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Tehrān, Iran

Mahmoodi M.,Biomaterial Group | Khosroshahi M.E.,Biomaterial Group | Atyabi F.,University of Tehran
2010 17th Iranian Conference of Biomedical Engineering, ICBME 2010 - Proceedings | Year: 2010

Polyelectrolyte coated nanopatrticles (NPs) interact with bioactive molecules such as, peptides, proteins or nucleic acids and have been proposed as delivery systems for these molecules. In this study, cationic NPs were prepared by coating chitosan (CS) on the surface of PLGA NPs. The tPA encapsulated PLGA and PLGA/CS NPs were fabricated via the W/O/W double emulsion solvent evaporation surface coating method. The CS coating was confirmed by zeta potential and FTIR. The surface morphology of NPs was also studied by TEM. In vitro drug release experiments of tPA encapsulated PLGA and PLGA/CS are determined by HPLC and showed a sustained release profile for three days with little initial burst release for PLGA/CS NPs. The mean particle size and encapsulation efficiency of tPA NPs were in the range of 280-360 nm and 46.7%±1.56, 50.8%±1.09, respectively. The encapsulation efficiency and the particles size were increased as a result of coating with CS. The release kinetics was evaluated by fitting the experimental data to standard release equation (Higuchie equation). This model was used to find the best fit for NPs. These results suggest that PLGA/CS NPs could serve as an effective vehicle for local delivery of tPA. © 2010 IEEE.

Khosroshahi M.E.,Biomaterial Group | Ghazanfari L.,Biomaterial Group
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2010

This paper describes coating of magnetite nanoparticles with silica shells. Controlled co-precipitation technique under N2 gas was used to prevent undesirable critical oxidation of Fe2+. The synthesized Fe3O4 (3 1 1) NPs were first coated with trisodium citrate (T S C) to achieve solution stability and then covered by SiO2 layer using stöber method. For uncoated Fe3O4 NPs, the results showed an octahedral geometry with saturation magnetization range of (82-96) emu/g and coercivity of about (80-120) Oe for particles between (35-96)nm, respectively. The best value of specific surface area (41 m2/g) was obtained at 0.9 M NaOH at 750 rpm. However, it increased to about 81 m2/g for Fe3O4/SiO2 combination with 50 nm as particle size, indicating the presence of about 15 nm SiO2 layer. Finally, the stable magnetic fluid contained well-dispersed magnetite-silica nanoshells which showed fast magnetic response. © 2010 Elsevier B.V. All rights reserved.

Khosroshahi M.E.,Biomaterial Group | Ghazanfari L.,Biomaterial Group
Surface Engineering | Year: 2011

The purpose of this research was to synthesise Fe3O 4/SiO2 nanoparticles (NPs) modified by amine groups for bioengineering applications. Magnetic iron oxide NPs were prepared via coprecipitation. The NPs were then modified with a thin layer of amorphous silica, as described by Stober. The particle surface was then terminated with amine groups. The results showed that smaller particles can be synthesised by decreasing the NaOH concentration, which, in the present case, corresponded to 35 nm using 0.9M NaOH at 750 rev min-1 with a specific surface area of 41 m2 g-1. For uncoated Fe3O4 NPs, the results showed an octahedral geometry with saturation magnetisation range of 80-100 emu g-1 and coercivity of 80-120 Oe for particles between 35 and 96 nm respectively. The Fe3O4/SiO 2 NPs with 50 nm particle size demonstrated a magnetisation value of 30 emu g-1. The stable magnetic fluid contained well dispersed Fe3O4/SiO2/3-aminopropyltriethoxysilane NPs, which indicated fast magnetic response. © 2011 Institute of Materials, Minerals and Mining.

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