Chemistry Reference
In-Depth Information
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Figure 10.8
Wet mass ( Δ
m
, fi lled circles) and dissipation difference (Δ
D
, line) mea-
sured as a function of time using QCM-D after addition of 0.05 mg/ml GMO-based
LCNP to a model cell membrane of DOPC bilayer at pH 4. The wet mass is calculated
from the Voigt viscoelastic model and the dissipation corresponds to the third harmonic
of the resonance frequency. [Reprinted with permission from Vandoolaeghe et al.
(2008). Copyright 2008 by the Royal Society of Chemistry.]
lipid-surfactant aqueous system, and thereby causes the sequentially increased
deposition of the phospholipids.
Supported lipid membrane models have been used to model the interaction
between LCNP and the cell membrane. Three surface-sensitive techniques,
ellipsometry, QCM-D, and NR, provide insight into the interaction mechanism,
revealing a kinetically controlled process (Vandoolaeghe et al., 2008, 2009c).
The ellipsometry measurements reveal a rapid increase in the adsorbed
amount after the introduction of CPNP to a supported DOPC bilayer on silica,
indicating a strong attraction between the particle and the bilayer. The adsorbed
amount decreases after about an hour, signifying a net release of materials
from the surface. The QCM-D measurement (Fig. 10.8) shows that after the
addition of CPNP, the surface becomes viscoelastic with a large change in dis-
sipation. The wet mass measured through viscoelastic modeling of the surface
layer indicates an initial adsorption of intact nanoparticles followed by relax-
ation and release. Subsequent NR measurement was used to monitor the
composition of the deuterated phospholipid bilayers versus time after LCNP
addition. The study shows signifi cant lipid exchange between the nanoparticles
comprised of hydrogenated GMO and the deuterated DOPC bilayer (Van-
doolaeghe et al., 2008). The exchange takes place regardless of the initial
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