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

A magnetic zirconium hexacyanoferrate-based Prussian blue analog (MB@ZrHCF) nanozyme was synthesized using dopamine (DA) reduction-assisted method and employed for colorimetric PO 4 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 (H 2 O 2 ). The catalytic reaction mechanism of MB@ZrHCF catalyzing H 2 O 2 to produce hydroxyl radical (∙OH) was studied. Then, MB@ZrHCF was successfully applied to the detection of H 2 O 2 . Additionally, the catalytic activity of the nanocomposite is inhibited due to the steric hindrance effect from the coordination of PO 4 3- and Zr(IV) node. Based on this, the MB@ZrHCF nanozyme can be used to detect PO 4 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 PO 4 3- sensing, which can be successfully applied to detect PO 4 3- in sea and tap water samples.