Functionalized polydiacetylene-glycolipid vesicles interacted with Escherichia coli under the TiO2 colloid

The interaction of the conjugated system between functionalized polydiacetylene-glycolipid vesicles and Escherichia coli was investigated under the bactericidal effect of TiO₂ colloid. With various pre-incubation and irradiation time, controllable bacteria quantity in the presence of TiO₂ colloid was obtained in real time. UV–visible and Raman spectra were utilized to monitor and evaluate the structural transition of bacteria-polydiacetylene-glycolipid vesicles conjugated system under the different conditions, which supplied the detailed information of the transform of the polydiacetylene backbone in real time. Thus controllable conjugated bio-interaction between two bio-interfaces was obtained through the introduction of the third factor and monitored in real time. This would be great aid in fundamental understanding more complex interfaces in the biological environment and would be applicable to the biomedical and biophysical fields.     

Inactivation of Escherichia coli on Immobilized CuO/CoFe2O4‐TiO2 Thin‐Film under Simulated Sunlight Irradiation

Composite photocatalysts of CuO/CoFe₂O₄‐TiO₂ were successfully synthesized by a sol‐gel method and fixed on ordinary tiles. The photosterilization of Escherichia coli was examined on CuO/CoFe₂O₄‐TiO₂ thin films under a xenon lamp irradiation. The film was characterized by XRD, and the morphology was observed by SEM. Disinfection data indicated that CuO/CoFe₂O₄‐TiO₂ composite photocatalysts have the much better photocatalytic activity than CuO/CoFe₂O₄ and TiO₂. The optimized composition of the nanocomposites has been found to be m_CuO/CoFe2O4:m_TiO2=3:7, with loadings ranging from 790 to 1400 mg/m². The photocatalytic inactivated rate of E. coli (10⁵ CFU/mL) reached 98.4% under the xenon lamp of 150 W within 30 min.     

Performance of nondenaturing micro 2-DE followed by third-dimension SDS-PAGE in the analysis of Escherichia coli soluble proteins

In a previous paper, we reported on the analysis of Escherichia coli (strain K‐12) soluble proteins by nondenaturing micro 2‐DE/3‐DE and MALDI‐MS‐PMF [Manabe, T., Jin, Y., Electrophoresis 2010, 31, 2740–2748]. To evaluate the performance of the 2‐DE/3‐DE technique, a nondenaturing 2‐DE gel just after the second‐dimension run was cut into 12 vertical strips, each 2 mm‐wide strip was set on a micro slab gel, and third‐dimension SDS‐PAGE was run in parallel. Each of the twelve 3‐DE gels showed about 150–200 CBB‐stained spots. Two of the 3‐DE gels were selected for the assignment of polypeptides using MALDI‐MS‐PMF and totally 161 polypeptides were assigned on the two 3‐DE gels, in which 81 have been assigned on the nondenaturing micro 2‐DE gel and 80 were newly assigned. Most of the newly assigned polypeptides resided in faintly stained spots on the 3‐DE gels, which indicates that the polypeptides were purified in the process of the third‐dimension separation. The comparisons of the apparent mass values estimated from the second‐dimension (nondenaturing pore‐gradient PAGE) mobility with those estimated from the third‐dimension (SDS‐PAGE) mobility suggested the oligomer structures of the assigned polypeptides and they matched well with those described in a database (UniProtKnowledgebase). The technique of nondenaturing micro 2‐DE/3‐DE, combined with MALDI‐MS‐PMF, could become an efficient method to obtain information on the quaternary structures of hundreds of cellular soluble proteins simultaneously because of its high efficiency in protein/polypeptide separation and assignment.     

