Figure 4.
(A) Responses of our system toward 50 μM biothiols molecules including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) and other amino acids. The inset shows the corresponding color. (B) A plot of the normalized absorbance values at 450 nm of the proposed system versus the concentration of cysteine in the urine sample. The inset shows the color responses of iodide-capped AuNPs to different concentrations of cysteine. (C) Correlation between the normalized absorbance results obtained in the diluted urine samples and the standard samples of cysteine with six concentrations (0.5, 1, 2, 5, 10, 20 μM) (R2 = 0.95).