Mechanistic insights into the interactions of magnetic nanoparticles with bovine serum albumin in presence of surfactants

• Interactions of MNPs with serum albumin was greatly enhanced in presence of cationic surfactant.
• Fluorescence studies revealed a blue shift in fluorescence quenching intensity of protein in presence of surfactant modified MNPs.
• Molecular association of MNPs with BSA in presence of CTAB was thermodynamically stable as indicated by enthalpy, entropy and Gibb’s free energy, favoring a hydrophobic interaction.
• A stable size of MNPs coated with serum albumin is achieved in presence of surfactant as revealed by DLS and Zeta potential measurement.
• Circular dichroism and thermal denaturation study by UV–vis supports the functional integrity of protein during the association with MNPs in presence of CTAB.

This work reports the physicochemical parameters and the nature of association between magnetic nanoparticles and bovine serum albumin (BSA) in presence of cationic and anionic surfactants. Magnetic iron oxide nanoparticles (MNPs) are first synthesized using chemical co-precipitation method and subsequently characterized by FTIR, XRD, DLS, TEM and Zeta potential. The bare nanoparticles are then coated with BSA and their interactions studied using fluorescence spectroscopy, dynamic light scattering and circular dichroism techniques. The spectroscopic investigation sheds light into various aspects of binding and size variation during the molecular association of BSA with the MNPs in absence and presence of cationic and anionic surfactants. Isothermal titration calorimetry was used to probe the thermodynamic parameters of the systems. MNPs-BSA system was found to be more stable in presence of cationic surfactant. This study provides valuable mechanistic insights into the interactions taking place at the interface of the nanoparticles which further helps in designing a stable colloidal MNPs systems.

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