Stimuli-Responsive Lipid -Based Self-Assembled Systems - Self-Assembled Supramolecular Architectures: Lyotropic Liquid Crystals - page 271

80 [nanorods] = 3 nM

L 2
H 2
Q 2 + H 2

70

60

1.5 nM

50

Q 2

40

0.3 nM

30

0nM

20

Laser On

Laser On Off Off

10

0 5 10 15 20 25 30

Time (s)

Figure 9.8 Incorporation of gold nanorods at increasing concentration into phytantriol-
based cubic phase facilitates reversible optical control over the apparent temperature
of the matrix ( T app ), and hence over phase transitions. Transitions from bicontinuous
cubic to inverse hexagonal to inverse micellar phase were in agreement with equilib-
rium heating studies. The phase structures formed on irradiation are illustrated sche-
matically on the right. [Adapted from Fong et al. (2010).]

between non-lamellar liquid crystalline phases on irradiation, with the matrix
returning to its original state when irradiation ceases (Fig. 9.8) (Fong et al.,
2010), opening up the potential for reversible, multidose drug delivery systems
from such materials.

9.3.2.3 Electromagnetic Field-Responsive Systems Electromagnetic
fi elds (EMF) can be used in drug delivery for two purposes: to focus delivery
to a target (Arruebo et al., 2007; Blasi et al., 2007; Jain et al., 2008), for example,
tumor site, where the system can cause cell death through intracellular hyper-
thermia (Yanase et al., 1997) or release drug or imaging dyes (Kumar et al.,
2009a). Carrier particles are magnetically sensitive by virtue of being magnetic
nanoparticles encapsulated within the membrane or in the aqueous interior
of polymers or liposomes, which are known as magnetoliposomes. After local
or systemic dosing of magnetoliposomes, the tumor-affected area can either
be placed between two poles of a magnet (Nobuto et al., 2004; Viroonchatapan
et al., 1996; Zhu et al., 2009) or the magnet is imbedded in the tumor (Kubo
et al., 2000), where the application of an EMF for some time results in the
increased accumulation of drug concentration in the tumor where the drug is
released from the liposome by diffusion or by heating of the bilayer by the
EMF. The use of low-frequency magnetic fi elds to disrupt the liposome loaded
with magnetic nanoparticles in the aqueous chamber has also been investi-
gated (Nappini et al., 2010) where magnetic nanoparticle motion causes dis-
ruptions in the bilayer and consequently drug release is achieved. EMF-sensitive