Silver nanoparticles within vertically aligned multi-wall carbon nanotubes with open tips for antibacterial purposes

• Published in: Journal of materials chemistry Vol. 21; no. 2; pp. 387 - 393
• Main Authors: Akhavan, O, Abdolahad, M, Abdi, Y, Mohajerzadeh, S
• Format: Journal Article
• Language: English
• Published: 14.01.2011
• Subjects: Escherichia coli
• ISSN: 0959-9428; 1364-5501
• DOI: 10.1039/c0jm02395g

Vertically aligned multi-wall carbon nanotube (CNT) arrays were fabricated in tip-growth mode on Ni/Si substrates using plasma enhanced chemical vapor deposition. In a purification process including hydrogenation and acid washing of the Ni/CNTs, the oxygen-containing functional groups were substantially reduced and a wide hollow core at the tip of the CNTs was formed by removing the Ni seeds. Sol-gel silver nanoparticles were deposited on the surface of the unpurified Ni/CNTs, while they could also be embedded within the hollow core of the Ni-removed CNTs. The persistency of the silver ions in the Ni-removed Ag-CNTs in comparison to the release of the silver ions from the Ag-Ni/CNTs in a dilute HNO 3 solution confirmed the effective embedding of the Ag nanoparticles within the hollow core of the Ni-removed CNTs. The Ni-removed Ag-CNTs showed a strong antibacterial activity against Escherichia coli bacteria in the dark (inactivation of 99.8 ± 0.1% of the bacteria as compared to the Ni-removed CNTs and the Ag-Ni/CNTs with 62 ± 11 and 47 ± 18% inactivation in 120 min), while the bacteria even exhibited some proliferation on the surface of the unpurified Ni/CNT arrays. In the context of cell membrane rupture of the bacteria through a direct contact mechanism, it was proposed that the Ni seeds acted as obstacles for an effective contact between the bacteria and the tips of the CNT arrays. Inactivation of E. coli bacteria on the surface of various vertically aligned CNT arrays; Ni-removed CNTs and Ni-removed Ag/CNTs.