Simple method for visual detection of glutathione S-transferase activity and inhibition using cysteamine-capped gold nanoparticles as colorimetric probes

An operationally simple colorimetric method for measuring glutathione S-transferase (GST) activity was developed using cysteamine-capped gold nanoparticles (AuNPs) in this work. This method was based that GST can catalyze the reaction of 1-chloro-2,4-dinitrobenzene (CDNB) and glutathione (GSH) to produce a conjugate (CDNB-SG). GSH could induce the aggregation of AuNPs, whereas the conjugate could not induce the aggregation of AuNPs. Thus, GST activity can be facilely assayed with the naked eye or a simple colorimetric reader. The convenient and simple colorimetric response of the assay makes them an attractive approach for drug-screening application.