Investigating the Size-Dependent Binding of Pristine nC₆₀ to Bovine Serum Albumin by Multi-Spectroscopic Techniques

The morphology of nanomaterials may affect their interaction with biomacromolecules such as proteins. Previous work has studied the size-dependent binding of pristine nC₆₀ to bovine/human serum albumin using the fluorometric method and found that the fluorescence inner filter effect might affect this interaction. However, if it is necessary to accurately calculate and obtain binding information, the fluorescence inner filter effect should not be ignored. This work aimed to further investigate the effect of the fluorescence inner filter on the interaction between pristine nC₆₀ with different particle sizes (140-160, 120-140, 90-110, 50-70, and 30-50 nm) and bovine serum albumin for a more accurate comprehension of the binding of pristine nC₆₀ to bovine serum albumin. The nC₆₀ nanoparticles with different size distributions used in the experiments were obtained by the solvent displacement and centrifugation method. UV-Vis spectroscopy and fluorescence spectroscopy were used to study the binding of nC₆₀ with different size distributions to bovine serum albumin (BSA) before and after eliminating the fluorescence inner filter effect. The results showed that the fluorescence inner filter effect had an influence on the interaction between nC₆₀ and proteins to some extent, and still did not change the rule of the size-dependent binding of nC₆₀ nanoparticles to BSA. Further studies on the binding parameters (binding constants and the number of binding sites) between them were performed, and the effect of the binding on BSA structures and conformation were also speculated.