纳米氧化钴对组蛋白H3修饰的影响及其机制

纳米氧化钴因其优异的性能被广泛应用于组织工程等领域,然而,广泛的应用增加了其对人类健康和环境暴露的风险。本文在详细表征纳米氧化钴的基础上,选用人永生化角质形成细胞HaCaT为模型,采用台盼蓝染色法检测纳米氧化钴对细胞生存率的影响,利用蛋白免疫印记法观察纳米氧化钴对组蛋白H3常见修饰位点的影响,通过对细胞内蓄积量、组蛋白H3修饰水平及DNA损伤的定量分析,探究了纳米氧化钴对组蛋白H3修饰的影响机制。表征结果显示,在分散介质中纳米氧化钴明显团聚,比表面积减少,二次粒径增大。生存率测定发现,实验最大剂量(1 mg·mL^(-1))作用24 h后,细胞生存率无明显变化。0.1 mg·mL^(-1)纳米氧化钴暴露1 h后,诱导了组蛋白H3第10位丝氨酸的磷酸化(p-H3S10)、第9位赖氨酸的乙酰化(Ac-H3K9)及第4位赖氨酸的三甲基化(Me3-H3K4)的上调,并持续长达24 h。同时,观察到第14位赖氨酸的乙酰化(Ac-H3K14)在纳米氧化钴暴露4 h后明显上调。第27位赖氨酸的三甲基化(Me3-H3K27)升高4 h后出现下降趋势。定量分析表明,纳米氧化钴的细胞内蓄积是其诱导组蛋白H3修饰变化的关键因素之一,且组蛋白H3修饰可能涉及DNA损伤修复途径。本研究通过体外实验证明了纳米氧化钴对组蛋白H3修饰的影响及可能的机制,为进一步评价纳米氧化钴的生物毒性及致癌风险提供了科学依据。

电池级纳米氧化钴的制备

研究了以氯化钴为原料,通过比较选择了价格相对低廉的碳酸氢铵代替草酸作沉淀剂制备前驱体,考察了反应温度、反应时间、氯化钴的浓度、碳酸氢铵溶液加料速度等因素对产品粒度大小的影响,从而得出最佳沉淀反应条件。在最佳反应条件下,制得的氧化钴产品平均粒径为200～300 nm,各项性能指标达到了Y级氧化钴国家标准的要求。

纳米氧化钴的制备及其超电容特性

实验制得粒径为3 nm左右的氧化钴微粒材料并以此制成电化学电极. 分析测试表明该氧化钴微粒不仅粒度小, 具有较大的比表面积(192 m2/g)及适宜的孔径分布(1～3 nm为主), 而且在一定程度上解决了小颗粒材料存在的团聚问题. 电化学测试表明, 此电极具有典型的电容性能, 单电极比容量为370～401 F/g, 主要以超电容形式存在.

纳米氧化钴修饰玻碳电极对亚硝酸根的电化学检测

研究了纳米CoO化学修饰电极对NO-2的测定。实验结果表明,在0.15 mol/L HAc-NaAc(pH 4.0)溶液中,该修饰电极对NO-2具有明显的催化和增敏作用。峰电流与NO-2浓度在8.0×10-7～6.0×10-3mol/L范围内呈良好的线性关系,检测限为1.0×10-7mol/L。研究了NO-2在该修饰电极上的电化学机理,并将该法用于右江水中NO-2的测定。

基于羟基氧化钴纳米片类酶特性荧光法检测食品中的甲醛

具有类氧化酶特性的羟基氧化钴纳米片(CoOOH)可催化邻苯二胺(OPD)氧化成黄色荧光2,3-二氨基吩嗪(DAP),而甲醛可与OPD发生反应产生席夫碱抑制DAP的生成,使体系在570 nm处的荧光强度降低。基于此,建立了一种检测食品中甲醛的荧光分析法。最佳条件下,该方法对甲醛的定量检测范围为5.2~59.3μmol/L,检出限为1.4μmol/L。以啤酒和冷冻水产品为样品进行添加回收实验,回收率均在94.6%~109.5%之间。该方法有望用于检测食品中的甲醛。

