Ultrasensitive microelectrode with enhanced surface area for clinical glutathione sensing and quantification

Glutathione, as an antioxidant, regulates oxidative stress in the human body. It is also an important biomarker of Alzheimer's and Parkinson's diseases. An ultrasensitive graphene oxide-silica-silver nanoparticles modified carbon fiber electrode was designed to detect reduced glutathione. The carbon fiber was dip-coated with GO-SiO 2 -AgNPs and inserted in the capillary. The fabrication was performed with the assistance of a handheld lens and under a microscope. The carbon fiber was connected to an external circuit through an electrolyte solution filled in a capillary tube and used as the working electrode. A linear correlation coefficient was obtained at optimized conditions from 0.25 μM to 3 μM versus Ag/AgCl. LoD and LoQ were 0.17μΜ±0.087 and 0.57μΜ±0.087, respectively. The proposed electrochemical sensor was successfully used for in vivo monitoring of glutathione. The sensor was compared with liquid chromatography- UV detection (HPLC-UV). The applicability of the sensor was successfully determined in in-vivo using a mouse. The developed sensor is fast, reproducible, and reliable. It is applicable for clinical diagnosis and monitoring of oxidative stress in real samples. • Graphene oxide –silica–Ag nanohybrid enhances carbon fiber electrode performance. • The increased surface area and catalytic activity allow for a rapid electrochemical process. • The sensor detected glutathione with extreme sensitivity in the 5–35 μM range. • The proposed sensor provides a promising tool for real-sample oxidative stress and clinical diagnostics.