Chitosan–gold nanoparticles as peroxidase mimic and their application in glucose detection in serum

Abstract

Artificial peroxidases have attracted considerable interest due to their significant advantages over their natural counterparts. Chitosan–gold nanoparticles (AuNPs) were discovered to function like a peroxidase in this study. The catalytic activity of AuNPs was illustrated by catalyzing the oxidation reaction of 3,3′,5,5′-tetramethylbenzidine (TMB) accompanied with a color change. The optimal catalytic activity was obtained at 50 °C and pH = 4.2. Interestingly, the peroxidase-like activity of AuNPs is higher than that of horseradish peroxidase and effective during a broad temperature range between 10–90 °C. The color change is dependent on the concentration of hydrogen peroxide, thus the determination of hydrogen peroxide was demonstrated with a limit of detection (LOD) of 0.6 μM. Furthermore, using peroxidase-like properties of the AuNPs, in combination with the highly specific reaction of glucose oxidase, selective detection of glucose was conducted with an LOD of 3 μM. In addition, the method was applied to detect glucose in 60% serum with an LOD of 12 μM. In conclusion, considering the high peroxidase-like activity, good cytocompatibility and ease of preparation, chitosan–AuNPs would have a wide range of potential applications in biocatalysis and bioassays.