TFRC and Parkinson disease: Next, to achieve the efficient BBB crossing and neuron-specific responsiveness of the artificial enzyme for PD treatment, the block strand composed of SNCA antisense oligonucleotide and TfR aptamer was designed and hybridized to the tyrosine aptamer on Apt-Fe3O4 to construct the functional nucleic acid-based responsive artificial enzyme FNA-Fe3O4 (Fig. 3d and Supplementary Fig. 7).