Direct Interaction Between Gold Nanorods and Glucose

In this work, we present the results of the study on the interactions between gold nanorods (GNRs) and glucose. The optical properties of GNRs have higher sensitivity to glucose compared with that of gold nanospheres. The long-wavelength bands of the GNRs obviously decrease as the concentration of glucose increases. At high glucose concentrations, the absorption peak in long-wavelength bands almost disappears, and the absorption intensities corresponding to the transverse plasmon band are also decrease. These results suggest that glucose could seriously affect the optical properties of GNRs. A possible interaction mechanism between gold nanorods (GNRs) and glucose has been proposed. Furthermore, the influence of glucose on different amount GNRs also has been studied.     

含超细Au颗粒的乳酸氧化酶和葡萄糖氧化酶生物传感器

制备了小于10 nm的金颗粒,并利用其进行固定化葡萄糖氧化酶和乳酸氧化酶的研究. 实验发现,金纳米颗粒可以大幅度提高葡萄糖氧化酶电极和乳酸氧化酶电极的电流响应,响应电流从相应浓度的几十纳安增强到几千纳安. 探讨了金纳米颗粒在固定化酶中所起的作用.     

金纳米棒的合成及应用研究进展

金纳米材料具有特殊的物理、化学性质。与其他形状的金纳米材料相比,金纳米棒同时具有化学和光学方面的备向异性,在材料科学、局域表面等离子体共振（LSPR）传感、生物医学等领域存在着巨大的应用前景。文章系统的评述了金纳米棒的合成及应用进展。具体内容包括金纳米棒的合成、金纳米棒的光学特性、金纳米棒在LSPR传感分析方面的应用以及金纳米棒在生物医学方面的应用。     

A New Amperometric Glucose Biosensor Based on Pectin Coating

In this article we describe the preparation and characterization of a new glucose oxidase (GOD) biosensor. The GOD biosensor was immobilized onto pectin by using chromium III sulfate and electrode was coated with GOD containing pectin. Immobilization conditions were modified according to the results obtained by coated electrode. Optimum conditions were obtained when 10 U GOD and 1% pectin was reacted with 0.01 M chromium III sulfate. Developed biosensor is very accurate, fast responding, and stable. We could easily detect 1 mM glucose with a response time below 1 minute and could use our sensor up to 14 times (within 27 days) with 90% accuracy.     

氧化锌纳米棒压电发电纺织品的制备

研究应用水热法在涤纶织物上生长氧化锌纳米棒,并采用扫描电镜、X射线衍射和原子力显微镜对制得的氧化锌纳米棒的形貌、晶型取向和压电性能进行测试分析。结果表明:织物表面生长的氧化锌纳米棒属于六方纤锌矿晶相,纳米棒垂直紧密排列在织物表面。水热法得到的纳米棒沿C轴取向生长,纳米棒直径从0.3μm到1μm不等。从电流-电压曲线可以看出:氧化锌纳米棒的半导体特性明显,且重复性良好,在氧化锌生长区域有明显的电流增强信号,说明氧化锌纳米棒压电性能优异。     

海藻酸钙凝胶固定葡萄糖氧化酶的研究

利用海藻酸钙凝胶颗粒固定葡萄糖氧化酶(GOD).确定了固定化条件,并考察了温度、pH值、储存时间对固定化酶和游离酶酶活力的影响,测定了酶活回收率.确定的固定化较优条件为:CaCl2 5.0%(质量体积比),海藻酸钠3.0%(质量体积比);固定化酶的最适催化温度为31℃、最适pH值为6.3,较游离酶分别提高7℃和0.6;固定化酶的平均酶活回收率为61.69%.此外,酶的储存稳定性能也有所提高,可重复多次使用.     

Insights into the Structures,Inhibitors, and Improvement Strategies of Glucose Oxidase

Glucose oxidase, which uses molecular oxygen as an electron acceptor to specifically catalyze the conversion of β-d-glucose to gluconic acid and hydrogen peroxide (H₂O₂), has been considered an important enzyme in increasing environmental sustainability and food security. However, achieving the high yield, low price and high activity required for commercial viability remains challenging. In this review, we first present a brief introduction, looking at the sources, characteristics, catalytic process, and applications of glucose oxidase. Then, the predictive structures of glucose oxidase from two different sources are comparatively discussed. We summarize the inhibitors of glucose oxidase. Finally, we highlight how the production of glucose oxidase can be improved by optimizing the culture conditions and microbial metabolic engineering.     

