Magnetic Fe3O4 nanoparticles were synthesized successfully by co-precipitation method and characterized using XRD, SEM and EDS analyses. Then doxorubicin (DOX, a known anticancer drug) was loaded onto nanoparticles. In vitro DNA interaction of free DOX and loaded DOX onto Fe3O4 nanoparticles (DOX-Fe3O4) was investigated by DNA-viscosity measurements, UV-visible and fluorescence spectroscopies. The obtained values for binding constant of DOX and DOX-Fe3O4 compounds from UV-visible spectroscopies were 0.04 × 105 and 0.68 × 105 L mol-1, respectively, which confirms DOX-Fe3O4 compound have a stronger interaction with CT-DNA compared to DOX. Considerable changes on viscosity of the compounds recommended that their binding mode with CT-DNA is intercalative binding. Fluorescence intensity of DOX and DOX-Fe3O4 was quenched via static process by regular addition of CT-DNA. Thermodynamic parameters suggest that Van der Waals forces and hydrogen bonding for DOX and electrostatic forces for DOX-Fe3O4 are predominantly responsible for interaction with CT-DNA. Competition fluorescence studies were done by Hoechst 33258 as a well-known groove binder and ethidium bromide (EtBr) as a known intercalator probe. Percentage of displacement for EtBr-DNA complex with DOX and DOX-Fe3O4 was 39% and 61%, and for Hoechst-DNA complex was 9% and 5%, respectively. These results confirmed that both compounds are intercalator binders, although DOX-Fe3O4 with a further 22% displacement is a stronger intercalator binder than DOX. The stronger interaction of DOX-Fe3O4 compared to DOX suggests that the current system can be used as a new and effective way to targeted therapy of anticancer drugs.
Keywords: DNA interaction; Doxorubicin; Fe(3)O(4) nanoparticles; Intercalative binding.
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