Nanosilver resonance scattering spectral method for determination of hydroxyl radical and its application

Silver nanoparticles were prepared under a microwave high-pressure condition using citric acid sodium as a reducer while the excess citrate was removed under high speed centrifugation. There is a resonance scattering (RS) peak at 470 nm for silver nanoparticles. In a pH 4.0 HAc-NaAc buffer solution, hydroxyl radicals from the Fenton reaction can oxidize silver nanoparticles to Ag , resulting in the RS intensity decreasing. The decreased RS intensity at 470 nm (△I 470 nm) is linear with respect to the concentration of H2O2 (C) in the range of 0.27-7.56 μmol/L with a detection limit of 0.23 μmol/L. Its regression equation is △I 470 nm = 24.3 C 13.8 with a correlation coefficient of 0.9959. This method was applied to screening the antioxidants with satisfactory results.     

A Sensitive Surface‐enhanced Raman Scattering Method for Determination of Melamine with Aptamer‐modified Nanosilver Probe

The small nanosilver was prepared by the sodium borohydride procedure. The aptamer was used to modify nanosilver to obtain a nanosilver‐aptamer (AgssDNA) SERS probe for the determination of melamine. In pH 6.6 phosphate buffer solution and in the presence of NaCl, the AgssDNA probe specifically combined with melamine to release nanosilver particles that were aggregated to nanosilver clusters, which exhibited SERS effect at 240 cm^?1. When melamine concentration increased, the nanosilver clusters increased, and the SERS intensity at 240 cm^?1 increased. The increased SERS intensity ΔI_{240 cm?1} is linear to melamine concentration in the range of 6.3–403.6 μg·L^?1, with a detection limit of 1.2 μg·L^?1. This assay was applied to determination of melamine in milk, with satisfactory results.     

Preparation of antimicrobial polycaprolactone‐silica composite films with nanosilver rods and triclosan using roll‐milling method

In this study, antimicrobial polycaprolactone composite films containing 12.5% silica and 0.15% silver nanorods were prepared using the roll‐milling method. The destruction of E. coli and S. aureus on the surface of the composite films was evaluated after 6 hr of incubation at 37°C. For the E. Coli, no bacterial contamination was detected after 6 hr and the film surface was completely disinfected with 100% reduction of the microbial contamination. For the S. aureus, 94% reduction of the bacterial contamination was observed after 6 hr. The results were compared with the composite films containing triclosan, a broad‐spectrum antimicrobial agent. The antimicrobial activity tests with 0.25% triclosan incorporated polycaprolactone‐silica composite films showed only 70% reduction of E. coli and 95% reduction of S. aureus after 6 hr. The results demonstrated that the use of silver nanoparticles in the biopolymer industry has huge potential for the self‐cleaning applications. Copyright © 2009 John Wiley & Sons, Ltd.     

纳米银焊膏封装大功率COB LED模块的性能研究

为提高大功率LED的散热能力,采用具有更高熔点和更优良的导电导热性能的纳米银焊膏作为芯片粘结材料,以Al2O3基陶瓷基板封装COB LED模块。同时以Sn/Ag3.0/Cu0.5和导电银胶两种粘结材料作为对比,分别在27,50,80,100,120℃等环境温度中测试3种模块的光电性能来评估模块的热管理水平;在100℃环境下进行加速老化实验,评估3种LED模块的可靠性。测试结果表明,纳米银焊膏封装的大功率LED模块光电性能优异,且具有较强的长期可靠性。     

高灵敏选择性检测凝血酶的适体纳米银共振散射光谱探针

采用四氢硼钠制备了较稳定的纳米银,并用凝血酶(TB)适体修饰纳米银制各了识别凝血酶的适体纳米银探针.在pH 7.0的Tris-HCl缓冲溶液及KCl存在下,适体纳米银探针与凝血酶特异结合生成G-四分体和纳米银聚集体,导致体系在480 nm处的共振散射峰增强.随着凝血酶浓度的增大,生成的纳米银聚集体越多,共振散射强度线性...     

头孢美唑钠与BSA及纳米银-BSA体系相互作用的研究

纳米银与牛血清白蛋白(BSA)均匀混合形成纳米银-BSA体系,运用荧光光谱,紫外吸收光谱,同步荧光光谱研究了注射用头孢美唑钠(Cefmetazole Sodium for Injection,CS)与BSA及纳米银-BSA体系的相互作用.头孢美唑钠对BSA具有荧光猝灭作用,其猝灭方式为静态猝灭,求出了猝灭常数,结合常数...     

On the Effect of Nanosilver Reinforcement on the Mechanical,Physical, and Antimicrobial Properties of Polyethylene Blown Films

The simultaneous effect of silver nanoparticles on the antibacterial, mechanical, and physical properties of polyethylene (PE) films is evaluated. For this aim, uniaxial tensile, film rupture, and permeability tests and X-ray diffraction analysis were conducted. The biocidal performance against Escherichia coli and Staphylococcus aureus bacteria was also assessed. The results show that reinforcements with as little as 1 wt% nanosilver provided absolute antibacterial performance, while generally maintaining the mechanical properties. The reinforcement causes noticeable alterations in the crystallization behavior, which is manifested in the variations of gas permeability of the PE films.     

纳米银的神经毒理学效应

纳米银是目前商品化程度最高的纳米材料之一。由于其独特的表面等离子共振性能、优良的抗菌活性,这种纳米材料已被广泛地应用于医药卫生、工业及日常生活等多个领域。随着纳米银应用领域的不断扩展,其生物安全性也受到了越来越多的关注。由于纳米银能够通过跨越血脑屏障等途径进入生物体脑部,因此纳米银的神经毒理学效应受到广泛关注,近年来已成为该领域研究热点之一。本综述总结了纳米银的脑累积效应以及进入脑组织的途径,主要包括经鼻通过嗅神经直接入脑和穿透血脑屏障。纳米银的神经毒性效应包括受暴露动物体的神经行为学改变、脑部的组织病理学效应或神经元和神经胶质细胞的形貌变化,与神经递质水平改变内在作用机制与氧化应激和炎性反应相关。纳米银的粒径、表面涂层和银离子释放是影响纳米银神经毒性的关键因素。本文最后提出当前纳米银神经毒理学研究中存在的问题及今后的研究方向。     

纳米银胶体颗粒制备新方法及其荧光增强效应研究

在纳米银胶体颗粒的制备中引入固相分散基体——天然纤维素,利用其表面丰富的羟基、醚基等含氧基团,均匀吸附银离子后,浸入低浓度硼氢化钠,经历脱附、还原过程生成银纳米颗粒的胶体溶液.与经典制备方法相比,反应过程温和且无需添加任何稳定剂,所制得的银纳米颗粒细小、均一、稳定性高.荧光增强实验表明,由于消除了大分子稳定剂的阻碍,胶体溶液在较低浓度下即可获得很好的荧光增强作用.