Comparative Evaluation of Chemical Reduction Methods by Ethanol and Bacillus licheniformis on The Physical Properties, Stability and Coating of Nanoparticles

ABSTRACT          Background and Objectives: Size of silver nanoparticles synthesized by ethanol and Bacillus lichenioformisis 20 nm and 15 nm, respectively. Nanoparticles can be used in treatment of several diseases. Chemical and biological methods have been used to synthesize silver nanoparticles. The aim of this study was to compare the size, shape and coating of silver nanoparticles synthesized by the chemical and biological methods.         Methods: Ethanol was used in the chemical reduction method and B. licheniformis was used in the biological method. Physical evaluation (salt test), absorbance measurement at 450 nm and imaging by transmission electron microscopy were performed to compare nanoparticles in terms of size, shape and coating.          Results: Observed maroon color, maximum absorption at 400-450 nm range and electron microscopy images confirmed the presence of nanoparticles. The shape of nanoparticles synthesized by the two methods was spherical. However, biosynthesized nanoparticles were smaller and had protein coating.           Conclusion: Given the smaller size of biosynthesized nanoparticles and presence of coating confirmed by the electron microscopy images, biosynthesis is recommended because of enhanced nanoparticles properties and reduced toxicity.             Keywords: Nanoparticles, Coating, Toxicity.