Cupriavidus metallidurans SHE好氧还原Se(Ⅳ)合成硒纳米颗粒的特性研究

利用贪铜杆菌(Cupriavidu smetallidurans)SHE在好氧条件下还原Se(Ⅳ)生成硒纳米颗粒,考察不同条件对还原过程的影响,并对还原产物进行表征.结果显示,菌株SHE还原Se(Ⅳ)的最适条件为pH=8、温度30℃、底物浓度1.0 mmol·L-1,在此条件下Se(Ⅳ)的还原率最高,可达100%.通过紫外光谱扫描、微观形貌分析、粒度分析及X射线衍射分析表明,合成的硒纳米颗粒为六方晶型,粒径为(130.2±27.0)nm.研究结果表明,菌株SHE可有效的还原Se(Ⅳ)生成硒纳米颗粒,为微生物合成纳米硒的潜在应用提供参考.     

Is there a silver lining? Aggregation and photo-transformation of silver nanoparticles in environmental waters

Is the aggregation of silver nanoparticles in environmental waters a silver lining? The answer is not simple. Clearly, however, the aggregation and photo-transformation of AgNPs are complicated and could be more significant than previously thought. The difference in the water chemistry that controls the aggregation and photo-transformation of AgNPs results in the varying behavior and fate of AgNPs among different water bodies.     

固液界面NOM吸附中疏水效应的影响研究

文章以腐殖酸和纳米Fe2O3为对象,着重研究了腐殖酸分子在纳米Fe2O3表面的吸附过程中的疏水效应,借助红外光谱和热重等分析方法研究了腐殖酸吸附前后的疏水性随溶液环境变化的规律。结果表明,当离子强度为0、0.005、0.01和0.05 mol/kg,pH值从7变到12时,纳米Fe2O3吸附溶解性腐殖酸分子后形成的复合体的热失重量随着pH值的升高先减小后增大。当pH值从7升高到10时,亲水性降低,疏水性增强;当pH值从10升高到12时,亲水性增强,疏水性降低。当离子强度为0.001 mol/kg,pH值从7变到12时,复合体的热失重量随着pH值的升高而减小,亲水性降低,疏水性增强。当pH值为定值,离子强度变化时,纳米Fe2O3吸附溶解性腐殖酸分子后形成的复合体的热失重量随着离子强度的增加不断变化,曲线呈现出波动趋势,亲、疏水性在交替变化。红外光谱分析结果说明,对纳米Fe2O3吸附溶解性腐殖酸分子后形成的复合体的亲疏水性起主要影响的官能团可能是亲水性的羟基-OH、羰基C=O和疏水性的CH2烷烃。     

不同环境因子对纳米羟基磷灰石在饱和填充柱中迁移规律的影响

选用石英砂填充柱模拟土壤体系,通过测量纳米羟基磷灰石（Nano-HAP）ζ电位、出流比等来考察不同环境因素（腐殖酸浓度、pH和离子强度）对其在饱和石英砂柱中迁移规律的影响.结果表明,随着腐殖酸浓度的增加,Nano-HAP胶体的ζ电位相应增加（绝对值增加）,吸附效率（α）相应降低,当溶液中腐殖酸浓度由0增加为10 mg/...     

Surface modification of mesoporous silica nanoparticle with 4-triethoxysilylaniline to enhance seawater desalination properties of thin-film nanocomposite reverse osmosis membranes

• Mesoporous silica nanoparticle was modified with 4-triethoxysilylaniline. • AMSN-based TFN-RO membranes were prepared for seawater desalination. • Water transport capability of the AMSN was limited by polyamide. • Polyamide still plays a key role in permeability of the TFN RO membranes. Mesoporous silica nanoparticles (MSN), with higher water permeability than NaA zeolite, were used to fabricate thin-film nanocomposite (TFN) reverse osmosis (RO) membranes. However, only aminoalkyl-modified MSN and low-pressure (less than 2.1 MPa) RO membrane were investigated. In this study, aminophenyl-modified MSN (AMSN) were synthesized and used to fabricate high-pressure (5.52 MPa) RO membranes. With the increasing of AMSN dosage, the crosslinking degree of the aromatic polyamide decreased, while the hydrophilicity of the membranes increased. The membrane morphology was maintained to show a ridge-and-valley structure, with only a slight increase in membrane surface roughness. At the optimum conditions (AMSN dosage of 0.25 g/L), when compared with the pure polyamide RO membrane, the water flux of the TFN RO membrane (55.67 L/m²/h) was increased by about 21.6%, while NaCl rejection (98.97%) was slightly decreased by only 0.29%. However, the water flux of the membranes was much lower than expected. We considered that the enhancement of RO membrane permeability is attributed to the reduction of the effective thickness of the PA layer.     

