Biomedical Engineering Reference
In-Depth Information
hydroxyl groups in the polymeric side chains with spermine.[47] These
protonable copolymers having polyaspartamide backbone can form complexes
with plasmid DNA even at low polycation/DNA weight ratios ranging from
0.75/1 to 2/1. The size of the polycation/DNA complexes decreased with
increasing polycation/DNA weight ratio, until nano-sized dimensions were
reached. They also indicated higher transfection efficiency than PEI in luciferase
transfection assay with both cell lines tested at C/P ratio of 10. However partial
hydrophobization of PHEA-Spm with C4 portion did not increase transfection
efficiency, although DNA interaction with polymers was strengthened to give
smaller polyplex sizes. The high transfection efficiency of these highly
bufferable polymers demonstrates that polyplexes can efficiently escape
endosome by the proton sponge mechanism as described for PEI.
Fig. 18. Transfection efficiencies of polyaspartamide-based oligoethyleneimine brushes/pRE Luc
complexes in HEK293 cells. Branched PEI (M.W. 25000) was used as a control. Data represent the
mean and standard deviation (n=2). (Zhang, M., et al., “Polyaspartamide-Based Oligo-ethylenimine
Brushes with High Buffer Capacity and Low Cytotoxicity for Highly Efficient Gene Delivery”,
Bioconjug. Chem.
, Vol. 20, No. 3, 2009, pp. 440-446. With permission).
9. Biocompatibility
The biocompatibility of polymeric drug carriers is a critical factor for biomedical
applications. Many polymer systems such as PEI, poly-L-lysine, and poly(amido
amide) have difficulties such as cytotoxicity of the cationic polymers derived
from
the
charge
density,
non-biodegradability,
and
elimination
by
the
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