Rapid and ultrasensitive detection of biomarkers of diseases is of great importance in early diagnosis and monitoring the patient health conditions. Herein, we report a simple design for a naked-eye colorimetric biosensor for detection and determination of Glutathione (GSH) in human serum. In the presence of Horseradish peroxidase (HRP) and trace concentration of H2O2 and flavone apigenin, and of course GSH, oxidation of GSH results in generation of large amount of superoxide radicals (O2 •− ) which leads to etching of Au nanorods (AuNRs). The etching of AuNRs results in a blue-shift in the localized surface plasmon resonance (LSPR) of AuNRs, accompanied by a vivid color change from grey to blue then pink. The etching mechanism was well understood by carrying out a series of control experiments. The as-design naked-eye colorimetric biosensor possessed limit of detection of 34 nM, where the whole test was completed in only 5 min. Furthermore, proposed sensor showed an excellent selectivity toward interference substances. The practical tests were performed using human serum as a complex biological medium, where the as-designed biosensor was able to detect and determine GSH with an acceptable accuracy. Our findings suggest that the as-designed biosensor could be used for practical detection and determination of GSH level in for real samples, which could be a breakthrough in diagnosis of several GSH-related diseases.
