Latent Redox Reporter of 4-Methoxyphenol as Electrochemical Signal Proxy for Real-Time Profiling of Endogenous HO in Living Cells.

Hydrogen peroxide (HO) plays a persuasive role in the human cell physiology. Developing an efficient assay platform and a highly sensitive tracking and quantification of HO in a physiological system is crucial to understand the neoplastic changes and/or redox homeostasis of cells. In this study, a novel turn-on latent electrochemical redox probe coupled with electrocatalytic signal amplification strategy is proposed. A custom-made readily available turn-on latent electrochemical probe 4-methoxyphenylboronic acid pinacol ester (4-MPBP) have been designed for the selective detection of endogenous HO in live cells. The electrochemical probe composed of a latent electrochemical reporter (4-methoxy phenol, 4-MP) bearing a recognition unit (boronic acid pinacol ester) for HO sensing. The selective analyte-triggered chemical transformation releases free electrochemical reporter 4-MP. The amount of HO was evaluated electrochemically at glassy carbon electrode (GCE) with a broad detection range of 0.5 μM-1 mM. An amplified signal response of released 4-MP to build a highly sensitive assay tool has been achieved via replacing the GCE transducer electrode with polydopamine@carbonnanotube-molebtinumdisulfie hybrid modified GCE as it delivered an exceptional dynamic detection range of 0.01-100 μM. The innovative blend of electrochemical molecular probe strategy, with electrocatalytic signal amplification technique has delivered outstanding assay performance at trace level sensing of HO. Next, we set up a platform for real-time in vivo monitoring of the endogenously produced HO in Caco-2 and MCF-7 cells through spermine-polyamine analogue and phorbol 12-myristate 13-acetate induction in SSAT/PAO gene and protein kinase C, respectively. As expected, the 4-MPBP latent probe coupled with electrocatalytic signal amplification strategy delivered outstanding performance for in situ HO release and tracking over time.