Photocatalytic activity and antibacterial efficacy of titanium dioxide nanoparticles mediated by Myristica fragrans seed extract

Abstract

The synthesis of semiconductor metal/metal oxide nanoparticles (NP) via the green synthesis routes is desirable due to its effectiveness, economical, and eco-friendly nature of the products. The present study aims to synthesize the titanium dioxide (TiO2) NP via the green synthesis route, using Myristica fragrans plant extract as the reducing agent, where the photocatalytic activity was evaluated. The physicochemical and morphological properties of TiO2 NP have been analyzed using spectroscopic and electron microscopic techniques. From the analysis, the powdered X-ray diffraction (XRD) indicated the formation of very well crystalline TiO2 particles in the anatase phase, while the Fourier transform infrared (FTIR) spectroscopy confirmed the presence of Ti[sbnd]O bonds, and UV–Vis spectroscopy proofed the optical properties. The field emission scanning electron microscopy (FESEM) analysis provided the surface morphological characteristics and the formation of spherical shape particles; and the electron diffraction X-ray analysis (EDX) indicated the elemental composition. The photocatalytic activity of the TiO2 NP was evaluated based on the degradation rate of two aqueous dye solutions, i.e. methylene blue (MB) and congo red (Con-R) using the 8 W Xenon lamp as the light source for the visible irradiation. The degradation activity of the Con-R dye is slightly higher (99% degradation in 45 min) than that of the MB dye (97% degradation in 60 min). Both degradations activity followed the first-order kinetic model. The high activity of TiO2 NP on both dyes was supported by the increased absorption of light, associated charge separation efficiency, and specific surface area as provided by the UV–Vis DRS analysis. The plant extract mediated the synthesis of TiO2 which formed stable particles without losing the semiconducting and photocatalytic properties, where the holes (h+) and superoxide radicals ([rad]O2-) contributed to the enhanced degradation of dye. The antibacterial activity of the TiO2 NP (50 and 100 µg/mL; 6 h) synthesized was evaluated by testing against two different bacterial cultures of K. pneumoniae and S. aureus. The results proved that the particles became active only in the presence of UV light exposed and no significant differences in bacterial inhibition efficiency between the two cell types (79% and 72%) as observed. The antibacterial activity of the TiO2 NP was proven by the epifluorescence microscopic analysis, total viable count (TVC), and zone of inhibition (ZOI).