Size-dependent binding of pristine fullerene (nC 60 ) nanoparticles to bovine/human serum albumin

The size of nC60 nanoparticles may exert profound influence on their binding to serum albumins and their ability to alter protein structure and conformation. To verify this speculation, in this work, five fractions of nC60 dispersions with different particle size distributions were prepared by centrifuge method and characterized using UV–Visible absorption spectroscopy and transmission electronic microscopy. In this work, the binding of five fractions of nC60 nanoparticles with bovine serum albumin (BSA) was demonstrated using fluorescence and synchronous fluorescence spectroscopy. Through the analysis and comparison of binding interactions, it was found that the diameter of nC60 nanoparticles plays a key role in the binding patterns of nC60 nanoparticles to BSA. The smaller nC60 nanoparticles had stronger binding to BSA and exhibited greater influence on the conformation change of BSA. Further study showed that human serum albumin (HSA) has similar binding interaction to nC60 nanoparticles, but the conformation changes of human serum albumin caused by five fractions of nC60 nanoparticles were different from bovine serum albumin. Despite the different particle sizes, the binding sites of nC60 nanoparticles to BSA/HSA were mainly in the vicinity of tryptophan residues. The possible interaction mechanism and the prospects were also discussed.