Hydrogen-bonded porphyrin frameworks hosting single-site iron centers as a robust peroxidase mimic for food antioxidant quantification.

Abstract

Rapid and accurate antioxidant detection is essential for assessing food quality, yet current total antioxidant capacity (TAC) assays remain constrained by limited sensitivity and susceptibility to matrix interference. Herein, we report a hydrogen-bonded organic framework nanozyme featuring isolated iron sites (HOF-FeTCPP) for colorimetric detection of food TAC. HOF-FeTCPP is assembled from iron-porphyrin building blocks into an ordered crystalline framework, wherein dispersed Fe(III) centers confined within the HOF matrix generate an enzyme-mimetic microenvironment that markedly enhances catalytic efficiency. Mechanistically, HOF-FeTCPP catalyzes the homolytic cleavage of hydrogen peroxide via iron valence cycling, efficiently generating hydroxyl radicals and thereby enabling the sensitive oxidation and colorimetric response of chromogenic substrates. Based on this, we constructed a colorimetric TAC detection platform characterized by high sensitivity, wide linear range and strong anti-interference capability, which demonstrated satisfactory accuracy and practicality in beverage samples analysis. This work pioneers the application of HOF nanozyme in food antioxidant detection, establishing a platform for rapid quality assessment and extending biomimetic framework materials into food analysis.