A facile label-free colorimetric method for highly sensitive glutathione detection by using manganese dioxide nanosheets

Glutathione (GSH) provides essential functions towards metabolism process in biological systems and is related to many diseases such as human immunodeficiency virus, Parkinson, cardiovascular diseases, etc. In this work, a very simple, fast and label-free colorimetric method for highly sensitive GSH quantification is proposed. This strategy is based on the color change of MnO 2 nanosheets solution from yellowish-brown to colorless. Without GSH, MnO 2 nanosheets exhibit a strong ultraviolet–visible (UV–vis) absorption peak at 376   nm with the color showing as yellowish-brown. Once GSH is introduced, MnO 2 nanosheets are reduced to Mn 2+ ions rapidly, which leads to a yellowish-brown color fading and a remarkable decrease of the absorbance at 376   nm. Based on the distinct color change, a method for highly sensitive and selective detection of GSH was realized with bare eyes and UV–vis spectroscopy, respectively. This method has a wide dynamic range from 0.5   μM to 100   μΜ and shows a good linear relationship from 0.5   μM to 10   μΜ with a detection limit of 0.1   μM. More importantly, this procedure is very simple and the whole assay can be accomplished quickly within 5   min. Additionally, this developed assay has also been successfully applied to the detection of GSH in biological fluids with satisfactory results.