1. are considered interesting in nanofactories [12]. The

1. Bio-synthetic nanoparticles
The application of nanoscale materials structures in the range of 1 to
100nm is a new up and
coming
area of nanoscience and nanotechnology. Nanomaterials provide different
solutions to
technological
and environmental challenges in the field of solar energy conversion,
catalysis,
biology,
biomedical science, and water treatment. Nanoparticles have a very high surface
to
volume
ratios. So, due to this property nanoparticles can be utilized in various
scientific fields,
where
large surface area is required. For example, in mostly catalytic industry
nanoparticles have
been
confirmed excellent catalysts 1. There are quite a lot of physical and
biochemical methods
for
nanoparticles synthesis but there is a lot of requirement to introduce
bio-synthetic processes
for
nanoparticles production due to their abnormal optical 2, chemical 3,
photoelectrochemical
4
and electronic 5 properties .The synthesis and congregation of nanoparticles
would be
beneficial
for the development of fresh, nontoxic and eco-friend environmentally
acceptable
“green
chemistry” most likely involving organisms like bacteria, fungi and even plants 6,
7 .
Both
unicellular and multicellular organs are considered as well-known to
manufacture inorganic
materials
either intra- or extracellular purposes. The Verticillium sp. fungal biomass
when
exposed
to aqueous AgNO3 solution resulted in the intracellular formation of silver
nanoparticles,
while
Fusarium oxysporum biomass resulted in the extracellular silver nanoparticles 8.
The
study of bio-synthetic methods for nanomaterials offers some important
contribution to
materials
chemistry. Microorganisms have gained more attention in biosynthesis of
nanoparticles.
Earlier
investigations expose that the microbes have the ability to reduce Au3+ ions to
generate
octahedral
gold particles of nanoscale size (i.e., 5–25 nm) and is incubated with gold
chloride in
the
bacterial cell body under ambient temperature and pressure conditions 9, 11.
Micro-organisms
like
yeast, bacteria and even fungi plays important role in remedy of toxic metals
by reduction of
metals.
Thus bio-synthetic processes are considered interesting in nanofactories 12.
The
following
figure shows different techniques and sources for nanocompounds synthesis.
2
Fig. 1 synthesis of nanoparticles from different methods
1.1
Use of micro-organism for nanoparticles synthesis
There is a constant touch between biological entities and inorganic
materials since from the
beginning
of life on earth. Due to this usual relation, life could only sustain on earth
with an
efficient
deposition of minerals. Now scientists turn into more and more concerned with
the
interaction
between inorganic nanoparticles and biological species. Recently studies have
revealed
that many microorganisms can be used for the production of inorganic
nanoparticles
either
by intracellular or by extracellular routes. Here, is summarizing some of the
organisms that
are
used in the biosynthesis of nanomaterials and describing some of their
properties that should
be innate
for the synthesis of nanoparticles of preferred characteristics.
1.2
Bacterial use for nanoparticles synthesis
Pseudo. Stutzeri AG259 extracted from silver supplies has been used for
production of Ag Nps.
13,
14 MTB (polyphyletic groups of bacteria) can be used to synthesize magnetic
nanoparticles 15.
Magnetotactic
bacteria such as “Gram- negative Magnetospiril. Magneticum” used
to
manufacture
two types of particles; some generate magnetic iron (II III) oxide
nanoparticles in
chains
structure and some construct iron (II III) sulphide nanoparticles, while some
other
bacterial
cell used to produce both categories of Nps. In the same way sulphate-reducing
bacteria
DS
desulfuricans NCIMB 8307, exogenous electron donor, has been found to
synthesize
palladium
nanoparticles 16, 17. L. bacillus strains present in buttermilk helps in the
growth of
3
well-defined morphological nanoparticles of Au, Ag, and Au-Ag alloy.
Recently, bacterial cell
such
as Pseudo. Aeruginosa was used for biosynthesis of gold nanoparticles via
extracellular
route
which can reduce gold ions 18.The formation silver nanoparticles via
intracellular and
extracellular
route from bacteria (Esch. coli, Pseudo. stut. AG259, S. typhus V cholerae,
Phoma
specie
3.2883, Pseudo. Aerug., and Staphylo. aureus) have been demonstrated by
reaction of
cells
with silver (I) nitrate (AgNO3) 19, 22. The suggested mechanisms for the bio
reduction of
silver
by bacteria involve (DNA) or sulfur-containing proteins 19. Another
achievement in better
control
on size and polydispersity of nanoparticles is by cell filtrate. Further, it
has been
explained
that by using cell filtrate for extracellular synthesis of nanoparticles would
be more
beneficial
rather than intracellular synthesis.
Another
method to control over the shape of gold nanoparticles synthesis has been
developed by
utilizing
Plect. Bory. UTEX 485, a filamentous cyanobacterium. When they reacted with
aqueous
soln. of Au (S2O3)23- and AuCl4- at temperature range from 25–100o C for up to
one
month
and for a single day at 200o C resulted in the formation of cubic gold
nanoparticles and
octahedral
gold platelets precipitates, respectively 23. The mechanisms of gold
bioassemilation
of
cyanobacteria (Plectonema boryanum UTEX 485) with gold (III) chloride solutions
form
octahedral
platelets. This mechanism involves two steps, in the first cyano-bacteria
interact with
aqueous
gold(III)-chloride to form precipitates of nanoparticles of amorphous
gold(I)-sulfide at
the
cell walls, and finally in the other step deposited metallic gold octahedral
(III) platelets close
to
cell surfaces and in solutions24. Elemental gold can be produce by
gold(I)-tiosulfate by
enrichment
of sulfate-reducing bacteria and this mechanism may have three steps including
iron
sulfide,
metabolism and contained reducing conditions 25.
1.3
Actinomycetes roll in nanoparticles formation
It has been examined that when microbes i. e extremophilic actinomycete,
Thermomo. Specie
reacted
with gold ions, metal ions are reduced extracellularly, giving gold
nanoparticles of
greatly
better polydispersity 26. However, in searching a mechanism or favourable
conditions
for
the synthesis of nanoparticles with desired characteristics, 27 a reaction
was carried out for
the
reduction of AuCl4 ions through extremophilic Thermomonospora specie biomass
that has
been
proved efficient method for the formation of monodisperse gold nanoparticles.
It might be
believed
that metal ion reduction and nanoparticles stability was due to enzymatic 

x

Hi!
I'm Isaac!

Would you like to get a custom essay? How about receiving a customized one?

Check it out