Microwave Assisted Biosynthesis of Silver Nano-particles by Aqueous Extract of Ocimum Sanctum (Tulsi).

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.

Toxicity Assessment of Silver Nanoparticles in Zebrafish Embryos.

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.