Fig. 3.

a UV–Vis absorption spectra of the feeding formulations and the final product BCFe@SRF. b Fluorescence emission spectra of free Ce6, BCFe@SRF and BCFe@SRF degration product excited by 404 nm laser. Insert: the corresponding fluorescence images. c The spectra of ABDA absorbance treated with BCFe@SRF upon different times of laser irradiation (670 nm, 50 mW·cm⁻²). d SRF release profiles from BCFe@SRF in PBS with or without Na₂S₂O₄ at 37 °C. e The schematic diagram of the iron redox cycling. f Observation on the iron redox cycling of BCFe@SRF