Biogenic Synthesis of AgNPs with Saussurea lappa C.B. Clarke and Studies on Their Biochemical Properties.

Nanotechnology has become an irreplaceable need and green synthesis of nanoparticles offers several advantages over physical and chemical methods. Medicinal plants are the main reservoirs of drugs and drug candidates. We report the biogenic synthesis of silver nanoparticles (AgNPs) using aqueous root extract of Saussurea lappa. Verification and characterization of these nanoparticles were done by UV-visible spectroscopy, XRD-analysis and Scanning Electron Microscopy and FT-IR. Extract-loaded-AgNPs showed the highest inhibition zone against Escherichia coli (11.0 mm) and intermediate against Pseudomonas aeruginosa (9.0 mm). The methanolic root extract of S. lappa alone, also moderately inhibited Pseudomonas aeruginosa (9.0 mm) and showed lower activity (6.0 mm) against Escherichia coli. Its aqueous roots extract inhibited (6.0 mm) the growth of tested organisms. Methanolic extract showed antioxidant potency (IC50 = 0.814 µg/mL). Experiments revealed the presence of phenols and flavonoids in the roots of Saussurea lappa. These findings provide promising interest to exploit Saussurea lappa for the biogenic synthesis of AgNPs and their biological applications.

Fabrication of Nanostructured Cadmium Selenide Thin Films for Optoelectronics Applications.

There is lot of research work at enhancing the performance of energy conversion and energy storage devices such as solar cells, supercapacitors, and batteries. In this regard, the low bandgap and a high absorption coefficient of CdSe thin films in the visible region, as well as, the low electrical resistivity make them ideal for the next generation of chalcogenide-based photovoltaic and electrochemical energy storage devices. Here, we present the properties of CdSe thin films synthesized at temperatures (below 100°C using readily available precursors) that are reproducible, efficient and economical. The samples were characterized using XRD, FTIR, RBS, UV-vis spectroscopy. Annealed samples showed crystalline cubic structure along (111) preferential direction with the grain size of the nanostructures increasing from 2.23 to 4.13 nm with increasing annealing temperatures. The optical properties of the samples indicate a small shift in the bandgap energy, from 2.20 to 2.12 eV with a decreasing deposition temperature. The band gap is suitably located in the visible solar energy region, which make these CdSe thin films ideal for solar energy harvesting. It also has potential to be used in electrochemical energy storage applications.