Fig. 3: Characterizations of artificial enzymes and their catalytic and fluorescence imaging performances.

a Schematic diagram of Apt-Fe₃O₄ catalysis. b, c Rates of hydroxylation of tyrosine to Dopa by Fe₃O₄, Apt-Fe₃O₄ and Ran-Fe₃O₄ in the presence of H₂O₂, AA and variable concentrations of tyrosine in aqueous solution (b) and in crowded solution (c). d Schematic diagram of strand displacement responsiveness and catalysis of FNA-Fe₃O₄. e PAGE analysis of the functional nucleic acids structure and the strand displacement reaction (red strand: tyrosine aptamer; green-yellow strand: block strand; blue strand: SNCA mRNA; green substrate: tyrosine). Gel was representative of n = 3 independent experiments. f, g Rates of hydroxylation of tyrosine to Dopa by FNA-Fe₃O₄ with or without mRNA in the presence of H₂O₂, AA and variable concentrations of tyrosine in aqueous solution (f) and in crowded solution (g). h The typical cyclic process of tyrosine capture and hydroxylation by 10 μg mL⁻¹ artificial enzymes in the presence of 100 μM tyrosine, 5 mM H₂O₂ and 5 mM AA. i Catalytic selectivity of 10 μg mL⁻¹ artificial enzymes for hydroxylation of 100 μM tyrosine and interference molecules in the presence of 5 mM H₂O₂ and 5 mM AA. b, c, f, g, h and i The results were expressed as mean ± SD (n = 3 independent experiments). b, c, f and g P-values were calculated by two-tailed t-test. Source data are provided as a Source Data file.