The purpose of this work was to determine the stability of pDNA/poly(L-lysine) complex
(DNA/PLL) during microencapsulation, prepare transferrin (TF) conjugated PEGylated
nanoparticles (TF-PEG-NP) loading DNA/PLL, and assess its physicochemical
characteristics and in vitro transfection efficiency. The DNA/PLL was prepared by mixing
plasmid DNA (pDNA) in deionized water with various amounts of PLL. PEGylated
nanoparticles (PEG-NP) loading DNA/PLL were prepared by a water–oil–water double
emulsion solvent evaporation technique. TF-PEG-NP was prepared by coupling TF
with PEG-NP. The physicochemical characteristics of TF-PEG-NP and in vitro
transfection efficiency on K562 cells were measured. The results showed that free pDNA
reserved its double supercoiled form (dsDNA) for only on average 25.7% after
sonification, but over 70% of dsDNA was reserved after pDNA was contracted with
PLL. The particle size range of TF-PEG-NP loading DNA/PLL was 150–450 nm
with entrapment efficiency over 70%. TF-PEG-NP exhibited the low burst effect
(<10%) within 1 day. After the first phase, DNA/PLL displayed a sustained release. The amount
of cumulated DNA/PLL release from TF-PEG-NP with 2% polymer over 7 days was 85.4%
for DNA/PLL (1:0.3 mass ratio), 59.8% and 43.1% for DNA/PLL (1:0.6) and DNA/PLL
(1:1.0), respectively. To TF-PEG-NP loading DNA/PLL without chloroquine,
the percentage of EGFP expressing cells was 28.9% for complexes consisting of
DNA/PLL (1:0.3), 38.5% and 39.7% for DNA/PLL (1:0.6) and DNA/PLL (1:1.0),
respectively. In TF-PEG-NP loading DNA/PLL with chloroquine, more cells
were transfected, the percentage of positive cells was 37.6% (DNA/PLL, 1:0.3),
47.1% (DNA/PLL, 1:0.6) and 45.8% (DNA/PLL, 1:1.0), which meant that the
transfection efficiency of pDNA was increased by over 50 times when PLL and
TF-PEG-NP were jointly used as a plasmid DNA carrier, in particular, the maximal
percentage of positive cells (47.1%) from TF-PEG-NP loading DNA/PLL (1:0.6) was
about 70 times the transfection efficiency of free plasmid DNA. The average cell
viability of TF-PEG-NP loading DNA/PLL was about 90%, which meant that
TF-PEG-NP appeared to be safer than PLL alone. As a result, TF-PEG-NP loading
DNA/PLL could be a more effective non-viral vector for the delivery of pDNA.