纳米金修饰分子印迹聚合膜电极检测双酚A

以纳米金修饰玻碳电极为基础电极,以双酚A为模板分子,以邻氨基苯硫酚为聚合单体,采用循环伏安法电聚合制备分子印迹聚合膜,利用循环伏安和交流阻抗法研究电极的电化学特性。结果表明,双酚A在修饰电极表面的反应是一个受吸附控制的等电子、质子转移的不可逆反应。采用差分脉冲伏安法检测双酚A,线性范围为5. 0×10~(-6)mol/L～4. 0×10~(-4)mol/L,检出限为2. 3×10~(-7)mol/L。将该电极用于自来水和牛奶样品的测定,结果均为未检出,加标回收率分别为93. 5%和95. 4%,3次测定结果的RSD分别为4. 0%和5. 7%。     

纳米银的体内毒性及毒作用机制研究进展

很多研究表明纳米银对机体的消化系统、呼吸系统、生殖系统等多个系统均会产生毒作用,且其毒作用受到多种因素的影响。目前关于纳米银的毒作用机制尚未明确,研究发现纳米银的毒作用机制可能与银离子释放,活性氧自由基产生,氧化应激的发生,炎症反应等有关,最新研究指出纳米银的毒性作用还可能与内质网应激和自噬有关,本文将就纳米银的体内毒性及毒作用机制进行综述。     

Induction of apoptosis and cytokine markers in colon cancer cells by magnesium oxide (MgO) nanoparticles

Magnesium oxide nanoparticles (MgONP) are predominantly utilized in industrial products. This study was undertaken to elucidate the mechanisms underlying toxic effect of MgONP in human colon cancer (HT 29) cells over 48 hr period. Cytotoxicity was evaluated by using MTT and neutral red uptake assays. Data demonstrated that MgONP reduced cell viability in concentration- and time-dependent manner. MgONP induced oxidative stress by decreasing glutathione (GSH) concentrations and elevation of reactive oxygen species (ROS) and lipid peroxidation levels. Increased caspase-3 enzyme activity and greater condensed, damaged chromosome was observed following MgONP exposure in HT 29 cells. The level of interleukin-4 (IL-4), tumor necrosis factor (TNF-α), and DNA fragmentation were significantly higher in MgONP incubated cells. The results showed that MgONP-induced toxicity in HT 29 cells may be mediated through oxidative stress.     

Cellular uptake and mutagenic potential of metal oxide nanoparticles in bacterial cells

Extensive production and consumption of nanomaterials such as ZnO and TiO₂ has increased their release and disposal into the environment. The accumulation of nanoparticles (NPs) in ecosystem is likely to pose threat to non-specific targets such as bacteria. The present study explored the effect of ZnO and TiO₂ NPs in a model bacterium, Salmonella typhimurium. The uptake of ZnO and TiO₂ bare NPs in nano range without agglomeration was observed in S. typhimurium. TEM analysis demonstrated the internalization and uniform distribution of NPs inside the cells. Flow cytometry data also demonstrates that both ZnO and TiO₂ NPs were significantly internalized in the S. typhimurium cells in a concentration dependent manner. A significant increase in uptake was observed in the S. typhimurium treated even with 8 and 80 ng mL⁻¹ of ZnO and TiO₂ NPs with S9 after 60 min, possibly the formation of micelles or protein coat facilitated entry of NPs. These NPs exhibited weak mutagenic potential in S. typhimurium strains TA98, TA1537 and Escherichia coli (WP2uvrA) of Ames test underscoring the possible carcinogenic potential similar to certain mutagenic chemicals. Our study reiterates the need for re-evaluating environmental toxicity of ZnO and TiO₂ NPs presumably considered safe in environment.     

Synthesis of nanoparticles by microorganisms and their application in enhancing microbiological reaction rates

Nanotechnology has attracted a great interest in recent years due to its expected impact on many areas such as energy, medicine, electronics, and space industries. This review provides the state-of-art knowledge on the synthesis of nanoparticles by microorganisms including bacteria, fungi, actinomycetes, and yeast, and their effect on microbiological processes. The available microbes and their predicted nanoparticle biosynthesis mechanism, the conditions to control the size/shape and monodispersity of particles, and microbiological reaction rate enhancement using nanoparticles as catalysts are presented. The current limitations and future scope for specific research are also discussed.