Evaluation of Biochemical Behavior and Stability of Gold Nanoparticles with High Intrinsic Peroxidase-Like Activity

Abstract

In this study, the biochemical behavior and stability of gold nanoparticles with intrinsic peroxidase-like activity were evaluated as potential native enzyme alternatives. The gold nanoparticles were synthesized at physiological temperature using bovine serum albumin as the stabilizer and then characterized by the TEM imaging method. Afterward, their peroxidase-like activity was checked upon irreversible oxidation of 3,3’-diaminobenzidine to produce a brown-colored indamine polymer, and the specific enzyme-like activity of the as-prepared nanoparticles was also calculated. The results showed a specific activity as high as 0.4212 UI µM-1 for the as-prepared gold nanoparticles. Thereafter, their stability and biochemical performances were evaluated considering their enzyme-like activity as a reliable index. The as-prepared nanoparticles showed their maximal activity at pH=5.0 and 20.0±1.0 ℃ according to the results of pH and thermal stability studies, in order. Besides, the nanoparticles saved above 80.0% of their maximal activity over pH=3.0-4.0. As a significant advantage compared to the natural enzymes, the as-synthesized gold nanoparticles revealed a pHindependent enzyme-like activity over a wide pH range of pH=7.0-10.0 along with a temperature-independent activity over t=23-28℃. The salt stability studies showed that their activity was not affected by variations in the ionic strength of the reaction media. The kinetics results showed a Vmax of 83.3 µM min-1 and a Km as very low as 0.005 M for the gold nanoparticles. Considering the above results, the as-prepared gold nanoparticles can be considered high stable nanozymes with high intrinsic peroxidase-like activity and excellent catalytic efficiency.