Silver Nanoparticles

Five different natural products (plant parts and honey) collected in the month of February-2014 from Riyadh, Saudi Arabia were used for the silver nanoparticles synthesis. Details of the products used for the experiment are given in Table1.

Table1: List of plants/natural products used for biosynthesis of silver nanoparticles

3.2 Preparation of extracts:

Extraction is the crucial first step in the synthesis of nanoparticles, because it is necessary to extract the desired chemical components from the materials for further separation and characterization.

Weighing 100 g of fig was thoroughly washed in distilled water, surface sterilized with 0.1% sodium hypochlorite for 1 min. After that the fruits were dried in hot air oven at 50oC for one

Preparation of silver nitrate solution and reaction mixture:

Aqueous silver nitrate solutions of 5 mM and 10 mM were prepared using silver nitrate powder and triple deionized water in a fixed ratio. The reaction mixture was prepared by taking 10 mL of the prepared filtrates obtained from the plant and 90 mL of silver nitrate solution. However, 20 g honey was dissolved in 80mL deionized water. 15mL of this honey was added to 20mL aqueous solution of AgNO3 (10−3 M) and stirred well for 1min. Reduction was indicated by golden yellow colour of the solution (Philip, 2010).

This reaction mixture was prepared with each molar concentration of silver nitrate solution and incubated at room temperature for up to 5 h. Observations were made after each hour of incubation to observe changes in color ranging from light greenish to dark brownish.

A small amount of the reaction mixture was centrifuged at 18,000 rpm for 25 min, the supernatant was collected. The collected supernatant was heated at 50–90°C and the change in color for 15 min, indicating the formation of bio-nanoparticles in the reaction mixture, was

High energy electron beam falls upon ultrathin samples allow for image resolutions that are of the order of 1-2 Å. The morphology and size of AgNPs were characterized by TEM (Philips CM-10). A thin film of the sample was prepared onto a carbon coated copper grid. A beam of electrons is transmitted through an ultrathin specimen. These electrons interact with the specimen and form an image. The image is magnified and focused onto an imaging device, such as a fluorescent screen, on a layer of photographic film.

TEM analysis performed for further characterization of the AgNPs sample (shape and size). Samples for TEM studies were prepared by placing a drop of the silver nanoparticles colloidal suspension on carbon-coated grids. TEM images were obtained by using a transmission electron microscope, JEOL JEM-1011(Figure 6). The particle size distribution of silver nanoparticles was evaluated using Image