Fabrication of Glutathione-S-Transferase–ZnO Nanoconjugate Ensemble FET Device for Detection of Glutathione

This article reports fabrication and characterization of field effect transistor (FET) device consisting of zinc oxide (ZnO) nanoparticle-glutathione-S-transferase (GST) composite channel for successful in vitro detection and quantification of glutathione (GSH) in solution and in cancerous cell. The functionalized channel layer is synthesized by means of electrostatic binding between ZnO nanoparticles and GST. Detection of glutathione can be confirmed by the change in output current characteristics of the device in real time whenever the conjugation reaction between GSH and 1-chloro-2, 4-dinitrobenzene (CDNB) in the presence of GST takes place on the channel of the device. The characterized device had a sensitivity of 60.22 μA/dec and limit of detection (LoD) of 43.96 nM. Thus, from the device characteristics, GSH could be quantified. Subsequently, laboratory grown HeLa, MCF-7 (both cancerous), and human embryonic kidney (HEK-noncancerous) cells were characterized with the fabricated device and both the cancerous cells resulted in significantly higher drain current compared to noncancerous HEK cells. The fabricated device resulted in a sensitivity of 210.86 nA/cell and LoD of 30 cells when characterized with HeLa cells. This detection paves way for a device-based early detection scheme for cancer by measuring the GSH concentration in human cell cytosol.