基于CoOOH纳米片氧化酶活性的比率荧光传感器检测抗坏血酸

研究建立一种基于羟基氧化钴纳米片(CoOOH)类氧化酶活性的比率荧光传感器,可快速、灵敏、准确地测定抗坏血酸(Ascorbic acid,AA)。在氢氧化钠溶液中,以氯化钴为原料、次氯酸钠为氧化剂,在超声条件下制备具有类氧化酶活性的CoOOH纳米片,并采用透射电子显微镜(TEM)、紫外可见吸收光谱(UV-vis)、X射线衍射(XRD)和傅里叶红外光谱(FT-IR),对所合成的材料表面形貌、光吸收特性、结晶度以及表面基团进行表征,并通过对照试验对所合成的CoOOH纳米片构建比率荧光传感器的可行性进行验证。以检测体系中CoOOH纳米片浓度及孵育时间为单因素,优化检测AA的最佳条件,并建立相应的标准曲线。结果表明,CoOOH纳米片呈典型的纳米级六边形片状,其他表征结果也与以往报道的相符。CoOOH纳米片最佳工作浓度为39.1μmol/L,最佳孵育时间为25 min。在最优条件下,428 nm处的荧光强度(F_(428))与568 nm处荧光强度(F;)比值F_(428)/F_(568)与AA浓度在0.5~10.0μmol/L范围内呈现良好的线性关系,线性方程为y=0.79416x+0.37917(R^(2)=0.9965),检测限303 nmol/L(RSN=3)。将其应用于果汁饮料样品检测,回收率在88.0%~115.9%之间,且检测结果与国家标准方法的检测结果相符。以上结果表明该传感器对检测AA有较好的选择性和准确度,为AA的快速检测提供一种新思路。

纳米Co_3O_4型固体pH电极的响应及应用

测定酸度目前广泛采用玻璃电极.然而,由于玻璃电极是采用极薄的玻璃膜作为H+的敏感膜,致使电极极易破碎,亦难以用于对玻璃有腐蚀作用的体系,如含氟体系.此外它还具有体积大、成本较高、膜阻抗高而难以实现微型化、以及使用前需活化处理等缺点.多年来对非玻璃型pH电极的研究一直是个热门的研究课题.其中以金属/金属氧化物型固体pH电极倍受关注[1～6].本文对氧化钴(Co3O4)型固体pH印刷电极的响应性能、选择性、重现性以及在含氟腐蚀体系pH测定中的应用进行了研究.

钆-叶酸-四氧化钴铁磁性纳米粒子对卵巢癌细胞靶向性能的影响

[目的]探讨钆-叶酸-四氧化钴铁磁性纳米粒子通过靶向结合卵巢癌COC1细胞,在核磁共振成像时对卵巢癌组织对比度的性能影响。[方法]利用透射电镜观察纳米粒子靶向进入卵巢癌细胞的过程,采用荧光光谱法测定不同浓度下纳米粒子进入细胞的定量,MTT法检测纳米粒子的细胞毒性,再通过核磁共振成像技术分析不同浓度纳米粒子对T1层面成像、T2层面成像的作用。[结果]纳米粒子能够靶向进入卵巢癌COC1细胞,并呈剂量依赖性;在进入细胞48h内未显示出细胞毒性,并能够在T1、T2两个层面增加核磁共振成像的组织对比度。[结论]钆-叶酸-四氧化钴铁磁性纳米粒子能够增加卵巢癌核磁共振成像组织的对比度,提高其分辨率,有可能成为一种既能改变T1成像,又能改变T2成像分辨率的新的靶向磁性造影剂。

Catalytic performance of cobalt oxide-supported gold-palladium nanocatalysts for the removal of toluene and o-xylene

