Enhancement of antibacterial properties of Ag nanorods by electric field

Abstract

The effect of an electric field on the antibacterial activity of columnar aligned silver nanorods was investigated. Silver nanorods with a polygonal cross section, a width of 20–60 nm and a length of 260–550 nm, were grown on a titanium interlayer by applying an electric field perpendicular to the surface of a Ag/Ti/Si(100) thin film during its heat treatment at 700 °C in an Ar+H₂ environment. The optical absorption spectrum of the silver nanorods exhibited two peaks at wavelengths of 350 and 395 nm corresponding to the main surface plasmon resonance bands of the one-dimensional silver nanostructures. It was found that the silver nanorods with an fcc structure were bounded mainly by {100} facets. The antibacterial activity of the silver nanorods against Escherichia coli bacteria was evaluated at various electric fields applied in the direction of the nanorods without any electrical connection between the nanorods and the capacitor plates producing the electric field. Increasing the electric field from 0 to 50 V cm^?1 resulted in an exponential increase in the relative rate of reduction of the bacteria from 3.9×10^?2 to 10.5×10^?2 min^?1. This indicates that the antibacterial activity of silver nanorods can be enhanced by applying an electric field, for application in medical and food-preserving fields.     

Multifunctional silver film with superhydrophobic and antibacterial properties

Material properties are strongly dependent on material structure. The large diversity and complexity of material structures provide significant opportunities to improve the properties of the materials, expanding their applications. Here, we discuss the fabrication of a multifunctional silver film prepared by controlling the nucleation and growth of silver particles. Silver films with high hydrophobicity and antibacterial activity were fabricated by adopting an electrochemical approach. The dependence of the hydrophobic and antibacterial properties on the size and shape of the silver particles was first investigated. Small-sized silver particles exhibited a high antibacterial rate, while a porous silver film composed of dendritic particles showed a significant hydrophobic activity. By regulating the reaction time, current density, and silver salt concentration, a silver film with a contact angle of 150.9° and an antibacterial rate of 54.7% was synthesized. This study demonstrates that finding a compromise between different material structures is a suitable way to fabricate multifunctional devices.

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不锈钢基片上制备Ag+/TiO2抗菌薄膜的研究

用溶胶—凝胶法在经过表面氧化处理的不锈钢基板上制备了含银的锐钛矿型二氧化钛复合薄膜,对薄膜进行了XRD、SEM、光学显微镜等分析,并对不锈钢的抗菌性和其他性能进行了测定,讨论了样品中结构与性能的关系。     

铬酸银纳米棒组装体的简易合成及其光学性能

在简单温和的条件下利用模板法,首次合成出了铬酸银纳米棒组装体,构成该组装体的纳米棒长度约为150～250nm,直径约70nm.当激发波长为383nm时,发射出432nm的蓝光;产物在紫外-可见光谱356nm处有明显的宽化吸收.     

Gold nanorods core/AgPt alloy nanodots shell: A novel potent antibacterial nanostructure

In the light of the current problems of silver nanoparticles （Ag NPs） in terms of antibacterial performance, we have designed a novel trimetallic corelshell nanostructure with AgPt alloy nanodots epitaxially grown on gold nanorods （Au@PtAg NRs） as a potential antibacterial agent. Both Escherichia coli （E. coli） and Staphylococcus aureus （S. aureus） were studied. The antibacterial activity exhibits an obvious composition-dependence. On increasing the Ag fraction in the alloy shell up to 80%, the antibacterial activity gradually increases, demonstrating a flexible way to tune this activity. At 80% Ag, tile antibacterial activity is better than that of a pure Ag shell. The improved antibacterial ability mainly results from the high exposure of silver on the shell surface due to the dot morphology. We thus demonstrate that forming alloys is an effective way to improve antibacterial activity while retaining high chemical stability for Ag-based nanomaterials. Furthermore, due to the tunable localized surface plasmonic response in the near-infrared （NIR） spectral region, additional control over antibacterial activity using light--such as photothermal killing and photo- triggered silver ion release--is expected. As a demonstration, highly enhanced antibacterial activity is shown by utilizing the NIR photothermal effect of the nanostructures. Our results indicate that such tailored nanostructures will find a role in the future fight against bacteria, including the challenge of the increasing severity of multidrug resistance.     

直流电沉积法制备单晶Ag纳米棒阵列

在较低温条件下,采用直流电沉积法在AAO模板中成功制备出了大面积生长均匀的单晶Ag蚋米棒阵列.利用扫描电子显微镜(SEM),能谱仪(EDS),透射电子显微镜(TEM),选区电子衍射(SAED)和XRD等分析手段对样品进行形貌表征及成分分析.结果表明,阵列中的Ag纳米棒尺寸均匀,保持着良好的平行度,直径接近200nm,与AAO模板的孔径大小相当,且可以通过控制沉积时间来实现对Ag纳米棒长度的控制.     

