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as inorganic nanoparticles (silica nanocolloids) (Muller et al., 2011; Salonen
et al., 2010b) or clay platelets (Laponite) (Guillot et al., 2009a; Muller et al.,
2010a,b), also stabilize the emulsions, which are then generally called Ramsden-
Pickering or Pickering emulsions (Pickering, 1907; Ramsden, 1903). These are
discussed in more detail in Section 6.3 of this chapter. Comprehensive litera-
ture reviews concerning ISAsomes (Yaghmur and Glatter, 2009) and various
emulsifying systems, including surfactants, proteins, hydrocolloids, and
nanoparticles, along with their underlying principles (Dickinson, 2009) have
recently been published.
Water, the third basic component for ISAsomes, is used in pure form or
loaded with certain additives, which can range from drug molecules and per-
fumes to food and proteins. The amount of water may vary depending on the
application; 80-95% water is used for most applications, although it can be as
low as 30% for concentrated emulsions (Salentinig et al., 2008).
There are several methods for the preparation of stable ISAsomes (Garg
et al., 2007; Salentinig et al., 2008; Spicer et al., 2001), but the two main
approaches are “ top - down ” and “ bottom - up. ” The top - down approach starts
with the formation of the bulk lyotropic phase, which is subsequently dispersed
in the water by using a high-energy source, such as ultrasonication, high-
pressure homogenization, or strong shear forces. In the bottom-up approach,
ISAsome formation is initiated by a precursor at the molecular length scale.
Progressive hydration and nucleation then lead to structured nanoparticles.
The ISAsome precursors can be prepared by at least three different tech-
niques; namely, hydrotrope (Spicer et al., 2001), spray-drying (Spicer et al.,
2002 ), or freeze - drying.
For lower concentrations of dispersed phase (
10-30% ISAsomes in the
total dispersion), ultrasonication is very convenient; however, for concentra-
tions above
∼
30%, the shearing method produces better results. Shearing
can also produce highly concentrated ISAsome dispersions (up to ca. 70% of
dispersed hydrophobic material) (Salentinig et al., 2008). This technique can
be easily scaled up for the continuous production of ISAsome systems. We
have also shown recently that by simply optimizing shear conditions one can
create W/O nanostructured emulsions that, most interestingly, do not require
any type of stabilizer (Kulkarni et al., 2010a). These are discussed further in
the last section of this chapter.
As mentioned earlier, the internal structure of ISAsomes can be tuned to
create various liquid crystalline phases. It is known that the addition of diglyc-
erol monooleate, or F-127, converts Pn3m into Im3m (Guillot et al., 2010;
Yaghmur et al., 2006a), the latter also controls the size of the ISAsomes. The
particle size can be also tuned by varying the concentration of the dispersed
phase and the shear rate of the Couette cell (Salentinig et al., 2008). The lattice
parameters of the nanostructures can also be modulated by varying the lipid
components; for example, GMO and PT are used for many applications similar
to DU-based systems (Dong et al., 2010; Lee et al., 2009; Nguyen et al., 2010).
Structural tuning can also be induced by addition of various component/s
such as oil [tetradecane (TC),
R
(
∼
+
)limonene (LM), etc.], glycerol, or other
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