A novel ultrasensitive electrochemiluminescence biosensor for glutathione detection based on poly-L-lysine as co-reactant and graphene-based poly(luminol/aniline) as nanoprobes

In this work, an ultrasensitive electrochemiluminescence (ECL) biosensor was constructed using poly-L-lysine (PLL) as a novel co-reactant of luminol and poly(luminol/aniline) nanorods loaded reduced graphene oxide (PLA@rGO) as nanoprobe, which enable highly sensitivity detection of glutathione (GSH). To the best of our knowledge, it is the first time that PLL was used for the co-reactant of luminol. Notably, about a 5-fold enhancement was obtained compared with the individual PLA@rGO using GCE. Due to the remarkable quenching effect between the excited state of PLL and the reduced form of GSH in the ECL system of luminol/PLL, the ECL sensing platform exhibited wide linear ranges of 1.0 x 10(-9)-1.0 x 10(-4) M and 1.0 x 10(-4)-1.0 x 10(-2) M and a low detection limit of 7.7 x 10(-10) M. Simultaneously, the biosensor was also successfully applied to detect GSH in human serum sample with high recoveries. Hence, this work would open a new platform for the wide application of PLL in immunoassay and various sensors.