**3. Biosynthesis of silver (Ag) nanoparticles**

Plants have the ability to store heavy metals in their various parts. As a result, biosynthesis techniques employing plant extracts have produced a simple means to stabilize efficient growth, simple, cost-effective synthesis process, along with traditional preparation methods for the production of NPs [21]. Silver NPs have been synthesized and studied extensively due to their unique chemical, physical and



#### **Table 1.**

*Different type of metallic NPs biosynthesized from plants extracts.*

biological properties [22]. Plants have biomolecules such as proteins, carbohydrates and coenzymes with the ability to reduce metal salts. Other biosynthesis processes of Ag NPs from herbal extracts perform extract-assisted biological synthesis and have yielded many advantages over chemical and physical methods of synthesis of NPs. It is also a fact that these routes are simple, cost-effective, eco-friendly for high production [23]. Synthesis of Ag NPs from *Arbutus unedo* leaf extracts and its organic compounds are responsible for the stabilization and reduction of ions. Various green-synthesized Ag NPs for natural capping agents can be used for drug delivery in pharmaceutical drugs. In most studies, the synthesis of Ag NPs by plant extracts is a simple method (**Table 1**) [54].
