Tunable assembly of Ferric ion-dopamine molecules into hedgehog-like nanozyme for colorimetric and sensitive detection of acrylamide in thermally processed foods

The ferric ion-polydopamine coordination hedgehog-like superstructure (hedgehog-like Fe-PHS) was fabricated using the metal–ligand crosslinking strategy, which was used as a colorimetric sensor for acrylamide (AA) visual detection. The hedgehog-like Fe-PHS exhibited outstanding peroxidase-like activity toward the decomposition of H2O2 and production of hydroxyl radical (OH), and oxidized colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxTMB. The TMB oxidation was quenched by glutathione and then recovered via a thiol-ene Michael addition reaction between glutathione and AA. The increase in AA concentrations accelerated the TMB oxidation and recovered the dark blue color. Thus, the hedgehog-like Fe-PHS was used as a colorimetric sensor for detecting AA. A wide linear range from 0.75 to 36.00 µM (R2 = 0.9950) and a low limit of detection of 0.27 µM with excellent selectivity were obtained. AA was visually detected with "naked eye" using hedgehog-like Fe-PHS. Meanwhile, the hedgehog-like Fe-PHS colorimetric sensor was successfully applied for detecting AA in thermally processed foods, and its practical feasibility was verified using the HPLC method.