Numerical calculation of plasmonic field absorption enhancement in CdSe-quantum dot sensitized ZnO nanorods by Ag nanoparticle periodic arrays

Plasmonic field absorption enhancement (PFAE) of Ag nanoparticles (Ag NPs) periodic arrays in CdSe-quantum dot (QD) sensitized ZnO nanorods was numerically investigated by the three-dimensional finite difference time domain (FDTD). The Ag NPs with spherical morphology were found to have an optimum PFAE compared to other Ag NP morphologies such as cubic and pyramidal. The results also showed that PFAE intensity in CdSe-QD-sensitized ZnO nanorods is increased with the reduction of Ag NP diameter until 10 nm and decreases thereafter. Moreover, the optimum density of spherical Ag NPs for optimum PFAE was observed as 20%. PFAE in CdSe-QD-sensitized ZnO nanorods is improved with increasing space between ZnO nanorods until 180 nm and reduces thereafter. Finally, the results showed that PFAE of Ag NPs for the high distance between ZnO nanorods is dependent on radiation angle; while for the low distance between ZnO nanorods it is free of radiation angle.     

ZnO纳米团簇与CdSe纳米棒复合膜的光电化学性能研究

用水热法合成了粒径均匀、分散良好的花状ZnO纳米团簇和CdSe纳米棒.讨论了ITO/ZnO/CdSe复合膜电极光电性能的影响因素,对比研究了ITO/ZnO纳米团簇及ITO/CdSe纳米棒膜电极的光电化学性能,实验表明:复合膜电极拓展了在长波方向的光吸收,提高了光电转换效率;当ZnO与CdSe复合摩尔比为1∶3时,ITO/ZnO/CdSe纳米复合膜电极在本实验中得到最高光电转换效率(IPCE)25.27%,远远高于单一ITO/ZnO花状纳米团簇膜电极和ITO/CdSe纳米棒膜电极.     

Facile synthesis of Ag/ZnO nanorods using Ag/C cables as templates and their gas-sensing properties

A solid-state chemical reaction with the assistance of Ag/C nanocables was implemented for the preparation of Ag/ZnO nanorods. This is the first time Ag/ZnO nanorods are fabricated by using Ag/C cables as template. Compared with the traditional organic surfactant, Ag/C cable is a new and effective template to control the shape of precursors in the solid-state reaction under ambient conditions. The results of systematical gas-sensing studies demonstrate that the sensor based on Ag/ZnO nanorod materials has high sensitivity, good selectivity and short response and reversion time to ethanol. It demonstrates that Ag/ZnO nanorods can be used as gas-sensing material.     

镀银碳纳米管的抗菌性研究

用离子束辅助沉积(IBAD)方法在碳纳米管表面制备银膜.用琼脂平板法测试了抗菌率,测试菌种为革兰氏阴性大肠杆菌(E.coil)和革兰氏阳性金黄色葡萄球菌(S.aureus);用扫描电子显微镜(SEM) 观测了镀银碳纳米管的微观形貌;用能量散射X射线谱(EDX)分析了镀银碳纳米管表面元素的原子百分比;用X射线光电子能谱(XPS) 分析了镀银碳纳米管的表面元素的价态.研究结果表明,镀银碳纳米管具有优良的抗菌性能,且比在热解碳上镀银样品的抗菌性强.     

掺银离子TiO2薄膜的结构及与不锈钢基板的界面反应

采用溶胶-凝胶法在不锈钢表面制备掺银的TiO2薄膜,研究氧化处理对不锈钢表面Ag/TiO2抗菌薄膜组成和性能的影响,利用X-射线衍射谱(XRD)、扫描电子显微镜(SEM)和X-射线光电子能谱(XPS)等对经氧化处理和未经处理的不锈钢表面Ag/TiO2薄膜进行比较,研究薄膜的结构、界面反应特征及机制.发现:未经氧化处理的不锈钢由于其中的铁原子进入薄膜与TiO2反应形成钛酸铁固溶体薄膜;经氧化处理后不锈钢表面形成一层比较致密的氧化铁层,阻止了不锈钢内部的铁原子扩散进入薄膜与TiO2反应,表面同时形成钛酸铁和锐钛矿型的TiO2薄膜;锐钛矿型的TiO2与银离子反应形成钛酸银,既保持了银离子的高杀菌性能(样品的6小时抗菌率达到100%),同时又不至使金属银形成而使材料变色.在未经氧化处理的不锈钢表面,掺银TiO2薄膜中的银离子转化为单质银,抗菌性能低.     

