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. 2022 Jun 18;20:404–417. doi: 10.1016/j.bioactmat.2022.06.005

Fig. 2.

Fig. 2

The pH-responsive performances and •OH generation of Mn-ZnO2 NPs. (a) Schematic illustration of the release of dual Zn-Mn ions and H2O2 and subsequent •OH generation from Mn-ZnO2 NPs. (b) UV–vis spectra of the Pierce™ Quantitative Peroxide (PQP) solution incubated with Mn–ZnO2 NPs at neutral (pH 7.4) or acidic (pH 5.5) conditions. Release profiles of (c) Zn2+ and (d) Mn2+ from Mn-ZnO2 NPs at different pH conditions. (e) The MRI images (left) and γ1 values (right) of Mn–ZnO2 NPs under different pH conditions. (f) ESR signals detected under different conditions (H2O, ZnO2 NPs at pH 7.4 or 5.5, Mn-ZnO2 NPs at pH 7.4 or 5.5). (g) The UV-vis-NIR absorption spectra of different solutions (MB, MB plus ZnO2 NPs at pH 7.4 or 5.5, MB plus Mn-ZnO2 NPs at pH 7.4 or 5.5). (h) The UV-vis-NIR absorption spectra of NaHCO3 (25 mM)/MB (5 μg/mL) mixed solutions at pH 5.5 with the presence of Mn-ZnO2 NPs at different concentrations. (i) The time-dependent UV-vi-NIR absorption spectra of MB reacted with 200 μg/mL Mn-ZnO2 NPs and 25 mM NaHCO3 at pH 5.5.