Global Environment Center, Korea Institute of Science and Technology, Hawolgok-dong, Seongbuk-gu, Seoul 136-791, Republic of Korea.
Langmuir. 2011 Aug 16;27(16):10256-64. doi: 10.1021/la201851r. Epub 2011 Jul 21.
Carbon nanotubes (CNTs) have been widely used in a variety of applications because of their unique structure and excellent mechanical and electrical properties. Additionally, silver (Ag) nanoparticles exhibit broad-spectrum biocidal activity toward many different bacteria, fungi, and viruses. In this study, we prepared Ag-coated CNT hybrid nanoparticles (Ag/CNTs) using aerosol nebulization and thermal evaporation/condensation processes and tested their usefulness for antimicrobial air filtration. Droplets were generated from a CNT suspension using a six-jet collison nebulizer, passed through a diffusion dryer to remove moisture, and entered a thermal tube furnace where silver nanoparticles were generated by thermal evaporation/condensation at ∼980 °C in a nitrogen atmosphere. The CNT and Ag nanoparticle aerosols mixed together and attached to each other, forming Ag/CNTs. For physicochemical characterization, the Ag/CNTs were introduced into a scanning mobility particle sizer (SMPS) for size distribution measurements and were sampled by the nanoparticle sampler for morphological and elemental analyses. For antimicrobial air filtration applications, the airborne Ag/CNT particles generated were deposited continuously onto an air filter medium. Physical characteristics (fiber morphology, pressure drop, and filtration efficiency) and biological characteristics (antimicrobial tests against Staphylococcus epidermidis and Escherichia coli bioaerosols) were evaluated. Real-time SMPS and transmission electron microscopy (TEM) data showed that Ag nanoparticles that were <20 nm in diameter were homogeneously dispersed and adhered strongly to the CNT surfaces. Because of the attachment of Ag nanoparticles onto the CNT surfaces, the total particle surface area concentration measured by a nanoparticle surface area monitor (NSAM) was lower than the summation of each Ag nanoparticle and CNT generated. When Ag/CNTs were deposited on the surface of an air filter medium, the antimicrobial activity against test bacterial bioaerosols was enhanced, compared with the deposition of CNTs or Ag nanoparticles alone, whereas the filter pressure drop and bioaerosol filtration efficiency were similar to those of CNT deposition only. At a residence time of 2 h, the relative microbial viabilities of gram-positive S. epidermidis were ∼32, 13, 5, and 0.9% on the control, CNT-, Ag nanoparticle-, and Ag/CNT-deposited filters, respectively, and those of gram-negative E. coli were 13, 2.1, 0.4, and 0.1% on the control, CNTs, Ag nanoparticles, and Ag/CNTs, respectively. These Ag/CNT hybrid nanoparticles may be useful for applications in biomedical devices and antibacterial control systems.
碳纳米管（CNTs）由于其独特的结构和优异的力学和电学性能，已被广泛应用于各种领域。此外，银（Ag）纳米颗粒对许多不同的细菌、真菌和病毒表现出广谱的杀菌活性。在这项研究中，我们使用气溶胶雾化和热蒸发/冷凝工艺制备了Ag 涂覆的 CNT 杂化纳米颗粒（Ag/CNTs），并测试了它们在抗菌空气过滤中的用途。使用六喷嘴碰撞雾化器从 CNT 悬浮液中生成液滴，通过扩散干燥器除去水分，然后进入热管式炉，在氮气气氛中于约 980°C 下通过热蒸发/冷凝生成 Ag 纳米颗粒。CNT 和 Ag 纳米颗粒气溶胶混合并附着在彼此上，形成 Ag/CNTs。为了进行物理化学特性表征，将 Ag/CNTs 引入扫描迁移率颗粒 sizer（SMPS）中以进行粒径分布测量，并通过纳米颗粒采样器进行形态和元素分析。对于抗菌空气过滤应用，生成的空气中的 Ag/CNT 颗粒连续沉积在空气过滤介质上。评估了物理特性（纤维形态、压降和过滤效率）和生物特性（针对表皮葡萄球菌和大肠杆菌生物气溶胶的抗菌测试）。实时 SMPS 和透射电子显微镜（TEM）数据表明，直径小于 20nm 的 Ag 纳米颗粒均匀分散并牢固地附着在 CNT 表面上。由于 Ag 纳米颗粒附着在 CNT 表面上，因此通过纳米颗粒表面积监测仪（NSAM）测量的总颗粒表面积浓度低于每个 Ag 纳米颗粒和 CNT 生成的总和。当 Ag/CNTs 沉积在空气过滤介质的表面上时，与单独沉积 CNT 或 Ag 纳米颗粒相比，对测试细菌生物气溶胶的抗菌活性得到增强，而过滤压降和生物气溶胶过滤效率与仅沉积 CNT 时相似。在停留时间为 2 小时的情况下，革兰氏阳性表皮葡萄球菌的相对微生物存活率分别为对照、CNT-、Ag 纳米颗粒-和 Ag/CNT-沉积过滤器上的 32%、13%、5%和 0.9%，而革兰氏阴性大肠杆菌分别为对照、CNTs、Ag 纳米颗粒和 Ag/CNTs 上的 13%、2.1%、0.4%和 0.1%。这些 Ag/CNT 杂化纳米颗粒可能在生物医学设备和抗菌控制系统的应用中具有重要意义。
