Biomedical Engineering Reference
In-Depth Information
62
with increasing MW of the PEI segment in chitosan-g-PEI.
Yu
et al.
prepared copolymers poly(L-lysine)-graft-chitosan (PLL-g-
Chi). The gel retardation electrophoresis showed that the PLL-g-Chi
copolymers possessed better pDNA-binding ability than chitosan.
The gene transfection effect in HEK 293T cells of the copolymers
was better than that of chitosan and was dependent on the PLL
grafting ratio. The PLL-g-Chi copolymers could be used as an effective
gene delivery vectors.
63
2.3.3.2 Cyclodextrins
Cyclodextrins (CD) is non-toxic and non-immunogenic and is pro-
duced from starch by means of enzymatic conversion. It is cyclic
oligomer of glucose units having a unique amphiphilic structure
that consists of a hydrophobic cavity and hydrophilic exterior
and thus building CD as water-soluble. CD contains a number
of glucose monomers ranging from six to eight units in a ring,
creating a cone shape and thus (a) α-cyclodextrin: six-membered
sugar ring molecule, (b) β-cyclodextrin: seven sugar ring molecule,
and (c) γ-cyclodextrin: eight sugar ring molecule.
CD forms inclusion complexes with small hydrophobic
molecules and has been incorporated into a gene delivery polymer
to provide a facile and versatile attachment site for targeting ligand.
Forrest
derivatized PEI with β-CD (CD-PEI) on approximately
10% of the polymer's amines. Human insulin was derivatized with
a hydrophobic palmitate group (pal-HI), which could anchor the
protein to CD-PEI/DNA polyplexes. CD-PEI was non-toxic to HEK293
cells and mediated fourfold higher gene expression than unmodified
PEI. Addition of the pal-HI to CD-PEI enhanced gene expression.
CD-binding moieties are attached with relative ease to various types
of ligands; thus CD-PEI may be a useful material for testing novel
cell-specific targeting compounds.
et al.
64
The influence of CD in forming grafting complexes showed
that the more the grafting percentage of the CD, the less cytotoxic
the polymer will be. Transfection efficiency also increased if the
grafting percentage was increased.
reported linear and
branched PEI (LPEI and bPEI), grafted with β-CD, and investigated
them as
65
Pun
et al.
toxicity
and transfection efficiency are sensitive to the level of CD grafting.
The CD containing polycations are combined with adamantane-
in vitro
and
in vivo
gene delivery agents. The
in vitro
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