Using the molten salt and polyvinyl alcohol-protected reduction method,we fabricated Co3O4 octahedron-supported Au-Pd（x（AuPdy）/Co3O4;x =（0.18,0.47,and 0.96） wt%;y（Pd/Au molar ratio） =1.85-1.97） nanocatalysts.The molten salt-derived Co3O4 sample possessed well-defined octahedral morphology,with an edge length of 300 nm.The Au-Pd nanoparticles,with sizes of 2.7-3.2 nm,were uniformly dispersed on the surface of Co3O4.The 0.96（AuPd1.92）/Co3O4 sample showed the highest catalytic activity for toluene and o-xylene oxidation,and the temperature required for achieving 90%conversion of toluene and o-xylene was 180 and 187 ℃,respectively,at a space velocity of 40000 mL/（g·h）.The high catalytic performance of Co3O4 octahedron-supported Au-Pd nanocatalysts was associated with the interaction between Au-Pd nanoparticles and Co3O4 and high concentration of adsorbed oxygen species.

Effects of Co_3O_4 nanocatalyst morphology on CO oxidation:Synthesis process map and catalytic activity

This study focuses on drawing a hydrothermal synthesis process map for Co3O4 nanoparticles with various morphologies and investigating the effects of Co3O4 nanocatalyst morphology on CO oxidation.A series of cobalt-hydroxide-carbonate nanoparticles with various morphologies（i.e.,nanorods,nanosheets,and nanocubes） were successfully synthesized,and Co3O4 nanoparticles were obtained by thermal decomposition of the cobalt-hydroxide-carbonate precursors.The results suggest that the cobalt source is a key factor for controlling the morphology of cobalt-hydroxide-carbonate at relatively low hydrothermal temperatures（≤ 140℃）.Nanorods can be synthesized in CoCl2 solution,while Co（NO3）2 solution promotes the formation of nanosheets.Further increasing the synthesis temperature（higher than 140 ℃） results in the formation of nanocubes in either Co（NO3）2 or CoCl2 solution.The reaction time only affects the size of the obtained nanoparticles.The presence of CTAB could improve the uniformity and dispersion of particles.Co3O4 nanosheets showed much higher catalytic activity for CO oxidation than nanorods and nanocubes because it has more abundant Co^（3＋） on the surface,much higher reducibility,and better oxygen desorption capacity.

A binder-free, flexible cathode for rechargeable Na-O_2 batteries

Rechargeable Na-O2 batteries have attracted significant attention as energy storage devices owing to their theoretically high energy storage capacity and the natural abundance of sodium. However, practical applications of this type of battery still suffer from low specific capability, poor cycle sta- bility, instable electrolytes, and unstable polymer binders. Herein, we report a facile method of synthesizing binder free and flexible cathodes with C0304 nanowire arrays vertically grown onto carbon textiles. When employed as a cathode for Na-O2 batteries, this cathode exhibits superior performance, including a reduction of charge overpotential, high specific capacity （4687 mAh/g）, and cycle stability up to 62 cycles. These enhanced performance can be attributed to the synergistic effect of the porosity and catalytic activity of the C0304 nanowire catalyst.

基于便携式智能手机的多信号传感平台对人血清中ALP的现场分析

碱性磷酸酶(ALP)是人体中必备的物质,在维持生物体正常运作中发挥着极其重要的作用,对二者的检测在许多疾病的诊断中具有重要意义[1-2]。在本研究中,我们设计了基于智能手机的便携式光学(荧光或比色)传感平台,并将其应用于ALP的快速检测,该平台在即时医疗分析中具有极大的潜力。在此传感系统中,具有氧化酶模拟特性的羟基氧化钴纳米片(CoOOH nanoflakes)可以将邻苯二胺(OPD)氧化为2,3-二氨基吩嗪(OxOPD),其在565 nm处显示强荧光发射,吸光度在420 nm。ALP催化底物L-抗坏血酸-2-磷酸三钠盐(AAP)水解生成AA,CoOOH纳米片被AA还原成Co2+,从而抑制OxOPD的形成,而AA自身被氧化成脱氢抗坏血酸(DHAA)。DHAA进一步与OPD反应,生成喹喔啉(DFQ),其在430 nm处出现蓝色荧光。另外,该荧光和比色响应信号可以通过智能手机内置摄像头捕获,进而通过人工智能浓度分析应用程序自动识别捕获的图像并读取其R,G,B值,从而对人血清中的ALP浓度实现快速准确的现场分析。

