Sensitive electrochemiluminescence biosensor for glutathione using MnO₂ nanoflower as novel co-reaction accelerator...

In this work, MnO₂ nanoflower (NF), as novel and more effective co-reaction accelerator, was applied to construct a new ternary electrochemiluminescence (ECL) system of Ru complex/tripropylamine (TPrA)/MnO₂ NF. Compared with the classic Ru complex/TPrA binary ECL system, the reaction efficiency of co-reactant TPrA in the new ternary ECL system was obviously enhanced, leading to the significantly improved ECL signal by accelerating the dissociation of co-reactants into more active radicals. Then, an ECL biosensor was fabricated based on the proposed ternary ECL system, realizing the sensitive determination of glutathione (GSH). In order to realize the efficient nucleic acid amplification, a certain amount of GSH was firstly converted to a large number of intermediate DNA in assistance of Hg²⁺, which acted as walker could walk along with the DNA triplex immobilized on the electrode and cut off the DNA strand (S2) labeled with ferrocene (Fc). Owing to the fact that Fc possessed obvious quenching effect to the ECL of Ru complex labeled on the other side of S2, the ECL signal recovered significantly. Thus, the proposed ECL biosensor achieved the sensitive determination of GSH, and the detection limit was 50 nM.