الفهرس | Only 14 pages are availabe for public view |
Abstract Although nanoparticles can be made using various physicochemical methods that remains expensive and involves the use of hazardous chemicals. Biological synthesis of nanoparticles appears as a suitable process since it requires less energy, is environmentally safe, emerges as an eco-friendly, scalability, exciting approach, it has low manufacture costs of scalability, and better nanoparticle stabilization, compared to chemically synthesized nanoparticles. This study illustrates simple, green synthesis of AgNPs in vitro using cell lysate supernatant (CLS) of fungal species and to investigate its potential antimicrobial, antiviral activities, and cytotoxic effects against some tumor cell lines. The production ability of silver nanoparticles was investigated by the means of UV-V spectroscopy where changing of the color of the culture filtrate from yellow to brown, indicated the presence of extracellular silver nanoprticles. In addition, electron microscopy (Transmission and scanning electron microscopy) are used for characterization of extracellular silver nanoparticles and Atomic absorption spectroscopy, X-ray microanalysis and Transmission electron microscopy were used for characterization of intracellular silver nanoparticles. The parameters controlling the biosynthesis process of nanosilver including temperature, pH, time of incubation, concentration of substrate and weight of biomass were fully investigated. The results revealed that, The production of extracellular silver nanoparticles by isolated fungi Penicillium citreonigrum, Penicillium citreonigrum, Aspergillus niger and Penicillium aurantiogriseum and Streptomyces albus is reported in this study. The biosynthesized nanoparticles exhibited typical plasmon absorption maximum of silver nanoparticles (420nm). The result of scanning electron microscope (SEM) and transmission electron microscope (TEM) showed that the spherical silver nanoparticles were found to have size between 10 and 50 nm. The fugal isolate Fusarium moniliforme and actinomycetes isolate Streptomyces albus were reported in this study for production of intracellular silver nanoparticles. X-ray pattern revealed the crystalline nature of the silver nanoparticles. Atomic absorption spectrophotometer measured the remaining silver ions in the culture media, which indicated the ability of isolates to uptake the silver ions and biotransform it to nanoparticles. In addition, TEM showed the presence of the silver nanoparticles inside the cells microbial isolates. AgNPs exhibited pronounced cytotoxic activity against HepG2, HCT-116 and MCF-7 cell lines in vitro. By studying the mode of action using inverted microscope and SEM it was found that, AgNPs were very effective on the number and on the cell contact which lead the cells to apoptosis AgNPs exhibited promising cytoprotective efficacy towards Herpes simplex type 2 virus. Also, AgNPs had no toxic effect on the Vero cells (normal cells) compared with silver nitrate. The mode of antiviral action of the silver nanparticles indicated the best time to exert their effect on HSV-2 just after the virus inoculation (at zero time) by high percentages. Silver nanoparticles have broad spectrum antimicrobial activity against Gram positive and negative bacteria and pathogenic fungi.Studying the mode of action of the silver nanoparticles on E. coli and P. notatum revealed that there were a leakage of protein, lipid, glucose and LDH enzyme from bacterial and fungal cells. There were extreme changes in the morphological structure and in the number of growing cells and also, there were damages in the treated cells including cell wall, cell membrane and in cytoplasmic organells of the cells. In conclusions, • The studies showed that the microbial susceptibility to AgNPs is different for each microorganism. • Penicillium citreonigrum and Streptomyces albus have capacity to biosynthesize extracellular silver nanoparticles. • Fusarium moniliforme and Streptomyces albus have capacity to biosynthesize intracellular silver nanoparticles, which are intracellularly accumulated. • This property is present in whole cells and in free cell extracts indicating that this process is probably enzymatically mediated, due to the requirement of NADH as cofactor for this biological transformation. • In addition, AgNPs showed a promising result as antimicrobial against pathogenic bacteria and fungi, antiviral against Herpes simplex type 2 virus and antitumor substance against the tumor cell lines such as HepG2, HCT-116 and MCF-7 in vitro. • Moreover, from these results the biological synthesized silver nanoparticles from fungi and actinomycetes can be used in different biological applications in different fields of science including medicines, pharmaceutical industry, agriculture and electronics. |