Characterization and release behaviors of ATMO‐21 from as‐fabricated NPs (AcDex‐ATMO‐21 NPs, SpAcDex‐ATMO‐21 NPs, and B1L@SpAcDex‐ATMO‐21 NPs). a) TEM images of B1L@SpAcDex‐ATMO‐21 NPs. Scale bar, 200 nm. b) Size of B1L@SpAcDex‐ATMO‐21 NPs measured by TEM; the inserted photograph is a photograph of B1L@SpAcDex‐ATMO‐21 NP solution. c) Zeta potentials of as‐fabricated NPs. Data are presented as means ± SD (n = 3). d) ATMO‐21 loading efficiency in NPs. Data are presented as mean ± SD (n = 3, one‐way ANOVA, *p < 0.05, **p < 0.01, ***p < 0.001). e) Degradation of B1L@SpAcDex‐ATMO‐21 NPs (without ATMO‐21) incubated at pH 7.4 and pH 5. Data are presented as means ± SD (n = 3). f) Release of ATMO‐21 from B1L@SpAcDex‐ATMO‐21 NPs incubated at pH 7.4 and pH 5. Data are presented as means ± SD (n = 3). g) TEM images of morphology monitoring of AcDex‐ATMO‐21 NPs, SpAcDex‐ATMO‐21 NPs, and B1L@SpAcDex‐ATMO‐21 NPs at different time points (0, 2 h, 6 h, and 24 h) of incubation in simulated cell conditions at pH 7.4 and pH 5. Scale bar, 100 nm. h) Fluorescence spectra of B1L@SpAcDex‐ATMO‐21 NP solutions incubated at pH 7.4 and pH 5.