Ultrasensitive Detection of Hydrogen Peroxide Using Methylene Blue Grafted on Molecular Wires as Nanozyme with...

In this study, we present the development of an electrochemical sensor designed for ultrasensitive detection of endogenous H₂O₂. This sensor relies on signal amplification achieved through nanozyme activity exhibited by methylene blue (MB) grafted onto a peptide support. The sensor exhibited excellent selectivity and sensitivity, with a limit of detection of 18 nM and a linear detection range of 20-200 nM. Thus, we have validated the concept of the MB-peptide system, serving as both an electroactive label and a catalyst for H₂O₂ decomposition under electrochemical conditions. The implemented signal amplification system enables the rapid detection of H₂O₂, with an overall assay time of 1-2 min, a significant improvement compared to amperometric detection using surface-immobilized enzymes.