Interaction of doxorubicin delivered by superparamagnetic iron oxide nanoparticles with DNA.

We studied the interaction of superparamagnetic iron oxide nanoparticles (SPIONs), covered by trisodium citrate, with doxorubicin (DOX) and DNA using the spectrophotometric method. We calculated the binding parameters in the binary (DOX-SPION and SPION-DNA) and the ternary (DOX-SPION-DNA) systems. Our studies showed that the nanoparticles do not interact with DNA. We also observed that one nanoparticle loads rather a large number of DOX molecules with a quite high binding constant value (k = 1.2 × 10 M). The DNA addition to the DOX-SPION system induces DOX release from the SPION surface and the formation of DOX-DNA complexes. The presence of nanoparticles has almost no effect on the constant of doxorubicin binding to DNA (k ≈ 3 × 10 M). At high DNA concentrations, almost all DOX molecules bind to DNA. Accordingly, the use of SPIONs as DOX carriers does not require an increased drug dose to achieve a therapeutic effect. Thus, SPIONs are perspective nanocarriers for DOX delivery.