A signal “off–on” voltammetric aptasensor of interleukin-18 based on bimetallic iron and nickel organic framework nanozyme

By synthesizing a bimetallic iron and nickel organic framework (FeNi-MOF) hybrid as the nanozyme, herein we developed an innovative voltammetric ‘off–on’ aptasensor platform of interleukin-18 (IL-18) for the first-time. This nanozyme catalyzes the conversion of 1,2-diaminobenzene to diaminophenazinc (DAP), an electroactive substance. However, upon binding to the aptamer (Apt) sensing of IL-18, its enzyme-like activity is inhibited as the active sites are obscured by the Apt, leading to the disappearance of DAP current (signal ‘off’). Interestingly, in the presence of IL-18, the activity is restored because specific binding between the Apt and IL-18 displaces the Apt from the FeNi-MOF surface, resulting in an increase in DAP current (signal ‘on’). After optimizing key conditions, this ‘off-on’ nanozyme-based electrochemical aptasensor demonstrates excellent detection performance for IL-18 and provides a novel, simple, and reliable strategy for detecting various biomarkers by simply altering the relative Apt.