Titanium dioxide nanoparticles: green synthesis, characterization, and antimicrobial/photocatalytic activity

The work aims to biosynthesize and characterize titanium dioxide nanoparticles (TiO2-NPs) to evaluate antimicrobial activity, cytotoxicity, and photocatalytic activity (under visible irradiation). X-ray diffraction (XRD), N-2 adsorption/desorption, zeta potential (ZP), field emission gun scanning electron microscopy (FEG-SEM), and scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX) were used to characterize. The antibacterial potential was evaluated by minimal inhibitory activity (MIC) against S. aureus and P. aeruginosa. Central composite rotational design (CCRD 2(3)) was used for experimental design. XRD diffractogram and FEG-SEM micrograph showed characteristic peaks of TiO2-NPs (about 32 nm) and spherical shapes, respectively. TiO2-NPs had a negative charge surface (- 4.9 mV) with type V and H1 hysteresis and S-BET = 118 m(2) g(-1), Dp = 9.2 nm and Vp = 0.2 cm(3) g(-1). EDX results indicated the presence of TiO2-NPs and the effectiveness of the green synthesis. The antimicrobial activity showed that there was no inhibition of any pathogen. About the safety profile, there was no reduction in cell viability in the 293 T, MDBK, and HaCat cell lines, and reactive oxygen species (ROS) generation did not cause significant differences about the untreated control, indicating biocompatibility. The photocatalytic activity showed degradation of 90% of RhB dye using the ideal condition ([RhB] = 10 mg L-1, [TiO2-NPs] = 3.5 g L-1, and pH = 7.0) by CCRD under visible irradiation with a pseudo-first-order kinetic model (k = 0.0146 min(-1)). Therefore, TiO2-NPs present applications as alternative metallic nanoparticles for wastewater treatment and show potential for antimicrobial activity.