Nanotechnology refers to an emerging field of science that includes, the synthesis and development of various nanomaterials. Nanoparticles can define as objects ranging in size from 1-100 nm that, due to their size, may differ from the bulk material (Chen et al., 2006). Nanoparticles are very essential in developing sustainable technologies for the future, for humanity, and the environment. Synthesis of Nanoparticles by plants is a green chemistry approach that interconnects nanotechnology and plant biotechnology (Chung et al., 2016). Nanotechnology has emerged as one of the leading fields of the science had tremendous application in diverse disciplines including biotechnology and agriculture, and this is mainly due to the physicochemical properties of nanoparticles, such as the large surface area to volume ratio of nanoparticles (NPs) which provides an enormous reactive interface between the particle and its local environment. Although, in general, nanoparticles are considered a discovery of modern science, they have a very long history (Alzya et al.,2017). Predominantly the nanoparticles’ extremely small size and large surface area to volume ratio leads to the significant differences in properties (e.g., biological, catalytic activity, mechanical properties, melting point optical absorption, thermal and electrical conductivity) not seen in the same material at larger scales in their bulk form. Because of these unique physicochemical and optoelectronic properties, nanoparticles are of particular interest for several applications ranging from catalysts, chemical sensors, electronic components, medical diagnostic imaging, pharmaceutical products, and medical treatment protocols (Sperling et al., 2008). Nanotechnology has become one of the most promising technologies applied in all areas of science. Metal nanoparticles produced by nanotechnology have received global attention due to their extensive applications in the biomedical and physiochemical fields (Abobatta, 2018). Nowadays, synthesizing metal nanoparticles using microorganisms and plants has been extensively studied and has been recognized as a green and efficient way for further exploiting micro-organisms as convenient nano factories (Yang et al., 2016). In recent years, biological synthesis has emerged as an attractive alternative to traditional synthesis methods for producing nanoparticles (Jagpreet Singh et al., 2018). Biosynthesis involves using an environment-friendly. Biosynthesis of nanoparticles by micro-organisms is a green and eco-friendly technology (Mohanpuria et al.,2008). Both prokaryotes, and eukaryotes are used for synthesis of metallic nanoparticles viz. silver, gold, platinum, zirconium, palladium, iron, cadmium and metal oxides such as titanium oxide, zinc oxide, etc. These microorganisms include bacteria, actinomycetes, fungi and algae (Jagpreet Singh et al., 2018). The synthesis of nanoparticles may be intracellular or extracellular according to the location of nanoparticles (Saba Hasan et al., 2015). Nowadays, there is a growing need to develop eco-friendly processes, which do not use toxic chemicals in the synthesis protocols. Recent studies have shown that green biologically based methods using microorganisms and plants to synthesize nanoparticles are safe, inexpensive, and an environment-friendly alternative (Guidelli et al.,2011). Green synthesis approaches include mixed-valence polyoxometalates, polysaccharides, Tollens, biological, and irradiation methods which have advantages over conventional methods involving chemical agents associated with environmental toxicity. Selection of solvent medium and selection of eco-friendly non-toxic reducing and stabilizing agents are the most critical issues which must be considered in green synthesis of NPs (Zolfaghari et al., 2013).
In the past few years, several studies have been made to prepare the silica from natural resources and its effects on purification and characterization studies. Silica nanoparticles have been the subjects of researchers because of their unique properties (e.g., size and shape depending on optical, antimicrobial, and electrical properties) (Pollini et al.,2011).
Punica granatum are belonged to the family Punicaceae (commonly known as pomegranate) and is one of the oldest known edible fruit. It is widely cultivated throughout India (Morgan et al., 2010). Punica granatum is an ethnomedicinal important plant and depicted ameliorating therapeutic value which was used in the treatment of various diseases such as cardiovascular diseases, diabetes, dental conditions, allergic dermatitis, diarrhea and, in the treatment and prevention of cancer (Miguel et al., 2010). Pomegranate juice, peel, and oil have anticancer properties, including interference with tumor cell proliferation, cell cycle, invasion, and angiogenesis, according to studies (Bassiri-Jahromi et al., 2018). These could be linked to pomegranate's anti-inflammatory properties. The extract of P. grantum has more medicinal values such as antioxidant, antibacterial, antidiabetic, cardio protective, and anticarcinogenic activity (Rahemi et al., 2012).
The present investigation aimed to study the green synthesis of silica nanoparticles using P. granatum leaf extract. The biosynthesized silica nanoparticles were characterized by different analytical techniques. In addition, the antibacterial activity for P. granatum leaf mediated nanoparticles was investigated against the selected Gram negative and pathogenic bacteria.