Effects of Polyols and Organic Solvents on Thermostability of Lipase

The effects of polyols and organic solvents on the thermostability of lipase were studied. The thermodeactivation process of lipase obeyed a series deactivation model and four kinetic parameters were determined. The rate constant of the first deactivation process was found to be a key one. All the polyols used had a positive effect for stabilization of lipase and the extent of effect increased with polyol concentration and carbon number of polyol. The effect of organic solvents on the thermostability of lipase was investigated by incubating the lipase in the organic solvents before measuring their activities. The behavior of the thermodeactivation depended upon the organic solvents used; increased activity was observed in some solvents. © 1997 SCI     

超声波均质和GOD脱糖预处理鸡蛋清

考察了超声波均质及葡萄糖氧化酶(GOD)脱糖对鸡蛋清(CEW)粘度、蛋清中溶菌酶浓度和活力的影响. 结果表明,超声波均质和GOD脱糖均能有效降低蛋清的粘度,从而得到低粘度的均匀料液. 但随着超声波功率的增加和超声处理时间的延长,溶菌酶的浓度及活力呈下降趋势. 而经GOD脱糖处理后的料液溶菌酶活力随GOD加入量的增大而降低,浓度则先升高后下降. 将两种处理方法结合使用,料液粘度可以降至4.0 mPa×s,此时溶菌酶损失19.48%,酶活降低19.13%.     

CeO_2掺杂对Cu/SiO_2催化剂热稳定性的影响

采用蒸氨法制备了CeO2掺杂的Cu/SiO2催化剂,考查了CeO2掺杂对Cu/SiO2催化剂在草酸二甲酯催化加氢制取乙二醇反应中热稳定性的影响。采用H2-程序升温还原(H2-TPR),透射电镜(TEM)对催化剂的物理化学性能进行了表征。在反应温度T=200℃,压力P=3.0 MPa,液时空速LHSV=0.4 h-1,氢气、草酸二甲酯摩尔比H2∶DMO=80∶1,400℃高温处理2.0 h的条件下测定了催化剂的活性变化。结果表明,CeO2掺杂对Cu物种的分散起到了促进作用,提高了催化剂的热稳定性。     

Templated Synthesis of Gold Nanorods (NRs): The Effects of Cosurfactants and Electrolytes on the Shape and Optical Properties

Seeded growth of gold nanorods (NRs) has been accomplished in a micellar medium containing mixed surfactants or a high salt concentration. Cetyl trimethylamoniumbromide (CTAB) forms micelles upon which the growth of rod shaped gold nanoparticles occurs. AgNO₃ is introduced into the growth solution to enhance the formation of NRs. The roles of non-ionic surfactants such as Tween and Triton, and of electrolytes such as sodium chloride and potassium chloride have been examined. As the concentration of these additives in the growth solution is increased, the aspect ratio of the NRs increases to a critical limit, after which it decreases again. Upon carefully controlling the content of Triton X-100 or Tween 20 in the growth solution, these non-ionic surfactants assisted in fine-tuning the shape of gold NRs (e.g. rectangular or “dogbone”). The growth pattern of the NRs fits into the model of a soft template formed by the mixture of CTAB and non-ionic surfactants.     

Glucose oxidase immobilization on stainless steel to mimic the aerobic activities of natural biofilms

In non-sterile aqueous media, stainless steels (SS) may exhibit a non-stable behavior resulting from interactions between microbial species and passive film. They can induce the increase of the Open Circuit Potential (OCP) and they do so when they are organized in biofilms. Numerous studies have reported the catalytic effect of biofilms, involving enzymes, and their influence on the local physicochemical conditions related to their heterogeneous structure. To date, there are no enzymatic models able to mimic the interfacial processes: generation of oxidant species and specific physicochemical conditions.In our study, a SS-modified electrode based on a classical enzyme immobilization technique was conceived. Glucose oxidase (Gox) was immobilized in a polymeric film poured on SS surface to concentrate the enzymatic activity near the metal/polymer film interface. Electrochemical tests were performed to compare the effect of Gox when immobilized or free in the electrolyte. These experiments provided fine details about the reduction of both oxidants involved in the Gox-catalyzed reaction: H₂O₂ and O₂.The cathodic processes presented major differences between free and immobilized enzyme whereas the OCP ennoblement was found to be mainly due to an electrochemical effect of H₂O₂ in both cases. The immobilized Gox provoked a strong depletion of oxygen near the metal/polymer interface, indicating that the reduction current recorded was principally due to the H₂O₂ reduction.     

制备工艺对ATO纳米棒形貌结构的影响

以SnCl4·5H2O和SbCl3为原料,采用化学共沉淀法成功制备了高含量棒状纳米级掺锑二氧化锡(ATO)导电粉体,研究了掺锑量、热处理温度及热处理时间对纳米棒形貌结构的影响。初步探讨了ATO纳米棒的形成机理,并用热重分析(TG)、透射电镜(TEM)、X-射线衍射(XRD)、比表面法(BET)对棒结构进行了表征。     

氢氧化镁纳米棒的制备及热分解动力学研究

以氯化镁和轻质氧化镁为原料,采用液相法制备出碱式氯化镁纳米棒;再以碱式氯化镁纳米棒为前驱物,经沉淀转化法合成出直径约100～150nm,长约3～5μm的氢氧化镁纳米棒。采用Romero方法,对非等温热重法得到的氢氧化镁纳米棒热分解动力学数据处理分析后,得出氢氧化镁纳米棒的热分解反应遵循随机成核和随后生长（F1）机理,表观活化能E=187kJ／mol,指前因子A=3．84×10^11。     

