Effect of crude and carboxyl-functionalized carbon nanotubes on protein-protein interaction

Carbon nanotubes (CNTs) could serve as nanovehicle for drug delivery. It is proposed that this class of emerging materials is capable to penetrate into cells without causing cell death. However, relatively little is known about the potential biological risks from CNTs. Nanoparticles present enormous surface areas and are found to enhance the rate of protein fibrillation by decreasing the lag time for nucleation. Protein fibrillation is associated with protein misfolding diseases including Type II Diabetes, Alzheimer’s, Parkinson's,Creutzfeld-Jacob disease and Dialysis-related amyloidosis. In the present study, via Congored binding assay and circular dichroism (CD) spectroscopy we investigated the amyloidogenic effects of crude and carboxylated-CNT on the in-vitro fibrillogenesis of hen-egg lysozyme at acidic condition. Our results showed that the formation of lysozyme amyloid fibrils at pH 2.0 and 55°C was remarkably increased by the addition of crude unmodified CNTs, whereas carboxylated CNTs did not enhance theprobability of appearance of a critical nucleus for nucleation of protein fibrils.