Yang_2022_Toxicol.Res.(Camb)_11_654

BACKGROUND: Although superparamagnetic iron oxide nanoparticles (SPIONs) are used as carriers for candida rugosa lipase (CRL) in biomedical fields, their interactions and the influences on CRL are still unknown. Consequently, SPIONs were synthesized, characterized, and incubated with CRL to explore their molecular interactions and interacting consequences in this study. METHODS: The toxic effects of SPIONs on CRL and their molecular interactions were explored through transmission electron microscope, isothermal titration calorimetry, zeta potential measurements, multi-spectroscopic techniques, and biological enzyme activity tests. RESULTS: Results revealed the adsorption of SPIONs to CRL and the reduction of CRL aggregation. The unfolding and loosening of CRL structure as well as the change of secondary structure with the decrease of alpha-helix were found under SPIONs exposure. Moreover, higher SPIONs concentrations contributed to larger conformational changes and less aggregation of CRL. Meanwhile, it showed that hydrophobic forces were the dominant driving forces in the binding process, with the participation of electrostatic forces. CRL binds to SPIONs with the stoichiometry of 20.7 and the binding constant of 9.9 x 10(6) M(-1). No obvious changes were found in CRL activity due to no interference to Ser-209, Glu-341, and His-449 residues. CONCLUSION: This study examined the biological compatibility of SPIONs at the molecular level and provided important information about the structure and function of CRL upon binding to SPIONs. Our work might contribute to comprehend the molecular toxicity of SPIONs and the risks of engineered nanoparticles to human health.