Biomedical Engineering Reference
In-Depth Information
shown by Xie
et al.
[174]. h is process was similar to naturally occurring
biomineralization [175], where organisms sequester and interact strongly
with inorganic ions, providing scaf olds for the minerals formed, mostly
through functional proteins. Rangnekar
et al.
[176] found that the enzymes
which have free and exposed thiol groups were able to catalyze the synthe-
sis of gold nanoparticles, and the enzymes which do not have free exposed
thiol groups were unable to catalyze the formation of gold nanoparticles.
Several other enzymes have also been used successfully for the synthesis of
gold nanoparticles like β-glucosidase [177], trypsin [178], pepsin [179] and
serrapeptase [180]. Das
et al.
[181] used lysozyme enzyme for the synthe-
sis of nanoparticles of silver, gold and their alloy. h ey also reported that
amino acids like phenylalanine, tyrosine, tryptophan, and histidine are the
key players during synthesis as well as stabilization [181]. Silver nanoparticle
synthesis has also been reported using pure enzymes like lysozyme [182]
and a i brinolytic enzyme produced by
Bacillus cereus
NK1 [183]. Recently
we have synthesized silver nanoparticles using pure enzyme alpha amylase
(isolated from
Aspergillus oryzae
) [184]. h e nanosilver particles were char-
acterized by UV-Visible spectroscopy, Dif erential Light Scattering (DLS)
and Transmission electron microscopy (TEM). UV-Visible studies show the
absorption band at 422 nm due to surface plasmon resonance. h e TEM
studies show the monodisperse nanoparticles, 22-44 nm in diameter, with
triangular and hexagonal shape. Govendar
et al.
[185] described the synthesis
of platinum nanoparticles by hydrogenase enzyme. h us, enzymes can pos-
sibly serve as a set of structurally diverse biological tools assembling unique
nanostructures. An additional attraction is that enzymes are commercially
available in pure form and they have diverse chemical, biochemical and
biological functions. h e reaction and products in these studies are impor-
tant not only because they provide a simple “green chemistry” approach to
the production of high-quality metal nanoparticles (good control of shape
and size) for a wide variety of applications, but also because they show that
interactions between proteins and metal ions and/or metal surfaces can be
used advantageously for metal nanoparticles' synthesis. h ese studies also
motivate the development of fully biosynthetic approaches, where rationally
designed multifunctional peptides can be used for the synthesis of metal
nanoparticles.
8.3 Applications
Metal nanoparticles synthesized by various methods have been used in
diverse applications [186]. Figure 8.2 shows applications of nanoparticles
