Fig 2: 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.

Fig 3: Intracellular biological effects of the artificial enzymes.a Schematic diagram of Cat-Fe3O4 Catalysis. b Schematic diagram of strand displacement of ASO-Fe3O4. c Artificial enzymes mediated changes in intracellular dopamine levels. d Dopa incubation induced dramatic fluctuations in intracellular dopamine levels. Arrows represent Dopa removal time point (adding fresh culture medium). e SNCA expression in diffierent treated SH-SY5Y cells. f, g Confocal imaging of normal cells (without EGFP fluorescence) and PD cells (express EGFP fluorescence) (f) and co-cultured cells by FNA-Fe3O4 (g). h Flow cytometry analysis corresponding to each panel in (f) and (g). c, d The results were expressed as mean ± SD (n = 3 biologically independent samples). c P-values were calculated by two-tailed t-test. e-h one representative data was shown from three independently repeated experiments. Source data are provided as a Source Data file.