Interaction of Colloidal Gold Nanoparticles with Protein

The interaction between nanoparticles (NPs) with biomaterials has many applications. In the present research, the interaction between colloidal gold nanoparticles and human protein, human chorionic gonadotropin) was studied to find out the changes in the structure of protein at the presence of colloidal gold nanoparticles and the quantity of protein that colloidal gold nanoparticles absorbed on the hCG surface. Colloidal gold nanoparticles were synthesized through the reduction of HAuCl₄ using ammonium hydroxide. The gold nanoparticles were estimated at 20 nm in diameter. The results showed that there was a significant adsorption of colloidal gold nanoparticles absorbed on the hCG surface. Sips equation was used to express the absorption of isotherms and to calculate the absorption parameters and thermodynamic constant. Fluorescence study indicated a mild change in the tertiary structure near the microenvironment of the aromatic amino acids tyrosine and phenyl alanine, which was due to the interaction forces between the colloidal gold nanoparticles and hCG protein that affected the environment. It can be concluded that the colloidal gold nanoparticles had effects on the tertiary structure of proteins and affected the availability of hCG concentration.