Ag-Conjugated Nanoparticle Biosynthesis Mediated by Rosemary Leaf Extracts Correlates with Plant Antioxidant Activity and Protein Content

In recent years, the world has witnessed an explosion of interest in biogenic synthesis of metallic nanoparticles (NPs), using plant extracts; however, the plant constituents involved in this reaction are poorly characterized. Here, major components of Rosemary (Rosmarinus officinalis L.) leaf extracts were isolated monthly during 2012-2013 and their competences for Ag–conjugated nanoparticle biosynthesis were studied. Formation of Ag/AgCl–NPs was examined using UV-visible spectroscopy and characterized by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and Transmission electron microscopy (TEM). Correlation analysis showed that extracts with more protein contents and higher total reducing capacity were more efficient in biosynthesis of Ag/AgCl–NPs. There existed no correlation between total phenolic, ascorbic acid and anthocyanin contents with Ag/AgCl–NPs biosynthesis activity. These results partly explain the mechanisms controlling plant mediated biosynthesis of nanoparticles, with possible applications in standardization of plant materials harvested throughout a year.