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Biogenic methods of synthesis of nanoparticles (NPs) using plant extracts have been given a great attention due to its nontoxicity and environmental friendliness. In this study, TiO 2 NPs were synthesized from titanium tetrabutoxide and extract of root of Kniphofia foliosa . NPs of TiO 2 were biosynthesized at different volume compositions of titanium tetrabutoxide to the plant extract with a ratio of 1 : 2, 1 : 1, and 2 : 1, respectively. These green synthesized NPs of TiO 2 were characterized by thermogravimetric analysis (TGA/DTA), X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), and Fourier transform infrared (FTIR) spectroscopy. TGA/DTA analysis has confirmed that the synthesized NPs of TiO 2 were stable above the temperature of 500°C. The sharp and intense peaks at 2 θ values of 25.3, 38.0, 47.9, 53.2, 54.8862, 62.7, 70.2, and 75.0 have confirmed formation of crystalline NPs of TiO 2 in the sample of 1 : 1 and 2 : 1 ratios, and less crystalline samples for TiO 2 NPs prepared in a 1 : 2 ratio. Comparison between FT-IR absorption bands of the plant extract and that of calcined NPs of TiO 2 confirmed the purity of synthesized nanomaterials, except unavoidable adsorption of moisture on the surface of TiO 2 NPs in an open air. The antibacterial activity of biosynthesized TiO 2 NPs and that of ethanolic root extract of Kniphofia foliosa was investigated via the disc diffusion method against human pathogen bacteria strains of Staphylococcus aureus , Escherichia coli , Klebsiella pneumonia , and Streptococcus pyogenes . Among the different ratios, TiO 2 (1 : 1) NP shows better performance towards Gram-negative bacteria due to its smaller average crystalline size and uniform morphology observed in SEM image relative to the other two ratios of TiO 2 NPs. Antibacterial activity of the ethanolic root extract of Kniphofia foliosa itself showed better performance towards Gram-negative bacteria than NPs of TiO 2 that might be due to antibacterial activity of residue of ethanol left with the plant extract.
Bekele et al. (Tue,) studied this question.