Fura-2荧光探针研究Ca2+对大肠杆菌细胞的跨膜作用

以Fura-2／AM作为荧光探针,研究了Ca^2 对大肠杆菌HB101细胞的跨膜作用．考察了不同浓度外源钙离子处理不同生长时期细胞的跨膜行为,并采用停流技术测定了荧光动力学．结果表明大肠杆菌在用CaCl2溶液处理后,胞外Ca^2 可大量进入胞内,且进入细胞的钙离子量与胞外钙离子浓度相关;处于对数生长前期的细胞与对数生长后期和稳定期的细胞相比,胞内自身Ca^2 浓度低,但其摄取外源Ca^2 的能力最强,这应该与其生理代谢活性是相关的,而且这一时期是大肠杆菌细胞最易建立人工诱导感受态的时期．该研究对于测定革兰氏阴性菌细胞内Ca^2 浓度及胞外离子的跨膜传导行为,以及探索钙离子诱导的大肠杆菌人工感受态建立的生理机制都具有重要意义．     

TiO2微粒功能化多孔Al2O3膜的光电化学研究

用恒电位法制备了多孔Al2O3薄膜,通过在Al2O3薄膜孔内水蒸汽水解钛酸异丙酯生成了锐钛矿型TiO2微粒,制备出了Al2O3与TiO2微粒的复合薄膜．用XRD,SEM,光电化学方法进行了研究．实验表明：该复合薄膜具有光电转换特性,在光催化、光电化学太阳能转换中具有应用价值．     

Preparation of the Ag2O2-PbO2 Modified Electrode and Its Application towards Escherichia coli Fast Counting in Water

A novel nano crystalline Ag2O2-PbO2 film chemically modified electrode (CME) was prepared and the CME was characterized by X-ray diffractometer (XRD) and atomic focrce microscope (AFM). By chronoamperometry, the nano Ag2O2-PbO2 CME was used as bioelectrochemical sensor to determine the population of Escherichia coli (E.coli) in water. Compared with conventional methods, it is found that the technique we used is fast and convenient in counting E.coil     

Photochemical disinfection of Escherichia coli with a TiO2 colloid solution and a self-assembled TiO2 thin film

Effect of long-wavelength irradiated TiO₂ colloid solutions on E. coli disinfection and the kinetics mechanism have been investigated. In addition, uniform thin films of TiO₂ are deposited on an ordinary glass by self-assembled techniques. The modified glass also shows the photokilling effect on bacteria in the air.     

微量热法和荧光显微法研究CdTe量子点敏化的纳米TiO2对大肠杆菌的抗菌活性及细胞损伤机制

通过水热合成法和自组装方法分别合成了CdTe(QDs)量子点与CdTe(QDs)敏化的纳米TiO₂复合物,并将CdTe(QDs)/TiO₂与TiO₂均配成浓度为1×10^-2 mol/L的悬浮液. 取一小环大肠杆菌(E. coli)的营养肉汤培养基至5 mL LB培养基中,则E. coli的浓度配成大约1×10⁶ cell/mL的悬浮液以作备用. 在37.0 ℃条件下,利用LKB-2277生物活性检测仪并采用停流法进行检测,研究了CdTe(QDs)/TiO₂对E. coli的抗菌行为. 通过测定和分析产热功率-时间曲线,获得细胞生长速率常数(k)、最大产热功率(P_m)、传代时间(t_G)以及抑制率(I)等热动力学常数. 结果表明：在0～4.0×10^-5 mol·L^-1浓度范围内,生长速率常数(k)和抑制率(I)均与浓度成一定的线性关系. 生长速率常数(k)和最大产热功率(P_m)随着CdTe(QDs)/TiO₂的浓度增加而下降,而传代时间(t_G)和抑制率(I)随着CdTe(QDs)/TiO₂ 的浓度增加而增加;其中,CdTe(QDs)/TiO₂的生长速率常数斜率(0.0001)小于TiO₂的生长速率常数斜率(0.0005),可以初步判断CdTe(QDs)/TiO₂对E. coli的代谢影响较TiO₂要大. TiO₂和CdTe(QDs)/TiO₂对E. coli代谢活性均有一定的抑制作用. 在相同浓度时,CdTe(QDs)/TiO₂的抑制率斜率(0.84)大于TiO₂的抑制率斜率(0.26),进一步说明了CdTe(QDs)/TiO₂相比TiO₂具有对E. coli 更强的细菌抑制作用;结合Hadama荧光显微方法,进一步佐证了CdTe(QDs)/TiO₂相对于TiO₂表面结构的改变可能是导致其抗菌效果较好的主要原因之一. 从而为深入揭示纳米材料影响微生物生长代谢过程的热动力学规律和细胞损伤机制提供理论支撑.     

