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HO
OH
O
HO
OH
O
OH
O
R =
Gb2
O
N
HO
P
O
OH
RO
O
O
O
O
HO
OH
O
O
HO
O
OH
O
OH
OH
O
O
O
Gb3
HO
HO
OH
OH
Fig. 14 Glycolipids containing galabiosyl (Gb2) and galatriosyl (Gb3) sugar moieties.
monomers. To explain these results, the authors hypothesized that
liposomes may display a more flexible cluster effect of sugar units, thus
giving a conformation more suitable for binding to Stxs. In addition, the
replacement of the amine group of the phosphatidylethanolamine resi-
due with a methylene group led to the loss of toxin neutralizing activity,
due to the lack of liposome formation.
2.6 Other nanosystem-based glycotargeting
Over the last decade, additional glycosylated nanosystems were investi-
gated to deliver drugs to targeted cells using original glycolipid struc-
tures. In a recent report, new glycosyl-nucleoside-lipid (GNL) based
liposomes coated with sugar moieties were developed to facilitate the
internalization of the vesicles into stem cells.
40
The potential clinical
utility of stem cells is increasing remarkably, especially in emerging areas
such as regenerative medicines. The glycolipid structure (Fig. 15) was
constructed by connecting three natural building blocks (double stearic
chain lipid, nucleoside and glucose moieties) using double-click chem-
istry approach. Extruded liposomes including various mole ratios of soya
lecithin and GNL (100/0, 90/10, 80/20 and 0/100) with a diameter ranging
from 50 to 150 nm, were evaluated in terms of ability to promote inter-
actions with the stem cell surface and further internalization. These
studies revealed the importance of both glucosyl and nucleoside moieties
for the cellular uptake. A sugar clustering effect coupled with additional
interactions (p-p stacking, H-bonding) originating from nucleoside resi-
dues was demonstrated to explain the ecient cell
internalization
properties of these novel glycoliposomes.
Another strategy used vesicles constituted of catanionic surfactants
resulting from the association of ionic surfactants of opposite charges. A
triple-chained catanionic surfactant (TriCat) was recently obtained via
a spontaneaous acid-base reaction in water between N-hexadecylamino-
1-deoxylactitol and bis(hydroxydodecyl)phosphinic acid, followed by pH
measurements until stabilization (Fig. 16).
41
A fluorescent double-
chained catanionic amphiphile molecule (FluoCat) was also synthesized
in order to label vesicles. In aqueous medium, TriCat-containing cata-
nionic systems with or without the addition of FluoCat (TriCat and Tri-
Cat/FluoCat 19/1) spontaneously self-assembled into stable vesicles,
characterized by a narrow size distribution that did not exceed 200 nm in
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