PHYS01200704032 Debes Ray - Homi Bhabha National Institute

Chapter 8: Summary
self-assembly for P85 and P105 leads to a sphere-to-rod micellar shape transition at higher
temperatures and its effect on the gold nanoparticle synthesis has been examined. It is found
that irrespective of the shape of block copolymer micelles the synthesis carried out at
different temperature gives rise to the spherical nanoparticles in all the cases. However,
increasing temperature increases the reaction kinetics drastically, resulting in much faster
synthesis of nanoparticles.
We have developed two methods of high-yield synthesis of gold nanoparticles, where
the yield can be enhanced by manyfold, and are discussed in Chapter 6 [207-209]. In the first
method based on step addition, the gold salt is added in small steps for the continuous
formation of nanoparticles. This method works as the minimum ratio of block copolymer-togold
salt can be maintained by the choice of the step size and the resultant yield by the
number of steps. The time between two steps is decided by the time required to complete the
synthesis in each step. The application of this method is limited by the longer synthesis time
which increases as the number of steps increased to increase the yield. In the second method
(additional reductant method), the presence of additional reductant (e.g. trisodium citrate) is
utilized to enhance the reduction and hence yield. The nanoparticle yield has been found to
increase drastically with gold salt concentration in presence of additional reductant and has
been synthesized up to two order higher gold salt concentrations than earlier works. This
method can be viewed as the additive effect of the enhanced reduction by trisodium citrate
with control and stabilization by the block copolymers.
Chapter 7 discusses the optimization of high-yield synthesis of gold nanoparticle for
probing their interaction with proteins [220,221]. The stable and high-yield gold
nanoparticles using additional reductant method have been synthesized at very low block
copolymer concentration to minimize any direct interaction of proteins with the block
copolymer. The stability, yield and structure of nanoparticle have been found same
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