Advancing Targeted Functionalization of Metal-Organic Frameworks for the Design of Electrochemical Sensors

The present work explores the use of proton-conducting metal-organic frameworks (MOFs), functionalized with selected chemical groups (fMOFs), for the development of electrochemical sensors. The introduced functionalization aimed to improve the homogeneity of sensor composites containing electron-conducting components-multiwalled carbon nanotubes and/or gold nanoparticles (AuNPs)-thereby ensuring uniform proton-electron transport and enhancing the material's affinity toward analyte molecules. Owing to the strong interaction between AuNPs and sulfur-based functionalities, the magnesium-based CPO-27 (MOF-74) framework was modified with thiocyanate (NCS^-) groups. To assess the effect of analyte-tailored functionalization aimed at the biogenic amine tyramine, the sulfonated framework JUK-14 was used, as -SO₃ ^- groups exhibit strong affinity toward amino functionalities, and compared with its nonsulfonated counterpart, UCY-14. Overall, this study demonstrates the strong potential of functionalized metal-organic frameworks to enhance the analytical performance of electrochemical sensors.