Efficient CO2 Capture and Photoreduction by Amine‐Functionalized TiO2

Amine‐functionalization of TiO₂ nanoparticles, through a solvothermal approach, substantially increases the affinity of CO₂ on TiO₂ surfaces through chemisorption. This chemisorption allows for more effective activation of CO₂ and charge transfer from excited TiO₂, and significantly enhances the photocatalytic rate of CO₂ reduction into methane and CO.     

Preconcentration of Ultra-trace Cadmium with Nanometer-size TiO2 Colloid and Determination by GFAAS with Slurry Sampling

Cadmium-a heavy metal used in coatings, batteries and plastics-can accumulate in human’s liver and kidney, causing osteoporosis and cancer1,2. The monitoring of its content is, therefore, of great importance. But the average concentration of cadmium in w…     

大肠杆菌HB101感受态的热化学研究

利用LKB-2277生物活性检测系统,测定了在生理盐水中,采用氯化钙法建立大肠杆菌感受态过程中的代谢热输出。生理盐水中大肠杆菌及其感受态进行内源代谢的热化学方程满足:P=K~c+A,dc/dP~0=K'c^0,氯化钙处理后,K与P~0均增大,说明内源代谢活性增强,这与大肠杆菌感受态建立过程中一系列生理生化活性的调整是一致的,表明大肠杆菌感受态的建立很可能有其内在的调节机制,而不完全是人工诱导的。     

GSH Protects the Escherichia coli Cells from High Concentrations of Thymoquinone

The aim of the present study was to evaluate the potential protective effect of glutathione (GSH) on Escherichia coli cells grown in a high concentration of thymoquinone (TQ). This quinone, as the main active compound of Nigella sativa seed oil, exhibits a wide range of biological activities. At low concentrations, it acts as an antioxidant, and at high concentrations, an antimicrobial agent. Therefore, any interactions between thymoquinone and glutathione are crucial for cellular defense against oxidative stress. In this study, we found that GSH can conjugate with thymoquinone and its derivatives in vitro, and only fivefold excess of GSH was sufficient to completely deplete TQ and its derivatives. We also carried out studies on cultures of GSH-deficient Escherichia coli strains grown on a minimal medium in the presence of different concentrations of TQ. The strains harboring mutations in gene ΔgshA and ΔgshB were about two- and fourfold more sensitive (256 and 128 µg/mL, respectively) than the wild type. It was also revealed that TQ concentration has an influence on reactive oxygen species (ROS) production in E. coli strains—at the same thymoquinone concentration, the level of ROS was higher in GSH-deficient E. coli strains than in wild type.     

亲水作用色谱/质谱联用方法用于大肠杆菌代谢组分析

建立了两性离子亲水作用色谱/质谱联用方法用于大肠杆菌胞内极性代谢物的分离分析。选取52个代表性极性物质对方法进行考察,发现此方法有较好的线性范围,且大部分物质最低检测限均在ng/mL数量级。平行制备6份样品进行分析,结果显示85%以上代谢物峰面积的RSD值小于30%。6个内标物质在低、中、高3个浓度下的日内精密度（RSD）均小于20%,大部分物质的相对回收率都在可接受的范围内（70%~130%）。把此方法用于yfcC基因改造的3株大肠杆菌代谢组分析,发现一些小肽、氨基酸、核苷、有机酸、磷脂等物质在基因改造后发生明显变化。此研究结果表明,建立的两性离子亲水作用色谱/质谱方法检测到的物质化学性质分布广,跨越了极性磷脂到小肽的各个范围,且具有良好的重复性、稳定性和适用性。     

The Effect of Surface Terminations on the Initial Stages of TiO2 Deposition on Functionalized Silicon

