Green Synthesis of Silver Nanoparticles by Using Neem (Azadirachta Indica) and Amla (Phyllanthus Emblica) Leaf Extract

The present study describes a novel green synthesis of silver nanoparticles by using Azadirachta indica and Phyllanthus emblica leaf extract. The green synthesized silver nanoparticles had been confirmed by UV-Vis spectrum. Based on the findings, it seems very reasonable to believe that this greener way of synthesizing silver nanoparticles is an environmentally viable technique. Introduction Silver is an effective antimicrobial agent, exhibits low toxicity (Sondi and Sondi 2004). Although there are many routes available for the synthesis of silver nanoparticles, bio-inspired synthesis such as use of plant sources offers several advantages such as cost-effectiveness, eco-friendliness and the elimination of high pressure, energy, temperature, and toxic chemicals necessary in the traditional synthesis methods (Sun and Xia 2002). A variety of techniques including physical and chemical methods have been developed to synthesize silver nanoparticles. The physical methods are highly expensive and chemical methods are harmful to the environment (Yang et al 2011). Therefore, there is a growing need to develop eco-friendly nanoparticles that do not use toxic chemicals in the synthesis (Saad et al 2011). The recent reports include the synthesis of nanoparticles using medicinal plants (Mukunthan and Elumalai 2011). This stands as a great application in the field of nano-medicine. Medicinal property of the extract and nano-silver could play vital role in treatment of many diseases. Most of the reported green synthesis methods using plants took more than 1 hour for the formation of colloidal silver. In the present paper, the emphasis is on a greener synthesis of Ag-NPs using an extract from the leaves of Azadirachta indica and Phyllanthus emblica. The nanoparticles obtained through this method will be referred to as ‘greener’ silver nanoparticles (Gr-Ag-NPs). The antibacterial properties of Gr-Ag-NPs have received most attention; they were made to interact with Pseudomonas aeruginosa and Staphylococcus aureus. We also evaluated the leaf extract for their antibacterial properties using the same experimental methods in order to compare them with Gr-Ag-NPs. The results suggested that Gr-Ag-NPs had better antibacterial properties. Thus greener synthesis of Ag-NPs which not only have environmental advantages but also showed better antibacterial properties than those plant leaf extract. We assume that some organic molecules present in the leaf extract reduce the Ag+ to Ag-NPs. Our present conclusion undoubtedly reveal that it is really possible to have a much greener way to synthesize AgNPs without compromising their antibacterial properties and thus plant extracts may prove to be a good alternative to obtain Ag-NPs with enhanced antibacterial properties. Materials and methods Plants and Chemicals Healthy leaves of Azadirachta indica and Phyllanthus emblica were collected from the Kurukshetra University campus. The chemicals, media and reagents used in the present studies were taken from Hi Media Laboratories, CDH and Rankem etc. The chemicals were of AR grade. Preparation of plant leaf extract, silver ion complex and green synthesis silver nanoparticles The plant leaves of Azadirachta indica and Phyllanthus emblica were washed thrice with tap water and distilled water and kept in the room temperature for air dry. After drying the known amount of leaf samples were chopped into fine and small pieces. The chopped 25 gram of leaves added with 100 ml of distilled water and boiled up to 100°C for 30 minutes. After the desired reaction period the desired samples were filtered through Whattman filter paper to get the leaf extract. Leaf extracts were stored at -20°C for further study. For the preparation of 1mM silver nitrate, 0.0421gm of AgNO3 was added to 100 ml of double distilled water. The solution was mixed thoroughly and stored in colored bottle in order to prevent auto oxidation of silver. For the synthesis of plant mediated silver nanoparticles, the leaf extract and 1mM silver nitrate solution were taken in 1:4 ratio respectively and kept on a water bath at 60°C for 30 minutes until the color change was observed. This indicates the preliminary confirmation for the formation of plant mediated silver nanoparticles. UV visible spectrophotometer is the main technique to examine the silver nanoparticles in the aqueous suspension. Green synthesized silver nanoparticles from Azadirachta indica and Phyllanthus emblica were taken for UV spectra Analysis (320750 nm). Results It is well known that silver nanoparticles exhibit yellowish colour in aqueous solution due to excitation of surface plasmon vibrations in silver nanoparticles. The appearances of yellowish colour in the reaction tubes suggest the formation of silver nanoparticles. Silver nitrate was used as reducing agent as silver has distinctive properties such as good conductivity,