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In this paper, we report the formation of new conjugates constituting single-wall nanotube (SWNTs) and multi-wall nanotube (MWNTs) comprising silver-doped titanium dioxide (TiO2/Ag) having outstanding antimicrobial and toxic properties. At first, the raw SWNTs and raw MWNTs were chemically treated with sulfuric acid and nitric acid to produce functionalized SWNTs (F-SWNTs) and functionalized MWNTs (F-MWNTs) surface. Then TiO2/Ag nanoparticles (NPs) were loaded with F-SWNTs and F-MWNTs using in situ sol–gel technique. The raw SWNTs, raw MWNTs, and conjugates’ samples were characterized via ultraviolet–visible (UV–Vis) spectrophotometer, Fourier transform infrared (FTIR), Raman spectroscopy, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). These measurements confirmed the loading of TiO2/Ag NPs on SWNTs and MWNTs walls. The optical band gap of R-SWNTs and R-MWNTs was decreased from 3.74 to 3.6 eV and from 3.9 to 3.64 eV, respectively, after decoration of TiO2/Ag. The XRD results confirmed the hexagonal structure of R-SWNTs and R-MWNTs with (002) plane, while the conjugates’ samples showed anatase phase of TiO2 with (101) plane. The R-SWNTs and R-MWNTs dispersions revealed poor killing ability toward both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). In contrast, the prepared SWNTs–TiO2/Ag and MWNTs–TiO2/Ag conjugates exhibited significant inhibitory effect against bacterial strains after 24 h of incubation. The cytotoxicity of these newly developed conjugates was assessed toward uterine cancer (SiHa) cell and normal (WRL68) cell lines. The SWNTs–TiO2/Ag and MWNTs–TiO2/Ag conjugates were able to selectively kill tumor cells (~ 60 to 40%), whereas less affecting normal cells (~ 10%).

In this study, raw single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) were chemically treated with sulfuric acid (H2SO4) and nitric acid (HNO3) in a ratio (3:1). These carbon nanotubes (CNTs) have been coated with Ag-doped TiO2 nanoparticles (NPs) by using the sol–gel method. All samples have been studied by X-ray diffraction (XRD), Fourier transform-infrared (FTIR) spectroscopy, UV–vis spectroscopy, field-emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), and zeta potential analyzer. X-ray diffraction analysis revealed that the polycrystalline structure of silver (Ag) embedded with anatase titanium (TiO2) nanoparticles, while SWCNTs and MWCNTs were verified by EDS spectra due to covering of the (002) peak of carbon nanotubes (CNTs) by the (101) diffraction peak of the TiO2. The FTIR results confirmed the formation of oxygen functional groups onto the SWCNTs and MWCNTs. FESEM results indicated that TiO2/Ag nanoparticles (NPs) successfully loaded onto SWCNTs and MWCNTs. UV–vis absorbance results show a decrease in the energy band gap of MWCNTs-Ag/TiO2 and SWCNTs-Ag/TiO2 in comparison with pure TiO2. Antibacterial activities of nanocomposite samples against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were evaluated by an international recognized test (ASTM E2149). The results showed that nanocomposite samples have a strong bacterial inhibition against E. coli and S. aureus. Gram-negative bacteria appeared to be more resistant to nanocomposite materials than Gram-positive bacteria under illumination by UV light.