Biosynthesis of silver nanoparticles using Rhizophora mucronata plant aqueous extract and investigation of its antibacterial activity

The development of ecofriendly and non-toxic processes for synthesis of nanoparticles is one of the most important aspects of nanotechnology. Silver nanoparticles are widely used in medicine because of their antimicrobial and antibacterial properties. Biosynthesis of silver nanoparticles (AgNPs) using the aqueous extract of leaf, stem and root of Rhizophora mucronata as the mangrove plant of southern coasts of Iran and its antibacterial activity was investigated. Leaf extract showed the maximum synthesis of AgNPs. UV-visible spectroscopy in 420 nm confirmed the synthesis of AgNPs. The crystalline nature of AgNPs was confirmed based on the XRD pattern. TEM images showed that the shape and size of nanoparticles was circle and in the range of 0 to 80 nm with the mean size of 32.44 nm. FE-SEM analysis showed nanoparticles with a size range from 10 to 19 nm. EDS spectrum confirmed the presence of silver in the nanoparticles with the maximum percentage of 73.5 %. FTIR indicated the presence of different functional groups like alcohol, aromatic loops, alkanes, phenol group and alkyl halides in the synthesis process. Gram-positive Bacillus cereus bacteria with the largest growth inhibition zone and gram-negative pseudomonas aeruginosa bacteria with the smallest growth inhibition zone were found the most sensitive and the most resistant bacteria, respectively. Results indicate that Rhizophora mucronata leaf extract is capable of synthesizing silver nanoparticles in the solution of nitrate silver at room temperature with antibacterial activity.