Colorimetric and smartphone-visual detection of biothiols in human serum and red wine based on POD-like activity of Fe-CDs

• Colorimetric detection of biothiols at 652 nm. • Smartphone-visual detection of biothiols in human serum. • Paper-based determination of GSH in wine. An efficient mimic peroxidase platform of Fe-CDs/GOx based on the hybrid cascade system to produce in-situ H 2 O 2 for the visualized detection of glucose has been also developed in our group. Herein, the [Fe-CDs + H 2 O 2 + TMB] system was further performed to detect the biothiols (GSH, Cys, and Hcy) as representatives of the –SH group. The result exhibits that the higher concentration of biothiols can cause the absorbance signal at 652 nm to decrease, and the deep-blue color of oxTMB turns green until it is faded in 20 min by the naked eye. The colorimetric method showed the LOD are 0.54, 0.29, and 1.41 μM for GSH, Cys, and Hcy respectively, without interference in the presence of other amino acids . The smartphone-based and paper-based determination display good respect for biothiols in human serum or GSH in red wine. These simple and convenient strategies provide potential applications in the fields of clinical diagnosis and foods.