Effect of varied Ag nanoparticles functionalized CNTs on its anti-bacterial activity against E. coli

•CNTs were functionalized with Ag nanoparticles.•Ag nanoparticles concentration was varied.•The functionalization was characterized with FTIR and Raman spectroscopy. Detailed Raman spectroscopy of CNTs showed CNTs were single walled.•The nanohybrid was tested for its antibacterial activity and compared with a positive and a negative standard.•The system is a potentially useful for drug delivery. In this paper, we present the effect of the functionalization time of silver nanoparticles with carbon nanotubes (CNTs) for its antibacterial activity. CNTs were synthesized via conventional CVD process. Iron nanoparticles used as catalysts were deposited by buffer layer assisted growth (BLAG). The structure and morphology of the synthesized CNTs were examined by the scanning electron microscopy (SEM) and X-ray diffraction (XRD). Raman spectroscopy confirmed the formation of small diameter CNTs of semiconducting nature. The synthesized CNTs were purified and then functionalized for varied time with Ag nanoparticles, as confirmed by the FTIR spectroscopy. Functionalization of CNTs at different times resulted in the formation of different sized Ag nanoparticles attached to the CNTs. Finally the antibacterial assays were performed against Escherichia coli to quantify the effect of varied sized Ag-NPs on the sensitivity of CNTs. It was revealed that the antibacterial activity was dependent on the size of Ag nanoparticles as it showed an inverse relation between the dilution factor and the susceptibility. The minimal inhibitory concentration of CNTs-Ag conjugate was also determined for its antibacterial activity.