• Macromolecular Research
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• 제14권3호
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• pp.348-353
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• 2006

For enhancing the gene delivery efficiency of polyplexes, a new formulation was developed using PEI conjugated Pluronic F127 copolymer as an effective additive. Low molecular weight, branched polyethylenimine Mw 600 (LMW BPEI 600) was conjugated to the terminal end of Pluronic F127. The PEI-modified Pluronic copolymers formed a micellar structure in aqueous solution, similar to that of unmodified Pluronic copolymer. PEI modification of Pluronic copolymer increased the size of micelles while concomitantly raising the critical micelle concentration (CMC). The PEI-modified Pluronic copolymer was used as a micellar additive to enhance the gene transfection efficiency of pre-formulated polyelectrolyte complex nanoparticles composed of luciferase plasmid DNA and branched PEI Mw 25k (BPEI 25k) or polylysine Mw 39k (PLL 39k). The luciferase gene expression levels were significantly enhanced by the addition of the BPEI-modified Pluronic copolymer for the two formulations of BPEl and PLL polyplexes. The results indicated that the BPEI-modified Pluronic copolymer micelles ionically interacted on the surface of DNA/BPEI (PLL) polyplexes which might facilitate cellular uptake process.

• Bulletin of the Korean Chemical Society
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• 제29권8호
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• pp.1565-1568
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• 2008

• Bulletin of the Korean Chemical Society
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• 제25권7호
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• pp.1025-1030
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• 2004

A hybrid linear polymer-dendrimer block copolymer, poly(ethylene glycol)-block-poly(L-lysine) dendrimer, was synthesized and introduced to form polyionic complexes with DNA. The copolymer formed core-shell type nanoparticles with plasmid DNA. From dynamic light scattering experiments, the mean diameter of the polyplexes was observed to be 154.4 nm. The complex showed much increased water solubility compared to poly(L-lysine). The plasmid DNA in polyplexes was efficiently protected from the enzymatic digestion of DNase I. The cytotoxicity and transfection efficiency for 293 cells was measured in comparison with poly(Llysine).

• Macromolecular Research
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• 제17권1호
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• pp.19-25
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• 2009

In order to enhance the gene delivery efficiency and decrease the cytotoxicity of polyplexes, we synthesized Solutol-g-PEI by conjugating polyethyleneimine (PEI) to Solutol (polyoxyethylene (10) stearate), and evaluated its efficiency as a possible nonviral gene carrier candidate. Structural analysis of synthesized polymer was performed by using $^1H$-NMR. Gel retardation assay, particle sizes and zeta potential measurement confirmed that the new gene carrier formed a compact complex with plasmid DNA. The complexes were smaller than 150 nm, which implicated its potential for intracellular delivery. It showed lower cytotoxicity in three different cell lines (Hela, MCF-7, and HepG2) than PEI 25 kDa. pGL3-lus was used as a reporter gene, and the transfection efficiency was in vitro measured in Hela cells. Solutol-g-PEI showed much higher transfection efficiency than unmodified PEI 25 kDa.

• Archives of Pharmacal Research
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• 제28권6호
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• pp.722-729
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• 2005

With the aim to improve the specificity and to reduce the cytotoxicity of polyethylenimine (PEI), we have synthesized the conjugates of the branched PEI (25 kDa) with transferrin. The trans-ferrin-PEI (TP) conjugates with five compositions were synthesized using periodate oxidation method and confirmed by FT-IR spectroscopy and gel permeation chromatography. The free amine contents of TP conjugates, which were able to condense and deliver DNA, increased as the amount of PEI increased. TP/DNA polyplexes were characterized by measuring gel elec-trophoresis, ethidium bromide fluorescence quenching, particle size and zeta potential of complexes. Complete complexation of the polyplexes was observed above the N/P ratio of 5 in TP/DNA, and above 3 in PEI/DNA, respectively. The zeta potential of the complexes decreased as the amount of transferrin in TP conjugates increased. Transfection efficiency of TP conjugates was evaluated in HeLa cell and Jurkat cell systems. Among the five compositions of TP conjugates, TP-2 system mediated a higher $\beta$-galactosidase gene expression than PEI system in Jurkat cell which was known to express elevated numbers of transferrin receptors. From the results of the cell viability based on MTT assay, TP conjugates showed lower cytotoxicity com-pared with the PEI system. We expect that the TP conjugate can be used efficiently as a non-viral gene delivery vector.

• Bulletin of the Korean Chemical Society
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• 제32권2호
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• pp.651-655
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• 2011

We synthesized a novel cationic dendrimer consisting of a poly(amidoamine) dendrimer (PAMAM, generation 4) backbone with both L-arginine (Arg) at the termini and 6-aminohexanoic acid (Ahx) between the original core polymer and the peripheral Arg units. The sequential chemical modification of PAMAM G4 with Ahx and Arg resulted in higher transfection efficiency with much less cytotoxicity. PAMAM G4-Ahx-Arg formed stable polyplexes at weight ratios of 8:1 or higher (polymer: plasmid DNA), and the mean polyplex diameter was $180{\pm}20nm$. PAMAM G4-Ahx-Arg showed much higher transfection ability than PAMAM G4 or PAMAM G4-Ahx. Furthermore, PAMAM G4-Ahx-Arg was much less cytotoxic than PEI25KD and PAMAM G4-Arg. In addition to Arg grafting of the PAMAM dendrimer, which endows a higher transfection capability, the addition of Ahx spacer increased dendrimer hydrophobicity, introduced flexibility into the conjugated amino acids, and reduced cytotoxicity. Overall, it appears that the concomitant modification of PAMAM with Ahx and Arg could lead to new PAMAM conjugates with better performances.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3676-3680
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• 2012

An Epstein-Barr virus (EBV)-based plasmid contains the EBV nuclear antigen 1 (EBNA1) gene and EBV replication origin (oriP) sequence. Since EBNA1 (the only EBV-encoded protein) is combined with oriP, it is replicated simultaneously with chromosomal DNA in human, primate, and canine cells and is faithfully segregated at a stable copy number upon cell division. Consequently, it can be used to stably express gene inserts over a prolonged time in target cells. We have previously shown that the polyamidoamine (PAMAM) dendrimer can be surface-modified with L-arginine. Arginine is present at a high frequency in the transactivator of transcription (Tat) sequences of human immunodeficiency virus (HIV). It presents high membrane permeability and permits effective transfer of DNA inside the cells. In this study, we constructed two kinds of recombinant DNA by inserting the luciferase gene and enhanced green fluorescence protein (eGFP) gene as reporter genes into the pCEP4 plasmid vector. We measured dynamic light scattering (DLS) and zeta potential after preparing PAMAM-based cationic polymer/EBV-based plasmid complexes. We performed transfection of HEK 293 cell lines with the polyplexes, and monitored luciferase activity and green fluorescence protein (GFP) expression. Our results show that PAMAM-based cationic polymer/EBV plasmid complexes provide enhanced and sustained gene expression.