*2.1.1 Physical preparation method*

The physical method uses a "top-down" approach in which the bulk material is pulverized into fine particulate matter by means of force applied, such as crushing, impact, disruption, degradation, cutting, cryo-grinding, grinding, processing and homogenization. Physical methods use the milling process in micro-particle fracturing, and few examples involve ball milling, high-energy ball milling (HEBM), grinding, cryo-grinding, refining and homogenization: high process homogenization (HPH) and medium-pressure homogenization (UHPH). These physical productions are versatile methods that manufacture nanoparticles of larger size, diameter and volume, which are still controlled, generate surface defects, contamination, costly and time-consuming. It may also be possible to produce nanoparticles of the same size, but instrument assembly is very expensive and maintenance is too costly. This imperfection in the form of efficient and expensive maintenance culminated in the space travel of biological sources and methods for the nanoparticle manufacturing process [2]. The synthesis of nanoparticles using biological methods includes the synthesis of nanoparticles using living things or matter. There are several other ways to synthesize nanoparticles, such as chemical and biological methods.
