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ÖZBAŞ, SUNA

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ÖZBAŞ

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End date: 2009 × Start date: 2002 ×

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    Evaluation of antisense oligonucleotide loaded chitosan nanoparticles; characterization and antisense effect
    (GOVI-VERLAG PHARMAZEUTISCHER VERLAG GMBH, 2009) ÖZBAŞ, SUNA; Ozbas-Turan, S.; Akbuga, J.; Enneli, B.
    The objective of this study was to investigate the effect of different formulation parameters [i.e. molecular weight and concentration of chitosan, concentration of tripolyphosphate (TPP) and use of alginate] on physico chemical and antisense properties of antisense oligonucleotide (AsODN) loaded chitosan nanoparticles (NPs). Preparation methods of phosphodiester (PO) and phosphorothioate (PS) AsODNs-NPs were also compared. AsODNI was designed to target the beta-galactosidase (beta-gal) gene. HeLa cells were used for in vitro transfection studies and beta-gal was assayed spectrophotometrically. AsODN-NPs obtained were in general positively charged with size between 221.4-525.7 nm depending on formulation. Encapsulation efficiency of NPs depended on the type of backbone of the AsODN. PO-AsODN encapsulation into NPs (78-94%) was less efficient than PS encapsulation (91-98%). The pH of the chitosan solution affected AsODN entrapment. PO-NPs exhibited faster AsODN release than NPs containing PS. In general higher beta-gal inhibition was obtained after transfection of AsODN-NPs in cell culture studies. PS-NPs exhibited a higher inhibition effect and the highest (90.71%) inhibition was obtained with formulation PT-2. PS-adsorbed NPs showed an 88% reduction in beta-gal. This study can form the basis for forthcoming in vivo studies related to AsODN carrier systems that will use chitosan.
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    Plasmid-DNA loaded chitosan microspheres for in vitro IL-2 expression
    (ELSEVIER SCIENCE BV, 2004) ÖZBAŞ, SUNA; Akbuga, J; Ozbas-Turan, S; Erdogan, N
    Interleukin-2 (IL-2) expression plasmid (pCXWN-hIL-2) loaded chitosan microspheres were evaluated for using in gene-based immumotherapy. Chitosan microspheres containing pCXWN-hIL-2 were prepared by using a precipitation technique. In addition, the effects of different factors such as the concentration (0.35-0.70%) and the molecular weight of chitosan (low and medium molecular weights), the plasmid amount (5-10 mug/ml) and the presence of glutaraldehyde during the encapsulation process, on microsphere characteristics were investigated. The size of microspheres changed between 1.45 and 2.00 mum. All the formulation factors affected the size of microspheres. The structure of plasmid remained unchanged during the encapsulation process and the release studies. Plasmid encapsulation efficiency of chitosan microspheres was high (82-92%). The zeta potential values of microspheres was approximately +5.2 to +12.4 mV. In vitro release properties of microspheres changed with formulation variables. In vitro release of DNA changed with the concentration and molecular weight of chitosan and initial plasmid amount. Addition of glutaraldehyde is not necessary for a formulation. MAT-LyLu, the rat prostate adenocarcinoma cell line, was used for the determination of the in vitro transfectional activity of IL-2 encoding plasmid DNA loaded chitosan microspheres and the level of IL-2 expressed into the cells was assayed using a ELISA kit. High level of IL-2 expression was obtained with plasmid-loaded chitosan microspheres. Microspheres showed similar IL-2 production as lipofectin. The molecular weight of chitosan used and the amount of plasmid influenced the in vitro IL-2 production in the cells. Encapsulation of IL-2 encoding gene into chitosan microspheres might be a useful strategy to increase the expression and to control the delivery of cytokine gene to cells. (C) 2004 Elsevier B.V. All rights reserved.
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    Controlled release of interleukin-2 from chitosan microspheres
    (JOHN WILEY & SONS INC, 2002) ÖZBAŞ, SUNA; Ozbas-Turan, S; Akbuga, J; Aral, C
    Chitosan microspheres were evaluated for sustained-release of recombinant human interleukin-2 (rIL-2) in this study. In addition, the effects of different formulation factors, such as chitosan and protein concentrations, the volume of sodium sulfate solution, addition technique of rIL-2, and presence of glutaraldehyde during the encapsulation process, on microsphere characteristics were investigated. Chitosan microspheres containing rIL-2 were prepared by using the precipitation technique. The average diameter of microspheres was between 1.11-1.59 mum. Recombinant IL-2 encapsulation efficiency in these micropheres was high (75-98%). Formulation factors had no effect on the microsphere size. Recombinant IL-2 had been released from chitosan microspheres over a period of 3 months. The encapsulated rIL-2 remained biologically active and could be completely recovered from the release medium. Briefly, rIL-2 was released from chitosan microspheres in a sustained manner. The efficacy of rIL-2 loaded chitosan microspheres was studied using two model cells, HeLa and L-strain cell lines. Chitosan microspheres were added to the cells at different concentrations, and the amount of rIL-2 was assayed using the ELISA kit. Cell culture studies indicated that microspheres were uptaken by cells, and rIL-2 was released from the microspheres. Cellular uptake of rIL-2-loaded microspheres was dose dependent. It can be said that chitosan microsphere is a suitable carrier for rIL-2 delivery. (C) 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association.