Investigation of the Fe2O3 nanoparticles interaction with human serum albumin using fluorescence and circular dichroism (CD) techniques

Nanoparticles (NPs) have broad applications in various industries, that it can be expected them find a way to enter into the environment and affected the living organism with unexpected consequences. According to the broad applications of the Fe2O3 nanoparticles (nFe2O3) in different industries, in this study, its interaction with human serum albumen (HSA), as an abundant protein in blood, was investigated using intrinsic fluorescence at different temperature ranges, extrinsic fluorescence and circular dichroism (CD) methods. Results showed, with increasing NP concentration in media, intrinsic fluorescence intensity of the protein decreased in all temperatures. Based on the quenching rate constant (Kq), it revealed that interaction between HAS and nFe2O3 take place through static mechanism. Thermodynamic parameters indicate the sign of enthalpy and entropy are negative, which implies the role of hydrogen bands and Van der Waals forces in this interaction. The negative sign of free energy (∆G°), revealed this reaction is exergonic and spontaneously. On the other hand, ANS fluorescence intensity increased more for HSA in interaction with NP in contrast to the ANS. Furthermore, Far-UV CD spectra shows an alteration in the secondary structure of this protein in interaction with the NP. The results all together revealed changes in the structure of HSA upon exposed to this nanoparticle which can affected its performance.