As atomic layer deposition (ALD) emerges as a method to fabricate architectures with atomic precision, emphasis is placed on understanding surface reactions and nucleation mechanisms. ALD of titanium dioxide with TiCl₄ and water has been used to investigate deposition processes in general, but the effect of surface termination on the initial TiO₂ nucleation lacks needed mechanistic insights. This work examines the adsorption of TiCl₄ on Cl−, H−, and HO− terminated Si(100) and Si(111) surfaces to elucidate the general role of different surface structures and defect types in manipulating surface reactivity of growth and non-growth substrates. The surface sites and their role in the initial stages of deposition are examined by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Density functional theory (DFT) computations of the local functionalized silicon surfaces suggest oxygen-containing defects are primary drivers of selectivity loss on these surfaces.     

氧空位修饰的暴露TiO2{001}的Ru/TiO2增强光热协同CO2甲烷化活性和稳定性

利用太阳能在温和条件下实现CO₂还原反应,不仅可以缓解过度消耗化石能源造成的能源危机,还可以改善诸如温室效应和海洋酸化等环境问题.光热协同催化可以有效降低催化反应温度,具有较大的应用前景.本文利用Ru与暴露TiO₂{001}晶面的TiO₂载体产生的金属-载体相互作用,经过高温氢气煅烧后,获得具有丰富表面氧空位的Ru/TiO₂催化剂.活性测试结果表明,具有丰富表面氧空位的Ru/TiO₂表现出优异的CO₂甲烷化活性,反应过程中甲烷的TOF值在300°C时可以达到22 h-1,但该催化剂却表现出较差的稳定性,在反应10小时后,甲烷的TOF值逐渐降低到19 h-1.将紫外光引入到Ru/TiO₂热催化甲烷化体系中,甲烷的TOF值增加到30 h-1,且兼具高稳定性.热催化反应过程中逐渐消失的表面氧空位和部分氧化的Ru是活性降低的主要原因.在光热协同反应中,光生电子的产生稳定了Ru表面的电子密度,同时也再生了催化剂上表面氧空位,这有效地提高了反应的活性和稳定性.程序升温原位红外和X射线光电子能谱实验结果表明,当催化剂表面具有丰富的表面氧空位时,CO₂可以有效地在Ru纳米粒子上解离成CO中间体,随后吸附在Ru上的CO中间体解离成表面碳物种,并加氢产生甲烷.在热催化反应过程中,Ru纳米粒子逐渐被氧化成Ru Ox物种,且表面氧空位被CO中间物种覆盖,降低了催化反应的稳定性.当紫外光引入到上述反应中,催化剂的表面氧空位可有效提高光生载流子的分离能力.TiO₂载体产生的光电子转移至Ru表面,稳定了金属Ru纳米粒子的价态.另外,载体产生的光生空穴加速了H₂质子化,提高了催化剂对氢气的活化迁移能力,促进了CO中间体的加氢甲烷化反应,进而再生表面氧空位.因此在紫外光照下,兼顾提高了热催化CO₂甲烷化的活性和稳定性.值得注意的是,当Ru负载于暴露少量TiO₂{001}晶面的TiO₂载体上时,产生了强金属-载体相互作用并抑制了H₂在催化剂上的吸附活化,不利于产生表面氧空位.因此暴露少量TiO₂{001}晶面的Ru/TiO₂催化剂也不利于光生载流的产生和分离,这导致热催化或光热协同催化反应活性较低.     

Synthesis and photocatalytic activity of TiO2/conjugated polymer complex nanoparticles

A photocatalyst of nanometer TiO2/conjugated polymer complex was successfully synthesized and characterized by spectroscopic methods and photocatalytic experiments. The complex photocatalyst could be activated by absorbing both ultraviolet and visible light （λ = 190-800 nm）. Methylene blue （MB） could be degraded more efficiently on the complex photocatalyst than on the TiO2 under natural light. The conjugated polymer played a promoting role in the photocatalytic degradation of MB. The calcination temperature had an important effect in degradation of dye and could be summarized as 260℃ 〉 300 ℃ 〉 340 ℃ 〉 220 ℃ 〉 180 ℃.     

