Comparative study on silver nanoparticles properties produced by green methods

In the present study, properties of silver nanoparticles (AgNPs) such as average size, size distribution and morphology were investigated by Tollens, polysaccharide, modified polysaccharide and microbial methods. The synthesized AgNPs were characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamics light scattering (DLS) and energy dispersive X-ray (EDX) analyses. Analysis of reaction mixtures confirmed that Tollens, polysaccharide and modified polysaccharide methods generated smaller AgNPs with better size distribution as compared to that produced in microbial method. The average size of produced AgNPs by Tollens, polysaccharide and modified polysaccharide were 42, 30 and 20 nm respectively. Moreover, microbial method generated AgNPs with average size of 54 nm in the case of cell-free filtrate mediated synthesis and 84 nm in case of the supernatant mediated synthesis. Analysis of fungus-mediated synthesis of AgNPs showed that the size distribution of AgNPs produced by supernatant is narrower than that produced by filtrate. Also, cell-free filtrate resulted in the formation of smaller AgNPs with average size of 59 nm compared to the supernatant. The comparative analysis of produced AgNPs by the above mentioned methods confirmed that modified polysaccharide method led to the formation of AgNPs with smallest size and highest productivity.