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

Abstract

• The self-polymerization of dopamine chemically etched the ZIF-67, leading to the formation of a yolk-shell structure. • Ag NPs were confined between ZIF-67 and PDA coatings for better stability. • The ZIF-67/Ag NPs/PDA nanocomposites could detect chloride ion with good reproducibility, providing a promising potential for sensing of chloride ion for cystic fibrosis diagnosis. 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.