (QH‐EDH) was fused with PQQGDH, to enable electron transfer to the electrode in the absence of an artificial mediator. In this study, we constructed a direct electron‐transfer‐type CGM system employing QH‐GDH. This CGM system showed sufficient current response and high operational stability. Furthermore, we successfully constructed a compartmentless biofuel cell employing QH‐GDH.     

Ag@SiO2纳米复合物金属增强荧光释放法检测葡萄糖

制备了Ag@SiO2纳米复合物,罗丹明B通过物理掺杂结合在SiO2壳层。由于金属增强荧光效应,罗 丹明B的荧光增强到4.7倍。Ag核易被H2O2氧化,Ag核氧化后产生荧光增强释放效应。基于金属增强荧光 释放建立了一种新型葡萄糖检测方法,采用交联法在罗丹明B掺杂的Ag@SO2纳米复合物的SiO2壳层固定 葡萄糖氧化酶。检测浓度范围为0.2～6.8 mmol/L,检测限可达0.06 mmol/L。由于H2O2氧化Ag核反应迅 速,检测体系对葡萄糖的响应快速。     

基于蒸汽溶胶-凝胶法的碳纳米管/普鲁士蓝复合材料的制备及应用

采用蒸汽溶胶-凝胶法将碳纳米管/普鲁士蓝(MWCNTs/PB)纳米复合材料固定于金电极表面,利用碳纳米管与普鲁士蓝纳米粒子间良好的协同效应,制备了用于检测过氧化氢的MWCNTs/PB复合修饰电极。进而在修饰电极表面固定葡萄糖氧化酶,制备了葡萄糖生物传感器。结果表明,该传感器对葡萄     

硅溶胶-凝胶包埋纳米金和酶的葡萄糖生物传感器

采用溶胶-凝胶技术将金纳米粒子和葡萄糖氧化酶一次性固定于硅溶胶-凝胶的网络结构中,制备了葡萄糖生物电化学传感器并优化了传感器的制备条件。酶电极对葡萄糖具有良好的电化学响应,葡萄糖浓度在0.02~2.0 mmol/L范围内和催化电流呈线性关系,检出限为0.005 mmol/L。酶电极在4 ℃下贮存100 d后对葡萄糖的响应仅下降8%。该酶电极灵敏度高、响应快、稳定性好。