Comparative evaluation of half-maximum inhibitory concentration and cytotoxicity of silver nanoparticles and multiwalled carbon nanotubes using buffalo bull spermatozoa as a cell model.

There is a dearth of information regarding the safety of silver nanoparticles (Ag NPs) and multiwalled carbon nanotubes (MWCNTs) with respect to their impact on human/animal health and the environment. This study aimed to determine the half-maximum inhibitory concentration (IC50) of Ag NPs and MWCNTs by employing different doses and time interval combinations in buffalo bull spermatozoa. Semen samples containing 100 million spermatozoa each were incubated with 1, 10, 25, 50, 75 and 100 µg/mL of Ag NPs and MWCNTs at 37°C for 30, 60 and 120 min. Sperm viability was monitored by the MTT assay and eosin-nigrosin staining followed by estimation of IC50 values using correlation-regression analysis. Spermatozoa treated with IC50 doses of Ag NPs and MWCNTs were also assessed for different sperm functionality parameters including oxidative stress and membrane integrity. These parameters were observed to be significantly affected in treated spermatozoa compared with the controls. We concluded that both nanomaterials showed cytotoxicity, mediated principally via oxidative stress. This work has provided valuable toxicological information that will serve as a benchmark for future studies aimed at safe use of nanomaterials.

Mesoporous silica nanoparticle is comparatively safer than zinc oxide nanoparticle which can cause profound steroidogenic effects on pregnant mice and male offspring exposed in utero.

The increasing use of nanomaterials has naturally caused heightened concerns about their potential risks to human and animal health. We investigated the effect of zinc oxide nanoparticles (ZnO NPs) and mesoporous silica nanoparticles (MSN) on steroidogenesis in the corpus luteum (CL) of pregnant mice and testis of male offspring. Pregnant albino mice were exposed to ZnO NPs and MSN for 2 days on alternate days, gestation days 15-19. Hepatic injury marker enzymes increased in the higher concentration of NM-exposed mother mice, but histological examination revealed no changes in the placenta of pregnant mice, whereas testis of male offspring showed gross pathological changes. The expression pattern of progesterone biosynthesis-related genes was also altered in the CL of NP-exposed pregnant mice. In utero exposure of ZnO NPs increased the relative expression of StAR in 100 mg/kg body weight (BW) ZnO NP-treated and bulk ZnO-treated groups and P450 side-chain cleavage enzyme (P450scc) in 50 mg/kg BW ZnO NP-treated and 100 mg/kg of bulk ZnO-treated male offspring. Serum testosterone concentration significantly increased in the 100 mg/kg of bulk ZnO-treated group and decreased in the 250 mg/kg of MSN-treated group and a single dose of 300 mg/Kg BW of ZnO NPs caused miscarriages and adversely affected the developing foetus in mice.

Enhanced steroidogenic and altered antioxidant response by ZnO nanoparticles in mouse testis Leydig cells.

Zinc oxide nanoparticles (ZnO NPs) are important nanomaterials with myriad applications and in widespread use. The main aim of this study was to evaluate the direct effect of ZnO NPs on steroidogenesis by considering mouse testicular Leydig cells (TM3) as an in vitro model system. The uptake, intracellular behaviour, cytotoxicity and morphological changes induced by ZnO NPs (0-200 µg/ml) in a time-dependent manner in the TM3 were assessed. A significant ( p < 0.05) decrease in TM3 viability was observed at 2 µg/ml ZnO NP after a 1-h incubation time period. Increased antioxidant enzyme activity, namely, superoxide dismutase (SOD) and catalase, was regularly observed. Not surprisingly, apoptosis also increased significantly after a 4-h exposure period. Transmission electron micrographs illustrated that ZnO NPs were taken up by Leydig cells and resulted in the formation of autophagosomes, autolysosomes and autophagic vacuoles. Concomitant real-time data indicated that ZnO NPs significantly increased the expression of steroidogenesis-related genes (steroidogenic acute regulatory protein and cytochrome P450 side-chain cleavage enzyme) and significantly ( p < 0.05) decreased antioxidant enzyme gene (SOD) expression after a 4-h incubation period. Moreover, ZnO NPs exposure significantly increased testosterone production at 2 µg/ml concentration after a 12-h incubation period. Our findings confirm the adverse effects of ZnO NPs by being cytotoxic, enhancing apoptosis, causing steroidogenic effect in Leydig cells and increasing autophagic vacuole formation possibly via alteration of antioxidant enzyme activity in TM3 cells.