Design of controlled gene delivery system
based on biodegradable polycation and
layer-by-layer film
Lingxiao Xie, Yi Zou, Maria Muniz and Guangzhao Mao
Cationic polymer and DNA through electrostatic interaction
combined to form complex are by far the most widely used
non-viral gene delivery. However this system are much less
efficient in gene transfection experiment comparing to viral
system. Some strategies such as PEGylation, combination and
multifunction modification were developed in the cationic
polymer. Here will focus on degradable disulfide bond polymer
poly(amido amine) (PAA) and layer-by-layer (LbL) structure of
gene delivery to improve transfection efficiency, target
delivery, and decrease toxicity. The disulfide bond has drawn
increasing attention for the application on controlled drug
delivery systems due to its high redox sensibility, which is
derived from the fact that the concentration of
glutathione(GSH), a disulfide-bond-breaking agent, in the
tumor tissue is 1000-fold higher than that in the blood plasma
and the normal tissue. On the other hand, because of the
biodegradable property, the reduced molecules can be
metabolic by human body, which largely decrease safety
concern. The LbL film as gene delivery is through electrostatic
force to deposit cationic PAA and negative charged plasmid
DNA to form layer structure in dipping method. The
advantages of LbL film are their versatility, ease of preparation,
and ability to conformably coat virtually any substrates. The
mild aqueous conditions for encapsulating molecules into
multilayer films preserve the bioactivity of nucleic acids. In our
study, we successfully load DNA into LbL film with PAA and
adjust the film disassembly property and biocompatibility with
polyethylenimine (PEI), hyaluronic acid and fibronectin. Test
this film in vitro via human embryonic kidney cell (HEK 293).
Cells can grow on the film healthy without any specific
treatment and show transfection. The cell proliferation and
transfection efficiency were characterized by MTT assay and
flow cytometer. Our study contributes to a new cationic
polymer as gene carrier in novel structure, which can provide a
safety, and efficiency method in gene delivery system.