Bovine serum albumin (BSA) and zinc oxide nanoparticles (ZnO NPs) are chosen as a model system to investigate NPs-protein corona complex formation. ZnO NPs with average size of ∼ 20 nm are coated with BSA using covalent and non-covalent conjugation at temperatures of 4 °C and 20 °C. The interaction mechanism between ZnO NPs and BSA is studied by using UV-vis absorption, fluorescence, synchronous fluorescence and Raman spectroscopy. Raman spectra of BSA in the presence of ZnO NPs are registered for the first time and confirm decreased α-helix content, increased unstructured folding and β-sheet content in BSA structure. The synchronous fluorescence spectra revealed that the hydrophobicity of the tyrosine residue is decreased and that of the tryptophan is increased. The relation of elucidated changes in BSA structure of BSA-coated ZnO NPs cytotoxicity is tested for CHO cell viability and reactive oxygen species (ROS) generation in vitro. Covalent and non-covalent binding of BSA to ZnO NPs reduces ZnO NPs cytotoxicity and ROS generation, however changes in BSA conformation makes corona less protective against ZnO NPs.
Keywords: BSA; Cytotoxicity; Protein structure; ROS; Raman spectroscopy; ZnO nanoparticles.
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