[en] A new gene transfer system was developed by using polylipoplexes, which were prepared by hydrophobic modification of polyethyleneimine (PEI, MW 2000). PEI 25kDa is well known for its excellent transfection efficiency but it has extreme cytotoxicity; therefore, its application for medical use is strictly limited. PEI 2kDa is able to form complexes with DNA and has low cytotoxicity. However, unfortunately, it shows no transfection efficiency so it can not be a candidate carrier for gene therapy. We designed novel polycationic amphilphiles by conjugating hydrophobic moieties, such as cholesterol and myristate, to PEI 2kDa. Cholesterol-conjugated PEI (PEI-Chol: P10C, P17C and P30C) and myristate-conjugated PEI (PEI-Myr:P10M, P16M and P26M) are different from the other cationic lipids in that they can form lipopolyplexes with plasmid DNA that have extra multi-positive charges in their hydrophilic parts. From a different point of view, they are also considered to be PEI derivatives with a small proportion of hydrophobic moiety. As a result of the modification, PEI-Chol and PEI-Myr showed much enhanced transfection activity but somewhat increased cytotoxicity. We also examined the effect of the amount of hydrophobic moiety on lipopolyplex-mediated gene transfer and observed that P17C and P26M are the most effective carriers in the series of two groups. MTT assay indicated that the more myristyl groups were attached to PEI, the more injurious results were observed. In the case of PEI-Chol, however, the opposite tendency was observed

[en] Quaternary ammonium groups were introduced to Starburst polyamidoamine (PAMAM) dendrimers for a gene carrier. These quaternary dendritic carriers exhibited reduced cytotoxicity on 293T cells compared to parent dendrimers examined and their transfection efficiency were similar with parent dendrimers. Quaternization could be a promising tool to improve properties of dendrimers as a gene delivery carrier

[en] In this report, we describe the synthesis of mono- and di-valent cationic 3β [L-Lysinamide-carbamoyl] cholesterol (K-Chol) derivatives by solid-phase peptide synthesis method and the characteristics of K-Chol/ antisense oligodeoxynucleotide (ODN) complexes. K-Chol was able to interact with antisense ODNs electrostatically and constructed nanometer-sized complexes of 50-100 nm in diameter. The formation of KChol/ antisense ODN complexes was demonstrated by non-denaturing polyacrylamide gel electrophoresis assay and atomic force microscopy. The cell-associated radioactivity was measured to monitor the cellular uptake of the complexes containing radioactive antisense ODNs using HL 60 cells

[en] Biodegradable cationic poly(ester-amide) polymers were synthesized by double-monomer method, that showed excellent solubility in many organic solvents and water. Different degradation patterns were obtained by the regulation of monomer ratios and overall long period of time of DNA protection up to 12 days was shown by PicoGreen reagent assay. Good transfection profiles in the presence of serum and very low toxicity on mammalian cells may allow these polymers to become suitable for long-term gene delivery systems and therapeutic applications

[en] PLGA nano-half-shells were prepared by the oil-in-water emulsion solvent evaporation method. It is suggested that the structure results from the sequential events including fast solidification, phase separation and water escape. Since these nano-half-shells are nanostructures with low densities, they may have the possibility of being used as carriers for pulmonary drug delivery system. Nano- and microparticles composed of degradable polymers have been used for drug and gene delivery system. Recently, polymeric hollow microspheres were developed for pulmonary delivery of drugs and genes. In general, an oil-in-water (o/w) emulsion solvent evaporation method has been used for the preparation of poly(D,L-lactide-co-glycolic acid) (PLGA) nano- and microparticles which had spherical shapes, although hollow microspheres can be prepared by other methods such as water-in-oil-in-water (w/o/w) double emulsion solvent evaporation and jet spraying with a nozzle. In this article, we report that nano-half-shells could be prepared by the same oil-in-water emulsion solvent evaporation method by adding Pluronic F127 (poloxamer) to the organic phase. Generally, half-shells are not thought to be produced spontaneously, due to their high surface tension. Thus, poloxamer seems to play a key role in generating the thermodynamically unfavorable structure of nano-half-shells

[en] High concentrations of cationic colloidal silica nanoparticles (CCS-NPs) have been widely used for the enrichment of plasma membrane proteins. However, the interaction between the CCS-NPs and cells under the required concentration for the isolation of plasma membrane are rarely investigated. We evaluated the internalization and toxicity of the 15 nm CCS-NPs which were exposed at high concentrations with short time in human breast cancer cells (MCF-7) with transmission electron microscopy, energy dispersive X-ray spectroscopy, inductively coupled plasma atomic emission spectroscopy, and colorimetric assays. The NPs were observed throughout the cells, particularly in the cytoplasm and the nucleus, after short incubation periods. Additionally, the NPs significantly influenced the membrane integrity of the MCF-7 cells