Fig. 2. (A) UV-vis absorption spectra of papain-TMB solution containing H₂O₂ concentrations varied from 5.00 to 90.0 μM. (B) The relation between the absorbance at 652 nm and the H₂O₂ concentrations. (C) UV-vis absorption spectra of glucose-GOx–TMB-papain system in the presence of different concentration of glucose. (D) The calibration curve for glucose determination. Inset: Photographs for colorimetric detection of (B) H₂O₂ and (D) glucose, respectively.