Bivalent Metal Ions Tethered Fluorescent Gold Nanoparticles as a Reusable Peroxidase Mimic Nanozyme

Nanozymes are a class of mimic enzymes that have both unique properties of nanomaterials and catalytic functions. They are widely used in medicine, food, agriculture, and environment due to their high catalytic efficiency, stability, economy, and large-scale preparation. In this work, a simple, gentle method was applied to synthesize adenosine phosphates (AXP) templated gold nanoparticles (Au NPs) with small size, good optical properties, and peroxidase-like activities. In the presence of hydrogen peroxide (H2O2), the peroxidase substrate 3, 3′, 5, 5′-tetramethylbenzidine (TMB) could be oxidized to form blue-colored oxidized TMB (oxTMB), which demonstrates that the AuAXP NPs have peroxidase-like activities. Interestingly, the introduction of bivalent metal ions into AuAXP NPs allows their reusability. Among them, after three rounds of recycling, the catalytic activity of Mg@AuAMP could still reach 92.69% compared to the original level, which showed excellent reusability. In addition, the glutathione (GSH) detection was realized with a linear detection range of 0–200 μM due to the GSH-induced loss of peroxidase-like activities. Overall, this work provides a new idea of recycling for biosensor and catalytic analysis.