Fig. 3

Responsiveness and sensitivity of FTRNPs. (a) UV-vis absorption spectra of H₂O₂-treated FTRNPs at different pH levels. (b) The absorbance of FTRNPs at 650 nm at different pH levels before (off) and after “turning on” by H₂O₂.(off: without H₂O₂-treatment, on: with H₂O₂-treatment) (c) Photograph of FTRNPs solution at different pH levels after “turning on” by H₂O₂. (d) UV-vis absorption spectra of FTRNPs upon addition of H₂O₂ at different concentrations. (e) The absorbance of FTRNPs at 650 nm as a function of H₂O₂ concentrations. (f) Photograph of FTRNPs solution after “turn on” by H₂O₂ (0–80 µM). (g) PA images of FTRNPs before and after “turning on” by H₂O₂. (h) PA spectra of FTRNPs before and after “turning on” by H₂O₂. (i) PA images of FTRNPs after “turning on” by H₂O₂ (0–80 µM). (j) The PA amplitude of FTRNPs at 690 nm after “turning on” by H₂O₂ (0–80 µM)