Magnetic zirconium-based Prussian blue analog nanozyme: enhanced peroxidase-mimicking activity and colorimetric...

A magnetic zirconium hexacyanoferrate-based Prussian blue analog (MB@ZrHCF) nanozyme was synthesized using dopamine (DA) reduction-assisted method and employed for colorimetric PO₄^3- sensing. The MB@ZrHCF exhibits enhanced peroxidase-mimicking activity and ultrafast catalytic rate via the color reaction of 3,3',5,5'-tetramethylbenzidine (TMB) oxidized by hydrogen peroxide (H₂O₂). The catalytic reaction mechanism of MB@ZrHCF catalyzing H₂O₂ to produce hydroxyl radical (∙OH) was studied. Then, MB@ZrHCF was successfully applied to the detection of H₂O₂. Additionally, the catalytic activity of the nanocomposite is inhibited due to the steric hindrance effect from the coordination of PO₄^3- and Zr(IV) node. Based on this, the MB@ZrHCF nanozyme can be used to detect PO₄^3- in two linear ranges (10-100 µM and 100-200 µM) with a limit of detection of 2.25 µM. The proposed colorimetric sensor possesses excellent selectivity and reliability for PO₄^3- sensing, which can be successfully applied to detect PO₄^3- in sea and tap water samples.