Iron-induced 3D nanoporous iron-cobalt oxyhydroxide on carbon cloth as a highly efficient electrode for oxygen evolution reaction

The development of highly efficient and cost-effective electrode materials for catalyzing the oxygen evolution reaction(OER)is crucial for water splitting technology.The increase in the number of active sites by tuning the morphology and structure and the enhancement of the reactivity of active sites by the incorporation of other components are the two main strategies for the enhancement of their catalytic performance.In this study,by combining these two strategies,a unique three-dimensional nanoporous Fe-Co oxyhydroxide layer coated on the carbon cloth(3D-FeCoOOH/CC)was successfully synthesized by in situ electro-oxidation methods,and directly used as a working electrode.The electrode,3D-FeCoOOH/CC,was obtained by the Fe doping process in(NH4)2Fe(SO4)2,followed by continuous in situ electro-oxidization in alkaline medium of“micro go chess piece”arrays on the carbon cloth(MCPAs/CC).Micro characterizations illustrated that the go pieces of MCPAs/CC were completely converted into a thin conformal coating on the carbon cloth fibers.The electrochemical test results showed that the as-synthesized 3D-FeCoOOH/CC exhibited enhanced activity for OER with a low overpotential of 259 mV,at a current density of 10 mA cm^–2,and a small Tafel slope of 34.9 mV dec^–1,as well as superior stability in 1.0 mol L^–1 KOH solution.The extensive analysis revealed that the improved electrochemical surface area,conductivity,Fe-Co bimetallic composition,and the unique 3D porous structure together contributed to the enhanced OER activity of 3D-FeCoOOH/CC.Furthermore,the synthetic strategy applied in this study could be extended to fabricate a series of Co-based electrode materials with the dopant of other transition elements.

Interconnected 1D Co3O4 nanowires on reduced graphene oxide for enzymeless H2O2 detection

Enzymeless hydrogen peroxide （H2O2） detection with high sensitivity and excellent selectivity is desirable for clinical diagnosis. Herein, one-dimensional Co3O4 nanowires have been successfully constructed on reduced graphene oxide （rGO） via a simple hydrothermal procedure and subsequent thermal treatment. These Co3O4 nanowires, assembled by small nanoparticles, are interlaced with one another and make a spider web-like structure on rGO. The formation of Co3O4-rGO hybrids is attributed to the structure-directing and anchoring roles of DDA and GO, respectively. The resulting structure possesses abundant active sites, the oriented transmission of electrons, and unimpeded pathways for matter diffusion, which endows the Co3O4-rGO hybrids with excellent electrocatalytic performance. As a result, the obtained Co3O4-rGO hybrids can serve as an efficient electrochemical catalyst for H2O2 oxidation and high sensitivity detection. Under physiological conditions, the oxidation current of H2O2 varies linearly with respect to its concentration from 0.015 to 0.675 mM with a sensitivity of 1.14 mA.mM^-1.cm^-2 and a low detection limit of 2.4 μM. Furthermore, the low potential （-0.19 V） and the good selectivity make Co3O4-rGO hybrids suitable for monitoring H2O2 generated by liver cancer HepG2 cells. Therefore, it is promising as a non-enzymatic sensor to achieve real-time quantitative detection of H2O2 in biological applications.

