Abstract
Mannose polyethylenimine with a molecular weight of 25 k (Man-PEI25k) was synthesized via a phenylisothiocyanate bridge using mannopyranosylphenyl isothiocyanate as a coupling reagent, and characterized by 1H NMR (nuclear magnetic resonance) and FT-IR (Fourier transform infrared spectroscopy) analysis. Spherical nanoparticles were formed with diameters of 80–250 nm when the copolymer was mixed with DNA at various charge ratios of copolymer/DNA (N/P). Gel electrophoresis demonstrated that the DNA had been condensed and retained by the PEI derivates at low N/P ratios. The Man-PEI25k/DNA complexes were less cytotoxic than the PEI complexes with a molecular weight of 25 k (PEI25k) at the same N/P ratio. Laser scan confocal microscopy and flow cytometry confirmed that the Man-PEI25k/DNA complexes gave higher cell uptake efficiency in (Dendritic cells) DC2.4 cells than HeLa cells. The transfection efficiency of Man-PEI25k was higher than that of PEI25k towards DC2.4 cells. These results indicated that Man-PEI25k could be used as a potential DC-targeting non-viral vector for gene therapy.
Highlights
Polyethylenimine (PEI) is one of the most successful and efficient non-viral gene delivery systems to have been reported to date
Mannose is often used as a ligand in this context because it binds to the mannose receptors on the surfaces of cells to induce receptor-mediated endocytosis, which leads to an increase in the delivery efficacy of these systems [7]
Man-PEI25k was prepared through a phenylisothiocyanate bridge using mannopyranosylphenyl isothiocyanate as a coupling reagent, which was synthesized via a thiourea reaction (Scheme 1)
Summary
Polyethylenimine (PEI) is one of the most successful and efficient non-viral gene delivery systems to have been reported to date. Sun et al reported that mannosylated biodegradable polyethyleneimine (man-PEI-TEG) exhibited a low level of cytotoxicity and performed well in both cellular uptake and transfection assays in vitro. They demonstrated that man-PEI-TEG can be used as a DC-targeting gene-delivery system [11]. For the more free amine groups were used to conjugate mannose, the less surface positive charges of the PEI-Man copolymers remained, in other words, with the increasing of the ratio of mannose group displays lower cytotoxicity but limited delivering efficiency, and based on the previously report, the amount of mannose was sufficient at 5% for receptor mediated gene delivery to the cells [12]. The cytotoxicities and transfection efficiencies of the Man-PEI25k/DNA complexes were evaluated in vitro to determine the suitability of these copolymers as gene vectors
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