Etched CoFe Prussian blue analog nanozymes with superior peroxidase activity for colorimetric biosensing of hydrogen peroxide and dopamine.

Nanozymes represent a compelling alternative to natural enzymes due to their exceptional stability and cost-efficiency in diagnostic and therapeutic applications. In this work, a nanozyme etched CoFe Prussian blue analog (etched PBA) was designed and fabricated by a simple approach involving first synthesizing CoFe PBA and then chemical etching. The fabricated etched PBA acts as a peroxidase mimic catalyst. Compared to the naturally occurring enzyme (horseradish peroxidase), the etched PBA exhibited improved peroxidase-like catalytic efficiency for oxidizing 3,3',5,5'-tetramethylbnmenzidine (TMB). Particularly, the exceptional peroxidase-like activity of the etched PBA is attributed to modifications in its electronic and structural properties, which improved affinity for hydrogen peroxide (HO) and TMB. Hence, these findings highlight etched PBA as a promising peroxidase mimic, enabling a colorimetric assay for real-time HO and dopamine (DA) detection. HO was detected via PBA-catalyzed TMB oxidation (bluish-green color), while DA monitoring occurred through ox-TMB reduction. The detection thresholds for HO and DA were determined to be 0.083 μM and 0.05 μM, respectively, with broad linear ranges of 0.1 μM - 4.0 mM for HO and 0.1-240 μM for DA. In addition, the etched PBA was validated for real sample analysis, showing potential for enzyme catalysis, biosensing, and colorimetric analysis of pharmaceuticals and biomolecules.