Biological Effect Evaluation of Different Sized Titanium Dioxide Nanoparticles Using Bombyx mori (Silkworm) as a Model Animal

Titanium dioxide nanoparticles (TiO 2 NPs) are widely used in various disciplines, and it is imperative to evaluate their safety in the environment. In this paper, Bombyx mori (silkworm) was used as a model organism to evaluate the biological effects of different sized TiO 2 NPs, taking into consideration their effect on the larval growth, cocoon shell weight, tissues, and silk produced. The effect of the different sized TiO 2 NPs on the larval and cocoon shell weight was dose-dependent. The highest accumulation of titanium (Ti) following a modified TiO 2 NPs-treated mulberry diet was observed in the midgut. The expression of the light chain fibroin (FIBL) was three times higher in 0.33 g TiO 2 NPs-treated silk gland after 96 h. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis demonstrated that TiO 2 NPs-treated silk fiber (TiSF) exhibited a diminutive decrease in silk fiber (SF) crystallization and β-sheet compared to the control SF, respectively. The tensile tests of SF from silkworm fed with 0.03 g of 25 nm TiO 2 NPs were significantly improved when compared to the control SF. Significant changes in the surface morphology and thermal stability of SF were observed. The antimicrobial activity of TiSF was investigated against Pseudomonas aeruginosa and Staphylococcus aureus , with ciprofloxacin-treated SF acting as a control. It was documented that 0.09 g of 60 nm TiSF was most effective against P. aeruginosa at a zone of inhibition (ZOI) of 21.06 mm when compared with the control SF which recorded a ZOI of 17.19 mm. This study highlighted a different approach in evaluating the biological effects of TiO 2 NPs using the silkworm as a model and assessing their impact on the silk intrinsic property, which will be effective in biotechnology applications.