Proteomic investigation on bio-corona of functionalized multi­walled carbon nanotubes

Abstract Background The formation of bio-corona, due to adsorption of biomolecules onto carbon nanotubes (CNTs) surface in a physiological environment, may lead to a modified biological “identity” of CNTs, contributing to determination of their biocompatibility and toxicity. Methods Multi-walled carbon nanotubes surfaces ( f -MWCNTs) were modified attaching acid and basic chemical functions such as carboxyl (MWCNTs-COOH) and ammonium (MWCNTs-N) groups respectively. The investigation of interactions between f -MWCNTs and proteins present in biological fluids, like human plasma, was performed by electrophoretic separation (SDS-PAGE) and mass spectrometry analysis (nLC-MS/MS). Results A total of 52 validated proteins was identified after incubation of f -MWCNTs in human plasma. 86% of them was present in bio-coronas formed on the surface of all f- MWCNTs and 29% has specifically interacted with only one type of f- MWCNTs. Conclusions The evaluation of proteins primary structures, present in all bio-coronas, did not highlight any correlation between the chemical functionalization on MWCNTs and the content of acid, basic and hydrophobic amino acids. Despite this, many proteins of bio-corona, formed on all f- MWCNTs, were involved in the inhibitor activity of serine- or cysteine- endopeptidases, a molecular function completely unrevealed in the human plasma as control. Finally, the interaction with immune system's proteins and apolipoproteins has suggested a possible biocompatibility and a favored bio-distribution of tested f -MWCNTs. General significance Considering the great potential of CNTs in the nanomedicine, a specific chemical functionalization onto MWCNTs surface could control the protein corona formation and the biocompatibility of nanomaterials.