The optimization of gold nanoparticles-horseradish peroxidase as peroxidase mimic using central composite design for the detection of hydrogen peroxide

The oxidizing agent, hydrogen peroxide (H2O2), which is a part of reactive oxygen species (ROS) is well-known to contribute to oxidative stress-induced damage to biological molecules. An excess of free radicals can harm health and is associated with human diseases. Gold nanotechnology, a highly relevant nanomaterial, has been utilized as a new material in advanced sensor detection. In this study, colorimetric methods based on peroxidase enzymes were developed for measuring H2O2. The synthesized gold nanoparticles (AuNPs) showed a concentration of approximately 1.73 nM at a wavelength of 520 nm. The average diameter displayed a uniform size distribution, estimated at 18 nm, and an increase in the shell thickness of AuNPs-horseradish peroxidase (HRP) was observed in the TEM images. The AuNPs-HRP system demonstrated remarkable catalytic activity in the reaction of the chromogenic substrate tetramethylbenzidine (TMB) with H2O2, resulting in the production of an oxide product. The optimal conditions for the AuNPs-HRP system, as determined by central composite design (CCD), were a temperature of 25 degrees C and a pH of 7 within an 8 h period. A strong linear relationship was observed between different absorbance values and the H2O2 concentration, with a coefficient of determination of 0.9956. A portable platform was successfully used to determine H2O2 levels in beverages with recoveries ranging from 95.51% to 118.85%. These findings suggest that the AuNPs-HRP system could be applied to detect H2O2 in beverages.