AbstractThe 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. 相似文献
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.
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. 相似文献
Silver nanorods with ～100?nm in diameter and ～5?µm in length were synthesised by the soft solution-phase approach in the presence of poly(vinylpyrrolidone) (PVP), which was employed as a protecting agent. The obtained silver nanorods were characterised by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-visible spectrum. The molar ratio and injection rate of PVP and AgNO3 played an important role in controlling the morphology and aspect ratio of nanorods. The growth mechanism of silver nanorods was also discussed. Moreover, the conductive ink was prepared using as-synthesised products, and the electrical resistivity of the final consolidated trace with this kind of ink was up to 2.7?×?10?5 Ωcm. 相似文献
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. 相似文献
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. 相似文献
The spontaneous shape transformation of silver nanorods with an initial length of several hundred nanometers towards spherical particle shapes in aqueous solution is investigated by means of scanning electron microscopy, UV-vis absorption spectroscopy, anodic stripping voltammetry, and high-resolution transmission electron microscopy (HRTEM). The consolidation of the results reveals an increase in the particle number density with time. Moreover, HRTEM image analysis along the cross section of the rods evidences the presence of fivefold twinning defects which extend along the whole rod length. According to the analytical model of Monk et al. this kind of rod structure is only thermodynamically stable if the rod length is below a critical value at a given diameter. The rods investigated in the present work do not fulfill the stability criterion as they exceed the critical length. Thus, the rods decay into smaller "nanobuns" and defective as well as defect-free spheres. A mechanism based on findings from the literature, HRTEM image analysis of former rods, transition states, and the final particle structures is proposed. The defects along the surface are seen as starting points for the dissolution of material, which is reintegrated into the solid phase by homogeneous as well as heterogeneous nucleation and growth. 相似文献
