Metallic Nanoparticles for Biomedical Applications
49
Fig. 10 Schematic illustration of shape control of Au NPs synthesized using seed-mediated growth
method; a kinetically-controlled particles can be obtained by varying halides in the absence of
silver ions, b surface-controlled synthesis of particles using silver ions by changing halides and
c increasing order of destabilization of Ag UPD layer with halides. Reprinted with permission from
[62]. Copyright (2012) American Chemical Society
growth, particle size distribution is random or polydispersed. Another finding is that
the average size of particles synthesized with trisodium citrate is higher compared
to NaBH 4 reduced particles. Also, the mean diameter of particles synthesized using
trisodium citrate decreases as its concentration increases. Maximum absorbance is
observed with a minimum amount of trisodium citrate, while with NaBH 4 , maximum
absorbance is observed for higher concentration. It is because maximum absorbance
depends on the polydispersity of particles [69].
In the case of seed-mediated synthesis of MNPs, size of the seed, seed age and its
concentration (or ratio) play an important role in shaping the morphology as well as
the size of the NPs [31, 63–66, 75, 76]. Consider the synthesis of anisotropic Ag NPs
by a chemical method using CTAB stabilized seed. It has been found experimentally
that only by varying the seed ageing, the morphology of Ag NPs can be changed, as
illustrated in Fig. 12. The UV-Vis absorption spectrum analysis reveals that as the seed
age increases, it possess multiple plasmonic peaks. With 0 min seed age, the synthesized particles have a single peak at ~400 nm. As seed age increase, another peak
starts to appear after this. With 5 min, the second peak is not much visible, indicates
NPs with excess spherical and few anisotropic structures. At 15 min, the second peak
is becoming sharper with a reduction in the first peak absorbance intensity. For 20 and
30 min of seed age, the second peak starts to dominate over the first peak and starts to
appear the third peak before 400 nm. The appearance of the third peak indicates the
49
Fig. 10 Schematic illustration of shape control of Au NPs synthesized using seed-mediated growth
method; a kinetically-controlled particles can be obtained by varying halides in the absence of
silver ions, b surface-controlled synthesis of particles using silver ions by changing halides and
c increasing order of destabilization of Ag UPD layer with halides. Reprinted with permission from
[62]. Copyright (2012) American Chemical Society
growth, particle size distribution is random or polydispersed. Another finding is that
the average size of particles synthesized with trisodium citrate is higher compared
to NaBH 4 reduced particles. Also, the mean diameter of particles synthesized using
trisodium citrate decreases as its concentration increases. Maximum absorbance is
observed with a minimum amount of trisodium citrate, while with NaBH 4 , maximum
absorbance is observed for higher concentration. It is because maximum absorbance
depends on the polydispersity of particles [69].
In the case of seed-mediated synthesis of MNPs, size of the seed, seed age and its
concentration (or ratio) play an important role in shaping the morphology as well as
the size of the NPs [31, 63–66, 75, 76]. Consider the synthesis of anisotropic Ag NPs
by a chemical method using CTAB stabilized seed. It has been found experimentally
that only by varying the seed ageing, the morphology of Ag NPs can be changed, as
illustrated in Fig. 12. The UV-Vis absorption spectrum analysis reveals that as the seed
age increases, it possess multiple plasmonic peaks. With 0 min seed age, the synthesized particles have a single peak at ~400 nm. As seed age increase, another peak
starts to appear after this. With 5 min, the second peak is not much visible, indicates
NPs with excess spherical and few anisotropic structures. At 15 min, the second peak
is becoming sharper with a reduction in the first peak absorbance intensity. For 20 and
30 min of seed age, the second peak starts to dominate over the first peak and starts to
appear the third peak before 400 nm. The appearance of the third peak indicates the