Fig. 5

Catalytic and drug-loading properties of FeOOH&mSiO₂ Janus nanoparticles. (A) Absorption curve of methylene blue (MB) under different catalytic conditions (10 mM GSH, 10 mM H₂O₂, 125 µg/mL FMS, 125 µg/mL FMS + 10 mM H₂O₂ and 125 µg/mL FMS + 10 mM H₂O₂ + 10 mM GSH, respectively) determined by UV-vis absorption spectroscopy after being co-incubated for 3 h. The inset picture is the optical photograph of experimental group placed in absorbance-descending order. (B) Time-dependent curve of MB degradation under different GSH concentrations (0, 1.0, 2.5, 5.0, 10.0 mM). The inset picture is the optical photograph of experimental group placed in absorbance-descending order. (C) GSH (1 mM) depletion by FeOOH&mSiO₂ Janus nanoparticles determined by UV-vis absorption spectroscopy with DTNB as a probe. (D) X-ray photoelectron spectroscopy analysis of FMS and GSH-treated FMS (upper the former, lower the latter). Fe²⁺ and Fe³⁺ refer to standard fit peaks. Original XPS signals are weak because of the low content of Fe element in FMS samples (~ 10%). GSH concentration: 10 mM. (E) Illustration of the Fe³⁺-Fe²⁺ reaction circulation, in which Fe³⁺ depletes GSH, Fe²⁺ catalyzes Fenton reaction and degrades MB. All conditions are fixed as the experiment section except for the altered one. MB concentration: 10 µg/mL. pH: 5.4