**3.1 Preparation of plant leaf extract**

In general, the specific amount of the plant sample is determined in grams for the preparation of the extract in solvents, and the extract filtrate is diluted with sterile distilled water. The diluted filtrate is then used as a reducing agent for silver salts to form silver nanoparticles. The general procedure for the preparation of the extract is as follows: first, the 10 g leaf of Passiflora foetida washed with tap water and dried at room temperature. Second, washed dried leaf specimens chopped into small pieces and macerated directly into 75 ml of autoclaved distilled water. Eventually, the mixture is centrifuged at 4000 rpm for 10 min and filtered with the aid of muslin cloth or syringe filters (stored at 4 °C for future use). **Figure 1** shows the step-wise process of preparation of leaf extract by boiling method for the synthesis of silver nanoparticles [18]. As we are dealing with nanoformulation, it is very important to use the (diluted) plant extract at a minimum to reduce the amount of silver salt.
