Highly sensitive and selective electrochemical detection of catechol using surface molecularly-imprinted film integrated with ratiometric indicator displacement assay

Catechol (CC) is an important environmental pollutant due to its toxicity, non-degradability and widespread distribution. The rapid, sensitive, and selective detection of CC remains a challenging task owing to the coexistence of multiple phenolic pollutants with similar structures and properties in the environment. This article proposed an electrochemical sensing system that combined a molecularly imprinted sensing interface and ratiometric indicator displacement assay (IDA) for sensitive and selective detection of CC. A unique carbon nanotubes (CNTs) interpenetrating ZIF-8 material (CNT@ZIF-8) was successfully prepared and utilized as a support for surface molecular imprinting of CC. As a substrate material, CNT@ZIF-8 increased the electroactive surface area of the electrode, improved electronic conductivity, and promoted the bonding stability of molecularly imprinted polymer (MIP) film on the electrode. The developed sensing interface exhibited excellent adsorption affinity, enrichment ability, and signal transduction ability towards CC. On this basis, a novel IDA method based on ratiometric electrochemical signals was developed using epinephrine (EP) as a competitive indicator. The proposed electrochemical sensing platform had a wide linear range of 1–1000 μM with a detection limit of 0.23 μM and exhibited high anti-interference ability, good repeatability, superior regenerability, and long-term stability. The sensing system was applied to the analysis of CC in tap water and green tea samples, with recoveries of 94.4 %–104 % and 95.7 %–106.7 %, respectively, demonstrating broad practical application prospects. This study not only provides a promising conductive material for surface molecular imprinting and electrochemical sensing but also offers a reliable strategy for the electrochemical detection of CC.