Agriculture Reference
In-Depth Information
10.2.2 Synthesis of Nanoparticles
Nanoparticles can be synthesized by three processes, i.e., by physical, chemical, or
biological route. Chemical route employs toxic chemicals and is energy intensive,
thereby precluding biomedical applications. In physical method, narrow size dis-
tribution of the particles or monodispersity is often difficult to attain, whereas
biological method (intracellular and extracellular) is more cost-effective and
green method. For the application point of view, there is a need to develop green
synthesis procedure for synthesis of metal nanoparticles. Biological synthesis of
metal nanoparticles employs a greener approach effectively than physical and
chemical methods. Biosynthesis includes challenging of the fungal filtrate with
the respective salt; the biomolecules present in the fungal filtrate act as reducing
agents, whereas chemical synthesis is achieved by using chemicals like sodium
borohydride or trisodium citrate as a reducing agent (Lee et al.
2010
). The biolog-
ical route of metal nanoparticle synthesis has been demonstrated by exploiting
bacteria such as
Rhodococcus
sp. (Ahmad et al.
2003a
),
Thermomonospora
sp. (Ahmad et al.
2003b
),
Shewanella algae
(Ogi et al.
2010
),
Lactobacillus
strains (Prasad et al.
2007
), and
Pseudomonas aeruginosa
(Deshmukh et al.
2012
),
while yeast species have included
Candida glabrata
(Dameron et al.
1989
),
Schizosaccharomyces pombe
(Kowshik et al.
2003
), filamentous fungi like
Asper-
gillus niger
(Gade et al.
2008
),
Fusarium culmorum
(Bawaskar et al.
2010
), and
Fusarium
sp. (Gaikwad et al.
2013a
). Gade et al. (
2014
) recently have given green
synthesis approach of silver nanoparticle synthesis by using fungi.
Fungi are more advantageous for the synthesis of nanoparticles compared with
other organisms, particularly as they are relatively easy to isolate, grow, culture,
and maintain in the lab, easy downstream processing of synthesized nanoparticles
(Ingle et al.
2008
), and they secrete large amounts of extracellular enzymes
(Mandle et al.
2006
). Moreover, nanoparticles with high monodispersity and
dimensions can be obtained from microbial (Shahverdi et al.
2007
) and fungal
proteins (Mohanpuria et al.
2007
; Birla et al.
2013
; Gaikwad et al.
2013b
; Gade
et al.
2013
) as it has a capacity of hydrolyzing metal ions quickly and through
nonhazardous processes. There are many reports of mycosynthesis (synthesis by
fungi) of metal nanoparticles (Birla et al.
2009
; Gajbhiye et al.
2009
; Bawaskar
et al.
2010
; Gade et al.
2010a
,
b
,
2011
; Raheman et al.
2011
; Kumar et al.
2012
; Dar
et al.
2013
; Gade et al.
2014
). Many plants like
Carica papaya
(Mude et al.
2009
),
Opuntia ficus
-
indica
(Gade et al.
2010a
,
b
),
Murraya koenigii
(Bonde et al.
2012
),
Hydrilla verticillata
(Sable et al.
2012
),
Tagetes erecta
(Dhuldhaj et al.
2012
),
Lawsonia inermis
(Gupta et al.
2013
), and
Paederia foetida
(Madhavaraj
et al.
2013
), hop biomass in native and chemically modified form (Lopeza
et al.
2005
), and remnant water collected from soaked Bengal gram bean (Ghule
et al.
2006
) have been used for the synthesis of nanoparticles. However, alfalfa
(Gardea-Torresdey et al.
2002
,
2003
),
Chilopsis linearis
(Rodriguez et al.
2007
),
and
Sesbania
seedlings (Sambrook and Russell
2001
) have the potential of synthe-
sis of gold nanoparticles inside living plant parts.
