Biosynthesis of metallic nanoparticles using plant extracts and evaluation of their antibacterial properties

The increasing attention being paid to metallic nano particles (MNPs) is due to their intensive applications in different areas of science such as medicine, chemistry, agriculture, and biotechnology. The main methods for nanoparticle production are chemical and physical approaches that are often costly and potentially harmful to the environment. Since the eco-friendly synthesis of NPs with different chemical compositions, sizes, shapes and controlled dispersity is an important aspect of nano biotechnology and green nanotechnology, biosynthesis of nanoparticles has been proposed as a cost-effective and environmental-friendly alternative to chemical and physical methods. Plants contain abundant natural compounds such as alkaloids, flavonoids, saponins, steroids, tannins and other nutritional compounds. These natural products are derived from various parts of the plant such as leaves, stems, roots, shoots, flowers, barks, fruits and seeds. Since the plant extract contains various secondary metabolites, it acts as the reducing and stabilizing agent for the bioreduction reaction to synthesize the novel metallic nanoparticles. This approach has been actively pursued in recent years as an alternative, efficient, inexpensive, and environmentally safe method for producing nanoparticles with specified properties. The present review focuses on the synthesis of MNPs with particular emphasis on biological synthesis using plant extracts and most commonly proposed mechanisms regarding the antibacterial properties of nanoparticles.