Fig. 7: Analytical performance of the pFeSAN-based colorimetric system for GSH detection.

a Schematic illustration of the pFeSAN-based GSH biosensing system. b The linear relationship between the relative activity and the GSH concentration ranges from 50 nM to 1 mM. Inset shows the photograph of reaction solution in the different concentration of GSH. c Comparison of the performance of the detection of GSH with different methods. d Selectivity toward GSH of the pFeSAN-based colorimetric system against common interfering chemicals. The numbers from 1 to 15 are Ctrl, GSH, Na⁺, Ca²⁺, Mg²⁺, K⁺, glutamic acid, tryptophan, arginine, glycine, cysteine, ascorbic acid, glucose, glucose oxidase and BSA. e The linear relationship between the variation of relative activity and the number of cells. The inset: photographs of reaction solution with different cell numbers. **p = 0.0035. f DAB staining was performed to evaluate the level of GSH in tumor-bearing liver tissue. Scale bar = 200 μm. A representative image of three replicates from each group is shown. g Ki67 staining was performed to assess the proliferation of tumor cells in tumor-bearing liver tissue. Scale bar = 200 μm. A representative image of three replicates from each group is shown. h Pearson’s correlation coefficient of the oxidized DAB (brown)/Ki67 (red fluorescence), which appeared in tissue slices of tumor-bearing liver tissue (Pearson’s coefficient r = −0.76). These data are presented as mean values  ±  SD (n  =  3 independent experiments). Statistical significance was determined by two-tailed t test (**p  <  0.01). Source data are provided as a Source Data file.