Biosynthesis of Poly-(3-hydroxybutyrate) under the Control of an Anaerobically Induced Promoter by Recombinant Escherichia coli from Sucrose

Poly-(3-hydroxybutyrate) (PHB) is a polyester with biodegradable and biocompatible characteristics and has many potential applications. To reduce the raw material costs and microbial energy consumption during PHB production, cheaper carbon sources such as sucrose were evaluated for the synthesis of PHB under anaerobic conditions. In this study, metabolic network analysis was conducted to construct an optimized pathway for PHB production using sucrose as the sole carbon source and to guide the gene knockout to reduce the generation of mixed acid byproducts. The plasmid pMCS-sacC was constructed to utilize sucrose as a sole carbon source, and the cascaded promoter P_3nirB was used to enhance PHB synthesis under anaerobic conditions. The mixed acid fermentation pathway was knocked out in Escherichia coli S17-1 to reduce the synthesis of byproducts. As a result, PHB yield was improved to 80% in 6.21 g/L cell dry weight by the resulted recombinant Escherichia coli in a 5 L bed fermentation, using sucrose as the sole carbon source under anaerobic conditions. As a result, the production costs of PHB will be significantly reduced.     

微量热法研究硒对大肠杆菌生长代谢的作用

硒 是生物必需的微量元素之一．自从１９７３年Ｒｏｔｒｕｃｋ报导了第一个硒酶———红细胞谷胱甘肽过氧化物酶［１］,硒在生命科学中的研究取得了令人瞩目的进展．继红细胞谷胱甘肽过氧化物酶之后 ,从哺乳动物中还发现硒为多种酶所必需 ;此外 ,在不同的动物组织中一系列含硒蛋白被分离和鉴别．随着分子生物学技术的发展和硒在生物化学中的应用 ,人们对硒的生物化学本质有了更加深刻的认识 ,其中 ,遗传基因硒代半胱氨酸密码子ＵＧＡ的发现使硒的生物化学研究进入了一个新的阶段．与此同时 ,小分子有机硒化合物Ｅｂｓｅｌｅｎ生物活性的发现…     

SO_4~(2-)/TiO_2、PO_4~(3-)/TiO_2、BO_3~(3-)/TiO_2系列固体酸的酸性、结构和晶相的研究

制备了ＳＯ４２－／ＴｉＯ２（Ⅰ）、ＰＯ４３－／ＴｉＯ２（Ⅱ）、ＢＯ３３－／ＴｉＯ２（Ⅲ）系列固体酸。用ＩＲ、Ｒａｍａｎ光谱对该系列固体酸进行结构表征,结果表明ＳＯ４２－与ＴｉＯ２表面的结合为螯合式双配位结构和共价硫酸盐共存,ＰＯ４３－与ＴｉＯ２表面的结合为桥式三配位结构,ＢＯ３３－与ＴｉＯ２表面的结合为单齿单配位结构和螯桥混合式三配位结构共存。用由溶液中正丁胺的吸附等温线测定固体表面酸度的方法测定了样品的酸量,结果表明酸量大小为Ⅰ＞Ⅱ＞Ⅲ。用ＸＲＤ技术对该系列固体酸进行考察,衍射图分析提示该系列固体酸主要都为锐钛矿型晶型,但Ⅰ、Ⅱ、Ⅲ中又各自夹杂其它不同的晶型     

Total Synthesis of the Escherichia coli O111 O‐Specific Polysaccharide Repeating Unit

The first total synthesis of the O‐antigen pentasaccharide repeating unit from Gram‐negative bacteria Escherichia coli O111 was achieved starting from four monosaccharide building blocks. Key to the synthetic approach was a bis‐glycosylation reaction to combine trisaccharide 10 and colitose 5 . The colitose building block ( 5 ) was obtained de novo from non‐carbohydrate precursors. The pentasaccharide was equipped at the reducing end with an amino spacer to provide a handle for subsequent conjugation to a carrier protein in anticipation of immunological studies.