Papers by Author: You Kyoung Kim

Abstract: To improve the specific accumulation in tumor sites and aqueous solubility of atRA, the core-shell type of folate-PEG-g-PEI/atRA nanoparticles were prepared by complexation between cationic PEI segments in the copolymers and anionic charged atRA, and then characterized by 1HNMR, ELS, XRD, and TEM. In vitro atRA release from the nanoparticles was investigated as a function of drug content in sink condition. Cytotocicity of atRA against HepG2, KB cell lines were also evaluated by MTT assay. The lower the drug content, the faster atRA release. atRA incorporated in folate-PEG-g-PEI/atRA nanoparticles showed much higher cytotoxic effect compared with atRA itself.

Abstract: Novel, biodegradable poly(ester amine)s (PEAs) were synthesized using hydrophobic polycaprolactone diacrylate (PCLDA) and highly cationic polyethylenimine (PEI). This novel gene carrier can form stable DNA complexes with particle sizes around 200 nm, and showing excellent transfection efficiency and relatively low cytotoxicity compared with PEI 25K. Effect of hydrophobicity on transfection efficiency and cytotoxicity was profound and was relatively important parameter for the success of gene delivery.

Abstract: Polypropylenimine (PPI) dendrimers have been used by many researchers as gene delivery carriers due to their high functionality. Glucose as a kind of carbohydrate is biocompatible and hydrophilic. In this study, we synthesized glucosylated PPI (G-PPI) dendrimers to reduce cytotoxicity. Glucose substitution of G-PPI dendrimers was determined by the sulfuric acid micromethod. The G-PPI dendrimer was complexed with plasmid DNA in various N/P ratios, and the complex was characterized. G-PPI dendrimers showed good DNA binding ability and high protection of DNA from nuclease attack. The G-PPI dendrimer had low cytotoxicity compared to PPI dendrimer by cytotoxicity assay. Also, transfection efficiency was influenced by glucosylation degree and the transfection efficiency for the G-PPI-5 was slightly higher than that of PPI dendrimer in HeLa cell line.

Abstract: The strategies developed for gene delivery are generally classified into two categories of viral and non-viral vectors. The limitation of viral vectors, which have problems including toxicity, immunogenicity and inflammatory response has led to the development of a novel, synthetic vectors based on non-viral vectors. Chitosan, one of non-viral vectors, has been a good candidate in gene delivery field. Moreover, galactosylated chitosan (GC) had the specific recognition of hepatocytes by galactose in the GC. Also, carbonate apatite increased the rate of DNA endocytosis and the efficiency of gene transfer. We describe here a new concept for improving cell specificity and transfection efficiency by hybridization of carbonate apatite (CAp) with GC. The complex formation was confirmed by agarose gel electrophoresis. The complex optimized through controlling calcium ion and charge ratio was evaluated on the cell specificity and transfection efficiency.

Abstract: Thiolated polymers have been studied by many researchers because of the mucoadhesive properties of thiol group. Alginate is a natural and biocompatible polymer that has been widely used in drug delivery. In this study, thiolated chitosan microspheres (TCMs) were prepared by ionic gelation process with tripolyphosphate and then, the bovine growth hormone (BGH) was loaded as a model drug. Finally, the BGH-loaded TCMs (BTCMs) were coated with alginate to improve the stability in gastrointestinal (GI) track. The alginate-coated BTCMs (ABTCMs) were observed as spherical shapes. The average particle sizes of ABTCMs were 6.97±0.55 -m and the sizedistribution was shown uniformly. Release of BGH from ABTCMs was decreased by coating with alginate and increased rapidly with the change in medium pH from 1.2 to 7.4. Results indicate that the ABTCMs have a potential as a drug carrier for oral drug delivery.