Résumé
Although in vivo studies have been modeled using higher mammal systems, the lower vertebrate zebrafish (Danio rerio) has gained tremendous attention as a model system. Gold nanoparticles (GNPs) attract the interest of scientists due to their promising potential applications in medicine and targeted drug delivery. The purpose to use GNPs in vivo is that gold in bulk form is nontoxic and apply the positive potentials of nanoparticles. Bulk gold is century-long accepted as a safeto- use metal. Gold in its nanoform has distinct chemical and physical properties and the large amount of surface atoms make GNPs reactive. Moreover, GNPs can potentially access many cellular or subcellular structures, which are unreachable by the larger compound and may induce toxic effects. This paper addresses effects of spherical GNPs of average size 15 nm on reproductive organs after subacute exposure in adult male and female zebrafish. Gold nanoparticles were chemically synthesized and characterized by transmission electron microscope. The primary objective of this study was to determine if exposure to GNPs altered cellular morphology of gonads. The adult fish of both sexes were administered orally with these GNPs at a dose of 20 µg/gm. At the end of the study, quantification of gold content was estimated using two different tools: inductive coupled plasmon-atomic emission spectroscopy (ICP-AES) and inductive coupled plasmon-mass spectroscopy (ICP-MS). No gold metal accumulation was detected in treated group of male and female zebrafish at subacute exposures on estimation through ICP-AES. On analysis using ICP-MS, 0.44 ± 0.18 µg/gm organ weight was detected in ovaries and 4.6 ± 3.20 µg/gm organ weight was detected in testes of treated groups. However, the pattern of accumulation was found to be nonsignificant when compared with the control group at a p-value >0.05. Histopathological analysis of reproductive organs showed no significant changes in cellular morphology of testes and ovaries.
Résumé
Owing to widespread applications, synthesis and characterization of silver nanoparticles is recently attracting considerable attention. Increasing environmental concerns over chemical synthesis routes have resulted in attempts to develop biomimetic approaches. One of them is synthesis using plant parts, which eliminates the elaborate process of maintaining the microbial culture and often found to be kinetically favorable than other bioprocesses. The present study deals with investigating the effect of process microwave irradiation, interaction time on the morphology and size of silver nanoparticles synthesized using aqueous extract of Tulsi. Plant extract from ocimum sanctum (Tulsi) was used for the synthesis of silver nanoparticles (AgNPs) from silver nitrate solution. Silver nanoparticles were characterized by UV-Vis spectrophotometer and scanning electron microscope (SEM). The formation and stability of the reduced silver nanoparticles in the colloidal solution was monitored by UV-Vis spectrophotometer analysis. Nanoparticles ranges from 20 to 40 nm in size with nearly spherical shape were produced. SEM determination of the brown color stable samples showed the formation of silver nanoparticles and well dispersed nanoparticles could be seen in the samples treated with silver nitrate. These silver nanoparticles have proven to be stable for more than 3 months. It can be inferred from the study that fne tuning the bioprocess parameters will enhance possibilities of desired nano-product tail or made for particular applications.
Résumé
Genotoxic effects of silver nanoparticles (Ag-np) in a vertebrate model system were investigated. Effects and accumulation patterns of silver nanoparticles were studied using zebrafish embryos. Nanoparticles of silver were synthesized by chemical reduction of silver nitrate, using sodium borohydride as reducing agent and polyvinyl pyrolidene as a stabilizer. These nanoparticles were characterized by UV/ Vis spectrophotometer (absorption spectra), Transmission electron microscopy and were found to have the size range of 4 to 10 nm. Evaluation of cytotoxicity was carried out at various concentrations to obtain the LD50 value. Dose dependent decrease in percent viability was observed on exposure of embryos to different concentrations of silver nanoparticles with LD50 of 1.0 µg/ml. The results indicate that silver nanoparticles induce a dose-dependent toxicity in embryos and abrogate normal development.