A novel thienothiophene-based “dual-responsive” probe for rapid, selective and sensitive detection of hypochlorite

Background: Hypochlorite/hypochlorous acid (ClO⁻/HOCl) is a biologically crucial reactive oxygen species (ROS), produced in living organisms and has a critical role as an antimicrobial agent in the natural defense system. However, when ClO⁻ is produced excessively, it can lead to the oxidative damage of biomolecules, resulting in organ damage and various diseases. Therefore, it is imperative to have a straightforward, quick and reliable method for over watching the minimum amount of ClO⁻ in different environments. Results: Herein, a new probe TTM, containing thienothiophene and malononitrile units, was developed for exceptionally selective and sensitive hypochlorite (ClO⁻) detection. TTM demonstrated a rapid “turn-on” fluorescence response (<30 s), naked-eye detection (colorimetric), voltammetric read-out with anodic scan, low detection limit (LOD = 0.58 μM and 1.43 μM for optical and electrochemical methods, respectively) and applicability in detecting ClO⁻ in real water samples and living cells. Significance and novelty: This study represents one of the rare examples of a small thienothiophene-based molecule for both optical and electrochemical detections of ClO⁻ in an aqueous medium.