Biological synthesis of silver nanoparticle based on Eucalyptus obliqua and Mentha spicata plant extracts and evaluation of their physical properties

Nanoparticles are one of the most applicable materials in, science such as biotechnology, and medicine due to their distinguished characters. The previous studies indicated that over the half of total production of nanoparticles is dedicated to the conventional and bio inspired synthesis of silver nanoparticles. These nanoparticles have antimicrobial characteristics and widespread applications in medicine and industry. Conventional chemical methods for synthesis of silver nanoparticles usually use the reducing agents that they are not compatible to environment and sometimes toxic and the resulting nanoparticles cannot be involved in biological applications. So, green synthesis of nanoparticles is the process that based on green chemistry for the synthesis of bio-nanoparticle is very important. In this study, eucalyptus (Eucalyptus obliqua) and mint (Mentha spicatae) extracts of medicinal plants for biological production of silver nanoparticles was used as a reducing agent. By adding the extract to the solution of silver nitrate at different temperatures and incubation times silver nanoparticles were produced. Changing the color from pale yellow to dark brown was showed the production of silver nanoparticles. There is also the strong peak absorption (SPR) at wavelengths between 420 and 460 with using spectroscopy UV/Vis which indicate the production of silver nanoparticles. The size of the nanoparticles was determined by electron microscopy analysis (SEM and TEM). The average sizes of nanoparticles in both plants were between 10 and 20 nm. The produced nanoparticles by the mint plant at the same condition was more stable than eucalyptus that confirmed that mint has more ability to produce silver nanoparticles.