Antibacterial, antibiofilm and cytotoxic properties of Aloe vera-synthesized silver titanium nanoparticles

The green synthesis of silver (Ag) and titanium dioxide (TiO₂) nanoparticles (NPs) is of great interest due to their unique and controllable properties, as well as the eco-friendly and low-cost process involved. In this study, green-synthesized Ag, TiO₂, and AgTiO₂ NPs were prepared with four different ratios of TiO₂: Ag (1:0.5, 1:1, 1:1.5, and 1:2) using Aloe vera (A. vera) as a reducing agent. NPs were characterized and examined against multidrug-resistant (MDR) bacteria, MRSA, Klebsiella pneumoniae, and Salmonella Typhi. The antibiofilm and cytotoxic effects of the respective NPs were also investigated. The NPs' synthesis, morphology, crystalline structure, and coating were confirmed and characterized using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. Additional characterization, including transmission electron microscopy, high-resolution transmission electron microscopy, and selected area electron diffraction, was performed only on the best NPs showing the best biological effect. The produced NPs were found to be irregular spheres and polygonal in shape of 20-70 nm in size. AgTiO₂ NPs showed superior antibacterial activity against MRSA, followed by S. Typhi, then K. pneumoniae. Their MIC values ranged from 250 to 15.62 µg/mL, and MBC values ranged from 1000 to 15.62 µg/mL, while the biofilm inhibition ranged from 79.5 to 96.6%. All NPs showed cytotoxic at different concentrations, showing more cytotoxicity against Panc-1 cells. The AgTiO₂ (2:1) NPs were revealed to be the most effective and cytotoxic sample. In conclusion, AgTiO₂ (2:1) NPs showed to be a promising candidate for clinical evaluation due to their tremendous in vitro biological activities.