一种新型无机抗菌剂--钼酸银

介绍了一种新型无机抗菌剂钼酸银的制法与应用 ,特别是用作抗菌陶瓷制品和抗菌混凝土制品。     

纳米氧化高银的制备及抗菌性能

采用液相氧化沉淀法制备纳米氧化高银颗粒.以硝酸银为原料,氢氧化钠为沉淀剂,过硫酸钾为氧化剂,控制pH值为11,反应温度为80℃,在磁力搅拌器上反应30min,静置3h后,离心洗涤数次,70℃真空干燥3h,得到黑色纳米氧化高银颗粒.通过X射线衍射(XRD)、透射电子显微镜(TEM)对纳米氧化高银颗粒的形貌和结构进行表征;采用异养菌测试瓶法,用制备的氧化高银和粒径为30nm的纳米银对金黄色葡萄球菌进行抗菌性能测试.结果表明:制得的球形纳米颗粒粒径为10～30ntn;纳米氧化高银颗粒比纳米银具有更强的杀菌性能.     

Synthesis and optical properties of single-crystalline GaN nanorods

Single-crystalline GaN nanorods were successfully synthesized on Si(1 1 1) substrates through ammoniating Ga₂O₃/Mo films deposited on the Si(1 1 1) substrate by radio frequency magnetron sputtering technique. The as-synthesized nanorods are confirmed as single-crystalline GaN with wurtzite structure by X-ray diffraction (XRD), selected-area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). Scanning electron microscopy (SEM) displays that the GaN nanorods are straight and smooth with diameters in the range of 100-200 nm and lengths typically up to several micrometers. X-ray photoelectron spectroscopy (XPS) confirms the formation of bonding between Ga and N. The representative photoluminescence spectrum at room temperature exhibits a strong and broad emission band centered at 371.1 nm, attributed to GaN band-edge emission. The growth process of GaN nanorod may be dominated by vapor-solid (VS) mechanism.     

从无序到有序ZnO纳米棒的制备

采用3种不同的方法在氧化铟锡玻璃衬底上沉积一层ZnO纳米晶薄膜,然后采用改进的水热法在制备有ZnO纳米晶薄膜的衬底上生长ZnO纳米棒,实现了纳米棒从无序到有序的生长.从XRD和SEM图可得,有序的纳米棒沿(002)择优取向,基本与衬底垂直,平均直径约为40nm.     

掺银TiO2薄膜的亲水特性

采用溶胶—凝胶法及浸渍提拉法在普通的载玻片上制得含不同掺银量的TiO2薄膜,通过对薄膜及相应粉体的XRD、XPS及薄膜致密度的测量,分析了银的掺杂量对TiO2薄膜亲水特性的影响。结果表明：TiO2薄膜中银的掺杂量≤0．635mol％时有利于TiO2薄膜亲水性能的改善;表面羟基和表面桥氧的含量对TiO2薄膜的亲水性能均有直接影响。     

Sol-Gel法制备含银二氧化硅纳米薄膜

用sol-gel法在浮法玻璃表面制备了含银二氧化硅薄膜。用TEM和HEED测定了纳米薄膜的微结构。用光谱仪、高阻计和光纤传感器等分别测定了样品的透光率、电阻率和气敏性。     

纳米无机抗菌材料抗菌性能研究

本文选择了两种有代表性的无机抗菌材料 ,采用抑菌圈实验法对它们的抗菌性能进行了定性研究 ,同时采用细菌总数测定法定量地测试了纳米氧化锌的抗菌性能。并探讨了它们的抗菌机理。     

Highly monodispersed ZnO nanorods: preparation and optical properties

Simple and low cost solution synthesis method was used to synthesise ZnO nanorods. Dodecyl benzene sulfonate was used to control the growth process and monodispersed nanorods with diameters in the range of 25 to 44 nm were obtained. X-ray diffraction, transmission electron microscopy and high resolution transmission electron microscopy measurements demonstrate the structure and morphology of the products. Laser power- and temperature-dependent photoluminescence (PL) experiments confirm the good ultraviolet emission characteristics. Short exciton lifetime feature relevant to thin nanorods was examined by time-resolved PL. Good optical quality and the size characteristics of the obtained products are discussed.     

键合型纳米银-腈纶纤维的制备及其抗菌性质

用部分偕胺肟化的腈纶纤维与硝酸银溶液反应,使纤维表面络合上银离子,再用甲醛溶液还原Ag(Ⅰ)成金属Ag,得银复合腈纶纤维。控制AgNO3浓度,可得到银粒尺寸在纳米级的纳米银复合腈纶纤维(Ag—PAN)。用IR光谱和SEM进行表征。对Ag-PAN进行抗菌实验,结果显示：Ag—PAN对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌有很强的杀灭作用,Ag含量达0．8％的Ag-PAN对大肠杆菌、金黄色葡萄球菌和枯草芽孢杆菌的杀灭率超过99．99％。Ag含量迭1．3％时,Ag-PAN对3种菌的杀灭时间均在0．5h以内。