Green biomimetic synthesis of Ag–TiO2 nanocomposite using Origanum majorana leaf extract under sonication and their biological activities
Diksha Bhardwaj, Ruby Singh
Abstract
Abstract Background Studies of plant extract-mediated synthesis of nanoparticles is extensively explored and studied in recent time due to eco-friendly, cost-effectiveness and minimal use of toxic chemicals for synthesis. In this study, the synthesis of Ag–TiO 2 nanocomposites (NCs) was carried out using Origanum majorana leaf extract under ultrasound irradiation. Origanum majorana leaf extract plays an important role as reducing and capping agent in synthesis of Ag–TiO 2 nanocomposites (NCs). The antimicrobial activities of synthesised Ag–TiO 2 NCs have been studied against Gram-positive and Gram-negative bacteria. In addition to this, the antioxidant activity of green Ag–TiO 2 NCs was also evaluated on the basis of free radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS), and hydrogen peroxide free radicals. Results Green-synthesised Ag–TiO 2 NCs were successfully characterised on the basis of UV–Vis spectrophotometer, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction analysis (XRD), scanning electron microscopy energy-dispersive X-ray spectroscopy (SEM–EDS) and transmission electron microscopy (TEM). The results revealed the spherical shape of nanocomposite with an average size 25–50 nm. The synthesised Ag–TiO 2 NCs have showed significant antimicrobial activity against Escherichia coli , Bacillus subtilis and Aspergillus niger in comparison to TiO 2 nanoparticles (NPs). The antioxidant evaluation of biomimetic synthesised Ag–TiO 2 NCs also exhibited strong activity than TiO 2 NPs and comparable to standard. Conclusion Green-synthesized Ag–TiO 2 NCs provide a promising approach that can satisfy the requirement of large-scale industrial production bearing the advantage of low cost, eco-friendly and reproducible.