Conversion of rod-shaped gold nanoparticles to spherical forms and their effect on biodistribution in tumor-bearing mice

Gold nanorods that have an absorption band in the near-infrared region and a photothermal effect have been used as nanodevices for near-infrared imaging and thermal therapy. Choice of the optimal shape of gold nanorods which relates optical properties and in vivo biodistribution is important for their applications. In the present study, to investigate the relationship between the shape of gold nanorods and their biodistribution after intravenous injection, we first prepared two types of gold nanorods that had distinct aspect ratios but had the same volume, zeta potential, and PEG density on the gold surface. Biodistributions of the two types of gold nanorods after intravenous injection into tumor-bearing mice were then compared. Although a slight difference in accumulation in the spleen was observed, no significant difference was observed in the liver, lung, kidney, and tumors. These results suggest that biodistribution of the gold nanorods in the aspect ratio range of 1.7 to 5.0, diameter of 10 to 50 nm, and volume of approximately 4 × 10³ nm³ was dependent mainly on surface characteristics, PEG density, and zeta potential.     

Effect of pH on the Interaction of Gold Nanoparticles with DNA and Application in the Detection of Human p53 Gene Mutation

Gold nanoparticles (GNPs) are widely used to detect DNA. We studied the effect of pH on the assembly/disassembly of single-stranded DNA functionalized GNPs. Based on the different binding affinities of DNA to GNPs, we present a simple and fast way that uses HCl to drive the assembly of GNPs for detection of DNA sequences with single nucleotide differences. The assembly is reversible and can be switched by changing the solution pH. No covalent modification of DNA or GNP surface is needed. Oligonucleotide derived from human p53 gene with one-base substitution can be distinguished by a color change of the GNPs solution or a significant difference of the maximum absorption wavelength (λ_max), compared with wildtype sequences. This method enables detection of 10 picomole quantities of target DNA.     

高热稳定性低氯聚苯砜树脂合成及表征

结合缩聚方法和封端修饰方法合成苯酚封端的聚苯砜(PPSU)树脂,利用离子色谱方法对PPSU树脂的氯端基含量进行定量测试,并采用毛细管流变仪和高温注塑等方法对比评估了不同氯端基含量PPSU树脂的热稳定性和颜色.结果表明,通过苯酚封端,PPSU树脂的氯端基含量可由3000 mg/kg以上降至700 mg/kg以下,氯端基含...     

富GIF啤酒酵母制品对糖尿病大鼠空腹血糖和糖耐受量的影响

目的研究富GTF啤酒酵母制品对糖尿病大鼠空腹血糖和糖耐受量的影响。方法采用腹腔注射四氧嘧啶建立糖尿病大鼠模型,将模型大鼠随机分为3组,分别每天服用普通面包酵母0.1g、富GTF啤酒酵母干粉0.1g和富GTF啤酒酵母胶囊1粒,每天测空腹血糖。30d后进行糖耐受量试验,测0、0.5和2h各时间点血糖。结果富GTF啤酒酵母胶囊和富GTF啤酒酵母干粉不降低正常大鼠血糖。服药30d后,富GTF啤酒酵母胶囊组糖尿病大鼠空腹血糖下降52.45%,富GTF啤酒酵母干粉组血糖下降32.34%,而面包酵母干粉无降糖作用。各样品组糖耐受量2h后均下降,富GTF啤酒酵母胶囊组血糖下降迅速。结论富GTF啤酒酵母胶囊降血糖效果显著,优于富GTF啤酒酵母干粉,并能显著改善糖尿病大鼠糖耐受量。     

N-苯基马来酰亚胺/苯乙烯/丙烯腈乳液共聚物与PVC共混

通过乳液共聚合成了Ｎ－苯基马来酰亚胺／苯乙烯／丙烯腈三元共聚物,与聚氯乙烯（ＰＶＣ）共混得到耐热ＰＶＣ共混物,研究了共聚物组分含量对ＰＶＣ共混物的力学性能、流变性的影响,用热分析法以及维卡软化点测定仪对共混物的耐热性进行了表征,同时考察了共混物的微观结构与形态。     

Quaternized chitosan as support for the assembly of gold nanoparticles and glucose oxidase: Physicochemical characterization of the platform and evaluation of its biocatalytic activity

We report for the first time the use of quaternized chitosan (QCHI) for the immobilization of gold nanoparticles (NP) and glucose oxidase (GOD), the characterization of the resulting platform and its biocatalytic activity using glucose as substrate. The chemical substitution of chitosan has allowed us to work at physiologic pH to build up self-assembled layers of QCHI-NP as platform for the enzyme immobilization. The adsorption of GOD was analyzed by surface plasmon resonance (SPR) to compare the surface coverage of GOD in absence and presence of the QCHI-NP platform. The results obtained with cyclic voltammetry and scanning electrochemical microscopy (SECM) revealed that the adsorption of NP improves the conductivity of the structure and its electrochemical reactivity, facilitating the oxidation of the hydrogen peroxide produced by GOD. The electrodes modified with NP present higher amperometric response demonstrating the efficient transduction of the enzymatic activity in this structure.