Fig. 2: Preparation and characterization of UCNP-Cro/FA.
A Element mapping images of UCNP-OA. B FTIR spectra of UCNP-OA and UCNP-NH2. C UV–vis absorption spectra of UCNP-NH2, Cro, FA-PEG, and UCNP-Cro/FA. UCNP-Cro/FA exhibited absorption peaks corresponding to FA-PEG at 284 nm and Cro at 804 nm. D Digital photograph of UCNP-NH2, UCNP-FA, and UCNP-Cro/FA in aqueous solution with or without NIR irradiation. E, F Size distribution of UCNP-NH2 and UCNP-Cro/FA in aqueous solution examined by DLS and TEM. G Comparison of size and zeta potential of different nanoformulations (n = 3 independent experiments in each group). H Fluorescence imaging of UCNP-Cro/FA solutions after incubation with various concentrations of Fe3+ ions. Ex/Em=780 nm/820 nm. I UV–Vis absorbance spectra of UCNP-Cro/FA solution with the addition of Fe3+ ions at different concentrations. J The absorbance of 1,10-phenanthroline-ferrous iron at 510 nm after different treatments of UCNP-Cro/FA + Fe3+ ions solution. UV and NIR lasers induced the valence conversion of Fe3+ ions in solution, indicating the photoreduction of Fe3+ ions by UV irradiation (n = 3 independent experiments in each group). K UV–vis absorption spectra of 1,10-phenanthroline-ferrous iron in UCNP-Cro/FA + Fe3+ ions solution under 980 nm NIR irradiation for different times, showing the time-dependent production of Fe2+ ions. L Variation of UCNP-Cro/FA + Fe3+ ions solution absorption spectra with 980 nm NIR irradiation. M) Schematic illustration of UCNP-Cro/FA in response to Fe3+ ions and NIR light irradiation. Created in BioRender. Luwen, Z. (2025) BioRender.com/n85y153. Experiments in (A), (D), (E), (F) and (H) were repeated three times independently with similar results. Error bars represent the mean ± SD. Source data are provided as a Source Data file.
