Fig. 4. (a) Schematic synthetic process of FePt@FeO_x@TAM-PEG NP. (b–e) Measurement of ˙OH generation via TMB probe for FePt@FeO_x-PEG or FePt@FeO_x@TAM-PEG NP in different pH (pH = 3.4, 4.4, 5.4, 6.4, and 7.4). (f) ESR spectra of different groups at different pH. (g) ROS staining images using DCFH-DA probe of tumor slices for different groups (green indicates ROS and blue indicates cell nucleus). (h) The corresponding quantification of fluorescent intensity from (g). Reproduced with permission from ref. 44. Copyright 2021, Wiley-VCH.