| Tri-block poly (lactide) poly(ethylene glycol) poly(lactide) (PLA–PEG–PLA) copolymers
are among the most attractive nano-carriers for gene delivery into mammalian cells, due to
their biocompatibility and biodegradability properties. However, the low efficiency of the
gene delivery by these copolymers is an obstacle to gene therapy. Here, we have investigated
nanoparticles formulated using the polyethylenimine (PEI) associated with PLA-PEG-PLA
copolymer for efficient DNA encapsulation and delivery. PLA-PEG-PLA/DNA and PLAPEG-
PLA/PEI/DNA nanoparticles with different concentrations of PEI were prepared by the
double emulsion-solvent evaporation technique. PLA-PEG-PLA/PEI/DNA was characterized
for particle size, zeta potential, morphology, biocompatibility, DNA protection, DNA release,
and their ability for gene delivery into MCF-7 cells. We found that enhancing the mass ratio
of PEI: (PLA-PEG-PLA) (w/w%) in the PLA-PEG-PLA/PEI/DNA nanoparticles results in
an increase in particles size, zeta potential, encapsulation efficiency, and DNA release. The
electrophoretic analysis confirmed that the PLA-PEG-PLA and PLA-PEG-PLA/PEI could
protect DNA from ultrasound damage and nuclease degradation. MTT assay showed that
the PLA-PEG-PLA/PEI/DNA had low cytotoxicity than PEI complexes. The potential of
PLA-PEG-PLA/PEI/DNA nanoparticles with different concentrations of PEI as a non-viral
gene delivery vector for transferring pEGFP-N1 to MCF-7 cells was examined by fluorescent
microscopy and flow cytometry. The flow cytometry analysis revealed that by increasing the
mass ratio of PEI: (PLA-PEG-PLA) (w/w%) in PLA-PEG-PLA/PEI/DNA nanoparticles, the
efficiency of the gene delivery into MCF-7 cells was improved. The results also demonstrated
that PLA-PEG-PLA/PEI/DNA nanoparticles in the serum medium improved the efficiency of
gene delivery more than two-fold, compared to PEI/DNA complex. |