Fig. 3 Schematic structure of liposome containing DPPC, cholesterol and
sulfated CD amphiphiles.
Fig. 2 Electron micrographs of vesicles after negative staining with uranyl
acetate. Vesicles composed of DPPC, cholesterol and amphiphilic CD 5b.
(A) 100+10+0, (B) 100+10+1, (C) 100+10+5 and (D) 0+0+100 by molar
ratio.
the air–water interface and interesting erythrocyte-like lipo-
somes (Fig. 3). We are currently investigating the feasibility of
these compounds as drug delivery systems and looking at their
biological activity; the results will be reported as soon as
possible.
This work was supported by a grant from the New Energy and
Industrial Technology Development Organization (NEDO).
the neutral CD amphiphiles 4a–c, suggesting that much
improved self-assembly of these sulfated CD amphiphiles at the
air–water interface results from the introduction of 6-O-sulfate
groups into the precursors 4a–c.
A mixture of compound 5b with dipalmitoyl phosphati-
dylcholine (DPPC, Wako Pure Chemicals) and cholesterol
dissolved in dichloromethane was dispersed in water by using a
sonication bath at 50 °C for 20 min. The emulsion was
concentrated to a half volume solution by spraying N2 gas, a
small amount of pure water was added and followed by
treatment in a sonication bath for 10 min. The residue was
similarly concentrated by spraying N2 gas to obtain a gel of the
lipid mixture. After diluting the gel with a suitable volume of
pure water, the mixture was treated by voltex mixer for 3 min
and the obtained suspension was chromatographed on a column
of Sephadex G-50 with pure water to afford the fraction
containing CD nanoparticles. Morphologies of the liposomes
prepared from 5b, DPPC, and cholesterol were investigated by
using a transmission electron microscope (TEM) (HITACHI H-
800, accelerating voltage 75 kV) after negative staining with
uranyl acetate solution. TEM views of liposomes prepared from
the different ratio of lipids are shown in Fig. 2. As indicated in
Fig. 2(B)–(D), it appears that vesicles containing compound 5b
exhibited much larger diameters (100–300 nm) than those of the
liposomes composed of DPPC and cholesterol [DPPC+choles-
terol = 10+1, Fig. 2(A)]. Addition of the sulfated CD
amphiphiles seemed to induce the formation of interesting
erythrocyte-like liposomes having controlled encapsulation
capacity for fluorescent-labelled compounds. Since some
sulfated derivatives of b-CD show potent inhibitory effects on
the replication of HIV-1,17 sulfated CD amphiphiles syn-
thesised here might greatly contribute to the creation of new
CD-based carrier molecules having significant biological
functions.
Notes and references
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In summary, we have designed novel amphiphilic CD
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