Silver and its compounds have been used for antibacterial and healing of disease and applications for thousands of years. Ancient Greek and Romans used silverware to store water, food, and wine to avoid wastage. Hippocrates (father of medicine) used silver preparations to treat ulcers and promote injury feeling. Silver nitrate was also used for injury care and instrument disinfection. At the beginning of the 19th century silver preparations were developed for injury infection and burn care. But in the 1940s the medical applications of silver gave way to the clinical introduction of antibiotics. With the development of antibiotics and their extra use, bacteria resistance has become a serious problem since the 1980s and silver start receiving attention again in the development of nanotechnology in the early of this century [1]. Lots of studies focus on the synthesis of silver nanoparticles with controlled size and shape. After that variety of synthetic methods have been developed including physical, chemical, and biological methods. A physical method is classified into two parts mechanical and vaporization process. Physical methods involved mill, pyrolysis, and arc discharge. By physical synthesis, it is possible to obtain silver nanoparticles of uniform size and high purity. Chemical synthesis is the most used method to obtain silver nanoparticles. In chemical synthesis, silver ions are reduced to silver atoms, and the process can be divided into two steps: nucleation and growth. Colloidal silver nanoparticles whose size and shape are controlled by the growth rate of nucleation. Reducing agents, capping agents, and stabilizers are also important for obtaining silver nanoparticles with good dispersion stability and uniform size distribution [2].
Silver nanoparticles have many unique physical and chemical properties. Hence, they are used in a variety of fields such as food, medicine, consumers, and industry. Due to its excellent properties, it is required for many applications such as antibacterial agents, consumer products, industrial and healthcare products, optical sensors, medical device coatings, cosmetics, and so on. In the pharmaceutical industry, in diagnosis, a drug is dispensed as an anticancer drug to kill tumours of anticancer drugs. Recently, Ag nanoparticles have been used in many textiles, keyboards, clothes injuries, and biomedical devices. The metal properties of Nano size are unique and this surface can change the physicochemical and biological properties due to the volume ratio. To this end, the Nanoparticles were established for different purposes. It is interesting to show biologically prepared Ag nanoparticles with a high manufacturing rate and high stability. For the synthesis of silver nanoparticles, some synthetic methods are used, but biological methods can produce different sizes and translational research forms under optimization conditions; simple and fast, non-transparent is a green approach. Finally, a green chemical approach to the synthesis of silver nanoparticles is promising. After synthesis, the physicochemical properties of the particles can affect their biological properties, so certain particle characterization is required. Efforts in this direction such as to characterize nanoparticles produced prior to application, to demonstrate safety issues, and to maximize the potential of nanomaterials for purposes such as human health, Nanomedicine, or the medical industry are needed. Properties of Nanomaterials such as size, shape, size distribution, surface area, solubility, etc. should be evaluated prior to toxicity or biocompatibility. Many analytical techniques have been used for studying the synthesized nanoparticles, including UV vis-spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), scanning electron microscope (SEM), Transmission Electron Microscope (TEM), Atomic Force Microscope (AFM), etc. Focusing on the synthesis of silver nanoparticles whose size and shape are controlled many routes are explored and designed. Various synthetic methods have been developed, including physicochemical and biological methods. The physical process can be divided into two parts: the mechanical process and the evaporation process. The physical methods are milling, paralysis, and ark discharge [3, 4]. Physical synthesis can provide uniform size and high-purity silver nanoparticles [5–9]. Chemical synthesis is currently the most used method to obtain silver nanoparticles due to its facile route. In chemical synthesis, silver ions are reduced to silver atoms, and the process can be divided into two steps: nucleation and growth. The growth rate of nucleation can yield silver nanoparticles whose size and shapes are controlled [10–12]. Reducing agents, capping agents, and stabilizers are also important for obtaining silver nanoparticles with good dispersion stability and uniform size distribution [13–16]. However, physical and chemical methods are relatively expensive, time-consuming, and hazardous. To overcome the shortcomings of these methods, biological or green synthesis uses macromolecular substances in bacteria, fungi, and algae, such as enzymes, cellulose, polysaccharides, or organic components such as enzymes, alcohol, phenolic compounds, flavonoids etc. in plants to reduce silver nanoparticles using reduction. Green synthesis is a facile, economical, environmentally friendly, and reliable route of obtaining silver nanoparticles [17–22].