An electrochemical sensor based on ZIF-67/Ag nanoparticles (NPs)/polydopamine (PDA) nanocomposites for detecting chloride ion with good reproducibility

In this study, a novel electrochemical sensor based on ZIF-67/Ag NPs/PDA nanocomposites for sensing of chloride ion with good reproducibility is reported. The ZIF-67/Ag NPs/PDA nanomaterials were prepared through reducing a pre-prepared precursor ZIF-67/Ag+ with dopamine (DA), accompanied by oxidation-of-DA-induced etching of ZIF-67. The resultant ZIF-67/Ag NPs/PDA nanocomposites had a yolk-shell structure and a characteristic porous surface with a diameter ranging from 400 nm to 600 nm. The oxidation of DA was found to play a crucial role for the formation of the core-shell-structured ZIF-67/Ag NPs/PDA nanocomposites. Furthermore, comparative experiments showed the critical role of the presence of a PDA coating in enhancing the stability of Ag NPs sandwiched between the PDA coating and the underlying ZIF-67 substrate. The as-prepared electrochemical sensor exhibited a near Nernst-equation relationship versus Cl-ion concentration ranging from 2 mM to 400 mM with a limit of detection (LOD) of 1 mM. Meanwhile, the as-prepared electrochemical sensor showed good response reproducibility for Cl- determination, indicating a promising potential for chloride determination for cystic fibrosis diagnosis.