Enhancing electrochemical properties of two-dimensional zeolitic imidazole framework by incorporating conductive polymer for dopamine detection

The zeolitic imidazole framework with leaf-shaped morphology (ZIF-L) has a wide range of promising applications in gas storage, battery materials, catalytic reactions, and optoelectronic devices due to its planar leaf-like structure and large surface area. However, the low conductivity, weak catalytic activity, and poor stability in the water dielectric of ZIF-L limited its further practical application. To solve the problems, we added the conductive polymer heterocyclic poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS) in ZIF-L for the sensitive detection of dopamine (DA). The synthesized composite ZIF-L/PEDOT: PSS (ZIF-L/PEDOT) not only retained the surface morphology of ZIF-L but also exhibited excellent electrochemical properties. The higher electrical conductivity of ZIF-L/PEDOT compared to ZIF-L was due to the enhanced electron transfer at the interface between ZIF-L and PEDOT: PSS. As a result, we developed an electrochemical biosensor based on the ZIF-L/PEDOT composite, which had a limit of detection of 7 nM for DA and a wide linear range from 25 nM to 500 μM. Furthermore, the current dropped was negligible after 28 days, proving the biosensor had excellent stability. Based on the above outstanding performance, the ZIF-L/PEDOT-based biosensor was successfully used to detect DA in human serum samples. These results demonstrated that ZIF-L/PEDOT was expected to play an essential role in disease detection.