Barleria prionitis Leaf Mediated Synthesis of Silver and Gold Nanocatalysts

Abstract

Development of rapid, efficient, eco-friendly processes for synthesis of metal nanoparticles is one of the most significant thrust areas of nanobiotechnology. Medicinal plants are rich source of bioactive principles of diverse therapeutic importance. However, this unique phytochemistry can play a critical role not only in reduction of metal ions to their corresponding nanoparticles but also help to stabilize the same. Herein we report for the first time the synthesis of silver and gold nanoparticles using a medicinal plant, Barleria prionitis leaf extract. The synthesis was complete within 5 h and UV-vis spectra exhibited signature peaks at 420 nm and 540 nm for silver and gold nanoparticles, respectively. 3 mM AgNO3 and 2 mM HAuCl4 showed maximum synthesis of silver nanoparticles and gold nanoparticles, respectively at 50°C. High resolution transmission electron microscopy revealed that majority of the silver nanoparticles was spherical in a size range between 10 to 20 nm while gold, between 10 to 25 nm. Various exotic shapes were seen in case of gold nanoparticles like spheres, triangles and pentagons. The bioreduced nanoparticles were further characterized and confirmed using energy dispersive spectra, dynamic light scattering, X-ray diffraction spectrometry. Reducing sugars, ascorbic acid, starch, citric acid along with phenolics were found to be present in the extract that might play a major role in bioreduction and stabilization. GCMS/MS analysis further confirmed the diverse phytochemistry confirming tetradecane, 1-dodecanol, 3,7,11-trimethyl- and tert-hexadecanethiol as most predominant. Both silver and gold nanoparticles exhibited efficient catalytic reduction of o-nitrophenol.