Table 1. Synthesis of AgNPs Using Different Methods: Advantages and Disadvantages.

synthesis methods	synthesis principle	advantages	disadvantages
physical method	Physical method for the AgNPs synthesized by using physical energy to harvest AgNPs with a narrow size distribution.8	Radiation is used as a reducing agent, so no dangerous chemicals involved produce a large number of silver nanoparticles in a single process within a short time. The silver nanoparticles produced are contamination-free and do not need further purification.	Expensive, less yield along with high consumption of energy, contamination of solvent, and random distribution.
chemical method	Silver ions reduce to the silver atoms by using chemical reducing agents.	Simple production, economics, and high yield.	Less use of capping agents for AgNP synthesis is toxic and hazardous; the manufactured particles require further purification as their surfaces are contaminated with chemical sediments; lack of regular sizes; require more steps to stop self-aggregation; and the release of hazardous byproducts during synthesis.
photochemical method	By using photochemically generated intermediates, production of metal course and reduction of metal ions.	A clean process with good spatial resolution and convenience.	High costs and experimental environment are required.30
biological method	The reduction of silver ions to silver atoms by using biomolecules is derived from living organisms.	Cost-effective and abundance of raw materials.31