Construction of an Ag⁺-functionalized structural color hydrogel sensor for colorimetric detection of glutathione

An Ag⁺-functionalized structural color hydrogel (Ag⁺-SCH) sensor is constructed for colorimetric detection of glutathione (GSH). The hydrogel is prepared by using the coordination of Ag⁺ and 1-vinylimidazole (1-VI) as cross-linking network. GSH acts as a competitive ligand to break the coordination between Ag⁺ and 1-VI, leading to the expansion and structural color change of the hydrogel. Quantification was achieved by measuring particle spacing changes, yielding a dynamic range of 0.1-200 μM with a limit of detection (LOD) of 0.04 μM. Alternatively, smartphone-based hue analysis enables sensitive GSH detection with a LOD of 0.79 μM. The sensor has proven to show high selectivity, excellent reusability, and long-term stability. In human serum tests, the Ag⁺-SCH performed comparably to commercial kits, while offering significantly lower cost. This portable, low-cost platform meets practical needs for GSH monitoring in diverse settings.