الفهرس 
Chemical synthesis of NPs
Microorganisms usedOnly 14 pages are availabe for public view
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Abstract
This study aims to use well identified different
microorganisms as economic and healthy for biosynthesis of
AgNPs to solve problem of toxicity of by-product of toxic
chemicals used in chemical method.
Five cultures, two fungal cultures (Fusarium oxysporum f. sp.
lycopersici (EMCC 632) and Trichoderma viride (EMCC 107))
and three bacterial cultures (Pseudomonas aeruginosa (DSM
50090), Lactobacillus rhamnosus (ATCC 7479) and
Lactobacillus helveticus (CCM 7193)), were used. These cultures
exhibited high ability for biosynthesis extracellular enzymes
which were chosen as the pure cultures for NPs synthesis.
1- The first screening program for AgNPs synthesis by
these five cultures as follows:
a) Incubate equal weight 10 g from each used fungal
culture with solution of silver nitrate with concentration
of 1M for 5 days at temperature 28ºC.
b) Incubate each screened bacterial culture with solution of
silver nitrate with concentration of 1M for 72 h at
temperature 28ºC.
2- Study the ability of each culture to biosynthesis AgNPs
and selected the most effective culture for AgNPs synthesis with the smallest size through measuring the
particle size for each result.
3- Observation of AgNPs intracellularly by Confocal Laser
Scanning Microscopy and Transmission Electron
Microscopy.
4- Study the factors affecting on controlling of AgNPs
size synthesized by F. oxysporum:
a) Optimum silver nitrate concentration for F. oxysporum was
found to be 10-2 M for smallest AgNPs synthesis.
b) The smallest size of AgNPs showed under static condition.
c) Optimum incubation temperature was found to be 50º C for
smallest AgNPs synthesis.
d) The optimum wet weight of F. oxysporum was 11 g.
e) The optimal pH value was found to be 6 for smallest
particle size.
f) The smallest size for AgNPs synthesized with using the
fungal age at about 7 days and for 72 h of incubation with
metal substrate.
g) AgNPs showed stability by measuring the particles size
after 12 months.
h) Zeta potential measurement at-34.6 showed that silver
nanosuspension to be stable without any aggregation after
12 months from its synthesis.5- AgNPs synthesized was applied under all optimal
conditions for their controlled biosynthesis.
6- Study the characterization and analysis of AgNPs by
UV-Vis spectrophotometer, TEM, EDAX, XRD and
FTIR.
7- Biological applications of the synthesized AgNPs
resulted from biosynthesis method were found to be as
antibacterial agent against gram negative, gram positive
bacteria and as antitumor against the human
breastcarcinoma cell line MCF-7.
Conclusions
Biological synthesis of NPs is attracting attention as they
do not involve the harsh conditions that are required in the
chemical and physical synthesis methods, the low cost of the
method as well as its simplicity and efficiency offers an
alternative to chemical procedures.
We have shown that many different cultures of fungi and
bacteria have the ability to biosynthesis AgNPs with different
efficiency and with different size. This is an economical,
ecofriendly and simple process of biosynthesis of NPs.Thus our results selected F. oxysporum as the most
effective culture for AgNPs biosynthesis with the smallest size.
F. oxysporum was observed to have the ability to synthesis
the smallest AgNPs at substrate concentration (silver nitrate) of
10-2 M under static condition with incubation temperature at 50ºC,
wet weight of fungus 11 g at a pH 6 and age of fungus at about 7
days for 72 h of incubation time with silver nitrate. The resulted
AgNPs showed stability after 12 months (1 year) of storage at
room temperature that confirmed by zeta potential measurement.
Our present investigation reports the biosynthesis of AgNPs after
optimization conditions with the size in the range of 8-12 nm,
these AgNPs were found to be spherical in shape.
Control over the size of AgNPs seems to be very easy with
the use of microorganisms. Though the mechanism of NP
synthesis by microorganisms is not yet fully understood the
participation of proteins and reducing agents in their synthesis
seems to be the most suitable answer.
Further these biosynthesized AgNPs were found to possess
significant biological applications as antibacterial agent against
gram positive and gram negative bacteria and as antitumor against
the human breastcarcinoma cell line MCF-7.