Cationic Polymers for the Delivery of Therapeutic Nucleotides - Nanotechnology for the Delivery of Therapeutic Nucleic Acids - page 40

PEG (AD-PEG) conjugates to form particles, and gene expression
observed was equal or greater than LPEI. Tail vein injections into
mice of pDNA formulated with CD-LPEI and AD-PEG do not reveal
observable toxicities, and both nucleic acid accumulation and
expression are observed in liver.

66
As non-viral gene delivery vectors, Yang synthesized

series of novel cationic star polymers by conjugating multiple
oligoethylenimine arms onto α-CD core. Prepared polymers are found
to be less toxic, biocompatible and do not elicit immune reactions.

et al.

67

Jiang studied target ligand folic acid and cell-penetrating

peptide octaarginine coupled with the gene vectors composed of
β-CD and low MW PEI (600 Da) for highly efficient gene delivery
to tumor cells. Study provides a promising means to produce gene
nanovectors for

et al.

in vivo applications.

68

2.3.3.3 Dextran, dextran-spermine
Dextran is a biodegradable and biocompatible polymer. Its straight
chain consists of α-1,6 glycosidic linkages with few α-1,3 glycosidic
linkages as the branch linkage. Dextran is readily soluble in water
and electrolyte solutions. It binds to erythrocytes and platelets,
increasing their electronegativity and thus reducing erythrocyte
aggregation. Dextran is biocompatible and used as plasma expanders
and for various other uses.
Cationic dextrans were prepared with reagents carrying
positive charge; conjugation through primary amines is one of the
most commonly used methods. Cationization of dextran increases
its gene delivery efficiency similar to that of PEI.

69, 70

Tseng et al.

reported various degrees of grafting of dextran onto PEI in an
effort to investigate how the conjugation affected the mechanisms
of transgene expression. Grafting of dextran onto PEI was found to
significantly diminish the cytotoxicity, buffering capacity, cellular
entry, and the integrity of the DNA-polymer complexes. Results
demonstrated that the conjugation of dextran onto the primary
amines of PEI inhibited the entry of plasmid across the cell
membrane.

71
Cationic polysaccharides are also synthesized by conjugation
of various oligoamines to oxidized polysaccharides via reductive
amination.

72

More than 300 different polycations were prepared
starting from various polysaccharides of different MW and
oligoamines having two to four amine groups. Although most of these