Colorimetry/smartphone dual-mode sensing of ascorbic acid by a Co-Fe Prussian blue analog-based peroxidase-like platform

Recently, enthusiasm for catalysts-based nanozymes in various catalytic systems has been growing significantly. However, the low catalytic capacity of reported enzyme-mimic catalysts has not met the requirements for practical applications. In this work, Co-Fe Prussian blue analogs yolk-shelled nanocubes (Co-Fe PBAs YSHCs) successfully prepared by a template-assisted ion exchange method are demonstrated for efficient AA sensing. The as-prepared Co-Fe PBAs YSHCs display superior and desirable peroxidase-like activity. The unique YSHCs structures can expose large active sites and enhance the stability during the colorimetric sensing process. As a result, the Co-Fe PBAs YSHCs sensing platform can sensitively and accurately determine AA in both colorimetric and smartphone sensing modes, the wide linear ranges for AA were 1–95 μM with a low limit of detection of 0.9 μM. In addition, the Co-Fe PBAs YSHCs sensing platform can be explored for AA detection in human serum samples, yielding satisfactory recoveries. This work provides an ideal method for preparing catalysts and pioneers the investigation of nanozymes with peroxidase-like activity in biosensing platform. Scheme 1. Illustrations of the Co-Fe PBAs-based sensing platform. • Co-Fe Prussian blue analogs yolk-shelled nanocubes are successfully prepared for efficient AA sensing. • The Co-Fe PBAs YSHCs displays a superior and desirable peroxidase-like activity. • The unique YSHCs structures can expose large active sites and enhance the stability. • A wide linear range of 1–95 μM and a low limit of detection of 0.9 μM are achieved based on Co-Fe PBAs YSHCs.