Chemistry Reference
In-Depth Information
et al., 2009b). The NR data agrees well with the AFM result that a slight height
deformation occurs upon adsorption (Neto et al., 1999 ).
10.4.2
Model Biological Interface—Implications for Drug Delivery
The LCNP has a promising future for biological applications, in particular as
an agent for intravenous, topical, oral, and nasal delivery. Here we should not
only consider the uptake of LCNP through the skin, mucosa or the cell mem-
brane or strive to limit the hemolytic activity of the LCNP as drug delivery
vehicles. An often very important factor for the development of drug delivery
vehicles is their stability. This means that the vehicles should be in a stable
dispersion, and the loss of material in terms of adsorption to vials, catheters,
tubes, and other delivery devices should be minimal. Unwanted consequences
can occur if the LCNP is disintegrated by contact with an interface, for instance,
what happens with the GMO-based CPNP with the hydrophobic surface as
discussed above. There are also instances where a maximum possible adsorp-
tion is desirable, such as when the LCNP is used as surface coatings for enhanc-
ing drug delivery. So it is indeed important to control the LCNP interaction
with the surface to achieve selective deposition only on surfaces with certain
properties. To date, only a few studies have tried to elucidate the interfacial
interaction between LCNP with the type of surfaces they will encounter. Here
we will discuss the interaction between LCNP and three model biological
interfaces: cell membrane (Vandoolaeghe et al., 2008, 2009c), mucous mem-
brane (Svensson et al., 2008a,b), and leaf surface (Dong et al., 2011).
10.4.2.1 Cell Membrane
Lipid bilayers are the main building block for
the cell membrane for which the models have become more and more
complex. We recommend the excellent review on the development of the
models by Tien and Ottova (2001). Supported phospholipid bilayers have
been used as the simplest models for cell membranes and can be prepared in
several different ways (Hughes et al., 2008; Richter et al., 2006; Sackmann,
1996; Tiberg et al., 2000; Wacklin, 2010). Spreading of vesicles on surfaces is
one method to form a bilayer on a hydrophilic surface and rests on the fact
that the phospholipids form a fl at bilayer rather than a curved one on the
vesicle. It can be regarded as a deposition of spherical vesicle on a surface,
which depending on the surface properties and vesicle stability, leads to burst-
ing and spreading of the vesicles (Reimhult et al., 2002, 2003). Another inter-
esting technique used to form lipid bilayers on surfaces is to solubilize the
lipid with a nonionic surfactant, for example, DOPC with
n
- dodecyl -
- D -
maltopyranoside (DDM) (Tiberg et al., 2000). The lipid bilayer is prepared
by co-adsorbing lipid with a surfactant that could be easily rinsed off the
surface after adsorption. A series of subsequent additions of mixed lipid-
surfactant solutions of decreasing total concentration, followed by an aqueous
rinse after each step, removes the excess of the soluble surfactant. In each
dilution step, the system gradually approaches the two-phase region of the
β
Search WWH ::
Custom Search