Adsorption of plasma protein human serum albumin on surface functionalized multi-walled carbon nanotubes: Insights into binding interactions and effects on protein fibrillation

Carbon nanotubes (CNTs) have potential applications in various biomedical and biotechnological fields, importance of protein-CNTs interactions in living cells, as well as their concerns about the nanotoxicity of these CNTs, have not been well investigated. This study examines by experimentally human serum albumin (HSA) interaction with different surface functionalized multi-walled carbon nanotubes (MWCNTs). The adsorption was done on HSA onto 1,2-propanediol functionalized MWCNTs (MWCNTs-OH) and cysteamine functionalized MWCNTs (MWCNTs-SH) and estimates the corresponding adsorption parameters. During the adsorption process, pristine MWCNTs (p-MWCNTs) exhibit a higher adsorption capacity compared to MWCNTs-OH and MWCNTs-SH, with the order being: p-MWCNTs > MWCNTs-SH > MWCNTs-OH. Here also Isothermal Titration Calorimetry (ITC) experiments were employed to analyze the interaction of HSA onto MWCNTs-OH and MWCNTs-SH. The possible binding parameters were indicated that HSA forms complexes with MWCNTs-OH and MWCNTs-SH at specific nearby binding sites. And anti-fibrillation activity of surface functionalized MWCNTs was assessed using Thioflavin T (ThT) and Congo Red (CR) spectroscopic techniques, the secondary conformational changes were observed through circular dichroism (CD) experiments, additionally, the inhibitory role of surface functionalized MWCNTs in HSA fibril formation was confirmed through microscopic evaluations.