Fig. 4: Cellular availability of the artificial enzymes.

a Schematic of FNA-Fe₃O₄ crossing the in vitro BBB model. b Transport efficiency of the artificial enzymes across the BBB in vitro. c Flow cytometry analysis of cellular uptake of the artificial enzymes. d Confocal fluorescence images of the gradual cellular internalization of FNA-Fe₃O₄ at different time interval. e, Cell viability of BV2 cells incubated with the artificial enzymes at different concentrations. b, e The results were expressed as mean ± SD (n = 3 biologically independent samples). b P-values were calculated by two-tailed t-test. c, d One representative data was shown from three independently repeated experiments. Source data are provided as a Source Data file.