Fig. 4. (a) Chemical equation for the generation of H2O2 through UA/uricase reaction. (b) NIR-II emission spectra of 100 μL of NaCeF4:Er/Yb NCs (0.5 mg mL–1) after the addition of 100 μL of H2O, uricase (0.011 U mL–1), UA (900 μM) and uricase (0.011 U mL–1) + UA (900 μM), respectively, upon excitation at 980 nm. (c) Calibration curve for the UA assay. The control experiment was carried out by replacing UA with H2O under otherwise identical conditions. The inset shows the linear range (0.411–900 μM) of the calibration curve.
