ABSTRACT: Polymer nanoparticles have been used as non-viral gene delivery systems and drug delivery systems. In this study, biodegradable poly(L-lactic acid) (PLA)/polyethylenimine (PEI) and poly(D,L-lactide-co-glycolide) (PLGA)/PEI nanoparticles were prepared and characterized as gene delivery systems. The PLA/PEI and PLGA/PEI nanoparticles, which were prepared by a diafiltration method, had spherical shapes and smooth surface characteristics. The size of nanoparticles was controlled by the amount of PEI, which acted as a hydrophilic moiety, which effectively reduced the interfacial energy between the particle surface and the aqueous media. The nanoparticles showed an excellent dispersive stability under storage in a phosphate-buffered saline solution for 12 days. The positive zeta-potentials for the nanoparticles decreased and changed to negative values with increasing plasmid DNA (pDNA) content. Agarose gel electrophoresis showed that the complex formation between the nanoparticles and the pDNA coincided with the zeta-potential results. The results of in vitro transfection and cell viability on HEK 293 cells indicated that the nanoparticles could be used as gene delivery carriers.
International Journal of Pharmaceutics 08/2005; 298(1):255-62. · 3.35 Impact Factor
ABSTRACT: 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 transferrin-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 electrophoresis, 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 compared with the PEI system. We expect that the TP conjugate can be used efficiently as a nonviral gene delivery vector.
Archives of Pharmacal Research 07/2005; 28(6):722-9. · 1.59 Impact Factor
ABSTRACT: To confirm a new evaluation technique for biodegradability of biopolymer microspheres in vivo condition, magnetic microsphere
system was adopted for tracing the microspheres injected and lodged in mice. Microspheres of poly(DL-lactic acid), poly(L-lactic
acid) and poly (DL-lactide-coglycolide)(PLGA) were prepared by solvent-extraction method and their organ distribution and
biodegradation in mice was examined. Magnetic microspheres lodged in mice organs were recollected from the homogenates of
mice organs with a constant flow magnetic separation apparatus. Recollected microspheres were observed by scanning electron
microscopy and also were assayed for their magnetite content by atomic absorption spectrophotometry to evaluate the biodegradability
of polymeric microspheres. This method seems to be practical and simple to estimate the biodegradability of biopolymers over
the conventional methods.
Archives of Pharmacal Research 11/1993; 16(4):312-317. · 1.59 Impact Factor
ABSTRACT: Magnetically responsive gelatin microspheres for the targeting of drugs have been prepared using a water-in-oil emulsion technique
with chemical cross-linking of the protein. The manufacturing variables affecting microsphere size, size distribution and
surface characteristics have been examined as well as the magnetic responsivenessin vitro.
Sesame oil was utilized for non-aqueous phase and magnetic gelatin microspheres of different size from 1.89 to 14.88 μm in
mean diameter could be obtained with variation of HLB values of non-ionic surfactants. The content of magnetite which uniformly
distributed throughout the microspheres was 26.7% (w/w). It was possible to control the localization of magnetic gelatin microspheres
at specific sites within capillary models by using external magnetic field of under 5K gauss.
Archives of Pharmacal Research 01/1986; 9(3):145-152. · 1.59 Impact Factor