Silver nanoparticles (Ag-NPs) are among the most widely used nanomaterials in the world. Nanotoxicological data on these additives remain unclear. The aim of this study is to evaluate the in vivo effects of Ag-NPs bioaccumulation on the hematological cells of adult zebrafish Danio rerio after three weeks of oral exposure. Four concentrations of Ag-NPs (65 nm nanosphere), are used: control group 1 (0. 00 g/kg of food), group 2 (0. 05 g/kg of food), group 3 (5 g/kg of food) and group 4 (50 g/kg of food). The experiment is conducted in triplicate. Cytological and histological results show, a significant increase in neutrophils associated with a significant decrease in lymphocytes in both group 3 and 4 compared to the control group (p<0, 05 and p<0, 005, respectively). This reflects an elevated neutrophil/lymphocyte ratio (NLR), suggesting a biased immune response associated with hyperplasia of the hematopoietic tissue and histopathological images of nephrological lesions, following medium to high dose of Ag-NPs intake. Besides, microscopic observation of cell morphology revealed lymphocyte activation only in groups 2 and 3 (p<0, 005 and p<0, 05, respectively). These results suggest that Ag-NPs induce a dose-dependent bioeffects on the immune system in zebrafish. This study reports that at low doses, Ag-NPs may activate lymphocytes but do not alter the NLR, thus demonstrating an immunostimulatory effect. The present investigation is the first study, as far as we know, reporting that Ag-NPs induce a dose-dependent immunomodulation in zebrafish

Background: The threat of antimicrobial resistance is increasing worldwide. Niosomes are a new drug delivery system that increases the antimicrobial potential of antibiotics. Accordingly, this study aimed to evaluate the antibacterial activity of niosomes loaded with curcumin-Silver nanoparticles (Cur-AgNPs) and curcumin-copper nanoparticles (Cur-CuNPs). Methods: Initially, a unique combination of metal and curcumin nanoparticles was prepared in free and encapsulated forms to investigate the synergistic effects of the two drugs and to evaluate them through a niosomal carrier. Particle size and polydispersity index were measured using dynamic light scattering (DLS), and entrapment efficiency (EE) was measured through indirect centrifugation. The rate of drug release from the loaded niosomes was assessed through in vitro dialysis. Finally, the antibacterial activity of Cur-AgNPs and Cur-CuNPs loaded niosomes on Staphylococcus aureus and Pseudomonas aeruginosa were measured. Results: The curcumin-loaded niosomal formulations and the simultaneous combination of Cur-AgNPs and Cur-CuNPs had an optimum particle size of less than 200 nm and uniform dispersion. These formulations also showed high entrapment efficiencies and slow release for more than 72 hours. Conclusion: A significant increase in antibacterial activity was observed when using curcumin in combination with metal nanoparticles loaded in niosomes, indicating that the concomitant use of metal nanoparticles and curcumin had a synergistic effect in inhibiting bacterial growth.