SnO2@Co3O4 hollow nano-spheres for a Li-ion battery anode with extraordinary performance

SnO2@Co3O4 hollow nano-spheres have been prepared using the template-based sol-gel coating technique and their electrochemical performance as an anode for lithium-ion battery （LIB） was investigated. The size of synthesized hollow spheres was about 50 nm with the shell thickness of 7-8 nm. The fabricated SnO2@Co3O4 hollow nano-sphere electrode exhibited an extraordinary reversible capacity （962 mAh-g-1 after 100 cycles at 100 mA-g-1）, good cyclability, and high rate capability, which was attributed to the Co-enhanced reversibility of the Li20 reduction reaction during cycling.

Designed synthesis of cobalt-oxide-based nanomaterials for superior electrochemical energy storage devices

Cobalt oxides, such as C0304 and CoO, have received increasing attention as potential anode materials for rechargeable lithium-ion batteries （LIBs） owing to their high theoretical capacity. Nanostructure engineering has been demonstrated as an effective approach to improve the electrochemical performance of electrode materials for LIBs. In this review, we summarize recent developments in the rational design and fabrication of various cobalt oxide-based nanomaterials and their lithium storage performance, including 1D nanowires/belts, 2D nanosheets, 3D hollow/hierarchical structures, hybrid nanostructures with carbon （amorphous carbon, carbon nanotubes and graphene） and mixed metal oxides. By focusing on the effects of their structure on their electrochemical performance, effective strategies for the fabrication of cobalt oxide/carbon hybrid nanostructures are highlighted. This review shows that by rational design, such cobalt-oxide-based nanornaterials are very promising as next generation LIB anodes.

Hierarchical Co3O4 porous nanowires as an efficient bifunctional cathode catalyst for long life Li-O2 batteries

Hierarchical Co3O4 porous nanowires （NWs） have been synthesized using a hydrothermal method followed by calcination. When employed as a cathode catalyst in non-aqueous Li-oxygen batteries, the Co3O4 NWs effectively improve both the round-trip efficiency and cycling stability, which can be attributed to the high catalytic activities of Co3O4 NWs for the oxygen reduction reaction and the oxygen evolution reaction during discharge and charge processes, respectively.

Oxidation behavior of cobalt nanoparticles studied by in situ environmental transmission electron microscopy

The dynamics of oxidation of cobalt nanoparticles were directly revealed by in situ environmental transmission electron microscopy.Firstly,cobalt nanoparticles were oxidized to polycrystalline cobalt monoxide,then to polycrystalline tricobalt tetroxide,in the presence of oxygen with a low partial pressure.Numerous cavities(or voids) were formed during the oxidation,owing to the Kirkendall effect.Analysis of the oxides growth suggested that the oxidation of cobalt nanoparticles followed a parabolic rate law,which was consistent with diffusion-limited kinetics.In situ transmission electron microscopy allowed potential atomic oxidation pathways to be considered.The outward diffusion of cobalt atoms inside the oxide layer controlled the oxidation,and formed the hollow structure.Irradiation by the electron beam,which destroyed the sealing effect of graphite layer coated on the cobalt surface and resulted in fast oxidation rate,played an important role in activating and promoting the oxidations.These findings further our understanding on the microscopic kinetics of metal nanocrystal oxidation and knowledge of energetic electrons promoting oxidation reaction.

Effect of catalyst confinement and pore size on Fischer-Tropsch synthesis over cobalt supported on carbon nanotubes

This paper studies the impact of structure of cobalt catalysts supported on carbon nanotubes(CNT) on the activity and product selectivity of Fischer-Tropsch synthesis(FTS) reaction.Three types of CNT with average pore sizes of 5,11,and 17 nm were used as the supports.The catalysts were prepared by selectively impregnating cobalt nanoparticles either inside or outside CNT.The TPR results indicated that the catalyst with Co particles inside CNT was easier to be reduced than those outside CNT,and the reducibility of cobalt oxide particles inside the CNT decreased with the cobalt oxide particle size increasing.The activity of the catalyst with Co inside CNT was higher than that of catalysts with Co particles outside CNT.Smaller CNT pore size also appears to enhance the catalyst reduction and FTS activity due to the little interaction between cobalt oxide with carbon and the enhanced electron shift on the non-planar carbon tube surface.