Pharmaceutical Manufacturing Handbook: Production and

APPLICATIONS OF CYCLODEXTRINS IN NANOPARTICLES 1233
after encapsulation into nanoparticles and during its release. Nanoparticles were
reported to be stable after freeze drying [40, 41] .
Nanoassemblies were formed by mixing solutions of β - CD polymer and dextran
hydrophopbically modifi ed with alkyl chains (C12) and loaded with the model
hydrophobic drug benzophenone. Nanoassemblies were characterized as 110 – 190 nm
with relatively low drug - loading values ranging between 0.3 to 1.01% w/w. Authors
suggested that hydrophobic model drug and hydrophobically modifi ed dextran
compete for the apolar CD cavity; however, benzophenone does not impede the
hydrophobic dextran to interact with β - CD polymer to form supramolecular assemblies
at the nanoscale [42] .
Another group has worked on the oligo(ethylenediamino) - β - cyclodextrin modifi
ed gold nanoparticles (OEA - CD - NP) as a vector for DNA binding. Possessing
many hydrophobic cavities at the outer space, OEACD - NP was believed to have a
capability of carrying biological and/or medicinal substrates into cells. Presence of
the CD moieties was suggested to be the key parameter in the high affi nity to DNA
for the gold nanoparticles. In addition, CD moieties were demonstrated to reduce
the cytotoxicity of gold nanoparticles arising from the gold clusters that impair
plasma membrane functions and lead to cell death [43] .
Nucleic acid delivery was also studies by Park et al. using CD - based nanoparticles
prepared from β - CD - modifi ed poly(ethylenimine) (CD - PEI). The inclusion - forming
capability of β - CD was used in order to immobilize the nanoparticles on solid surfaces
(adamantine - modifi ed self - assembled monolayers). CD - PEI nanoparticles
were proposed as delivery systems onto solid surfaces to attain specifi c and high
affi nity loading. The interaction is schematized in Figure 4 [44] .
=
O O
OH
O
O OH
O O
O
O
O
OH
O
O
OH
HO
HO O
HO
O OHHO
O
OH
HO
HO
HO OH OH HO
HO
OH
OH HO
OH
+
Scheme 1A
Adamantane β-cyclodextrin Inclusion complex
CD-PEI/DNA
complex
Specific
binding with
high affinity
50-μm gold layer
Glass slide
CD-PEI
nanoparticle
AD-modified
surface
FIGURE 4 Schematic representation of β - CD – adamantane inclusion complex formation
and immobilization of CD nanoparticles on adamantine - modifi ed surface. ( Reprinted with
permission from ref. 44 . Copyright 2006 by the American Chemical Society. )