An efficient growth of silver and copper nanoparticles on multiwalled carbon nanotube with enhanced antimicrobial activity

Transition metal nanoparticles (NPs) such as silver (Ag) and copper (Cu) have been grafted onto carbon nanotube surface through wet chemical approach leading to the development of densely packed NP decorated carbon nanotubes. Chemically active surface and high-temperature stability are the basic attributes to use carbon nanotubes as the template for the growth of NPs. Ag NP-grafted carbon nanotubes (Ag-MWCNT) are prepared by complexing Ag ion with acid functionalized carbon nanotubes followed by the reduction method. Alternatively, Cu-grafted carbon nanotubes (Cu-MWCNT) are prepared by simple chemical reduction method. X-ray diffraction results reveal that the Ag or Cu NPs formed on the surface of carbon nanotubes are determined to be face centered cubic crystals. The morphology and chemical structure of NP-grafted carbon nanotubes are investigated using transmission electron spectroscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. The antimicrobial properties of acid-treated MWCNT (MWCNT-COOH), Ag-MWCNT, and Cu-MWCNT are investigated against gram negative Escherichia coli bacteria. Ag-MWCNT and Cu-MWCNT (97% kill vs. 75% kill), whereas MWCNT-COOH only killed 20% of this bacteria. Possible mechanisms are proposed to explain the higher antimicrobial activity by NP-coated MWCNT. These findings suggest that Ag-MWCNT and Cu-MWCNT may be used as effective antimicrobial materials that find applications in biomedical devices and antibacterial controlling system. (C) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 96B: 119-126, 2011.