An increase in secondary metabolites in response to various biotic and abiotic stresses is compared with ionizing radiation. A ∼5- to 20-fold increase is noted with ∼20 Gy irradiation dose. It increases the yield of secondary metabolites by enhancing the activity of certain key biosynthetic enzymes. Identification of the optimum dose is the important step in the large-scale production of secondary metabolites at industrial level.
The present article focuses on the influence of gamma irradiation and post-irradiation storage conditions on FT-IR spectra of 1 mm thick polystyrene irradiated with 51, 77 and 129 kGy. The increase in amplitude corresponding to 3600, 3400 and 2100 cm stretching frequencies clearly showing the formation of O-H and C=O bonds (~ 25%). On prolonged storage (2160 h) in the dark, there is an increase in O-H group (~ 28%). The electron cloud facilitates the formation of hydroxyl group in irradiated polystyrene. The post-irradiation treatment with heat conversely showed a reduction of O-H, C-H and C=O (9-16%) groups due to radical-radical recombination at higher temperatures and light intensities. This investigation finds its applications in memory devices, optical sensors, radiation dosimetry and different space and radiation facilities.
Eco-friendly bio-compatible silver nanoparticles (Ag NPs) were successfully synthesized using Zingiber officinale extract in a simple green route at room temperature. The phytoconstituents present in Zingiber officinale (Z. officinale) extract act as reducing and stabilizing agents. The size and crystallinity of spherical Ag NPs were confirmed through transmission electron microscopy (TEM) and X-ray diffraction (XRD) studies. The formation of silver nanoparticles was also confirmed from the UV-vis and FTIR spectra. Luminescence properties of europium (Eu) and samarium (Sm) complexes in the presence of silver were studied. The intensity of luminescence from Eu and Sm complexes were found to get enhanced or quenched with their concentrations in Ag NPs. Interesting nonlinear optical properties exhibited by Ag NPs were observed in the Z-scan experiment suggesting that they can be used as optical limiters for the picosecond (ps) time scale green laser. Silver nanoparticles were tested against colon cancer (HCT116) cells in vitro by MTT assay and they exhibited smaller IC 50 values with better inhibition efficiency. Ag NPs induced apoptosis through the activation of Reactive oxygen species (ROS) and Caspase-3 pathways. Antibacterial activity of Ag NPs was analysed against Acinetobacter baumannii (A. baumannii) and Staphylococcus aureus (S. aureus) and they were found to be efficient in inhibiting the bacteria. The results indicate that the biosynthesized eco-friendly nanoparticles having high stability can lead to many applications such as good luminescence enhancement, optical limiting characteristics, anticancerous and antibacterial properties in optics and biomedicine.
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