Interaction of Ifosfamide-Loaded Superparamagnetic Iron Oxide Nanoparticles with Human Serum Albumin—A Biophysical Study

Combined techniques like fluorescence, circular dichroism (CD), and Fourier transform infrared (FT-IR) were applied to study the interaction between ifosfamide-loaded superparamagnetic iron oxide nanoparticles (ISION) and human serum albumin (HSA) at physiological pH. The fluorescence results showed the existance of a static quenching mode for HSA-ISION interaction. The binding constant at 298 K was in the order of 10 5  M −1 , showing high affinity occurred  between ISION and HSA. The thermodynamic parameters obtained at three different temperatures (288, 298, and 308 K) indicated that the dominant binding forces are the electrostatic forces, for the values of the enthalpy change (Δ H °) and entropy change (Δ S °) were found to be −1.31 × 10 4  J · mol −1 and 55.4 J · mol −1  · K −1 , respectively. Fluorescence resonance energy transfer (FRET) analysis revealed that the average binding distance ( r ) between Trp of HSA and ISION was 5.25 nm. The results of CD and FT-IR spectra demonstrated that the secondary structure of HSA was altered in the presence of ISION.