TiO 2 nanoparticles: green synthesis, characterization, and investigation of antimicrobial properties, and developmental toxicity in zebrafish ( Danio rerio ) embryos.

The present study was designed to green synthesize titanium dioxide nanoparticles (G-TiO 2 NPs) using Salacia reticulata leaf extract as a reducing and capping agent to assess antidiabetic, anti-inflammatory, and antibacterial effects as well as toxicity evaluation in zebrafish. Besides, zebrafish embryos were employed to study the effect of G-TiO 2 NPs on embryonic development. Zebrafish embryos were treated with TiO 2 as well as G-TiO 2 NPs at four different concentrations, i.e., 25, 50, 100, and 200 µg/ml for 24-96-hour post-fertilization (hpf). The SEM analysis of G-TiO 2 NPs confirmed that the size was in the range of 32-46 nm and characterized by EDX, X-ray diffraction (XRD), FTIR, UV-vis spectra. During 24-96-hour post-fertilization (hpf), the results showed that 25-100 µg/ml of TiO 2 and G-TiO 2 NP instigated developmental acute toxicity in these embryos, causing mortality, hatching delay, and malformation. TiO 2 and G-TiO 2 NPs exposure induced axis bent, tail bent, spinal cord curvature, yolk-sac, and pericardial edema. Exposure of larvae to the highest concentrations of 200 μg/ml TiO 2 and G-TiO 2 NPs caused maximum mortality at all time points and reached 70% and 50%, respectively, at 96 hpf. Besides, both TiO 2 and G-TiO 2 NP revealed antidiabetic and anti-inflammatory effects in vitro . In addition, G-TiO 2 NPs exhibited antibacterial effects. Taken together, this study provided a valuable insight into the synthesis of TiO 2 NPs using green methods and the synthesized G-TiO 2 NPs possess moderate toxicity and potent antidiabetic, anti-inflammatory and antibacterial activities.