Binding Parameters of Magnetite Nanoparticles Interaction with Anticancer Drug Doxorubicin

Magnetic nanoparticles have received great interest for their use in cancer diagnostics and therapy. They can be loaded with the chemotherapeutic agents and used for the targeted delivery to the tumor and the retention of the drugs there under the external magnetic field. In the present paper, we investigated the interaction between magnetic Fe3O4 nanoparticles, both bare and coated with trisodium citrate, and anticancer drug doxorubicin in the base and acidic forms, respectively. The changes in the drug absorption spectra in the visible region and the shift of ferromagnetic resonance spectra taking place at the drug-nanoparticle interaction were analyzed. The spectrophotometric titration data were processed using the Langmuir model of equilibrium binding. For both systems, we report the calculated thermodynamic binding parameters including the drug-nanoparticle binding constants and binding site sizes. We show that in order to interact with the doxorubicin molecules in acidic form, the surface of the nanoparticles needs to be modified with trisodium citrate which provides their surface with the negative charge. At the same time, the bare magnetite nanoparticles are able to interact with the base form of the drug. The comparison of the binding parameters in both systems has shown that the nanoparticle-citrate-doxorubicin system is more promising in terms of biomedical application.