Abstract
Investigation of non-covalent interaction of hydrophobic surfaces with the protein G (PrG) is necessary due to their frequent utilization in immunosensors and ELISA. It has been confirmed that surfaces, including carbonous-nanostructures (CNS) could orient proteins for a better activation. Herein, PrG interaction with single-walled carbon nanotube (SWCNT) and graphene (Gra) nanostructures was studied by employing experimental and MD simulation techniques. It is confirmed that the PrG could adequately interact with both SWCNT and Gra and therefore fine dispersion for them was achieved in the media. Results indicated that even though SWCNT was loaded with more content of PrG in comparison with the Gra, the adsorption of the PrG on Gra did not induce significant changes in the IgG tendency. Several orientations of the PrG were adopted in the presence of SWCNT or Gra; however, SWCNT could block the PrG-FcR. Moreover, it was confirmed that SWCNT reduced the α-helical structure content in the PrG. Reduction of α-helical structure of the PrG and improper orientation of the PrG-SWCNT could remarkably decrease the PrG tendency to the Fc of the IgG. Importantly, the Gra could appropriately orient the PrG by both exposing the PrG-FcR and also by blocking the fragment of the PrG that had tendency to interact with Fab in IgG.
Highlights
The immobilization of oriented antibodies on nanostructures has been in the center of attraction especially in antibody-based biosensors[1]
And B, with an increase in single-walled carbon nanotube (SWCNT)/Gra concentrations from 5 μg/ml to 100 μg/ml -while keeping the concentration of the protein G (PrG) constant at 100 μg/ml, the concentration of the PrG was significantly reduced in the supernatant due to the adsorption of the PrG on SWCNT/Gra. It means that the addition of both CNS to the mixtures prepared more surfaces inducing the interaction of the PrG with both SWCNT and Gra
After incubation of the PrG with SWCNT/Gra, a sharp peak around 280 nm was exhibited indicating that SWCNT/Gra had been functionalized by the PrG as tryptophan, showed strong absorbance around 280 nm (Figs. 1E and F)
Summary
The immobilization of oriented antibodies on nanostructures has been in the center of attraction especially in antibody-based biosensors[1]. In the present study, experimental and molecular dynamics (MD) simulation studies have been both applied to discover the adsorption mechanism and the structural changes occurring in the PrG upon binding to an SWCNT and Gra nanostructure surfaces. These findings would remarkably improve the knowledge about different behaviors of similar proteins in presence of different types of CNS. Previous studies have indicated that various types of antibodies randomly interact with hydrophobic surfaces In this regard, using functionalized hydrophobic surfaces with the PrG, which not induce structural change in its FcR, will improve antibody loading[41,42]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
