Amorphous iron-catecholates featuring efficient peroxidase-like activity for quick colorimetric detection of tannic acid

Designing efficient nanozyme to construct rapid analytical method for tannic acid (TA) content control has significant influence in food science area. Herein, by one-step self-assembly between Fe3+ and 2, 3, 6, 7, 10, 11-hexahydroxytriphenylene (HHTP), an amorphous nanomaterial (Fe-HHTP) was synthesized and fully characterized by TEM, AFM, XRD, EDS element mapping and XPS. Then, its peroxidase-like activity was explored by using H2O2 and 3, 3′, 5, 5′- tetramethylbenzidine (TMB) as typical substrates. Due to the inhibition of TA on Fe-HHTP catalyzed chromogenic reaction, a rapid and accurate colorimetric method for TA detection was constructed. After thorough verification, the method featured with merits of low limit of quantitation (0.50 μmol/L), good linear range (0.5–100.0 μmol/L) and high accuracy (recovery rate of 95.85–98.06%). From mechanism study, the inhibition of TA on chromogenic reaction might be resulted from its antioxidation ability and the formation of Fe3+-TA complex. Finally, this method was applied to visual detection of TA content in different teas and red wines.