Determination of binding constant Kb of biocompatible, ferrite-based magnetic fluids to serum albumin

In this work, we investigated the interaction between molecular-coated magnetic nanoparticles (MC-MNPs) and serum albumin proteins (BSA) through the fluorescence quenching of the tryptophan residue present in BSA after the binding of MC-MNPs to specific sites. Three different biocompatible magnetic fluid (BMF) samples based on magnetite or cobalt–ferrite MNPs coated with citric acid or dextran were used. The binding constant and the stoichiometry of the investigated MNPs indicate that the BMF based on cobalt–ferrite is more site specific and more strongly bound to the BSA than the BMFs based on magnetite. The results may direct the design of new magnetic drug-carriers based on BMFs.